EPA 550/9-77-201
PROTECTION
AGENCY
OALIAS, TEXA5
NOISE EMISSION STANDARDS
FOR TRANSPORTATION EQUIPMENT
PROPOSED
BUS NOISE
EMISSION REGULATION
PART 1.
DRAFT ENVIRONMENTAL IMPACT STATEMENT
PART 2.
BACKGROUND DOCUMENT
AUGUST 1977
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF NOISE ABATEMENT AND CONTROL
WASHINGTON, D.C. 20460
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EPA 550/9-77^201
NOISE EMISSION STANDARDS FOR
TRANSPORTATION EQUIPMENT
PROPOSED
BUS NOISE
EMISSION REGULATION
PART 1
DRAFT ENVIRONMENTAL IMPACT STATEMENT
PART 2
BACKGROUND DOCUMENT
AUGUST 1977
U, U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF NOISE ABATEMENT AND CONTROL
WASHINGTON, D.C, 20U60
This document has been approved for general availability.
It does not constitute a standard, specification or
regulation,
-------
EPA 550/9-77-201
NOISE EMISSION STANDARDS FOR
TRANSPORTATION EQUIPMENT
PROPOSED
BUS NOISE
EMISSION REGULATION
PART 1
DRAFT ENVIRONMENTAL IMPACT STATEMENT
AUGUST 1977
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF NOISE ABATEMENT AND CONTROL
WASHINGTON, D.C. 20U60
This document has been approved for general availability,
It does not constitute a standard, specification or
regulation.
-------
UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF NOISE ABATEMENT AND CONTROL
DRAFT
ENVIRONMENTAL IMPACT STATEMENT
for the
PROPOSED BUS NOISE EMISSION REGULATION
August 1977
This document has been approved for general availability.
It does not constitute a standard, specification or regulation.
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SUMMARY SHEETS
FOR
DRAFT ENVIRONMENTAL IMPACT STATEMENT
Prepared By
OFFICE OF NOISE ABATEMENT AND CONTROL
U.S. ENVIRCNMENTAL PROTECTION AGENCY
1. Title of Action: Regulation of Noise Emissions for intercity,
school and urban transit buses. This is an Administrative Action.
2. Description of Action: The Environmental Protection Agency's
proposed regulation is intended to reduce the level of noise emitted
from intercity, school and urban transit buses. The regulation is also
intended to establish a uniform national standard for such vehicles dis-
tributed in commerce, thereby eliminating inconsistent state and local
noise source emission regulations that may impose an undue burden on
the bus manufacturing industry. The recommended action proposes to
establish noise emission standards for newly manufactured buses and to
establish enforcement procedures to ensure that these vehicles comply
with the standard.
The proposed regulation is based on anticipated health and wel-
fare benefits to the public by reducing noise emission from buses.
In arriving at the proposed regulation, the Environmental Protection
Agency investigated in detail the bus manufacturing industry, noise
'control technology, noise measurement methodologies, and costs of
compliance. Three major issues were identified requiring resolution:
(1) identification of vehicles to be regulated, (2) noise measurement
methodologies to be employed, and (3) noise levels and effective dates.
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All newly manufactured school buses, transit buses and intercity
buses are subject to the proposed regulation. Included are both gasoline
and diesel powered buses.
Incremental reductions in vehicle noise levels were concluded to
be preferable to a one-step requirement that all vehicles meet the most
stringent levels achievable and desirable. To minimize market impacts
from substitution of unregulated vehicles, identical effective dates
were set for all vehicles subject to the,standard.
3. Environmental Impact: Compliance with the proposed exterior noise
standards for buses, should result in a reduction of approximately 48.2
percent in potential speech interference impacts due to buses, a 39.5
percent reduction in potential sleep awakening impacts due to buses and
a 33.4 percent reduction in potential sleep disturbance impacts due to
buses by the year 2000.
Compliance with the proposed standards for interior noise levels
would result in a 42.7 percent decrease in potential passenger speech
interference impacts due to buses, a 92.4 percent decrease in potential
hearing loss risk for passengers exposed to 60 dBA prior to bus transit,
a decrease of 68.8 percent in potential hearing loss risk for passengers
exposed to a 70 dBA prior to bus transit and a reduction of 2.6 percent
in potential hearing loss risk for passengers exposed to an 80 dBA level
prior to bus transit. Similar percentage impact reductions will occur
for bus operators.
List price increases to quiet new buses to the most stringent level
(77 dBA) are estimated to range from 1.8 percent to 8.8 percent, depending
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on the bus type and size. The average list price increase for all buses
considered is estimated to be 3.2 percent.
The maximum impact of the proposed regulation on transit and inter-
city bus fares would occur if the total costs of the regulation were to
be financed entirely by fare increases. This is an extreme case since
transit systems and intercity bus carriers typically try to absorb
costs in order to forestall fare increases. Utilizing such an (worst
case) assumption, the Agency projects a maximum of a 1.0 to 1.7 percent
fare increase as a result of this regulation.
Annualized costs to users of all buses beginning in 1979 through
the year 2000 are expected to increase nearly $69 million as a result
of bus manufacture cost pass throughs plus normal markups as a result
of meeting the interior and exterior noise level limits.
Air quality, water quality, land use, solid waste disposal require-
ments, employment, regional economics, foreign trade, national GNP and
energy consumption are not expected to be significantly impacted by the
noise levels proposed. Fuel (energy) consumption of buses is expected
to increase by no more than an average of 3% with the implementation of
the proposed levels.
Persons wishing to obtain copies of the Draft Environmental Impact
Statement and the Background Document for the Proposed Bus Noise Emission
Regulation or the Proposed Regulation itself may receive them on request
from:
EPA Public Information Center (PM-215)
Room M2194D, Waterside Mall
U.S. Environmental Protection Agency
Washington, D.C. 20460.
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Persons wishing to comment on the Draft Environmental Impact
Statement, the Background Document or on the Proposed Regulation,
should write to:
Director, Standards and Regulations Division
Office of Noise Abatement and Control (AW-471)
Attn: Bus Noise Regulation Docket Number ONAC 77-6
U.S. Environmental Protection Agency
Washington, D.C. 20460.
IV
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TABLE OF CONTENTS
PART I
DRAFT ENVIRONMENTAL IMPACT STATEMENT
Page
Number
ABSTRACT 1
DRAFT ENVIRONMENTAL IMPACT STATEMENT 2
INTRODUCTION 2
PROPOSED NOISE REGULATION 3
Statutory Basis 3
Alternatives Considered 3
Proposed Regulatory Schedules 5
Enforcement 6
Relationship with Other Federal, State,
and Local Government Agencies 6
ENVIRONMENTAL IMPACT 8
Impact on the Population of the U.S. 8
Impact on Other Environmental Considerations 9
Energy Conservation 9
Land Use 9
Water Quality 9
Air Quality 10
Solid Waste Disposal Requirements 10
Wildlife 10
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PROPOSED BUS NOISE EMISSION REGULATION
DRAFT
ENVIRONMENTAL IMPACT STATEMENT
ABSTRACT
This Draft Environmental Impact Statement addresses a proposed noise
emission regulation for buses. In arriving at the proposed regulation,
the Agency carried out detailed investigations of bus design and manu-
facturing and assembly processes, bus noise measurement methodologies,
available bus noise control technology, costs attendant to bus noise
control methods, costs to test vehicles for compliance, costs of record
keeping, possible economic impacts due to increased costs, and the poten-
tial environmental and health and welfare benefits associated with the
application of various noise control measures. Data and information
generated as a result of these investigations are the basis for the
statements made in Part I of this document. Part I has been designed to
present, in the simplest form, all relevant information regarding the
environmental impact expected to result from the proposed action. Where
greater detail is required, the Agency encourages perusal of Part II, the
Background Document.
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INTRODUCTION
Congress passed the Noise Control Act (NCA) of 1972, in part, as
a result of their findings that inadequately controlled noise presents
a growing danger to the health and welfare of the nation's population,
particularly in urban areas. For this and other reasons, the Congress
established a national policy to "promote an environment for all Ameri-
cans free from noise that jeopardizes their health or welfare." To
further this policy, the NCA provides for the establishment of Federal
noise emission standards for products distributed in commerce and speci-
fied four categories of important noise sources for regulation, of which
surface transportation is one.
Approximately 93 million Americans are exposed to levels of urban
traffic noise which may jeopardize their health and welfare. Although
a small component of the urban noise problem, bus noise is perceived by
many as a major concern in comparison with noise from other vehicles.
Inasmuch as bus noise is only a part of urban traffic noise, quieting
buses alone is not sufficient to reduce traffic noise to a level requisite
to protect health and welfare. Accordingly, noise emissions from medium
and heavy duty trucks have already been regulated and noise regulation
levels for motorcycles are currently being developed.
Pursuant to the mandate of the NCA and EPA's approach to the control
6f surface transportation noise, noise emission regulations for medium
and heavy trucks (41 CFR 15538) were promulgated on April 13, 1976.
The Agency determined that regulation of all buses meeting the fol-
lowing definition is requisite to protect the public health and welfare:
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A bus is defined as any motor vehicle with a Gross Vehicle Weight
Rating (GVWR) in excess of 10,000 Ibs, designed for the transportation
of passengers on a street or highway, and includes a partially or fully
enclosed engine compartment, and an enclosed passenger compartment.
Details regarding identification of these vehicles as candidates for
regulation, their design features and functional characteristics are
contained in Sections 1, 2 and 5 of Part II, the Background Document.
PROPOSED NOISE REGULATION
This proposed regulation is intended to reduce the level of noise
emitted from buses. It also establishes a uniform national standard for
these vehicles when they are distributed in commerce, thereby eliminating
differing State and local noise control source emission regulations which
may impose a burden on the bus manufacturing industry.
Statutory Basis The proposed action establishes noise emission stand-
ards for newly manufactured buses and enforcement procedures to ensure that
this equipment complies with the standard. This proposed rulemaking is
issued under the authority of the Noise Control Act of 1972 (Pub. L. 92-574,
86 Stat. 1236).
Alternatives Considered The alternatives to the proposed regulation
available to EPA are the proposing of different regulatory levels and
effective dates, taking no regulatory action at all and labeling. The
latter two actions may be taken only if (a) the product does not contribute
to the detriment of the public health and welfare, or (b) in the Adminis-
trator's judgement, regulation is not feasible.
In Tables 6-1 and 6-2 (Section 6 of Part II the Background Document)
and Tables E-l and E-2 (Appendix E of Part II, the Background Document)
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are presented 15 alternative regulatory actions, for both exterior and
interior bus noise, the Agency considered as possible regulatory levels.
The regulatory alternatives presented for both exterior and interior
bus noise ranged from no action at all (Schedule 1) to a theoretical
maximum action (Schedule 15). In point of fact, the Agency considered
many more possible regulatory alternatives, however, detailed information
regarding health and welfare benefits (Section 6) and economic impact
(Section 7 and Appendix E) are presented only for the 15 exterior and
15 interior regulatory schedules outlined in the above tables.
Pursuant to section 5(b)(l) of the Noise Control Act, buses were
identified as major noise sources in May 1975. Subsequent to this
identification, comprehensive studies were performed to evaluate bus
noise emission levels requisite to protect the public health and wel-
fare, taking into account the magnitude and condition of use of buses,
the degree of bus noise reduction achievable through application of the
best available technology and the cost of compliance.
Representatives of the Agency carried our extensive interviews with
key members of firms in the bus industry to gain firsthand knowledge of
the industry and its products and to obtain and verify technological and
financial information. Similar interviews were conducted with key persons
in intercity bus companies, transit authorities, school districts, and
bus industry trade associations as well as officials of various Federal
agencies including the U.S. Department of Transportation.
The results of the above studies show that the regulation of
bus noise is feasible through available technology taking into account
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the cost of compliance. Accordingly, the Act permits no alternative
action to be taken other than regulation.
It should be noted, however, that if information is received during
the Notice of Proposed Rulemaking (NPRM) public comment period which
indicates either (1) buses should be regulated to different standards
or (2) buses do not constitute a major source of noise, then in the
first case the proposed standards should be revised or in the second
case the standards should not be issued.
Proposed Regulatory Schedules
The proposed noise emission standards and effective dates are shown
in Table 1.
Table .1
Proposed Noise Emission Standards
Average A-Weighted Sound Level (dBA)
1979 1983 1985
Exterior Bus Noise 83 80 77
Interior Bus Noise 86 83 80
Exterior bus noise levels are measured at a distance
of 50 feet. Interior bus noise levels are measured
at the noisiest seat location nearest the main body of
the engine.
The proposed regulatory levels for exterior bus noise are repre-
sented by Option 10 in Tables 6-1 and E-l of Part II, while the proposed
regulatory levels for interior bus noise are represented by Option 11
in Tables 6-2 and E-2 of Part II.
The above standards are required to be met by each product distri-
buted in commerce. To assure 100% compliance with such not-to-exceed
standards EPA predicts that manufacturers will design products some two
to three decibels below the standards.
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To eliminate designs which may fail rapidly when in use, the
proposed regulation also requires an acoustical assurance period, a
period over which manufacturers will be held responsible for designing
and building their products such that the sound control performance
of the manufactured vehicles will not deteriorate above the applicable
standards. For buses, this period is two years or 200,000 miles,
whichever occurs first.
Enforcement The EPA will use the following two methods to deter-
mine whether buses comply with the acceptable noise emission standard:
o Production verification - Prior to distribution into commerce
of any bus, as defined in this regulation, a manufacturer
must submit information to EPA which demonstrates that the
product conforms to the standards.
o Selective enforcement auditing - Pursuant to an administrative
request, a statistical sample of buses may be tested to deter-
mine if the units, as they are produced, meet the standard.
Relationship with Other Federal, State, and Local Government
Agencies The proposed regulation will affect several other government
regulatory efforts. It will also require supplementary actions by State
and local governments.
Federal Government Agencies - The General Services Administration
(GSA) currently has set no regulations on maximum sound emission levels
for bus vehicles. With the promulgation of this proposed regulation,
all bus vehicles procured by the Federal Government after the date of
implementation would have to comply with the standards.
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State and Local Governments - Although the Noise Control Act pro-
hibits any State or political subdivision thereof from adopting or
enforcing any law or regulation which sets a limit on noise emission
from such new products, or components of such new products, not iden-
tical to the standard prescribed by the Federal regulation, primary
responsibility for control of noise still rests with State and local
governments.
Nothing in the Act precludes or denies the right of any State or
political subdivision thereof from establishing and enforcing controls
on environmental noise through the licensing, regulation or restriction
of the use, operation or movement of any product or combination of pro-
ducts.
The noise controls which are reserved to State and local authority
include, but are not limited to, the following:
1. Controls on the manner of operations of products.
2. Controls on the time in which products may be operated.
3. Controls on the places in which products may be operated.
4. Controls on the number of products which may be operated
together.
5. Controls on noise emissions from the property on which
products are used.
6. Controls on the licensing of products.
7. Controls on environmental noise levels.
By use of the noise controls reserved to them, state and local
governments are able to supplement Federal noise emission standards and
to effect near-term relief from traffic noise. The EPA has developed a
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model ordinance to indicate the form and content of an instrument whereby
state and local governments may control transportation equipment noise
in the absence of Federal regulation or in the time frame before Federal
regulations become effective. The model ordinance is contained in Appen-
dix G of Part II, the "Background Document."
ENVIRONMENTAL IMPACT
Impact on the Population of the United States
Assessment of the intrusive nature of bus noise impact led the
Agency to a single event passby noise exposure analysis for assessing
the health and welfare impact of bus noise control for exterior noise
exposure. Measures of the three indicators of intrusiveness (sleep
awakening, sleep disturbance, and speech interference) were used for
the single event analysis. Compliance with the proposed standards for
exterior bus noise would result in a 39.5 percent reduction in potential
sleep awakening impacts due to buses, a 33.4 percent reduction in
potential sleep disturbance impacts due to buses, a 52 percent reduction
in potential speech interference impacts for people indoors due to buses,
a 39.3 percent reduction in potential pedestrian speech interference
impacts due to buses and a 49.8 percent reduction in potential speech
interference impacts for people outdoors due to buses.
The health and welfare effects from the reduction of interior bus
•noise were assessed in terms of potential passenger and operator hearing
loss risk and passenger speech interference. Compliance with the proposed
standards for interior noise levels for buses would result in an average
of a 42.7 percent decrease in potential passenger speech interference
impacts. In terms of the reduction of hearing loss risk due to lower
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interior bus noise levels the reductions will range from a 92.4 percent
decrease in potential hearing loss for passengers exposed to 60 dBA prior
to bus transit to a reduction of 2.6 percent in potential hearing loss
risk for those exposed to an 80 dBA level prior to bus transit. Similar
percentage impact reductions will occur for bus operators. These reduc-
tions are percentages taken from present day impacts to those that will
be realized in the year 2000.
For a detailed discussion of the analysis employed to assess the
health and welfare benefits due to bus noise regulation refer to Section 6
of Part II, the Background Document.
Impact on Other Environmental Considerations
Energy Conservation Additional weight, increased cooling system
capacities and possible greater muffler back pressures are expected to
negatively impact the fuel economy of buses by an overall figure of about
3%. Incorporated into this estimate are the fuel savings expected by the
implementation of viscous fan clutch technology, which will most probably
be used to reduce fan noise on various bus vehicles. The 3% estimate
translates into about a 1800 barrel daily increase in fuel consumption
for all buses as a result of the proposed regulation. This estimate is
based on industry submitted data. The actual impact on bus fuel con-
sumption will be a function of the design changes manufacturers implement
to comply with the standards.
Land Use The proposed regulation will have no adverse impact on
land use.
Water Quality The proposed regulation will have no adverse impact
on water quality or supply.
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Air Quality The proposed regulation will have no adverse impact
on air quality.
Solid Waste Disposal Requirements The proposed regulation will
have no adverse effects on solid waste disposal requirements.
Wildlife Although wildlife may possibly benefit from reduced noise
levels of transportation vehicles, not enough is known to conclude to what
extent any benefit on wildlife may result from the noise reduction achieved
from the proposed regulation.
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EPA 550/9-77-201
NOISE EMISSION STANDARDS FOR
TRANSPORTATION EQUIPMENT '
PROPOSED
BUS NOISE
EMISSION REGULATION
PART 2
BACKGROUND DOCUMENT
AUGUST 1977
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF NOISE ABATEMENT AND CONTROL
WASHINGTON, D.C. 20U60
This document has been approved for general availability.
It does not constitute a standard, specification or
regulation.
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TABLE OF CONTENTS
SUMMARY 1
Section 1 PROLOGUE 1-1
Statutory Basis for Action 1-1
Preemption 1-2
Section 2 IDENTIFICATION OF BUSES AS A MAJOR NOISE
SOURCE 2-1
Section 3 THE BUS INDUSTRY 3-1
General Industry Background 3-1
The Bus Market 3-5
Product Classification and Characteristics 3-9
Size and Growth of the Industry 3-21
Product Life Cycle 3-28
Nature of the Bus Industry 3-30
Bus Manufacturers Profile 3-37
Exports and Imports 3-59
Raw Material-Component-Aftermarket Suppliers 3-62
Baseline Industry Forecast 3-64
Section 4 BUS NOISE DATA BASE 4-1
Gasoline-Powered Conventional School Buses 4-1
Diesel-Powered Conventzoned School Buses 4-11
Forward Engine, Forward Control School Buses 4-13
Parcel Delivery Chassis Buses and Motor
Home Chassis Buses 4-14
Mid-Engine School Buses (Integral) 4-15
Rear Engine School Buses (Integral) 4-17
Rear Engine School Buses (Body on Chassis) 4-18
Urban Transit Buses 4-19
Intercity Buses 4-31
Section 5 NOISE ABATEMENT TECHNOLOGY 5-1
Component Noise Abatement Technologies 5-2
Engine Noise 5-2
Exhaust Noise 5-11
Air Intake Noise 5-20
Overall Noise Abatement 5-25
Conventional Gasoline-Powered School Buses 5-25
Conventional Diesel-Powered School Buses 5-45
Front-Engine Forward Control School Buses,
Parcel Delivery Chassis School Buses
and Motor Home Chassis Buses 5-49
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Mid-Engine School Buses 5-50
Rear Engine School Buses (Integral and
Body-on-Chassis) 5-53
Urban Transit Buses 5-55
Intercity Buses 5-74
Degradation of Noise Control Technology 5-83
Engine Noise Control Degradation 5-83
Exhaust Noise Control Degradation 5-84
Cooling System Noise Degradation 5-85
Section 6 POTENTIAL IMPACT OF PROPOSED BUS NOISE
REGULATION SCHEDULES ON THE ENVIRONMENT 6-1
Introduction 6-1
Health and Welfare Benefits of Bus Noise
Regulation 6-2
Measures of Benefits to Public Health
and Welfare 6-2
Regulatory Schedules 6-3
Outline of the Health and Welfare Analysis 6-6
Reductions in the Impact from Traffic Noise 6-7
Description of Traffic Noise Impact 6-8
Urban Street and Highway Traffic Noise 6-18
Vehicle Noise Levels in Urban Street
and Highway Traffic 6-19
Bus Noise Levels 6-21
Traffic Noise Levels 6-30
Reduction of Traffic Noise Impact 6-40
Reduction of Individual Passby Noise Impact 6-46
Sleep Disturbance 6-48
Speech Interference 6-70
Reduction of Interior Noise Impact 6-87
Hearing Loss Reduction 6-87
Speech Interference Reduction 6-97
Summary 6-110
Section 7 ECONOMIC IMPACT OF BUS NOISE CONTROL 7-1
Overview of Economic Impact Analysis 7-1
Economic Impact of Noise Regulations on
Users and Manufacturers 7-15
Economic impact of Noise Regulations on
Intercity Motor Bus Carriers and 7-15
Manufacturers
Analysis of User Costs 7-16
Costs Estimates From Appendix C 7-18
Estimates of Incremental Capital Costs 7-21
Estimates of Incremental Prime Costs 7-27
Impact on Quantity of Bus Service Demanded 7-30
Impact on Equilibrium Bus Production 7-30
Financial Impacts on Users 7-33
Financial Impacts on Producers, Including
Exporters and Importers 7-34
Annualized Costs for Intercity Bus Noise
Abatement 7-35
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Economic Impact of Noise Regulations on Urban
Transit Motor Bus Carriers and Manufacturers 7-37
Analysis of User Costs 7-37
Cost Estimates from Appendix C 7-40
Estimates of Incremental Capital Costs 7-43
Estimates of Incremental Prime Cost 7-48
Effect of UMTA Subsidies for Equipment
Purchases 7-50
Impact on Quantity of Bus Service Demanded 7-50
Impact on Equilibrium Bus Production 7-56
Financial Impacts on Producers, Including
Exporters and Importers 7-58
Annualized Costs for Urban Transit Bus Noise
Abatement 7-61
Economic Impact of Noise Regulations on School
Bus Carriers and Manufacturers 7-63
Introduction 7-63
Timing of the Regulation 7-64
Costs of Noise Abatement 7-67
Important Industry Considerations 7-68
Analysis of User Costs 7-77
Cost Estimates from Appendix C 7-79
Estimates of Incremental Capital Costs 7-79
Estimates of Incremental Prime Cost 7-85
Impact on Quantity of Bus Service Demanded 7-85
Impact on Quantity of Bus Production' 7-88
Financial Impact on School Bus Users 7-93
Financial Impacts on Producers, Including
Exporters and Importers 7-93
Annualized Costs for School Bus Noise
Abatement 7-97
Section 8 MEASUREMENT METHODOLOGY 8-1
Existing Procedures 8-1
Bus Noise Characteristics 8-6
Work Cycles 8-8
Measurement Distance 8-10
Enforcement Requirements 8-10
Test Measurements 8-11
Summary 8-15
Recommended Test Procedure for Measurement
of Exterior Sound Levels 8-17
Recommended Test Procedure for Measurement
of Interior Sound Levels 8-27
Section 9 ENFORCEMENT 9-1
General 9-1
Production Verification 9-2
Selective Enforcement Auditing (SEA) 9-7
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Administrative Orders 9-11
Compliance Labeling 9-12
Applicability of Previously Promulgated
Regulations 9-12
In-Use Compliance 9-13
Section 10 EXISTING NOISE REGULATIONS APPLICABLE TO
BUSES 10-1
Introduction 10-1
Review of Existing Noise Ordinances 10-1
Analysis of Existing Regulations 10-3
Appendix A FOREIGN TECHNOLOGY BUSES A-l
Appendix B NEW TECHNOLOGY BUSES B-l
Appendix C BUS NOISE ABATEMENT COSTS C-l
Appendix D ESTIMATES OF DEMAND ELASTICITIES FOR URBAN
BUS TRANSIT AND INTERCITY BUS TRANSPORTATION D-l
Appendix E UNIFORM ANNUALIZED COSTS OF BUS NOISE ABATEMENT E-l
Appendix F ADDITIONAL SUPPORTING INFORMATION FOR HEALTH
AND WELFARE ANALYSES (SECTION 6) F-l
Appendix G MODEL NOISE ORDINANCE
G-l
IV
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Summary
The subjects addressed in this document are intended to provide
background information on various aspects associated with the develop-
ment of regulations relative to the noise emissions from newly manufac-
tured buses.
Section 1 - "Prologue." sets forth the legal basis for the regu-
lations which may be promulgated under the Noise Control Act of 1972,
the procedure followed in the promulgation of such regulations, and a
brief statement relative to preemption of state and local regulations
by Federal regulations.
Section 2 - "Identification of Buses as a Major Source of Noise."
This section addresses the reasons for the classification of buses as a
major source of noise.
Section 3 - "The Bus Industry." This section presents general
information about the U.S. Bus Industry. It covers industry growth
statistics, descriptions of intercity, transit and school bus systems,
bus classifications, product life cycle estimates and other useful
descriptive material.
Section 4 - "Bus Noise Data Base." This section details the
results of exterior and interior bus noise level measurements conducted
by EPA on school, transit, and intercity buses. Bus noise data from
existing studies and from industry submissions are also presented.
Section 5 - "Noise Abatement Technology." In order to establish
regulations restricting bus noise emissions, it was necessary to deter-
mine what constitutes the "best available technology" for bus noise
reduction. Section 5 reviews the various components of exterior bus
noise: noise radiated from the engine surface, fan, intake, exhaust
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system and chassis. In addition to the exterior noise generating
components, the interior noise of buses is also discussed along
with the associated technology needed to reduce bus interior noise
levels.
Consideration is given to the total bus noise problem. The tech-
nology is examined to determine what modifications or redesign work
might be performed on buses in order to quiet them to levels below
those which presently exist.
Section 6 - "Potential Impact of Proposed Bus Noise Regulation
Schedules on the Environment." This section describes what health and
welfare benefits would accrue from the institution of various regulatory
standards for exterior and interior bus noise. The percentage of the
population affected by noise and the extent of the effect is measured
by the Equivalent Noise Impact (ENI) method. The reduction of potential
equivalent impacts of sleep disturbances, sleep awakenings, and speech
interferences from the lowering of exterior bus noise are detailed. In
addition, the reduction of potential equivalent impacts of hearing loss
risk and speech interference effects from a lowering of interior bus
noise are presented.
Section 7 - "Economic Impact of Bus Noise Control." In this section,
the economic impact of increased bus costs due to the basic engineering
changes (outlined in Section 5) that are believed to be required to achieve
various levels of interior and exterior bus noise is presented. The econ-
omic impacts on the three main types (intercity, transit, and school) of
bus manufacturers and bus operators are evaluated.
Section 8 - "Measurement Methodology" This section reviews and
examines the various test procedures that have been used to determine
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noise levels for buses. The EPA recommended procedures for the measure-
ment of exterior and interior bus noise emissions are presented.
Section 9 - "Enforcement." Enforcement of new product noise emission
standards applicable to buses is discussed in terms of production verifi-
cation testing of vehicle configurations, assembly line testing using sel-
ective enforcement auditing procedures or continuous testing of production
vehicles, and in-use compliance provisions.
Section 10 - "Existing Noise Regulations Applicable to Buses." This
section presents existing bus noise regulations, both foreign and domestic,
and the history of such regulations.
Appendix A - "Foreign Technology Buses." This appendix presents a
description of urban transit buses produced by European bus manufacturers
which are claimed to be considerably quieter than any similar transit bus
produced in the United States.
Appendix B - "New Technology Buses." This appendix looks at new
technological designs of quiet buses.
Appendix C - "Bus Noise Abatement Costs." Presented in this appendix
are the estimated cost increases and decreases required to manufacture
quieter buses, as compared to currently produced buses, for the various
technology levels discussed in Section 5. In addition, the lead time
estimates believed necessary for the industry to comply with the various
technology levels are presented.
Appendix D - "Estimates of Demand Elasticities for Urban Bus Transit
and Intercity Bus Transportation." This appendix reviews some of the
pertinent economic literature and reports estimates made of the fare
elasticity of demand for both transit (intracity) and intercity bus riders.
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Appendix E - "Uniform Annualized Cost of Bus Noise Abatement."
This appendix presents the annualized costs of various bus noise abate-
ment regulatory schedules. The costs are presented in terms of capital
costs and operating and maintenance costs due to the application of
additional noise abatement equipment to buses.
Appendix F - "Additional Supporting Information for Health and
Welfare Analysis (Section 6)." This appendix provides various tables
and figures in support of the health and welfare analysis presented in
Section 6.
Appendix G - "Model Noise Ordinance." This appendix provides infor-
mation for State and local governments to aid them in preparing local
noise ordinances for bus noise abatement.
-4-
-------
SECTION 1
PROLOGUE
Statutory Basis for Action
Through the Noise Control Act of 1972 (86 Stat. 1234), Congress
established a national policy "to promote an environment for all
Americans free from noise that jeopardizes their health and welfare."
In pursuit of that policy, Congress stated, in section 2 of the Act,
"that, while primary responsibility for control of noise rests with
State and local governments, Federal action is essential to deal with
major noise sources in commerce, control of which requires national
uniformity of treatment." As part of that essential Federal action,
subsection 5(b)(1) requires the Administrator, after consultation with
appropriate Federal agencies, to publish a report or series of reports
"identifying products (or classes of products) which in his judgement
are major sources of noise." Further, section 6 of the Act requires
the Administrator to publish proposed regulations for each product,
which is identified or which is part of a product class identified as
a major source of noise, where in his judgement noise standards are
feasible and when such products fall into various categories of which
transportation equipment (including recreational vehicles and related
equipment) is one.
On May 28, 1975, pursuant to subsection 5(b)(1), the Administrator
published a report which identified, among other new products, new buses
1-1
-------
as a major source of noise. As required by section 6, the Administrator
has proposed regulations for buses, which are "requisite to protect
the public health and welfare, taking into account the magnitude and
conditions of use of such product (alone or in combination with other
noise sources), the degree of noise reduction achievable through the
application of the best available technology and the cost of compliance."
Preemption
Under subsection 6(e)(1) of the Noise Control Act, after the
effective date of a regulation under section 6 of noise emissions from
a new product, no State or political subdivision thereof may adopt or
enforce any law or regulation which sets a limit of noise emissions
from such new product, or components of such new product, which is not
identical to the standard prescribed by the Federal regulation. Sub-
section 6(e) (2), however, provides that nothing in Section 6 precludes
or denies the right of any State or any political subdivision thereof
to establish and enforce controls on environmental noise (or one or
more sources thereof) through the licensing, regulation or restriction
of the use, operation or movement of any product or combination of
products.
The noise controls which are reserved to State and local authority
by.subsection 6(e)(2) include, but are not limited to, the following:
(1) Controls on the manner of operation of products.
(2) Controls on the time during which products may be operated.
(3) Controls on the places at which products may be operated
1-2
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(4) Controls on the number of products which may be operated
together.
(5) Controls on noise emissions from the property on which pro-
ducts are used.
(6) Controls on the licensing of products.
(7) Controls on environmental noise levels.
Federal regulations promulgated under section 6 preempt State or local
regulations which set limits on permissible noise emissions from the
new products covered by the Federal regulations at the time of sale of
such products, if they differ from Federal regulations.
Conversely, State and Local authorities are free to enact regul-
ations on new products offered for sale which are identical to Federal
regulations.
1-3
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SECTION 2
IDENTIFICATION OF BUSES AS A MAJOR SOURCE OF NOISE
In pursuit of subsection 5(b) of the Noise Control Act of 1972, the
Administrator has published a report (Federal Register, Vol. 40, No. 103,
pp. 23105-7) which identified buses as a major source of noise.
The following paragraphs will briefly describe the basis on which
buses were identified as such a noise source.
LEGISLATIVE BASIS
Subsection 6(a) of the Noise Control Act set forth four categories
of products for which a noise emission standard can be proposed for each
product identified as a major source of noise. The categories are:
1. Construction equipment
2. Transportation equipment (including recreational vehicles
and related equipment)
3. Any motor or engine (including any equipment of which
an engine or motor is an integral part)
4. Electrical or electronic equipment
PRIORITY BASIS
The criteria developed by EPA to identify products which are
major sources of noise and for which noise emission standards are requi-
site to protect the public health and welfare stipulate that at this time
first priority be given to products that contribute to community noise
exposure. (Medium and heavy duty trucks have been classified in this
category and have already been regulated.) Community noise exposure is
2-1
-------
that exposure experienced by the community as a whole as a result of the
operation of a product as opposed to that exposure experienced solely by
the users of the product. To determine which sources ought to be identi-
fied for regulation, EPA consideres their functionally weighted noise
impact. This measure includes both the intensity (loudness) and extensity
(population affected) of noise source impact.
DAY-NI'SHT AVERAGE SOUND LEVEL BASIS
The day-night average sound level, L , has been specifically
dn
developed as a measure of community noise. Since it is a cumulative
energy measure, it can be used to identify areas where noise sources
operate continuously or where sources operate intermittently but are pre-
sent enough of the time to emit a substantial amount of sound energy in
a 24 hour period.
EPA has identified an outdoor L of 55 dB as the day-night average
dn
sound level requisite to protect the public from all long-term adverse
health and welfare effects in residential areas, and an L (24) of 70 dB
eq
as the threshold of hearing impairment.
An abbreviated summary of the identified levels is given in Table 1.
TABLE 1
NOISE LEVELS PROTECTIVE OF HEALTH AND WELFARE
Human Response Leg Ldn
Hearing Loss (8 hours) 75
Hearing Loss (24 hours) 70
Outdoor Interference and Annoyance — 55
Indoor Interference and Annoyance — 45
The fractional impact of a noise environment on an individual as
used by EPA is proportional to the amount (in decibels) that the noise
2-2
-------
level exceeds the appropriate level identified in the "Levels Document"
as shown in Table 1. The fractional impact is zero when the noise
level is at or below the identified level. The fractional impact rises
to 1.0 at 20 decibels above the identified level and can exceed unity
in situations in which the noise level exceeds 20 decibels above the
identified level. The range from zero to 20 decibels above the
criterion level represents the range between those noise levels that
are totally acceptable and those noise levels that are totally
unacceptable to the individual in terms of annoyance responses. The
total Equivalent Noise Impact (ENI) is then determined by summing the
individual fractional impacts for all people affected by the environment.
Thus, two people exposed to 10 decibels above the identified
level (fractional impact = 0.5) would be equivalent to one person
exposed to 20 decibels above the identified level (fractional impact
=1.0).
OTHER PRE-REGULATION CONSIDERATIONS
The drawing-up of regulations necessitates other considerations.
Included among these other factors are available noise reduction techno-
logy, voluntary industry noise standards, the interrelationship of
regulations, lead time necessary for the development of a regulation,
economic impact, and the relative availability of data. All these factors
have been considered in the development of the proposed regulatory noise
levels for buses.
2-3
-------
SECTION 3
THE BUS INDUSTRY
GENERAL INDUSTRY BACKGROUND
Early buses, many of which utilized steam power, were designed
and constructed in Europe and America at various times during the 1800's.
Although some of these primitive buses were effective in passenger trans-
portation, none of them were used for more than short periods of time.
Reasons for their lack of success included poor roads, competition from
railroads and stagecoaches, and the unreliable operating characteristics
of the units themselves.
Bus transportation, as it is now perceived, began to take form in
the early 1900's following the development of the internal combustion
engine. Bus service was started in New York City and on the Pacific
Coast in 1905. In many cases the vehicles used were ordinary passenger
touring cars.
Development and improvement of bus design and construction were
begun early and have continued to the present time. Touring car
chassis were elongated to provide somewhat larger passenger carrying
capacity and eventually passenger carrying bodies were mounted on truck
chassis to provide the basis for the modern bus. During the middle
1930's, transit and intercity bus manufacturers began combining the
3-1
-------
chassis and body, utilizing principles of airplane construction. At
the same time, it became common to mount the engine at the rear of the
bus or under the floor instead of the traditional underhood mounting at
the front. These developments resulted in greater strength and longer
wear of buses, as well as greater comfort and safety for passengers,
better driving vision, greater passenger capacity, and improved riding
qualities.
The most significant development in the bus industry in recent years
is the Transbus Program. Performance specifications for a revolutionary
transit coach were established by the U.S. Department of Transportations
(DOT) Urban Mass Transit Administration. Three different prototypes
were built by AM General, CMC Truck & Coach Division, and Rohr Industries0
Flxible Company. The three buses underwent a year-long series of tests
involving engineering, performance, and public acceptance. Upon comple-
tion and evaluation, a "composite" bus incorporating the most significant
features of each of the three prototypes was to have been built for
further testing.
The purpose of the DOT-funded program was to build and evaluate
buses incorporating new design and mechanical features. As a result,
the present three prototypes are experimental and do not represent the
current state-of-the-art. For example, totally new powertrains and
suspensions are used. In an effort to make the buses more attractive
3-2
-------
to senior citizens, low curb height with the ability to "stoop" to
pick up handicapped people and wheelchairs was included in the specifica-
tions. A floor height of less than 20 inches was achieved by using
specially developed low-profile tires, revolutionary suspensions, and
chassis-mounted differentials with swing axles. Other specifications
called for noise and odor levels to be 90% below current levels and
emission levels that meet the 1975 California standards.
Given the above historical perspective, the following facts from
the Motor Vehicle Manufacturers Association exemplify the present size
of the bus industry:
- 1975 bus registrations = 470,000
- 1975 bus sales = 40,530
The general structure of the bus industry is schematically outlined
in Figure 3-1. The figure illustrates:
1. Bus manufacturing operations obtain raw materials and
components used in the manufacturing process from raw materials suppliers
and component manufacturers.
2. Channels of distribution differ from integral (transit and
intercity) buses and school buses. Integral bus manufacturers deal
directly with end-users, while the distribution channel for most school
buses is through body and/or chassis distributors.
3. Finished products are sold to school boards, intercity bus
companies, transit authorities, sightseeing bus companies, or airports for
3-3
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passenger transportation.
It should be stressed that Figure 3-1 is an overview of the struc-
ture of the industry and not all buyer/operators of buses are represented.
Most significant of those excluded are government departments and agencies.
Also, some integrally constructed buses are used as school buses.
THE BUS MARKET
The bus market is comprised of bus users and operators who provide
multiple passenger transporation to the public. The bus market includes
the following:
- Commercial Intercity Class 1, 2 and 3 Carriers
- Local or Regional Transit Systems
- School Boards or Administrations
- Churches, private schools and related organizations
- Federal, State and Local Government Agencies and
Departments
- All Other
o Airports
o Hotels
o Demand Response Agencies or Organizations
o Social Services
A brief overview of the most significant end-users is presented
below. In 1974, the following three market segments, intercity, transit
and school boards, accounted for approximately 75% of the buses in use.
3-5
-------
(a) Commercial Intercity -,
Class 1, 2, 3 Carriers
The intercity bus operation in the United States is performed by
approximately 950 operating companies utilizing some 20,500 motor coaches
(Figure 3-2). They provide regularly scheduled service over 270,000 miles
of highway and employ an estimated 46,600 people. Intercity bus oper-
ations service over 15,000 cities and towns and are the only public
intercity transportation service available to some 14,000 of them. In
1975, an estimated 354 million trips were taken by passengers traveling
a total of 25.6 billion passenger miles.
Operating revenue from intercity bus lines was $1,165.4 million
in 1975, up 29.3% from the 1970 level. During this same period, miles
operated and the number of revenue passengers declined 7.4% and 11.7%
respectively. In 1976, net operating revenues before income taxes
declined 24.3% of the 1970 figure.
(b) Transit Systems
Some 941 transit systems utilized 50,811 buses in 1975. They
transported 4,080.9 million passengers and employed almost 160,000
individuals (See Figure 3-3). Operating revenue attributed to motor
bus operations reached $1,437.7 million in 1975.
Inspection of the total industry figures indicates that in spite
of continued increases in revenue, transit systems have shown operating
losses through the last six years. These revenues have increased 17.3%
while losses are 5.9 times larger than they were in 1970. These losses
were $1,703.5 million in 1975 and $288.2 million in 1970.
1
Class designations are formed using annual revenue dollars.
Class 1 Carriers have revenues of $1,000,000 or more.
Class 2 Carriers have revenues between $300,000 and $1,000,000.
Class 3 Carriers have revenues less than $300,000.
3-6
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(c) School Boards or Administrations
Pupil transporation is provided by public school operations for
both public and private school children. These operations of the
transportation systems are either assumed by local boards or contracted
to independent operators. School bus operations are primarily funded
with public monies, although certain private schools receive no funding.
Depending on the local tax base and the area covered by the school
districts, these funds are allocated on a per capita pupil basis or
miles driven by the school bus fleet.
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children were transported by 267,704 buses at an operating cost of
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at public expense during the 1973/74 school year to be $87.04. This average
figure reflects a significant upward trend in the cost of pupil transportation
since the 1959/60 school year when the average cost per pupil was $39.78.
PRODUCT CLASSIFICATION AND CHARACTERISTICS
The most common bus classification is by end use which generally
determines the manufacturing process and the finished product. Four
general classifications exist:
Intercity
Intracity or Transit
School
Special Purpose
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(a) Intercity Buses
Intercity buses are integrally constructed vehicles combining body
and chassis into a single unit. Size of these vehicles are determined by
practical limitations and state restrictions (Figure 3-5).
As shown in Figure 3-6 there are five principal producers of inter-
city buses who, combined, offer some fifteen models. The most popular
of these nave passenger capacities of 41 or 49 passengers with a complete
vehicle weight of between 20,000 Ibs. and 29,000 Ibs. However, large
intercity carriers will generally order buses with restroom facilities
which reduces passenger capacity by six seats. Depending on the size
of the vehicle, two or three axles are utilized. Intercity buses usually
have one door for passenger boarding and exit. Product features generally
include reclining seats, individual reading lamps, air conditioning, and
adequate storage space under the floor of the passenger compartment.
Ihe typical intercity bus is utilized by a company engaged primarily
in providing passenger transportation over regular intercity routes with
regular time schedules. Approximately 90 percent of the total bus miles in
the country are generated in regular route service. Charter and special
service travel also play an important part in the industry's operation.
In addition, sightseeing bus operations and airports utilize a significant
number of intercity buses.
3-11
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(b) Intracity or Transit Buses
Intracity or transit buses are similar to intercity buses in that
both are integrally constructed vehicles. Intracity bus vehicle size
and weight are determined by practical limitation and state restrictions.
In 1975, as shown in Figure 3-7, four domestic manufacturers produced
some twenty-six models of transit buses. However, Highway Products has
ceased manufacturing operations for its Twin Coach line of transit
and suburban buses. The most popular transit buses seat between 44 and
53 passengers with a complete vehicle weight of between 17,500 Ibs. and
23,800 Ibs. Transit buses generally have two axles and utilize two doors
for passenger boarding and exit. Product features include seats designed
for both durability and comfort, and capacity for standing passengers
about equal to seating capacity.
The typical intracity bus is utilized by a transit company engaged
primarily in providing passenger transportation over regular local routes
with regular time schedules. Charter and special service travel play
a relatively minor role in the total intracity operation.
Suburban buses are very similar to intracity or transit buses in
construction and design. For this reason suburbans are generally not
considered as a separate bus classification. General Motors offers
two models of its suburban bus to the industry (Figure 3-8). As noted
above, Twin Coach suburban buses are no longer manufactured. Suburban
3-14
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buses generally have one door for passenger boarding and exit and
utilize many features of any intercity bus, such as reclining seats
and underfloor baggage compartments. The CMC suburban buses currently
being put into service, seat 53 passengers with a complete vehicle
weight of around 22,800 Ibs.
(c) School Buses
The vast majority of school buses, over 98% in 1974, are manu-
factured in a two stage process. The chassis, which is primarily the
same as a medium-duty truck chassis, is produced by a manufacturer and
then shipped as an incomplete vehicle to another manufacturer who
assembles the body on it. The chassis manufacturing process utilizes
the assembly line concept, while the body manufacturing and assembly
process utilizes the station or bay system concept.
Various configurations of two-stage school buses are available.
The most popular type, approximately 90% of school bus production in
1974, is the conventional school bus, which has the engine located for-
ward of the driver and passengers. The other two types of two-stage
school buses are the forward control type which resembles a transit
coach in appearance and the parcel delivery type which utilizes a
smaller chassis than does the conventional. Gas or diesel engines are
available for the above types of school bus with the exception of the
parcel delivery type school buses which are powered by gasoline engines.
3-17
-------
The remaining small number of school buses are integrally constructed
vehicles. The floor, sides, ends and roof are joined into a one-piece
construction to form the bus shell. These units are powered by diesel
engines located either at the rear or the mid-point of the bus. Only
two firms, Crown Coach and Gillig Brothers presently offer integrally
constructed school buses.
The size and weight of all school buses are limited by state and
local restrictions. In the case of the two-stage vehicles, the chassis
GVWR (Gross Vehicle Weight Fating) is also a determining factor. Figure
3-9 shows representative chassis specifications by manufacturer for the
conventional school bus. The most popular school bus models currently
being produced utilize chassis with seating capacities of between 30 and
72 passengers and a GVWR of between 16,000 Ibs. and 30,200 Ibs.
Six firms build school bus bodies which are assembled on the chassis.
Bodies are built according to customer specifications, consequently manu-
facturing flexibility is essential. Figure 3-10 presents the various types
of bodies manufactured by the six companies. Only Carpenter and Superior
have product offerings in all three types of two-stage school buses.
School bus bodies are designed for occupant safety and for durability.
Typically, there is one door for passenger boarding and exit, with an
emergency door at the rear.
3-18
-------
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3-19
-------
Figure 3-10
SCHOOL BUS BODIES BY MANUFACTURER AND TYPE
Manufacturer
Blue Bird
Carpenter Body
Superior Coach
Thomas
Ward
Wayne
Conventional
X
X
X
X
X
X
Forward
Control
X
X
X
X
Parcel
Delivery
X
X
X
Source: EPA interviews with above manufacturers;
Manufacturer's Product Catalogues.
3-20
-------
(d) Special Purpose Buses
Manufacturers will often custom build a vehicle for an end-user's
specific needs, such as airports, hotels, demand response agencies,
amusement parks, or prisons. These buses can be either two-stage or
integrally constructed. From the manufacturer's perspective, such
vehicles are generally treated in the same manner as their standard
units in terms of production and sale statistics. In addition, firms
not in the bus industry such as recreational vehicle manufacturers
may occasionally convert one of their products to fulfill an end-user's
specific needs. Consequently, for the remainder of this overview of the
industry, with the exception of the section devoted to end use, these
special purpose vehicles will not be treated in a separate and distinct
fashion.
SIZE AND GROWTH OF THE INDUSTRY
The demand for bus units is a derived demand based upon user/
operator requirements. This section will develop the current size
of the market for buses and identify the growth trends within each
principal segment.
(a) Geographic Concentration
In 1974 there were 446,558 buses registered in the United States
(Figure 3-11). Over fifty percent of these registrations were concen-
trated in eleven states.
3-21
-------
Figure 3-11
U.S. MOTOR BUS REGISTRATIONS BY STATES-1974
Private and
Commercial
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Dist. of Columbia
Total
(1) Includes municipal
(2) In some instances
Buses (1)
1,102
424
568
393
9,586
448
1,784
295
2,301
1,203
1,444
328
6,569
3,204
895
299
682
1,004
200
2,126
3,333
2,321
1,615
983
750
323
410
159
253
3,142
539
12,077
1,972
63
4,807
355
820
7,632
266
817
253
1,420
2,799
321
99
2,101
385
744
1,491
940
2,027
90,072
Commercial
School and
Other (2)
746
378
106
1,485
2,859
818
5,350
942
1,010
2,365
326
391
8,747
4,213
732
1,005
772
10,177
578
5,576
4,681
3,363
3,866
1,829
3,155
725
479
93
760
4,277
2,392
5,800
6,576
541
3,465
1,540
1,498
10,729
542
1,421
401
1,163
11,743
79
391
30
3,429
-
4,814
226
33
128,617
Publicly
Federal
15
21
233
7
89
26
4
-
53
37
8
141
33
24
8
5
45
11
6
55
4
12
10
44
38
41
5
44
3
14
341
39
19
40
29
62
30
44
2
9
39
34
119
40
-
61
106
6
10
2
132
2,200
Owned
School (3)
6,349
18
1,882
5,460
10,935
3,568
551
88
11,369
8,796
81
1,788
5,723
5,873
7,596
3,650
4,980
3,445
1,180
2,950
450
8,437
8,718
5,018
5,449
643
1,915
652
203
3,497
284
12,606
15,238
1,167
12,951
6,145
3,998
4,240
118
6,859
1,320
5,289
11,784
623
555
8,724
6,865
1,529
3,053
853
193
225,658
Total
School
Buses
7,095
396
1,988
6,945
13,794
4,386
5,901
1,030
12,379
11,161
407
2,179
14,470
10,086
8,328
4,655
5,752
13,622
1,758
8,526
5,131
11,800
12,584
6,847
8,604
1,368
2,394
745
963
7,774
2,676
18,406
21,814
1,708
16,416
7,685
5,496
14,969
660
8,280
1,721
6,452
23,527
702
946
8,754
10,294
1,529
7,867
1,079
226
354,275
Total
Buses
8,212
841
2,789
7,345
23,469
4,860
7,689
1,325
14,733
12,401
1,859
2,648
21,072
13,314
9,231
4,959
6,479
14,637
1,964
10,707
8,468
14,133
14,209
7,874
9,392
1,732
2,809
948
1,219
10,930
3,556
30,522
23,805
1,811
21,252
8,102
6,346
22,645
928
9,106
2,013
7,906
26,445
1,063
1,045
10,916
10,785
2,279
9,363
2,021
2,385
446,547
owned transit buses.
church, industrial and other
private buses are included here;
and in
other instances privately owned school buses could not be segregated from commercial
buses, and are included with the latter.
(3) This column consists primarily of publicly owned school buses but include a few privately
owned school institutional and industrial buses registered free or at a reduced rate.
Source: U.S. Federal Highway Administration.
3-22
-------
(b) Buses in Service by End Use and
Product Classification
End users generally utilize the type of bus that is manufactured
and designed for a specific application. In other words, intercity
carriers utilize intercity buses, transit systems utilize transit buses,
and school districts, private schools and churches utilize school buses.
However, exceptions do exist and an end user may utilize a type of bus
which is not necessarily designed for the specific application. Accord-
ing to manufacturers, trade associations, and end users, such situations
are rare. Thus, for purposes of analysis, Figure 3-12, which is the basis
for the following discussion, treats end use of the three types of bus
according to the traditional applications.
1* Total Buses. Bus registrations have increased 27% during
the period 1968 to 1974. The size of each segment in 1974 was as follows:
Intercity 4.6%
Transit 10.9%
School 79.4%
Federal Government 0.5%
Others 4.6%
2. Intercity Buses. Intercity buses are primarily utilized
•by Intercity Class 1, 2 or 3 Carriers, sightseeing bus companies, and
firms-providing transportation to and from airport locations. The National
Association of Motor Bus Owners estimates that in 1974, 20,600 intercity
buses were operated by intercity carriers. Robert A. Kay, Director of the
3-23
-------
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-------
Bureau of Motor Carrier Safety, Federal Highway Administration, has
estimated that in 1974, approximately 18,000 buses were operated by
sightseeing and airport bus lines.
The number of intercity buses utilized by Class 1, 2, 3 Carriers
has remained rather stable since 1968. However, a downward trend has
developed since 1970 when the population reached 22,000. In 1974, the
population was estimated to be 20,600, while preliminary estimates for
1975 are 20,500. Influencing this downward trend have been a 5% decline
in operating companies, a 7.4% decline in miles operated, and an 11.7%
decline in revenue passengers (refer to Figure 3-2).
3. Transit Buses. Transit buses accounted for 10.9% of the
total bus population in 1974. In the early 1970"s, transit bus popu-
lation demonstrated a downward trend which reached a low point in 1973
of 48,286 buses in use. The following two years have seen the transit
bus population on the rise, 48,700 units in 1974 and 50,811 units in
1975. Influencing this growth situation has been a rise in revenue
passengers, 3,560.8 million in 1972 compared with 4,080.9 million in
1975, a growth of some 14.6%. Related to this growth in revenue pas-
sengers has been a corresponding growth in operating revenues, from
$1,230.1 million in 1972 to $1,437.7 million in 1975, and increase of
16.9%. Despite these growth factors, net operating losses after taxes
have continued to mount, $288.2 million in 1970 compared to 1,703.5
million in 1975, an increase in losses of 591%.
3-25
-------
4. School Buses. School buses accounted for a significant
number, 79.4%, of total buses in 1974. The majority of school buses,
are utilized in transportation of students, the handicapped, etc., at
public expense. The vehicles used in this function are either owned by
a school district (or other public entities) or by a private company
which operates under contractual arrangement with a school district.
The remaining school buses are privately owned and operated in a variety
of situations without public funding. Common examples of users include
churches, private schools, and related groups or organizations.
The number of school buses in use has increased dramatically since
1968 when 262,204 vehicles were registered. In 1974, total registrations
of school buses had reached 354,634, a growth of some 35% since 1968.
Included within the above school bus figures are vehicles with a
GVW of 10,000 Ibs. or less and seating capacity of 16 or less. Such
vehicles are commonly called "Class II" school buses. Generally, Class II
school buses are converted vans or cab cut-a-ways. A converted van is a
type of light duty truck which is modified to meet state and local safety
regulations for pupil transport. Modifications include reinforcing the
floor, raising the ceiling, and adding windows. A cab cut-a-way is also
a light duty truck which comes to the body manufacturer with an enclosed
cab and a chassis upon which a small school bus body is built according
to required safety guidelines.
3-26
-------
Station wagons used as school buses along with the above vehicles
accounted for approximately 31,282 units according to 1973-74 estimates
by the Department of Health, Education, and Welfare's Office of Education.
Such vehicles are not included in the scope of this proposed regulation.
According to several manufacturers, these types of school buses have
enjoyed increasing popularity over the last few years. However, data to
substantiate such opinions cannot be documented from existing published
records.
5. Federal Government. Buses used by civilian branches of
the Federal Government represent only 0.5% of the total bus population.
All three types of bus are utilized by this end use segment. A signifi-
cant growth rate of almost 57%, 1,413 units in 1968 compared with 2,200
units in 1974, has characterized this market segment.
6. Others. As discussed earlier in the intercity bus section,
the majority of vehicles in this end use category are buses used in sight-
seeing and airport applications. Ihe remaining buses in this category
have many and varied applications. For example, amusement parks, hotels,
rental car companies, etc., use buses to provide transportation in con-
junction with some other activity- Ihis general end use category has
grown almost 21% to 20,772 vehicle in 1974 from 17,182 in 1968. From
industry interviews with several manufacturers, it can be assumed that
some part of the total 20,772 buses in this segment are smaller than
3-27
-------
16,000 Ibs. GVWR and seat less than 16 passengers.
(c) New Product Shipments
In 1974 manufacturers of buses shipped 35,729 units. Figure 3-13
presents a history of these shipments.
1. Intercity Buses. In 1974 total shipments of intercity
buses were 1,350 units, 26.9% above shipments of 1970. Intercity bus
shipments show a great deal of variation from year to year.
2. Transit Buses. Transit bus shipments have shown constant
growth through the last five years. 1974 shipments of 4,818 units are
3.3 times greater than shipments in 1970.
3. School Buses. In 1974 school bus shipments were 29,561
units, which is a slight decline from the peak level of 30,635 units
in 1972. Although the trend in school bus shipments has been upward
since 1965, the trend has not been constant with cyclical rises and
declines in annual shipments.
PRODUCT LIFE CYCLE
Beyond the end-use industry conditions outlined above, product life
cycle dictates the replacement activity within bus fleets. It is very
difficult to determine an average product life for the three major types
of bus. Product life is contingent on factors such as maintenance rou-
tines and procedures, geographic location, miles traveled, and the
3-28
-------
Figure 3-13
SHIPMENTS BY YEAR AND BUS CLASSIFICATION BASED ON REGISTRATIONS
Year
1974
1973
1972
1971
1970
1969
1968
1967
1966
1965
Intercity
1,350
1,276
1,353
977
1,064
NA
HA
NA
NA
NA
Transit
4,818
3,200
2,904
2,514
1,442
2,230
2,228
2,500
3,100
3,000
School
29,561
30,039
30,635
28,358
27,468
28,064
29,015
28,214
26,419
24,276
Source: National Association of Motor Bus
Owners; American Public Transit
Association; Interviews with Gen-
eral Motors and International
Harvester.
3-29
-------
economic conditions of the end-users. Given this situation, the follow-
ing are estimated ranges for product life with the original owner:
Intercity - 12 to 15 years
Transit - 10 to 15 years
School - 8 to 12 years
Certain factors can affect these ranges. For example, when a bus
is first put into operation it incurs its heaviest utilization. A
typical intercity bus will travel 250,000 miles during the first two years
of utilization. Transit buses, depending on the geographic location and the
attendant route size, will travel between 30,000 and 60,000 miles per year.
School buses travel an average of 38 miles per day, but individual mileage
totals vary substantially around this mean figure.
NATURE OF THE INDUSTRY
This section will describe the nature of the bus industry in terms of
channels of distribution, sales practices, pricing, and resale. It is
organized according to the three major product segments of Intercity,
Transit, and School Buses.
(a) Intercity Buses
The nature of the intercity bus segment is generally determined by
the following:
1. Channels of Distribution. The flow of new intercity buses
is incorporated in Figure 3-1. Note that the manufacturer deals directly
with the end-user and that a dealer or distribution network does not exist.
3-30
-------
All intercity bus prices are F.O.B. factory, and delivery of the
vehicle is the responsibility of the end-user. Ttoo alternatives are
primarily utilized: end-user personnel are sent to the factory to
drive the units to their destination, or an independent bus delivery
company will drive the completed unit from the factory to an end-user
designated location.
2. Sales Practices. Manufacturers of intercity buses deal
directly with intercity operators. Generally, bus requirements and
specifications are determined by the end-user, with custom units made
in accordance with a variety of special requirements. Each order is
separately priced in competitive bids.
Certain exceptions to the above exist. For example, the Greyhound
Corporation, the largest Class I Intercity Carrier, purchases its
vehicles from a subsidiary, Motor Coach Industries. Continental
Trailways, another large end-user, has maintained a purchase agreement
with Eagle International.
3. Pricing. The variety of end-user bus requirements and
specifications makes the determination of an average price difficult.
However, based on interviews with the National Association of Motor Bus
Owners, General Motors and Crown Coach, current prices would range
between $75,000 and $96,500.
4. Resale/Used Buses. The impact of the resale of used
buses on the nature of the intercity bus market is relatively insigni-
ficant. Original end-users of intercity buses generally utilize the
3-31
-------
vehicle throughout the usable life of the unit. After the useful life
of the vehicle is expended, the original end-user will either sell the unit
for salvage or strip the unit for useful parts and sell the remainder for
salvage or sell the unit to another end-user. Purchasers of used vehicles
generally are smaller intercity carriers and usually do not purchase new
vehicles.
(b) Transit Buses
Ihe nature of the transit bus segment is generally determined by
the following:
1. Channels of Distribution. The flow of new transit buses
into distribution as shown in Figure 3-1 is the same as the flow for new
intercity buses.
2. Sales Practices. The sales practices utilized in the transit
bus market segment are very similar to those practices employed in the
intercity segment. In. summary, manufacturers deal directly with end-users.
Also, transit coaches are custom-made according to customer specifications
and each order is separately priced in competitive bids by industry. The
significant difference lies in the formality of the bid procedure in the
transit market segment. This formal bid procedure is dictated by govern-
mental guidelines which are prerequisite to the awarding of grants and
subsidies.
3. Pricing. The most popular transit buses in use are 35 foot
and 40 foot vehicles which are manufactured according to customer specifi-
cations. Based on interviews with General Motors and several transit
3-32
-------
companies, current price ranges for the most popular models are:
35 foot - $55,000 to $68,000
40 foot - $60,000 to $75,000
4. Resale/Used Buses. Transit buses are generally utilized
by the original owner throughout their useful life. The original end-user
will dispose of a unit by either selling it for salvage or by stripping the
useful parts and selling the remainder for salvage, or by selling it to
another transit authority or end-user.
Transit authorities may occasionally purchase used buses to fill an
unexpected demand, to cover delays in new bus delivery, to obtain parts,
or to avoid costs of new bus purchases.
(c) School Buses
The nature of the school bus segment is generally determined by the
following:
1. Channels of Distribution. As depicted in Figure 3-1, dis-
tribution of conventional school buses differs greatly from that of
intercity and transit buses. School bus distribution is a complex two-step
distribution process. The difference principally is that either a chassis
dealer or a body dealer can sell the complete bus to the end-user. Most
orders will typically be handled by the school bus body manufacturer.
The distribution process begins with a bus body builder's pool
(inventory) of chassis. Given a local body dealer's order, a chassis
3-33
-------
is taken from inventory and a body installed to end-user specifications.
Typically, when a chassis is used the regional chassis manufacturer
representative is notified and credit is given to the local chassis
dealer.
In the case where a chassis dealer takes an order for complete
buses, the process is similar. The principal difference is that the
local body distributer is given commission on the sale of the body.
In both cases warranty service is provided on a local dealer basis
for the part of the product that each represents.
2. Sales Practices. As expected by the type of distribu-
tion, the principal sales of school buses are through dealers. National
selling responsibility for each part of the product is maintained by
body and chassis manufacturers.
There is a principal difference between the selling efforts of
chassis and body manufacturers. Chassis manufacturers view their
customers as body builders and principally concentrate their activites
at that level, although chassis manufacturers will become involved
in large bid situations. Body manufacturers, on the other hand,
promote their companies' products and services directly to the school
administrations.
The majority of school bus sales are made in public bids
to predetermined specifications. As previously noted, these specifi-
cations, beyond meeting minimum safety standards, vary greatly from
locality to locality.
3-34
-------
3. Pricing. Due to the variety of school bus model types,
a single price range would not accurately portray the proper perspec-
tive. Therefore, the following Table 3-1 presents school bus prices
by vehicle type.
4. Resale/Used Buses. School buses find rather a large
resale market: Typically, school authorities will sell used buses
to brokers. These buses in turn will be sold to such groups as
churches, boys' clubs, P.T.A.'s, Y.M.C.A.'s, and a wide variety
of other groups.
3-35
-------
TABLE 3-1
August, 1976 Prices for
Completed School Buses, by Type of Bus
Type of Bus Range of Prices Average Price
Gasoline Powered:
Conventional $11,000-18,000 $14,500
Forward Control $26,000-30,000 $27,000
Parcel Delivery $10,000-11,500 $11,000
Diesel Powered:
Conventional $17,000-25,000 $19,000
Forward Control $28,000-30,000 $30,000
Integral Mid-engine $37,000-90,000 $50,000
Integral Rear-engine $37,000-75,000 $50,000
Note: The average price expressed here is the price given by
respondents as closely approximating the mean price paid
for units of the respective type.
Source: Telephone interviews conducted between EPA consultants
and manufacturers and school bus distributors.
3-36
-------
BUS MANUFACTURERS PROFILE
The remainder of this discussion will profile individual bus manu-
facturers in terms of a general description, financial resources/ employ-
ment, production facilities, and market share. It is organized into four
sections as determined by the basic bus classifications and market segments
as follows:
Intercity Bus Manufacturers
Transit Bus Manufacturers
School Bus Chassis Manufacturers
School Bus Body Manufacturers
The basic information used in this section is developed from composite
tables of manufacturers shown in Figure 3-14 and 3-15. Market share
data are represented in Figure 3-16 through 3-19.
(a) Intercity Bus Manufacturers
The firms, subsidiaries, or divisions shown below account for the
vast majority of intercity bus production:
Crown Coach Corporation
Eagle International, Incorporated
CMC Truck & Coach
Motor Coach Industries, Limited
Prevost Car
1. Crown Coach Corporation. Established in 1904, this family
controlled business has operated on a profitable basis and has increased
3-37
-------
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Figure 3-17
TRANSIT BUS MARKET SHARES
ESTIMATED MARKET SHARES - TRANSIT BUSES
TOTAL TRANSIT BUS FLEET
Manufacturer Market Share
General Motors 75.2%
Flxible 17.8%
AM General 3.4%
Highway Products 1.1%
All Others* 2.5%
Footnote: *Includes imported buses.
Source: EPA estimates based on data from
American Public Transit Association,
Fleet Inventory.
ESTIMATED MARKET SHARES - TRANSIT BUSES
NEW EQUIPMENT DELIVERED. 1970-1975
Manufacturer Market Share
General Motors 65.2%
Flxible 26.9%
AM General 4,2%
Highway Products 1.7%
All Qthers* 2.5%
Footnote: *Includes imported buses.
Source: EPA estimates based on data from
American Public Transit Association,
Fleet Inventory.
ESTIMATED MARKET SHARES - TRANSIT BUSES
NEW EQUIPMENT DELIVERED, 1974-75
Manufacturer Market Share
General Motors 44.6%
AM General 26.3%
Flxible 22.4%
Highway Products 2.7%
All Others* 4.0%
Footnote: *Includes imported buses
Source: EPA estimated based on data from
American Public Transit Association,
Fleet Inventory.
3-44
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Figure 3-19
ESTIMATED FACTORY SHIPMENTS AND MARKET SHARE
SCHOOL BUS BODIES, 1974
Thomas
Ward
Manufacturer
Bird
_er Globe (Superior)
in Head (Wayne)
is
inter
)thers
total
Shipments
6,592
6,592
5,055
4,257
3,784
2,838
443
29,561
Market Share
22.3%
22.3
17.1
14.4
12.8
9.6
1.5
100.0%
Crown Coach and Gillig account for the majority with
integrally constructed buses. Also includes units
manufactured by firms not in the bus industry such as
recreational vehicle manufacturers.
Source: EPA compared estimated market share information
provided by body manufacturers with Dun & Brad-
Street sales estimates.
3-46
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net worth annually through retained earnings. In 1974, Crown had sales
of approximately $14 million, total assets of $18,165,223, and a tangible
net worth of $3,755,232. In addition to intercity buses, the firm also
manufactures integrally constructed school buses and fire trucks. Crown
is also a distributor of coaches and bodies for other manufacturers and
operates a coach maintenance division. Crown will employ between 275
and 450 people, depending on demand and seasonal fluctuations, in one
production facility of 65,000 square feet located in Los Angeles, Califor-
nia. The firm's integrally constructed vehicles compete primarily in
two market segments, intercity and school, and accounted for less than
1% of total sales in each market in 1974.
2. Eagle International, Incorporated. This company, a sub-
sidiary of Overseas Inns, S.A., Luxembourg was founded in 1973 to manu-
facture buses primarily for Continental Trailways, the second largest
U.S. intercity carrier. Prior to 1973, another subsidiary of Overseas
Inns manufactured such buses in Belgium. However, with the devaluation
of the U.S. dollar, the Belgian units could no longer be competitively
priced and Eagle was formed.
As noted above, Eagle was started to manufacture Silver Eagle
intercity buses primarily for Continental Trailways under an annual
contract. In the second half of 1975 this annual contract expired and
had not been renewed as of August 26, 1976. As a result, production
has been cut significantly. The number of employees has been reduced
from 350 to 150. Finally, on August 12, 1976, a meeting was held with
3-47
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many of the firm's creditors in order to work out a plan for repayment
of debts. The firm is maintaining its lease on a 157,000 square foot
plant in Brownsville, Texas. In 1974, Eagle accounted for approximately
17.5% of total intercity bus sales.
3. CMC Truck & Coach. In 1943, General Motors Corporation
acquired the assets of Yellow Truck & Coach Manufacturing Company and
business formerly conducted by that organization is today being carried
*
on by the GMC Truck & Coach Division. In 1974, General Motors had net
sales of $31,549,546,126; net income of $950,069,363; total assets of
$20,468,099,914; and employed approximately 734,000 individuals. Speci-
fic financial information for GMC Truck & Coach Division is not available.
General Motors is primarily an operating corporation, carrying on
activities through operating divisions. The firm also owns stock in
many other companies. Generally, GM is engaged in manufacture, assembly,
and distribution in the United States of various motor driven products
most of which relate to transportation equipment. Subsidiaries and
associated companies conduct similar operations in Canada and other
foreign countries.
Automotive products consist of passenger cars, trucks, buses,
motor homes, and their related components, as well as parts and
accessories. The greatest portion of such components, parts and
accessories is used in the manufacture of GM automotive products.
In addition, substantial amounts of such products are sold to outside
manufacturers, and are also marketed through distributors, dealers,
and jobbers.
3-48
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In the United States there are 29 major operating divisions, while
in Canada, GM manufacturing operations are carried on by a subsidiary.
Products are distributed to other world markets through the Overseas
Operations Division which has assembly and manufacturing operations in
21 countries.
CMC Truck & Coach Division operates two bus manufacturing facilities
in Pontiac, Michigan; one is devoted entirely to the production of inter-
city and transit buses, while the other manufactures school bus chassis
and medium duty trucks. The two plants jointly employ approximately 15,000
people. An existing facility, also in Pontiac, is being refurbished to
accomodate production of CMC's new transit bus, the RTS-2. Future plans
call for another facility for the manufacture of school bus chassis.
In 1974, CMC's respective estimated market shares were as follows:
Intercity 32.1%
Transit 44.6%
School Bus Chassis 18.5%
4. Motor Coach Industries, Limited. This company is a wholly
owned subsidiary of Greyhound Lines of Canada, Ltd. which is both a holding
and an operating company. Overall control rests with the Greyhound Corpora-
tion, a holding company with numerous subsidiaries whose business activities
can be categorized into six general groups: Transportation, Leasing, Consumer
Products and Pharmaceuticals, Food, Services, and Food Services. In 1974,
3-49
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Greyhound Corporation had sales of approximately $3,469,281,000; net
income of approximately $57,955,000; total assets of $1,357,328,236
and employed approximately 55,000.
Motor Coach Industries employs approximately 1,500 employees in
three plants located in Winnipeg and Fort Gary, Manitoba, Canada and
Pembima, North Dakota. Respectively, the two facilities contain 155,000
square feet and 135,000 square feet. In 1974, MCI accounted for 45.9%
of total intercity bus sales. Specific financial information is not
available.
5. Prevost Car. This Canadian-based manufacturer was formed
in 1957. Intercity buses account for approximately 60% of production,
motor homes account for 25% and the remaining 15% of production is
accounted for by specialty vehicles.
1974 sales were estimated to be $4.5 million with total assets of
between $2.5 million and $3.5 million. Two buildings with a total area
of 144,000 square feet are owned by the company and used as a manufac-
turing facility. Employment is estimated at 125-200.
Prevost Car is estimated to have less than a 1% share of the sales
of the total United States intercity bus market.
(b) Transit Bus Manufacturers
The following firms, subsidiaries or divisions account for the
3-50
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vast majority of transit bus production:
AM General Corporation
The Flxible Company
CMC Truck & Coach
Highway Products, Incorporated
1. AM General Corporation. In 1971, American Motors Corpora-
tion formed this wholly-owned subsidiary to assume the assets and govern-
ment contracts of the former general products division. AM General entered
the transit bus business in 1972 and has since recorded substantial gains.
1975 sales totaled $339.3 million which represents a 113% increase over 1974.
During this same period of time, the subsidiary went from a loss of $9.7
million to a profit of $188,000. Since entering the market, AM General has
become a major factor in the transit bus industry. During 1975, AMG was
awarded contracts valued at $83.7 million for 1,361 buses by 19 transit
authorities. 1974-5 sales accounted for 26.3% of the total market for new
transit buses. Bus manufacturing facilities include a 350,000 square foot
plant in Mishawaka, Indiana and another plant in Marshall, Texas.
The parent company, American Motors, is an operating corporation with
several wholly-owned operating subsidiaries. The company is primarily
engaged in the manufacture, assembly, and distribution in the Ifruted States
and foreign countries of various motor driven products, most of which relate
to transportation equipment. Automotive products include passenger cars,
utility and recreational vehicles and transit buses.
3-51
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2. The Flxible Company. This wholly-owned subsidiary of
Rohr Industries, Inc. was acquired by the parent company in 1970.
Flxible manufactures transit buses in a new 338,000 square foot plant
located in Delaware, Ohio. 1974-5 sales accounted for 22.4% of the
total transit bus market. Specific employment and financial informa-
tion is not available.
Rohr is a diversified company organized into two systems groups:
Aerospace and Marine Systems Group, and Rail and Industrial Systems
Group. The company designs and manufactures the following products:
power plant assemblies; thrust reversal systems and other components;
motor sections and nozzles for large solid propellant rocket motors;
spacecraft tracking and communications antennas; steel and aluminum
boats of various kinds; prestressed and precast concrete structural
components; automated materials handling and storage systems; rail
transit systems; personal transit systems; postal mechanization
systems; transit buses, and other aerospace, transportation, and
industrial systems. In the year ended July 31, 1975, Rohr had a net
loss of $7.6 million on sales of $456.3 million and assets of $313.8
million.
3. CMC Truck & Coach. This General Motors operating divi-
sion is the most significant factor in the transit bus market. For
a profile, refer to the Intercity Bus Manufacturers portion
of this section.
3-52
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4. Highway Products Incorporated. This subsidiary of Midwest
Management Corporation ceased operations in 1975. Highway Products had
manufactured and marketed transit buses under the Twin Coach product name.
In 1974, Highway Products had a net loss of $800,000 on sales of $11.7
million with assets of $5.4 million. The manufacturing facility, located
in Kent, Ohio, contains 250,000 square feet. As of July 18, 1975, the
company had employment of 150 at the plant location. 1974-75 transit bus
market share amounted to 2.7%.
The parent corporation is a holding company which maintains at least
six subsidiaries. These companies are involved in manufacturing aluminum
doors and windows, railroad hardware equipment, leasing and land develop-
ment, and travel bureau operations. On December 31, 1973, Midwest
Management Corporation had a tangible net worth of $756,096 with finances
unbalanced. 1973 sales were $28.2 million with a loss of $361,000.
(c) School Bus Chassis Manufacturers
The following firms or divisions account for the vast majority of
school bus chassis production:
Chrysler Corporation
Ford Motor Company
CMC Truck & Coach
International Harvester Company
1. Chrysler Corporation. Chrysler manufactures and markets
its conventional school bus chassis under the Dodge product line. Along
3-53
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with school bus chassis/ the 495,000 square foot plant in Windsor,
Ontario, Canada produces medium duty trucks and motor home chassis.
In 1973, Chrysler accounted for 2.0% of the total school bus chassis
market. Specific employment and financial information is not avail-
able.
The parent company and its subsidiaries are engaged primarily
in the manufacture, assembly and sale of cars and trucks and related
automotive parts and accessories. Other operations include the manu-
facture and sale of tractors, outboard motors, boats, inboard marine
engines, air conditioning, heating and cooling equipment, power metal
products, chemical products and defense-space products, including tracked
and wheeled vehicles and space boosters. In 1974, Chrysler had a net
loss of $52,093,772 on sales of $10,971,415,723 and assets of
$6,732,755,557. Employment numbered 25,929.
2. Ford Motor Company. Ford school bus chassis production
occurs at plants located in Louisville, Kentucky and Windsor, Ontario,
Canada. Ford's 1973 share of the school bus chassis market amounted
to 29.0%. Specific financial, employment, manufacturing and marketing
data for Ford's school bus chassis production operation are not avail-
able.
The corporation is primarily an operating company with several
subsidiaries. The manufacture, assembly and sale of cars, trucks and
related parts and accessories accounted for approximately 91% of sales
in 1974. In the United States, Ford ranks second in the industry in
3-54
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unit factory sales of cars and trucks. Outside the U.S., cars and
trucks are manufactured by several subsidiaries throughout the free
world. The remaining 9% of sales in 1974 was accounted for by opera-
tions dealing with tractors and farm implements, communications and
electronic systems, automotive production component materials, the
dealer organization, land developments, and public transit "people
mover" systems. Total sales for the year amounted to $23.6 billion
which generated net income of $360.9 million. Assets total approxi-
mately $14.2 billion. In 1974, Ford employed 235,256 workers in this
country and 464,731 on a worldwide basis.
3. CMC Truck & Coach. This General Motors operating divi-
sion markets its school bus chassis under the Chevrolet or CMC product
line. For a profile, refer to the Intercity Bus Manufacturers
portion of this section.
4. International Harvester. International Harvester manu-
factures school bus chassis and medium duty trucks in their Springfield,
Ohio plant which employs 4,000. In 1973, the company accounted for 45.9%
of the total school bus chassis market. Additional specific financial
information is not available.
The corporation is primarily an operating company with numerous
wholly-owned subsidiaries. International Harvester's principal products
t
are trucks, agricultural/industrial equipment and construction equipment.
The company is also a major producer of gasoline and diesel engines for
3-55
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use primarily with its products. International Harvester owns 17 manu-
facturing plants in the United States, while its subsidiaries own 18
manufacturing plants throughout the free world. As of October 31, 1974,
the company had approximately 73,870 U.S. employees and 110,990 total
worldwide employees. Sales for the year amounted to $4,965,916,000 with
a net income of $124,053,000. Total assets amounted to $3,362,962,000.
(d) School Bus Body Manufacturers
The following firms, subsidiaries or divisions account for the
vast majority of school bus body production:
Blue Bird Body Company
Carpenter Body Works
Superior
Thomas Built Buses
Ward'School Bus
Wayne Corporation
1. Blue Bird Body Company, Incorporated. A privately owned
company, Blue Bird was originally started in 1927. The company wholly-
owns five subsidiaries, all of which are associated with the school bus
market. Three of the subsidiaries are located in the United States, with
one in Canada and the other in Guatemala. The main plant, which is 500,000
square feet, is located in Fort Valley, Georgia. Some 650 of the company°s
1,000 workers are employed in the main plant.
3-56
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Although Blue Bird is primarily a conventional school bus body
manufacturer, it also produces forward control school bus bodies and
motor homes. In addition, one U.S. subsidiary manufactures school bus
accessories and parts. In 1974, Blue Bird had sales of approximately
$30 million which resulted in an estimated 22.3% share of the school
bus body market. Additional financial information is not available.
2. Carpenter Body Works, Inc. This privately owned company
was founded in 1918. The most significant portion of Carpenter's opera-
tion is the manufacture and assembly of conventional school bus bodies;
however, the company also builds forward control and parcel delivery
school bus bodies mounted on special chassis according to customer
specifications. The company's 375,000 square foot production facility
employs 630 workers and is the largest employer in Mitchell, Indiana.
1974 sales were reported over $20 million which resulted in approxi-
mately a 12.8% share of the total school bus body market.
3. Superior. An operating division of Sheller-Globe Corpora-
tion, Superior was acquired in 1969. In addition to conventional school
bus bodies, Superior manufactures forward control and parcel delivery
school bus bodies, ambulances, funeral hearses and military vans, most
of which are mounted on chassis furnished by automotive manufacturers.
A 698,000 square foot production facility, employing 1,800, is located
in Lima, Ohio. Another plant is located in Rasciusko, Mississippi. The
firm's estimated 1974 share of the school bus body market is 22.3%.
Additional specific divisional financial information is not available.
3-57
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The parent corporation, Sheller-Globe, is a diversified operation
with its products being classified into one of three categories: auto-
motive parts, assemblies, and related products; vehicles and transportation
equipment; and office products. 1974 sales were $286.8 million with a net
income of $7.6 million. Assets totaled $233.7 million.
4. Thomas Built Buses. This operating company has two
subsidiaries, one in Canada and the other in Ecuador. Conventional school
bus bodies represent the most significant portion of the operation. The
firm is also engaged in the manufacture and assembly of forward control
school bus bodies and other specialized vehicles. The firm employs 500
workers in a 42,200 square foot facility located in High Runt, North
Carolina. Thomas also operates a plant in Woodstock, Ontario, Canada. For
the fiscal year ending March 31, 1975, Thomas reported sales of approxi-
mately $30 million and assets of $14.6 million. During the prior fiscal
year, net income was reported as $1.6 million. The firm's 1974 estimated
share of the market is 14.4%.
5. Ward School Bus Manufacturing, Inc. This family owned
business is a subsidiary of Ward Industries, Incorporated which serves
as a holding company for three other subsidiaries. Manufacture and assembly
of school bus bodies is the primary operation of Ward School Bus Manufacturing.
The subsidiary employs between 500 and 600 workers in a 234,000 square foot
plant located in Conway, Arkansas. Ward's estimated share of the 1974 school
bus body market is 9.6%.
3-58
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6. Wayne Corporation. A subsidiary of Indian Head, Inc.,
this corporation manufactures ambulances, hearses, postal delivery
vehicles and other speciality vehicles. However, the most significant
part of the operation is the manufacture and assembly of school bus
bodies. The Wayne Corporation employs 500 to 800 workers at their
main plant in Richmond, Indiana. The 1974 estimated share of the
market is 17V1%. Additional specific information pertaining to this
subsidiary is not available.
The parent corporation, Indian Head, Inc., reported 1974 sales
of $615.4 million and net income of $22.5 million. Assets totaled
$353.5 million. Indian Head is a diversified company engaged in the
manufacture and processing of glass containers, metal and automotive
products, specialty textiles, utilities and communications products,
and micropublishing.
EXPORTS AND IMPORTS
With regard to all types of buses, the U.S. has experienced a
favorable balance of trade situation. In 1975, the U.S. exported a
total of 5,673 new and used buses with a value of almost $112.4 million.
During the same year, the U.S. imported a total of 881 units valued at
$20.1 million.
(a) Expor ts
Figure 3-20 shows U.S. bus exports in terms of units and value for
both, new and used buses. New buses figures are listed according to engine
type. In 1975, the U.S. exported more buses, 5,673 units valued at
$112,360,243,
3-59
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than in any year since 1968 when 4,929 units valued at $27,513,075 were
exported.
According to statistics compiled by the Motor Vehicle Manufacturers
Association, Ford is the leading exporter accounting for 43.6% of all
exports. The following Table 3-2 presents the percentage share of total
exports by manufacturer in 1975. It is significant to note that Chrysler's
entire bus production was exported rather than utilized domestically.
TABI£ 3-2
Percentage Breakdown of Total
(1)
U.S. Bus Exports by Manufacturer
Manufacturer % of Total Exports
Ford 43.6%
Chrysler 29.8
General Motors 19.2
International Harvester 7.3
Other 0.1
Total 100.0%
(1)
Note: In the case of school buses, data refers
only to chassis manufacturers.
Source: Motor Vehicle Manufacturers Association
3-61
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(b) Imports
Figure 3-21 presents U.S. bus imports in terms of units and value by
country of origin. U.S. imports of 881 units in 1975 represent a signifi-
cant decline of approximately 33% from the prior year's total of 1,319
units and an even larger decline of 38.5% from the peak year of 1972 when
the U.S. imported 1,433 units. With the exception of certain Canadian
manufacturers identified in prior sections, such as Motor Coach Industries
and Prevost Car, only two foreign bus manufacturers have been the source
of significant imports to the United States. Mercedes Benz accounts for
virtually all buses imported from West Germany and a subsidiary of Overseas
Inns (parent company of Eagle International) accounts for all buses imported
from Belgium. As discussed in the Bus Manufacturer Profile section, Continental
Trailways, the second largest intercity carrier, had maintained bus purchase
agreements with Overseas Inns which has a subsidiary with a plant in Belgium.
With the devaluation of the U.S. dollar, the manufacture of such units outside
the United States became economically unsound and Eagle International was
formed in 1973. According to industry sources at the National Association
of Motor Bus Owners, production of the Belgian units was gradually phased
out in 1975 with Eagle International assuming production of all Continental
^railways buses in the United States. Subsequently, the purchase contract
with Eagle has not been renewed by Continental.
RAW MATERIAL - COMPONENT - AFTERMARKET SUPPLIERS
As illustrated in Figure 3-1, bus manufacturers obtain raw materials
and components from suppliers and manufacturers. Ihe bus aftermarket is
3-62
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3-63
-------
served by those same firms which are classified as component suppliers.
These suppliers and manufacturers also supply the large auto and truck
manufacturing industries.
An examination of sales figures developed by the Motor Vehicle Manu-
facturers Association presents the relative importance of the bus industry
to suppliers when compared to the much larger auto and truck industries.
In 1975, auto, truck and bus sales are estimated to be 8,985,012 units,
of which buses accounted for an estimated 40,530 units or 0.5% of the total.
Figure 3-22 lists some suppliers which have been identified during inter-
views with bus manufacturers.
BASELINE INDUSTRY FORECAST
In order to measure the economic impact of the proposed bus noise
emission levels selected for study, a baseline forecast of industry
activity was established. Against this forecast, estimated post-
regulation activity will be compared so as to measure the change. This
section presents the baseline forecast and the methodology utilized in
its development. Figures 3-23, 3-24, and 3-25 respectively portray base-
line forecasts for intercity, transit, and school buses.
(a) Baseline Forecasts
The Department of Transportation's National Transportation Report
estimates that intercity passenger travel expenditures for the period
1975 to 1990 will annually increase 0.5%. During this same period of
time, the National Association of Motor Bus Owners estimates that the
3-64
-------
Figure 3-22
SELECTED SUPPLIERS TO THE BUS MANUFACTURING INDUSTRY
Bendix
Borg-W,
Caterp
Cummins
Dana
Donald
Eaton
Garloc
Midlan
Modine
Manufacturer
irner
Lllar
3
son
c (Stemco)
1-Ross
: (A P Parts)
LI International
Electric
;~Murray (Schwitzer)
'house
lanufacturing
1975 Sales
(S Millions)
$2,481
1,768
4,082
833
1,070
120
1,760
151
415
128
384
4,409
236
330
5,799
36
Manufactured
Component
Engine Accessories
Radiator
Engine
Engine
Transmission
Air Cleaner, Muffler
Axle
Muffler
Engine Accessories, Frame
Radiator
Muffler
Axle , Brake
Engine Accessories, Brake
Radiator Fan
Engine Accessories
Radiator
Source: Interviews with bus manufacturers; Dun & Bradstreet.
3-65
-------
Figure 3-23
BASELINE FORECAST
INTERCITY BUSES
Year Shipments
1976 1,256
1977 1,236
1978 1,256
1979 1,256
1980 1,256
1981 1,256
1982 1,256
1983 1,257
1984 1,257
1985 1,257
1986 1,257
1987 1,257
1988 1,257
1989 1,257
1990 1,257
Source: National Association of Motor Bus Owners estimate for
growth rate added to an average annual shipments figure
based on the years 1970-1974.
3^66
-------
Figure 3-24
BASELINE FORECAST
TRANSIT BUSES
Year
1976
1977
1978
1979
1980
1981-85
1986-90
Shipments
7,277
5,880
5,627
4,375
4,209
3,861
4,023
Source: Mid-points calculated from forecast ranges developed
by the American Public Transit Association as described
in the publication United States Transit Industry
Market Forecast.
3-67
-------
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3-68
-------
total bus population will increase at an annual rate of 0.25%. Con-
sequently, as shown in Figure 3-23, the annual shipments of intercity
buses will remain almost constant, either 1,256 or 1,257, during the
period 1976 tp 1990. It is signifcant to note that these annual ship-
ment figures represent approximate mid-points for forecast ranges
provided by General Motors.
Figure 3-24 presents a transit bus baseline forecast. The annual
shipment figures are based on forecasts developed by the American Riblic
Transit Association in 1976. Transit bus shipments are expected to peak
in 1976 at a level of 7,277 units. The period 1977 to 1985 is expected
to show continual declines to an annual figure of 3,861 units during the
period 1981 to 1985. The period 1986 to 1990 is forecast to have slight
annual increases to a level of 4,023 units.
The baseline forecast for school buses is presented in Figure 3-25.
The annual shipment figures have been developed by a regression analysis
based on ten years of historical data. School bus shipments are expected
to show continual annual growth during the period 1976 to 1990.
(b) Methodology
The intercity bus base line forecast was developed by utilizing an
estimated growth rate for the intercity bus population of 0.25%. This
growth rate was estimated by the National Association of Motor Bus Owners.
0.25% was converted to the actual number by which the entire intercity
bus population was expected to increase on an annual basis. The incre-
mental number represented by 0.25% was then added on to an average
3-69
-------
shipments figure of 1,204 units which is based on actual shipments
during the period 1970-1974.
Ihe transit bus baseline forecast was developed by establishing
mid-points for forecast ranges development by the American Public Transit
Association. The APIA forecast, United States Transit Industry Market
Forecast, was published in September, 1976.
Ihe baseline forecast for school buses was based on a regression
analysis on a ten year historical relationship between school bus regis-
trations and the following factors: population in the age group 5-14,
disposable personal income, state and local expenditures on education,
and Gross National Product. The distribution by type of bus is based
on market share estimates for 1975.
3-70
-------
REFERENCES
Section 3
1.) "A Study to Determine the Economic Impact of Noise Emission
Standards in the Bus Manufacturing Industry," Draft Final Report
submitted by A.T. Kearney, Inc., under EPA Contract No. 68-01-3512,
prepared for the Office of Noise Abatement and Control, September,
1976.
3-71
-------
SECTION 4
BUS NOISE EMISSIONS DATA BASE
Noise emissions from school buses, transit buses and inter-city
buses were measured by EPA in a series of tests. The following
discussion, describes the results of those tests. In addition, sound
level data from existing studies and from industry submissions are
presented.
For a discussion of the various testing procedures used for the
exterior and the interior noise measurements described in this section
refer to Section 8 (Measurement Methodologies).
(1) Gasoline-Powered Conventional School Buses
Current Exterior Noise Levels
Measurements taken for EPA of in-service and newly-manufactured
gasoline-powered conventional school buses indicate a range of noise
levels between 74 dBA and 84 dBA under the SAE J366b acceleration pro-
cedure (see Section 8). The data indicate that the noise level depends
on engine size and gross vehicle weight rating (GVWR). Table 4-1
presents a summary of all noise tests conducted on in-service school
22
buses. Measurements of noise emissions from new (1976) gasoline engine
25
school buses are shown in Table 4-2.
4-1
-------
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While there is no clear trend as to which side of the older, conven-
tional buses is noisier, exterior measurements from the new school buses
tested indicate that the streetside of the buses is generally noisier
than the curbside (see Table 4-2). It is believed that the difference
in standard deviations between the streetside and the curbside measure-
ments of the older buses indicates that the variation in noise levels is
probably a function of the test conditions and the age of the bus rather
than bus design itself. These data and past vehicle tests indicate that
production buses, if tested under carefully controlled test conditions,
will all produce noise levels within four to five decibels of each other.
Therefore, an allowance of 2 to 2.5 dB appears appropriate between the
mean design noise level and a regulated "not to exceed" level.
Figure 4-1 shows histograms of measured exterior noise levels on
each side of the gasoline powered in-service school buses along with
interior noise levels at the driver and the maximum levels from all
the buses. Figure 4-2 presents the same data for the new 1976 buses.
Maximum levels are shown separately because not all buses had higher
noise levels on one side.
Octave band spectra for gasoline-powered conventional school bus
noise are shown in Figure 4-3.
None of the conventional school bus body manufacturers that were
contacted was able to provide noise level data on their current produc-
tion buses. Chrysler Corporation did provide some noise data based on
Dodge gasoline truck chassis that have identical components to their con-
ventional school bus chassis. These data are summarized in Table 4-3.
4-4
-------
FIGURE 4-1
Histograms of In-Service Gasoline Engine
Conventional School Bus Noise Levels
(SAE J366b)
DRIVER SIDE
CURBSIDE
MEAN 80.52 dB (A)
STD. DEV. 2.94
MEAN 80.40 dB (A)
STD. DEV. 2.43
dB(A)
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4-6
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FIGURE 4-3
Typical Octave Band Spectrum of
Gasoline Engine Conventional
School Bus Noise
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4-7
-------
Table 4-3
Noise Data Supplied by
Chrysler Corporation
Model
D600
D600 &
D700
D700
Equivalent
Bus
Chassis
S600
S600 &
S700
S700
Engine
Displacement
3
(in )
318
361
413
Equivalent
School Bus
Chassis
S600
S600 &
S700
S700
Exterior Sound Level
(SAE J366b)
dBA
76.8 to 81.6
79.2 to 81.3
79.1 to 82.6
Source: Reference 22
Interior Noise Levels
Tests on both in-service and 1976 conventional school buses indicate
that the noise levels are significantly higher at the front of the bus
as opposed to the rear of the bus. During tests for new buses involving
an idling engine only, interior fan accessories only (heating and cooling
fans), and then an idling engine and interior fan accessories together,
the average noise level difference between the front and rear interior
of the buses tested was about 4 dBA (see Table 4-5).
Tests on new buses with all accessories on under maximum accelera-
tion conditions produced a range of interior noise levels from 85 to
89 dBA for the front interior and 81 to 84 dBA in the rear interior.
Interior noise levels at the driver's seat for the in-use school buses
tested under maximum acceleration conditions with all fan accessories
on ranged from 81 to 86 dBA while levels at the rear interior of the
buses ranged from 78 to 81 dBA. Full results on interior noise levels
are shown in Table 4-1 and 4-2 for both in-use and new conventional
gasoline-powered school buses, respectively.
4-8
-------
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4-9
-------
Current Component Noise Levels
Table 4-4 shows the estimated range of contributed noise levels of
conventional gasoline powered school bus major noise components. These
estimates are based on component noise levels of medium duty trucks using
1,2 3
similar engines and estimates made during a previous study. None of
the school bus body or chassis manufacturers contacted were able to
supply actual measured data for component noise levels of gasoline-engine
school buses or of equivalent trucks.
Table 4-4
Range of Component Noise Levels for Current
Gasoline Powered Conventional School Bus
Contributed Noise Level,
Noise Source dBA at 50 feet
(SAE J366b Procedure)
Engine, including air intake 69 to 73
and transmission
Exhaust 75 to 78
Fan 71 to 82.4
Chassis at 30 mph (including " 65 to 73
accessories)
Total Bus Noise 77 to 84
Source: References 1, 2 and 3
Tire noise is not included in Table 4-4 as a separate noise source
since with the use of maximum acceleration noise testing procedures the
vehicle does not exceed 35 mph; the velocity at which tire noise becomes
a major contributing factor to the overall noise level.
4-10
-------
(2) Diesel-Powered Conventional School Buses
Physical dimensions and weight rating for diesel-powered
conventional school buses are similar to those for gasoline powered
conventional school buses.
A variety of medium duty diesel engines are used in this type of
bus including the CAT 3208, the Ford V636, and the IHC D-150, D-170,
D-190, and the DT-460.
Current Overall Noise Levels
Very little data are available in the form of direct measurement
of noise from conventional diesel school buses. Since diesel powered
conventional school buses utilize medium diesel truck chassis, noise
levels from such trucks can be considered representative of thost f
buses. Unfortunately, very little data on noise from medium diesel
trucks are available, but noise levels from medium diesel trucks are
similar to those from heavy duty diesel trucks with similar size en-
gines. Thus, noise characteristics of a conventional diesel school bus
are described in terms of available noise data from conventional diesel
school buses as well as from diesel trucks.
None of the conventional diesel school bus manufacturers contacted
was able to provide noise test data for their buses. International
Harvester (IH) indicated that exterior noise levels measured from all of
their school buses were below 86 dBA. Moreover, school buses sold
in California and Oregon were said to meet those states' exterior noise
level standards of 83 dBA.
Table 4-6 gives the results of a study involving noise measurements
from diesel trucks. For school buses, the interior noise levels with
4-11
-------
closed truck windows would apply (see Section 8). Another study of noise
levels from two conventional heavy diesel trucks showed a variation in
exterior noise levels from 82.7 dBA to 86.8 dBA, slightly higher than the
exterior noise levels for the new gasoline -engine school buses (see Table
4-2).
Table 4-6, shown below, suggests that maximum acceleration exterior
noise levels for conventional diesel school buses range from 82.7 to 88
dBA at 50 feet. It is not clear from the data which side of the vehicle
is noisier. The interior noise levels at the driver's seat range from
88 to 94.5 dBA. Production buses, as evidenced from these data and past
tests, will exhibit noise levels within 4 to 6 dB of each other, if
tested under carefully controlled conditions. Here again, an allowance
of 2 to 2.5 dB between the mean design noise level and the regulated
level appears appropriate.
Table 4-6
Overall Noise Levels From Conventional
Heavy Diesel Trucks (SAE J366b Test Procedures)
Truck
Number
3
4
6
13
Exterior Sound Level
[dBA]
Curbs ide
86.5
88.0
85.5
87.5
Streetside
86.0
85.0
85.5
87.0
Interior Sound Level
[dBA]
Open Window
92.5
94.5
94.5
90.5
Closed Window
91.0
94.0
94.0
88.0
Source: Reference 4
4-12
-------
Current Component Noise Levels
For diesel vehicles, important noise sources are the engine, the
exhaust, and cooling fan. The typical range of noise levels from each
6
of these sources is between 75 dBA and 85 dBA.
Another major noise source in diesel engines is the intake noise.
Typical unsilenced intake noise levels for diesel truck engines at high
idle vary between 70 dBA and 85 dBA, measured at 50 feet from the engine
7
inlet.
(3) Forward Engine ForwardControl School juses
By forward control it is meant that the driver is located as far
forward and to the left as possible. The engine which can be either
diesel or gasoline is located to the right of the driver, or under the
floor between the two axles. This type of bus typically has a flat
front end.
C ur r ent Overa! 1 No i se Level s
Noise characteristics for this type of bus are similar to those
of conventional school buses. Current noise levels from forward engine
buses made by Blue Bird for states other than California are shown in
Table 4-7. These levels are similar to those given in Table 4-6 for
conventional diesel trucks. The forward engine forward control school
buses sold in California are said to meet the state standard of an 83
dBA exterior level under acceleration.
Concerning interior noise levels, the noise level at the driver
for front engine buses may be higher for these buses compared to con-
ventional school buses because of the close proximity of the engine to
the driver.
4-13
-------
Table 4-7
Noise Levels Fran Diesel Powered Forward Control
Forward Engine Buses by Blue Bird
(Sold in States Other Than California)
Type of
Engine Used
CAT 3208, 320A
Cummins V504, 504A
Detroit Diesel 6V53, 6V53A
Sound
Exterior
(J366b Test)
86
89
92
Levels dBA
Interior
(BMCS Test)
90
90
95
Source: Reference 15
Current Component Noise Levels
Although no data are available for component noise levels from this
type of bus, they are expected to be similar to those for conventional
school buses.
(4) Parcel Delivery Chassis Buses and Motor Home Chassis Buses
Carpenter Body Works' Cadet "CV" and Sheller-Globe1s (Superior)
"Pacemaker" models are built from parcel delivery vehicle chassis and
motor home chassis. GMC also recently introduced a motor home vehicle
that is also offered as a bus, called Transmode.
Current Noise Levels
GMC measured the noise level of one Transmode Bus in accordance
14
with the SAE J366b procedure. This level is reported as 81.7 dBA.
No interior noise level data was reported.
Since these buses use the same engines as full size conventional
school buses, the exterior and component noise levels are expected to
be similar. The interior noise levels at the driver's seat may be higher
for these buses as compared to conventional school buses because of the
closer proximity of the engine to the driver.
4-14
-------
(5) Mid-Engine School Buses (Integral)
The only mid-engine integral school buses available today are made
by Gillig Brothers and Crown Coach Corporation.
Current Overall Noise Levels
Although the engine location and engine types for mid-engine buses
differ from front and rear-engine school buses, their exterior noise
characteristics are not significantly different. However, in contrast
to the noise levels inside rear engine buses, the interior noise in a
mid-engine bus would be higher in the front of the bus than in the rear
because the engine is relatively closer to the front end.
Exterior noise levels from the Gillig buses, which were measured in
10 22
1975 , and Crown buses which were measured in 1973 , are shown in Table
4-8. These levels range from a low of 80.9 dBA on the curbside to a
high of 86.3 dBA on the streetside.
Table 4-8
Exterior Noise Levels From Diesel Powered
Mid-Engine school Buses at 50 Feet
Exterior Sound Level, dBA
Bus
Manufacturer Engine Curbside Streetside
Gillig
Gillig
Crown
Crown
Detroit Diesel 83.6
6-71
Cummins Diesel 80.9
NHHTC-240
Turbocharged
Detroit Diesel 82.6
6-71
Cummins Diesel 83.9
NHHTC-270
Turbocharged
86.3
82.1
84.9
85.9
Source: References 10 and 22
4-15
-------
For exterior noise considerations, mid-engine buses may be
considered to be similar to transit buses rear-engine integral school
buses. Interior noise, however, is expected to be higher for mid-engine
buses because of the shape and position of the engine compartment.
Crown Coach Corporation has indicated that the interior noise level
at the driver's seat in their buses is about 87 dBA when measured at
35 mph under full throttle conditions.
Cur rent Component Noise Levels
Data on component noise levels for mid-engine school buses are not
available.
In order to meet the California exterior noise standard of 83 dBA,
Gillig provides sheet metal covers with noise damping insulation around
10
the complete engine. The muffler is also wrapped with insulation.
Fan speeds are said to be as low as their cooling requirements will
allow.
Crown Coach Corporation also provides sound absorbing insulation
around their engine. Engine compartment doors are lined with 1.5 inch
thick acoustical material. Exhaust noise from their turbocharged
Cummins engine is said to be sufficiently low. Therefore, no special
exhaust noise treatment is provided for that engine. However, for the
Detroit Diesel 6-71 engine a heavier gauge muffler shell is used which,
when tested, provided the same attenuation as a wrapped muffler. Crown
also uses an acoustical floor in its buses. The floor, used since 1964,
is made up of one-half inch "Celetex" sandwiched between two 1/4 inch
and 5/8 inch thick plywood panels. (Celetex is a fire-resistant material
made by Georgia Pacific.)
4-16
-------
(6) Rear Engine^ School Buses (Integral_)
Gillig Bros, is the only manufacturer of rear engine integral school
buses. Urban transit and intercity buses, which are also integral rear-
engine buses, are discussed separately because of differences in engine
sizes, engine compartment layout, and ruggedness of construction.
Current: Overall _No_ise_ Levels
Although the integral rear-engine school buses and the urban transit
bus use different types of diesel engines, they have similar noise charac-
teristics. While urban transit buses use Detroit Diesel's naturally
aspirated 6V-71 and 8V-71 engines, the rear engine school buses, produced
by Gillig use either the naturally aspirated CAT 3208 or the turbocharged
Cummins 230 engine. Exterior noise levels for Gillig school buses are
shown in Table 4-9.
Table 4-9
Exterior Noise Levels at 50 Feet From
Gillig Integral Rear Engine School Buses
(SAE J366b Test)
Sound Levels, dBA
Type of Engine Curbside Streetside
Cumnins 230
(Turbocharged)
-With grille on engine
compartment doors 83.7 82.7
CAT 3208
(Naturally aspirated)
-With grille on 84.0 83.5
engine doors
-With solid engine doors 81.3 82.5
Source: Reference 10
4-17
-------
The streetside noise levels from the top two buses in Table 4-9
are slightly lower than those on the curbside because of an additional
inner compartment wall on the streetside of the engine compartment.
When Gillig replaced the grill on the engine doors with solid panels on
the Caterpillar engine powered bus, the noise levels were reduced as
seen in the table. Giving the same treatment to the Cummins engine
powered busxwould probably provide similar reduction. Because of a
lack of more detailed test data/ the reason for attaining relatively
greater noise reduction on the curbside from the Caterpillar engine
powered bus with solid engine doors is not clear.
Interior noise levels for rear engine school buses are not avail-
able but are expected to be similar to transit bus interior noise levels.
Current Component Noise Levels
No component noise data for rear-engine (integral) school buses
are available.
(7) Rear Engine School Buses (Body-on-Chassis)
There is one bus which falls into this category, the Carpenter
Corsair and Transit bus which is offered with a front-mounted engine as
well as with a rear-mounted engine. No noise level information is pre-
sently available for this type of bus.
Exterior, interior and component noise levels are expected to be
similar to diesel powered forward control school buses and rear engine
(integral) school buses.
4-18
-------
(7) Urban Transit Buses
Current Overall Noise Levels
Noise level measurements taken for EPA of 24 in-use urban transit
buses along with mean levels and standard deviations are presented in
Table 4-10 for various measurement procedures.
The variation in noise levels between in-use buses of identical
construction is thought to be due to the following reasons:
o The maximum noise occurs at transmission shift, which
does not always occur at the same engine rpm or test
location for each test for older buses.
o The rear engine compartment doors for the older buses
tend to be ill-fitting and failed to lock on many of
the buses tested causing some variation between test
runs.
The difference in noise levels between the curbside and streetside
of the buses occured because the fan and radiator are located on the
streetside of the bus causing higher levels on that side.
Histograms of in-service transit bus exterior noise levels under
maximum acceleration, pull-away, and stationary conditions and interior
noise levels in the front and rear of the bus under maximum acceleration
test conditions are shown in Figures 4-4 and 4-5. It should be noted
that in the interior tests involving the front and rear interior of the
bus, the higher noise level was measured in the rear location each time.
Noise levels of two CMC transit buses under different operating
22
conditions are given in Tables 4-11 through 4-14. The buses are
designated as #4400 and #704. Attention should be given to a
comparison of the noise levels on the streetside and curbside.
4-19
-------
TABLE 4-10
Summary of Exterior and Interior Noise Levels
for In-Service Transit Buses
MAKE AND
MODEL NO
GM-6504
GM-6302
GM-6323
GM-6610
GM-6400
GM-6401
GM-6321
GM-6408
GM-6616
GM-6503
GM-6703
GM-6601
FLX-6808
FLX-6812
FLX-6826
FLX-6800
AM-7110
AM-7120
AM-7130
AM-7135
AM-7540
AM-7545
6M-SO/S1
FLX-6509
MEAN
STD
TRANSMISSION
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Automatic
Standard
Automatic
EXTERIOR NOISE LEVELS (50 FT.)
(SAEJ366b)
STREET SIDE
83
(83)
82
(817)
84
(83.7)
82
(82)
82
(81.8)
84.25
(842)
86.1
(85.7)
79
(78.7)
82
(82)
(— )
835
(833)
82.5
(82.2)
81
(808)
8075
(807)
80
(80)
82.25
(82.17)
7975
(797)
80
(80)
80
(80)
80
(80)
81 75
(81.2)
7775
(77.5)
7875
(787)
81
(80.7)
81 5
(813)
1.96
(1.93)
CURB SIDE
81
(807)
795
(787)
80
(79.7)
80
(80)
797
(79.1)
83 1
(82.4)
81.5
(81.5)
7925
(788)
7825
(78 25)
78.75
(785)
8325
(818)
77
(77)
80
(80)
79.5
(797)
7875
(78.5)
81 5
(81.3)
8075
(807)
80.75
(807)
81
(81)
81
(8Q8)
77.75
(77 5)
79
(783)
78.75
(78.5)"
81
(808)
800
(798)
1 53
(1.44)
PULL-AWAY
STREET SIDE
87
(865)
82
(82)
85
(85)
82.5
(82)
82
(82)
855
(85.3)
86
(858)
81
(807)
8425
(84.17)
81.75
(81.5)
89.25
(89.25)
81.5
(812)
825
(82.3)
8025
(81.25)
81.75
(817)
82
(81.7)
8375
(835)
825
(825)
835
(833)
82
(82)
80.5
(803)
79.25
(792)
81
(81)
82.5
(82.5)
829
(82.8)
2.31
(2.25)
CURB SIDE
79.5
(795)
795
(795)
77
(77)
76.25
(76.2)
75.25
(752)
80.5
(803)
8225
(82)
7625
(76.75)
79
(79)
78
(77.7)
78
(77 S)
77
(768)
785
(78.5)
7675
(76.5)
765
(763)
81
(81)
78.25
(782)
7925
(79)
77.75
(775)
77.75
(77.7)
79
(787)
75.5
(75)
77
(76.8)
79.5
(79)
78 1
(78)
1.75
(1.74)
STATIONARY IMI
STREET SIDE
—
—
—
—
—
(86.7)
(86)
(— )
86.7
(867)
86
(86)
87
(87)
87
(87)
89
(89)
87
(87)
86
(86)
91
(91)
89
(89)
89
(89)
88
(88)
88
(88)
83
(83)
83
(83)
88
(88)
88
(88)
872
(87.1)
2.09
(1.98)
CURB SIDE
—
—
—
—
—
(— )
(— )
(~)
(— )
(— )
74
(74)
78
(78)
74
(74)
79
(79)
74
(74)
75
(75)
80
(80)
76
(76)
74
(74)
79
(79)
75
(75)
80
(80)
76
(76)
76
(76)
76.4
(76.4)
2.31
(2.31)
(SAEJ366b)
INTERIOR NOISE
REAR
83
(82.5)
87.2
(86.6)
89.5
(88.8)
86.75
(86.4)
83.5
(83.2)
84
(83.7) ,
82
(81.3)
83
(82.3)
90
(88.4)
87
(85.8)
8575
(84.8)
83
(82.8)
86
(85.8)
85
(85)
86.75
(85.8)
85
(84.8)
81
(80.6)
82.75
(82.2)
8025
(80)
81.25
(793)
80.25
(79.6)
83.5
(80.5)
82.75
(79.4)
85
(81.9)
84.3
(83.4)
2.67
(2.82)
NOTE Numbers in parentheses are computed from all data, while numbers not in parentheses are computed from the two highest noise levels.
4-20
-------
FIGURE 4-4
Histograms of In-Service Transit Bus Noise Levels
SAE J366b (Acceleration) and Pull-Away Test Levels
CO
LU
CO
ORIVERSIDE
MEAN 83.79 dB (A)
STD. DEV. 2.4
SAE J3666
10-
70
Jllll.1.
80
dB(A)
90
CURBSIDE
MEAN 79.92 dB (A)
STD. DEV. 1.57
70
PULL-AWAY TEST LEVELS (50 FT.)
£3
CO
o
o
DRIVERSIDE. FRONT DOOR
MEAN 81.37dB(A)
STD. DEV. 1.94
10-
5-
70
80
dB(A)
90
S3
V)
o
o
CURBSIDE, FRONTDOOR
MEAN 78.77 dB (A)
STD. DEV. 2.00
4-21
-------
FIGURE 4-5
Histograms of In-Service Transit Bus Noise Level Tests
Stationary Runup Levels (50 ft.)
CO
LU
fO
u.
O
DRIVERSIDE, FRONTDOOR
MEAN 83.82 dB (A)
STD. DEV. 2.45
10-
70
I
80
dB(A)
90
CO
LU
co
DRIVERSIDE, REAR DOOR
MEAN 84 dB (A)
STD. DEV. 2.87
iu—
5-
1
70 80
dB(A)
•
Ih,
91
CO
LU
CO
O
O
CURBSIDE, FRONTDOOR
MEAN 79 dB (A)
STD. DEV. 3.0
... ml .
i
0 80
dB(A)
9
INTERIOR, ACCELERATION
FRONT REAR
MEAN 75.82 MEAN 84.2;
STD. DEV. 2.08 STD. DEV. 2.4!
CO
LU
CO
=3
CO r
u. °~
O
O
z
REAR
FRONT -I
II .Illlllll..
70 80 9
dB(A)
4-22
-------
Table 4-11
Exterior Noise Levels, Bus #440D
Sound Level, dBA
Test Description
Accessories
Acceleration, J366b Test
Acceleration, J366b Test
Deceleration from
(no brakes)
Deceleration from
(no brakes)
Coast-by 30 mph
Coast-by 30 mph (
Coast-by 30 mph (
Coast-by 55 mph
Cruise 30 mph
30 mph
30 mph
fan off)
fan off)
OFF
ON
OFF
ON
OFF
ON
OFF
OFF
ON
Curbside
25 ft
81.5
81
70.5
73
72
70.5
80
75
50 ft
77.5
77
67
70
70
71
68
77
72
Streetside
25 ft
87.0
86
74
72
74
75
75
83
80
50 ft
84.0
81.5
66
71
71
71
70
80
76
Source: Reference 22
Tables 4-12 and 4-13 indicate that carpeting will lower very slightly
the noise level in the interior. Inside the non-carpeted buses, no
difference in noise level appears evident from a change in the height
of the microphone for noise levels taken at any one measurement location.
This indicates that a sitting or standing passenger in the same general
area of the bus receives the same noise exposure.
4-23
-------
Table 4-12
Exterior Noise Levels, Bus #705
Test Description
Curb Idle
0-5 mph, Wide Open
Throttle, Rear Corner
0-5 mph, Wide Open
Throttle, Rear Door
10 mph Drive By
30 mph Drive By
55 mph Drive By
25 mph Acceleration
50 mph Acceleration
30 mph Deceleration
55 mph Deceleration
55 mph Coast By
- 5 ft
- 5 ft
- 5 ft
- 50 ft
- 50 ft
- 50 ft
- 50 ft
- 50 ft
- 50 ft
- 50 ft
- 50 ft
Sound Level,
Curbside
77
88
90
66
72
78
75
78
71
77
77
dBA
Streetside
-
-
-
73
78
87
81
86
77
84
84
Source: Reference 22
4-24
-------
Table 4-13
Interior Noise Levels (Empty Bus), Bus #4400
Sound Level, dBA
Test Description
10 mph
30 mph
55 mph
- Front
Middle
Rear
- Front
Middle
Rear
- Driver'
Front
Middle
Rear
0-55 Acceleration
55-0 Deceleration
Standing
Standing
10 mph -
30 mph -
55 mph'-
's Ear
- Front
Middle
Rear
- Front
Middle
Rear
Without
Standing
68
70
74
73
75
80
—
79
79
84
-
81
82
78
78
80
Idle - Accessories Off, Middle -
Idle - Accessories On, Middle -
Accessories Off, Middle -
Accessories Off, Middle
Accessories Off, Middle
Carpet
Seated
67
71
74
72
76
81
77
79
79
83
79
81
84
76
77
81
63
69
67
72
78
With Carpet
Standing
68
70
-
72
73
78
—
77
77
84
77
79
84
75
77
81
-
-
-
-
~
Seated
67
70
75
71
72
78
77
75
77
83
76
79
84
74
77
83
61
68
63
69
76
Source: Reference 22
4-25
-------
Table 4-14
Interior Noise Levels (Empty Bus), Bus #705
Sound Level/ dBA
Test Description
10 mph - Front
Middle
Rear
30 mph - Front
Middle
Rear
55 mph - Front
Middle
Rear
0-55 Acceleration - Front
Middle
Rear
55-0 Deceleration - Front
Middle
Rear
Standing
74
75
79
75
77
85
77
79
85
78
82
89
77
77
86
Seated
73
75
78
74
77
84
78
80
85
78
81
86
76
79
85
Source: Reference 22
4-26
-------
11
The Flxible Co. has performed an extensive series of noise
measurements on their buses under controlled test conditions. Their
measurements are summarized in Table 4-15.
Table 4-15
Summary of Measured Transit Exterior Bus Sound Levels
The Flxible Company
Coach
40'
40'
35'
35'
Engine
6V-71
8V-71
6V-71
8V-71
NO.
Tested
7
9
3
1
Sound Level at 50
J366b Procedure,
Curbside
Mean
80.46
80.92
82.16
80.50
Std. Dev.
.55
.87
1.26
Feet,
dBA
Streetside
Mean
82.25
82.05
83.17
82.00
Std. Dev.
.69
.73
.76
Source: Reference 11
The mean interior noise level measured 24 inches from the rear
window under maximum acceleration conditions was 83.5 dBA with a stan-
dard deviation of 0.75. Flxible Co. also reports that interior noise
12
levels of some coaches can be 87 dBA at shift point.
AM General reports their exterior bus noise levels to be "in the
range of 80 to 86 dBA" when measured according to the existing SAE
13
J366b test procedure.
Based on the above data for new and in-use buses concerning
variation in noise level data, the medium design level of new buses
should be 2 to 2.5 dBA below a not to exceed standard.
General Motors Corporation has recently initiated a "Quiet Bus
21
Program". For a CMC new-look bus before it was "quieted", Model No.
4-27
-------
T8H5307A, CMC reports a mean noise level of 80.5 dBA using a modified SAE
J366b test procedure with the fan off, and 83.7 dBA with the fan on.
This model is a 40 ft, 53 passenger urban transit bus powered by an 8V-71
diesel engine. CMC also reports that for 15 identical transit coaches, of
this model (T8H 5307A) using a modified SAE J366b maximum acceleration
procedure a mean noise level of 81.2 dBA with the fan off (standard
deviation of 0.43) was measured while a mean level of 83.9 dBA was
9
measured with the fan on (standard deviation 0.75).
In four trials, while using a special dual muffler configuration,
CMC was able to lower the noise level of the "quieted coach" to just over
75 dBA under acceleration on the left side of the test coach and less
than 71 dBA on the right. GMC indicates this developmental coach would
meet a regulated level of 78 dBA. Exact results are shown in Table
4-16. The test used is a modified SAE J366b test with the starting point
adjusted so that the transmission shift, and therefore maximum noise, is
achieved in the end zone. All cooling fans were running during the test.
Run
1
2
3
4
Table 4-16
CMC Quiet Bus Program Exterior
Sound Levels SAE J366b
Left Side (dBA) Right
75.3
74.9
75.8
75.1
Side (dBA)
71.5
70.0
71.4
70.6
Source: Reference 21
4-28
-------
CMC also reported a reduction of interior noise levels for its "Quiet
Bus". Measurements were made at ear level in various coach seat positions
during a wide open throttle acceleration and maximum sound levels were
recorded. Observed data are shown in Table 4-17.
Table 4-17
CMC Quiet Bus Program Interior Sound
Level Data at Wide Open Throttle Conditions
Interior
Seat Location
Rear
Center
Driver
Unmodified Coach
SAE J366b
81 dBA
79 dBA
73 dBA
Modified Coach
SAE J366b
76 dBA
72 dBA
70 dBA
Source: Reference 21
Current Component
Noise Levels
For diesel powered urban transit buses of current configurations,
the important noise sources are the engine exhaust, engine, cooling fan,
air intake system, chassis, and tires. (Tire noise becomes important at
high speeds and may become the dominant noise source at highway speeds
when all the other sources have been quieted.) Data on relative
contributions of these sources (minus tire noise) were obtained for a
22
CMC transit bus during tests conducted by EPA. Additional data were
obtained from tests conducted for the U.S. Department of Transportation
15, 16
(DOT) by two major transit bus manufacturers. This data is summa-
rized in Table 4-18. All buses were 40 feet long and had Detroit Diesel
8V-71 engines except for the Rohr (Flxible) bus which was a 35 foot bus
with a 6V-71 engine. The CMC and Rohr buses demonstrated the potential
4-29
-------
of feasible retrofit techniques to lower bus noise. The manufacturers'
contracts with DOT required them to make these retrofit parts available
to transit bus users. (It should be noted that the CMC data in Table
4-18 was not obtained during their "Quiet Bus Program" but rather under
15
the retrofit study for DOT. )
An independent estimation of transit bus component noise levels con-
3
ducted by Wyle Laboratories is also included in Table 4-18.
Table 4-18
Urban Transit Bus Component Exterior
Noise Levels, dBA at 50 Feet
Engine
Mechanical
Exhaust
Cooling Fan
Intake
All Other
Sources
Overall
Sound Level
EPA
Tests
75
80
81
70
70
84.5
CMC
Standard
Bus
73
76
84
76
85.5
Quieted
Bus
71
74
73
76
80
Rohr
Standard
Bus
79
79
77
65
83.5
Quieted
Bus
75
65
73
65
78
Wyle
Estimate
79-80
80
78-85
60-75
68-73
84-87.5
SouKce: References 3, 15, 16 and 22
4-30
-------
The main contributor to interior noise for transit buses is the
engine. Engine noise is transmitted through the panels by vibration
and by flanking paths. The latter two transmission mechanisms are
very difficult to control and are thought to be the limiting factor
to interior noise reduction. Air conditioning ventilation noise is
also a contributing source to interior noise levels. Since all major
component noise sources are located in the rear of the bus, it is dif-
ficult to diagnose the relative contributions of component sources to
interior noise and as such no data is presently available.
(9) Intercity Buses
Exterior and interior noise level data gathered on intercity
buses for the three major U. S. intercity bus manufacturers (Eagle
International, General Motors Corporation and Motor Coach Industries)
are presented below.
Current Exterior Noise Levels
Exterior sound level data, measured by EPA, of 12 newly manufactured
intercity buses under various test procedures may be found in Table 4-19.
The buses tested emitted average exterior noise levels ranging between 82
and 87 dBA under maximum acceleration conditions (SAEJ366b) with a mean
level of 85.5 dBA. In addition, SAE J366b deceleration tests were run on
two intercity coaches with engine brakes fully engaged. The buses emitted
average maximum noise levels of 89.4 dBA under the SAE J366b deceleration
procedure as compared to average maximum noise levels of 87 dBA under the
SAE J366b acceleration procedure. The standard deviations exhibited in the
data indicate that a 2-2.5 dBA difference between an engineering design
level and a "not to exceed" regulatory level appears adequate for intercity
buses.
4-31
-------
TABLE 4-19
Summary of Exterior Noise Levels for Intercity Buses
BUS
SERIAL NO
S 12327
S 12337
S 12361
S 12239
S 12359
S 12322
S 12323
19699
19704
9678
9677
—
Mean
Std. Dev.
Mean
Std Dev
Mean
Std Dev
Mean
Std Dev
Mean
Std Dev
MODEL
MC-8
MC-8
MC-8
MC-8
MC-8
MC-5B
MC-5B
05
05
05
05
17
All
All
MC-8
MC-8
MC-5B
MC-5B
05
05
17
17
TRANSMISSION
Standard
Standard
Automatic
Automatic
Automatic
Standard
Standard
Standard
Standard
Standard
Standard
Automatic
All
All
All
All
Standard '
Standard
Standard
Standard
Automatic
Automatic
A-WEICHTED SOUND LEVELS, dB(A) AT 50 FEET
(SAEJ366b)
MAXIMUM
ACCELERATION
STREET SIDE
86
(85 1)
86
(852)
865
(857)
86
(855)
845
(84 25)
8725
(852)
87
(856)
85
(845)
855
(843)
853
(84)
84
(838)
82.5
(814)
855
(846)
133
(1 18)
858
(851)
76
( 48)
871
(854)
18
( 29)
85
(842)
67
( 31)
825
(81 4)
0
( 78)
CURB SIDE
825
(806)
8325
(813)
8325
(824)
8425
(829)
81
(79 75)
81
(796)
81
(795)
855
(845)
865
(848)
853
(84)
858
(838)
81
(79.9)
834
(819)
209
(205)
829
(814)
1 21
(130)
81
(795)
0
( 06)
858
(843)
53
C 46)
81
(799)
a
( 74)
PULL-AWAY
STREET SIDE
86
(85 63)
8475
(845)
84
(83 88)
9025*
(89 33)
89*
(88 25)
—
—
—
—
—
849
(849)
1 01
( 89)
849
(847)
1 01
( 89)
896*
(888)
88*
( 76)
—
—
—
—
CURB SIDE
8275
(82 63)
81
(80 75)
83*
(82 17)
8225*
(810)
—
—
—
—
—
819
(817)
1 24
(133)
819
(81 7)
1 24
(133)
826*
(816)
53*
( 83)
—
—
—
—
STATIONARY 1MI
STREET SIDE
865
(85 25)
875
(855)
88
(85 75)
8625
(846)
8675
(854)
86
(855)
855
(85 25)
848
(829)
84
(821)
84
(824)
848
(82.4)
80
(794)
853
(839)
2 11
(20)
87
(853)
73
( 42)
858
(85.4)
35
( 18)
84
(825)
46
( 33)
80
(794)
0
( 58)
CURB SIDE
85
(81 50)
8275
(79 80)
7725
(77 25)
8375
(806)
(.850)
81
(79 25)
8025
(789)
858
(823)
858
(851)
845
(821)
84.5
(80.4)
793
(77.6)
826
(803)
2.78
(223)
82
(796)
301
(170)
806
(79.1)
53
( 26)
852
(825)
75
(195)
793
(776)
35
(141)
STATIONARY MAXIMUM
GOVERNED SPEED
STREET SIDE
79.5
(775)
80
(78 25)
80.5
(78 75)
81
(78.5)
81 5
(79 25)
79
(78 75)
80
(78 75)
823
(81 1)
825
(806)
83
(805)
83
(82.9)
758
(75.4)
807
(792)
206
(191)
805
(785)
79
( 65)
95.5
(788)
71
(0)
827
(813)
36
(1 11)
758
(754)
.35
( 32)
CURB SIDE
79.5
(770)
78
(76)
75
(74)
78
(75)
78
(75 75)
77
(76)
77
(755)
845
(813)
845
(836)
82.5
(80.3)
82.5
(80.6)
785
(773)
79.6
(777)
3.14
(3.0)
777
(75.6)
1 64
(1 12)
77
(75.8)
0
( 35)
835
(815)
1 15
(1.49)
78.5
(773)
0
(1 16)
*Deceleration tests with engine brake
NOTE Numbers in parentheses are computed from all data, while numbers not in parentheses are computed from the two highest noise levels
4-32
-------
Data measured by using the SAE J366b procedure for a CMC manual
14
transmission production intercity coach Model P8M4905A is shown in
Table 4-20.
Table 4-20
CMC Intercity Bus
J366b Test Procedure
Cooling Fan On
Streetside Curbside
Cooling Fan Off
Streetside Curbside
84.2 dBA
81.4 dBA
80.6 dBA
79.1 dBA
Source: Reference 14
In addition, during a demonstration at the CMC noise test track in
Pontiac, Michigan, on December 16, 1975, maximum acceleration (SAE J366b)
noise levels at 50 feet of 83.4 and 84.1 dBA were measured on the street-
side of a CMC intercity coach while 82.8 and 83.2 dBA were measured on
22
the curbside. The test was performed with the transmission in second
shift.
Motor Coach Industries (MCI) reports a curbside noise level of
82.5 dBA and a Streetside noise level of 85 dBA using the SAE J366b pro-
cedure. At 70 mph cruise conditions, the same bus was said to produce
17
80.5 dBA on the curbside and 82.5 dBA on the Streetside.
4-33
-------
3
Wyle Research estimated SAE J366b noise levels for intercity
coaches at 84 to 86 dBA, which is about the same as their estimate
of 85.5 dBA for urban transit buses with 8V-71 engines.
Under high speed cruise conditions, tire noise levels at 50 feet
may reach 75 dBA at 55 mph for rib-type tires used for intercity
16
coaches. This estimate is based on measurements conducted by DOT and
the National Bureau of Standards at Wallops Island, Virginia, on a
loaded International Harvester Truck (Model No. 1890) of 25,640 pounds
GVWR.
Current Interior Noise Levels
Table 4-21 presents interior noise level data for 12 intercity
coaches recorded during various testing procedures. It is interesting
to note that in certain cases up to a 10 dB difference in noise level
is present from the front of the vehicle to the rear of the vehicle.
Besides the data reported in Table 4-22 Eagle International reports
19
levels of 72 to 73 dBA at the rear seat at 50 mph , after noise
treatment had been added around the engine compartment.
MCI reports levels of 70 to 71 dBA at an unspecified seat
17
location in their MC-5 35-foot coach. MCI also conducted measurements
under stationary and cruise conditions at various locations in the
coach with and without approximately 90 square feet of sound insulation
(Baryfoil #10.25) between the engine compartment and passenger compart-
ment. This insulation was found to have no consistent effect on interior
sound levels, which are summarized in Table 4-22.
4-34
-------
TABLE 4-21
Summary of Interior Noise Levels for Intercity Buses
BUS
SERIAL NO.
S 12327
S 12337
S 12239
S 12239
S 12359
S 12322
S 12323
19699
19704
9678
9677
—
Mean
Std Dev.
Mean
Std. Dev.
Mean
Std. Dev.
Mean
Std. Dev.
Mean
Std. Dev.
MODEL
MC-8
MC-8
MC-8
MC-8
MC-8
MC-5B
MC-5B
05
05
05
05
17
All
All
MC-8
MC-8
MC-5B
MC-5B
05
05
17
17
TRANSMISSION
Standard
Standard
Automatic
Automatic
Automatic
Standard
Standard
Standard
Standard
Standard
Standard
Automatic
All
All
All
All
Standard
Standard
Standard
Standard
Automatic
Automatic
MEASUREMENT
LOCATION
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Front
Mid
Rear
Rear
Rear
Rear
Rear
Rear
Rear
Rear
Rear
Rear
Rear
A-WEIGHTED SOUND LEVEL, dB(A) AT 50 FT.
(SAE J366b)
MAXIMUM
ACCELERATION
74.5
73.25
79.25
73.75
72
78.25
73
72
77.5
73.5
74
80.25
73
71
77
74.6
78
7975
7725
7675
81
71 25
765
81.75
695
74.75
81
6775
73
82
70.75
77
82
74
7925
84
80.3
2.06
78.5
1.37
80.4
88
81.7
.47
84
0
PULL-AWAY
73
72
77.5
73.75
74.25
79
73
71
755
77.25
76.5
79.25
75.25
74.5
79.5
—
—
—
—
—
77.3
1.76
773
1 76
794
.18
—
—
STATIONARY
IMI
74.25
73
77.3
73.5
72
77
72.5
71 7
76.6
73.2
72.5
77.5
73
70.75 •
74.7
75.5
78.75
78.5
74.5
77.75
80.15
71.5
75.75
82
72.25
72.75
82
70
77.25
72
76
82.5
75.8
80.5
84
79.1
2.91
76.6
1.13
79.3
1 17
82.2
29
84
0
STATIONARY
MAXIMUM
GOVERNED
SPEED
74.3
75.7
74.6
74
73
76.75
79
70
81
69
70
81
66
748
80
69.5
72.5
80
72
77
83
77.7
3.36
74.3
.98
77.9
1.59
80.5
.58
83
0
4-35
-------
Table 4-22
Interior Sound Levels in
Rear of MCI MC8 Coach, dBA
Standard
Coach
Insulated
Coach
Normal
Idle
64
63
High
Idle
65
65
Maximum
rpm
69
72
60 mph
Cruise
73
72
Source: Reference 17
18
Bray reports average front seat levels for intercity coaches
of 74 to 78 dBA and rear seat levels of 70 to 84 dBA.
Levels under normal street acceleration conditions at the rear
seat of a new CMC intercity bus ranged from 80 to 84 dBA, compared to
22
77 dBA at cruise (30 mph) and 72 dBA at idle.
For intercity buses, interior noise levels at pass-bys of 55 mph
are more representative of actual driving conditions than the interior
noise levels measured under maximum acceleration. However, maximum noise
levels are most likely to occur under maximum acceleration conditions.
Current Component Noise Levels
Data on component levels of intercity buses are presently not
available but are believed to be closely aligned with Urban Transit Bus
component noise levels. This is believed to be true since many of the
same noise generating sources (engine, transmission, cooling system)
are similar or identical to Urban Transit Buses. Thus, refer to the
Urban Transit Bus discussion on component noise levels for intercity
bus component levels.
4-36
-------
REFERENCES - SECTION 4
1. "The Technology and Costing of Quieting Medium and Heavy Trucks,
BBN Report No. 2719, prepared for the EPA Office of Noise Abatement
and Control, October 1974.
2. Burroughs, C. B., "Costs of Compliance for Regulations on New Medium
and Heavy Truck Noise Regulations," BBN Technical Memorandum, pre-
pared for EPA Office of Noise Abatement, January 1976.
3. Warnix, J. L. and Sharp, Ben H., "Cost Effectiveness Study of Major
Sources of Noise, Volume IV - Buses," Wyle Research Report
WR-73-10, prepared for the EPA Office of Noise Abatement and Control,
April 1974.
4. "Interior/Exterior Noise Levels of Over-the-Road Trucks: Report of
Tests," NBS Technical Note 737, National Bureau of Standards,
September 1972.
5. "Noise Control Retrofit of Pre-1970 General Motors Trucks and
Coaches," Final Report, U.S. Department of Transportation, Office
of Noise Abatement, October 1975.
6. "Background Document for Proposed Medium and Heavy Trucks Noise
Regulations," U. S. Environmental Protection Agency, October 1974.
7. Kevala, R. J., Manning, J. E., et al, "Noise Control Handbook for
Diesel-Powered Vehicles," Interim Report, Report No. DOT-TSC-OST-74-5,
U.S. Department of Transportation, Office of Noise Abatement and
Control, April 1975 (Reprint).
8. Correspondence, Bluebird Body Company to Booz, Allen Applied Research,
January 21, 1976.
9. General Motors Corporation Conference on Bus Noise Regulation,
December 16-17, 1975. CMC Summary Report (USG 350-76-1) submitted
to the EPA on January 15, 1976.
10. Correspondence with Gillig Brothers to Booz, Allen Applied Research,
January 19, 1976.
11. Correspondence, Flxible Co. to Booz, Allen Applied Research, dated
November 26, 1975.
12. Correspondence, Flxible Co. to Booz, Allen Applied Research, dated
October 8, 1975.
13. Correspondence, AM General Corp. to Booz, Allen Applied Research,
dated January 23, 1976.
4-37
-------
14. Comments of General Motors Corporation With Respect To Booz-Allen
and Hamiltan, Inc. Technology Study on Bus Noise Regulation
Performed Under Contract To The Office of Noise Abatement and
Control, Environmental Protection Agency, CMC report USG-350-76-5
submitted on January 23, 1976.
15. "Noise Control Retrofit of Pre-1970 General Motors Trucks and
Coaches," Final Report, U.S. Department of Transportation, Office
of Noise Abatement, October 1975.
16. "Sound Attenuation Kit for Diesel Powered Buses," Report Rll-SAK-
402-0101, by Rohr Industries (unpublished).
17. Correspondence, Motor Coach Industries to Booz, Allen Applied
Research, dated January 21, 1976.
18 Leasure, William A., et al, "Truck Noise -1, Peak A-weighted
Sound Levels Due to Truck Tires," Report No. OST/TST-72-1, U.S.
Department of Transportation, July 1972.
19. Private communication with Mr. Harry L. Cuthbert of Eagle
International.
20. Bray, Don E., "Noise Environments in Public Transportation," ASME
Meeting Reprint 1469, Joint ASCE-ASME Transportation Engineering
Meeting, July 26-39, 1971, Seattle, Washington.
21. Comments of General Motors Corporation With Respect To "The
Technology and Costs of Reduced Noise Level Urban Transit Buses,
(USG 350-76-52) submitted to the EPA - Office of Noise Abatement
and Control, November 18, 1976.
22. "An Assessment of the Technology for Bus Noise Abatement", Draft
Final Report submitted by Booz, Allen Applied Research under EPA
Contract No. 68-01-3509 prepared for the Office of Noise Abatement
and Control, June 22, 1976.
23. "Noise Levels of New MCI Buses," Booz-Allen & Hamilton Report sub-
mitted under EPA Contract No. 68-01-3509 to the U.S. EPA Office of
Noise Abatement and Control, October 7, 1976.
24. "Noise Levels of New Eagle Buses," Booz-Allen & Hamilton Report
submitted under EPA Contract No. 68-01-3509 to the U.S. EPA Office
of Noise Abatement and Control, November 16, 1976.
25. "Lima School Bus Test Report," Environmental Protection Agency,
Noise Enforcement Facility (Sandusky, Ohio), June 1976.
4-38
-------
Section 5
NOISE ABATEMENT TECHNOLOGY
For buses of current configurations, the important noise sources
are the engine, exhaust, cooling fan, intake, and chassis. The relative
contributions of these sources vary depending on the type of bus and on
the type of bus operation.
Engine
Engine noise is the mechanically radiated noise associated with
the combustion process and the mechanical components of the engine.
This noise is a result of vibration of the engine structure, covers,
and accessories. In general, noise from the transmission, turbocharger
•
(if so equipped), and the blower are included in the noise source
comprising engine noise. In the case of diesel engines, the air intake
is treated as a separate noise source from engine noise. For gasoline
engines the air intake noise component is included as part of the engine
noise.
Exhaust
Exhaust noise includes the noise produced by the exhaust gases at
the tail pipe exit, the noise generated by the vibration of the muffler
shell and piping, and the noise caused by leakage of the exhaust system
components (muffler, exhaust manifold, exhaust pipe, and tail pipe).
5-1
-------
Fan
Fan noise includes the various noise sources of the cooling system.
Although the predominant noise source is the fan, the shrouds, radiators,
shutters, and grills affect the noise produced by the cooling system.
Intake
In the case of diesel engines, intake noise includes the noise from
the air inlet, the air cleaner shell and ducting, and the leakage of the
air intake system components.
Chassis
Chassis noise refers to that noise generated by a bus when it is
coasting by at approximately 30 m.p.h. with the engine idling and the
transmission in neutral. This noise includes any wind or turbulent
noise caused by the passage of the bus. It is considered to be the
lowest level of noise attainable for a vehicle.
Component Noise Abatement Technologies
(1) Engine Noise
a. Gasoline Engines
In the case of gasoline engines, it is customary to lump engine,
air intake, and transmission noise together. This is done because the
air intake filter is mounted directly on the engine carburetor, in close
proximity to the engine. Transmission noise becomes an important noise
contributor on gasoline engine vehicles only after the noise from the
engine and the intake have been lowered below 70 dBA.
5-2
-------
Intake noise is relatively low in gasoline engines. This is true
because of the presence of the carburetor and the inherently quieter
air intake process. As a comparison, current intake noise levels for
diesel engines, which are considered noisier than gasoline engines,
1
range from 56 to 75 dBA.
Current gasoline bus engine noise levels under acceleration range
2
from 69 to 73 dBA. Chrysler Corporation estimates the combined
engine and air cleaner noise levels for their 1976 model school bus
chassis at 76 to 79 dBA. The EPA Background Document for Medium and
3
Heavy Truck Regulations estimates that engine noise levels range from
75.7 to 77 dBA for gasoline engines with ratings of 160 to 230 net
horsepower.
Several methods are available for lowering the contribution of
engine noise to overall bus noise levels. All of these techniques
have been successfully tested in the laboratory and, for some,
4,5
put into practice on diesel engines. These techniques, and their
expected noise reductions, are summarized below:
Noise Reduction at 3 Ft.
Covers and panels attached to the engine 3 to 5 dB
Close fitting engine covers 5 to 8 dB
Partial engine enclosures 5 to 10 dB
Complete engine enclosures Up to 15 dB
Major structural engine modifications 4 to 7 dB
5-3
-------
Noise reductions at other distances are expected to be somewhat
lower.
Turbocharging of diesel engines results in some engine noise
reduction because of its smoothing effect on the rate of combustion
pressure rise in the cylinder. This is not expected to be of signi-
ficant benefit to gasoline engines.
Conventional school bus cowls provide an inherent barrier to
some engine noise radiation. Improvements in the cowl design, addi-
tion of acoustic materials in the engine compartment, and provision
of belly underpans all are beneficial to the overall reduction of
engine noise.
Because interior noise levels are mostly controlled by engine
noise, both radiated and structurally transmitted, care in the place-
ment of fire-wall acoustical insulation and engine mounting is indicated
to reduce interior noise levels.
b. Diesel Engines
Diesel engine noise is the result of forces generated by combustion
6
and the mechanical aspects of the engine. Diesel engine combustion
forces are of sufficient magnitude to distort or vibrate the engine block,
crankcase and attachments. Primary combustion forces are at engine funda-
mental firing frequencies. These frequencies are relatively low, but the
structure responds to all harmonics of the basic firing frequency. The
steep pressure rise inherent in dlesel cycle combustion results in the
5-4
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introduction of high-frequency components into the engine structure
which are readily radiated by the sides of the block and rocker arm
covers. Changes in the character of or reduction of combustion forces
have been under investigation by researchers for a number of years.
Precombustion chambers or indirect injection (IDI) can be used
7
effectively to lower combustion rate related noise levels. IDI
is commonly used in diesel engines powering light-duty vans and
passenger cars. For heavy diesels of the type used in diesel school
buses and transit coaches, noise control by retardation of injection
timing and turbocharging has proved to be effective. Retardation
has been shown to have advantages in terms of power, fuel economy,
6
and emissions, but it also increases exhaust smoke.
Turbocharging also increases the horsepower output for a given
size engine and has advantages from the emissions viewpoint. Turbo-
charging is not as advantageous for transit buses as it is for trucks.
Current transit buses use naturally aspirated engines of adequate power.
Additional power would not be very useful because passenger capacities
cannot be increased without exceeding overall size and axle weight
regulations. The dynamic lag of turbochargers results in little in-
crease in engine power levels until the engine reaches maximum speed.
There is, therefore, no gain in dynamic torque and hence no improvement
in bus performance in city traffic conditions. However, a tailored
combination giving the desired characteristics can be developed.
5-5
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Another method to lower engine-radiated noise would be to alter
the stiffness or increase damping of all structures sufficiently to
prevent their response to input forces. The cast iron diesel engine
block is inherently damped and added damping has been found to offer
little improvement.
Thin walled components such as oil pan, rocker arm covers, and
manifolds can be isolated from the cylinder head casting by means of
soft gaskets, rubber washers at mounting bolts or, in severe cases, by
splitting the cover immediately above its mounting surface and joining
together by a bonded, rubber section. This is conceptually shown in
Figure 5-1.
A common method of reducing engine radiated noise is by noise
barrier panels attached to the engine exterior surfaces. These covers
or panels are made of a high-density barrier material lined with an
absorbent material, usually sheet metal lined with glass fiber or mineral
wool. These shields must be designed specifically for each engine model
since proper covering and edge sealing is quite important. Panels
generally are attached to and cover each side of the engine block and
oil sump. They must be contoured to the engine shape and be attached
through isolation mountings. Experience has shown they are more effec-
tive on in-line engines than Vee engines because of the greater, flat,
radiation area on in line engines. Current practice for urban transit
buses is to use Detroit Diesel V-6 or V-8 engines, which makes this
method less effective.
5-6
-------
Figure 5-1
Isolated Rocker Arm Cover
Cover
Isolator
c^r
\\
Engine Block
5-7
-------
Engine covers have definite disadvantages and advantages. They
restrict engine service operations. The possibility of undetected oil
leaks being absorbed by the panel-lining material creates a potential
fire hazard as well as destroys the noise absorption characteristics.
The engine physical dimensions are increased, making installation in
a vehicle more difficult. Heat radiation from engine surfaces is
6
reduced, but experience has shown that this effect is minimal.
Quality control must be maintained to assure seal of all panel edges
and joints. On the plus side, panels can be applied without redesign or
modification of the engine itself. They can be applied to present new
engines or even to engines in service as a retrofit package. This is
much easier than making changes to the basic engine structure. Reduc-
tions of 3 to 8 dBA at 3 ft. in engine noise radiation are possible by
means of close-fitting covers. However, from a practical standpoint,
a set of panels giving 8 dBA reduction would cover virtually all engine
and engine mounted accessory surfaces by many separate complex shaped
panels. In general, a 4 dBA reduction in overall engine sound levels at
50 ft. is close to the practical limit for engine-mounted barrier panels.
5-8
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Sound level reduction due to modified engine structure, reduced
piston slap, damping, and isolation can be used in conjunction with
barriers to produce overall reductions greater than 4 dBA, although
each additional decibel reduction is more difficult to achieve than
the preceding one. When the panels are combined with a partial en-
closure, the resultant reduction is often less than the sum of the
separate reductions due to each method.
The urban transit bus engine compartment already provides some
shielding from engine noise, at least on the curb side of the bus.
The large opening on the left side for admitting cooling air through
the radiator allows much engine and fan noise to escape on that side.
Rohr Corporation has experimented with a forward-facing air scoop in-
stalled over the radiator and by covering the standard grills with an
8
inverted Vee non-1ine-of-sight louver. A line-of-sight barrier
between the engine and the radiator opening was found to be effective.
General improvement of the engine compartment door seals and sound
isolation of the existing engine compartment walls can result in
additional engine radiated noise reduction. The design of radiator
grills to eliminate line-of-sight sound propagation and also to
provide sound absorption without excessive increase in cooling system
flow resistance is attainable, but will require some developmental
work.
5-9
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Shielding under the engine can be effective if the entire area under
the engine is treated. Engine noise reaches the receiver by two routes,
via straight line from the engine area and by reflection from the road
beneath the vehicle. Belly pans are effective in blocking the reflective
path and are currently available for all transit buses. In general,
however, belly pans are not specified or used extensively due to the added
engine servicing problems, restriction of cooling air exit, and problems
associated with sealing. A 2 dB reduction in the engine contributed noise
level can be expected by sealed belly pans in the case of buses. This will
be especially effective in reducing bystander and pedestrian ear level
noise since the reflective sound path from the engine off the road surface
toward the side of the bus will be virtually eliminated.
Full engine enclosures are in use for certain European buses.
Saab-Scania buses have a completely encapsulated engine, with remotely
placed dual radiators and electrically operated fans. The engine
enclosure is ventilated by a third fan, with air being admitted through
an opening in the roof. European bus technology is discussed in greater
detail in Appendix A.
Disadvantages of engine enclosures include reduced accessibility
to the engine compartment, added weight, some reduced passenger and freight
capacity due to increased engine compartment size, and a greater
potential fire hazard.
5-10
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Transmission noise for diesel buses can be lowered by the applica-
tion of damping material to reduce resonant amplification at troublesome
frequencies, by stiffening or by weakening housing areas to shift resonance
frequency components, by decoupling housing areas by slotting or adding
9
mass dampers, and by altering panel geometries. Engine shields can be
extended to include the transmission housing in the case of buses.
Engine mountings are important since engine vibrations can be
transmitted to the body framework and to the body panels through the
mounts. Engine mount design technology is sufficiently advanced to
provide good isolation at high frequencies between the engine and body
frame or chassis while allowing the large torque forces to be trans-
mitted to the transmission. Vibration isolation is important because
current bus interior noise levels are dominated by floor and body side
panel radiated noise which appears to be the result of engine vibration.
(2) Exhaust Noise
a. Gasoline Engines
Gasoline engine school buses, without exception, require the tail
pipe outlet to be at the rear of the bus, extending at least five inches
beyond the body wall. This results in ample exhaust pipe lengths for
adequate engine exhaust noise quieting. Moreover, gasoline engines can
tolerate higher back pressures to allow mufflers of greater restriction
to be used compared to diesel engines. The average back pressures of
11
current passenger-car mufflers range from 6 to 16 inches Hg. The
5-11
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exhaust systems for gasoline-powered medium trucks are designed for a
3-inch Hg back pressure allowance. Wide open throttle (WOT) operation
is common in the case of trucks and high back pressures and ensuing high
exhaust valve area temperatures can affect engine durability. However,
school bus applications seldom require WOT operation, and if they do,
it is limited to a few hours only per day. Thus, higher back pressures
may be allowable on bus chassis rather than on comparable truck chassis.
There are a few problems associated with school bus exhaust systems.
Even when the exhaust pipe outlet noise is lowered, the long exhaust and
tail pipe can still generate noise from the muffler shell and pipe walls.
Horizontal muffler and tail pipe systems are inherently noisier than
comparable vertical systems because of ground-reflected acoustical energy.
The large bus floor undersurface also reflects the sound which escapes
from the sides resulting in higher sound levels on both sides of the bus.
The positioning of the muffler in the exhaust system is also criti-
11, 12, 13
cal, and some improvement in exhaust noise levels can be
obtained by experimenting with this. Since school bus exhaust systems
are optimized for engine cruise conditions, the exhaust noise has a
characteristic tinniness during brief periods of high and low engine
rpm.
No quantitative information is available for gasoline truck, bus,
or automobile exhaust noise levels for the various engine and muffler
combinations employed. The EE& Background Document for Medium and
5-12
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and Heavy Truck Regulations reports that exhaust noise levels of current
gasoline trucks under acceleration are around 80 dBA at 50 feet. Chrysler
Corporation has estimated the current production school bus exhaust noise
levels at 50 feet to be from 75 to 78 dBA under acceleration conditions.
b. Diesel Engines
Naturally aspirated diesel engine exhaust noise levels with currently
1
available mufflers range from about 70 to 82 dBA. Turbocharging results
in reduced exhaust noise levels but the selection of a muffler to take
advantage of this noise reduction requires care because allowable back
pressures are generally lower.
Data is available from manufacturers on the acoustic performance
of a given muffler on a given diesel engine. However, changes in pipe
routing, installation, etc., can have significant effects. Because of
packaging problems, transit bus exhaust pipe often take winding routes
between the two manifolds and the horizontal muffler. Newer model buses
have a vertical tail pipe routed through the left side of the bus. Older
buses have a short horizontal tail pipe exiting at the rear under the
engine.
The location of a muffler between the bus floor and pavement worsens
the effect of muffler shell radiated noise.
(3) Cooling System Noise
a. Conventional School Buses
The cooling system fan is a major component source of noise for trucks
and buses. Sound levels of fan noise at 50 feet vary from near 70 dBA
5-13
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to 85 dBA depending predominantly on fan blade tip speed and the
position of radiator shutters. Other components of the cooling system
generate noise, but are of secondary importance. Noise from the water
pump, belts and pullies, and air flow through the radiator contribute
very little to the overall noise level.
Because they are part of the fan environment, the engine, radiator,
shroud, cab, and other components all affect the cooling ability of the
vehicle. They also affect the noise generated by the fan because of the
effect which each component has on the air flow or the flow resistance
against which the fan must operate. Studies conducted by two major
heavy truck manufacturers under the DOT Quiet Truck Program have indicated
that modifications to improve the fan environment are very effective
in reducing the fan noise levels by allowing lower fan tip speeds without
14, 15
reduction in cooling ability.
The potential for reducing fan noise hinges on the possibilities for
maximizing the cooling rate at a given fan speed, thereby minimizing fan
speeds and/or fan-on time. Several approaches to such an optimization
have been suggested:
o Fan redesign
o Improved fan shrouds
o Increased cooling system pressures
o Optimized radiator to fan and fan to engine clearance
o Radiator redesign
o Fan clutches
o Ducts and flow deflectors
o Ring shrouds to prevent tip recirculation.
5-14
-------
A combination of these techniques has resulted in lowering fan
noise levels from 81.5 dBA to 66 dBA on the left, and from 80 dBA
to 68 dBA on the right side of an IHC model CF-4070A diesel cab-over
14
truck without reducing the cooling capacity* Similarly, the fan
noise level was lowered from 80 dBA to 64 dBA by using a different
combination of techniques for a Freight-liner cab-over truck using a
15
Cummins NTC-350 engine.
The following noise reductions have been demonstrated in the
laboratory for a 20-inch 5-bladed truck fan:
Reduction
dBA
Sealed shrouds and optimized fan coverage 4.5
Optimum fan-to-radiator distance .5
Engine mounted air deflector 4.0
Contoured shroud with 1/4-inch tip clearance 7.5
Optimized radiator heat transfer 2.0
These reductions are not always cumulative.
Generally about one-third of the total energy of the fuel used
in a gas engine is released as heat to the cooling system. Another
one-third is released as heat to the exhaust or radiated away, and the
remaining one-third generates useful power. This ratio varies with engine
configuration, compression ratio, spark timing, valve timing, engine load,
and speed. At idle, for instance, no useful power is developed and all
the fuel energy is released as heat. The heat released to the cooling
system is released to the atmosphere through the radiator. The fan
draws air through the radiator to improve heat transfer.
5-15
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The noise generated by an engine cooling fan can be decreased
by changing the fan drive ratio to reduce the maximum speed. This
change will also reduce the speed of the water pump and the fan speed
at idle. Both of these changes could cause cooling performance problems.
The water pump capacity may be recovered by increasing the diameter of
the water pump impeller, which may necessitate redesigning the entire
water pump on some engine models. Reducing fan capacity requires a
larger radiator to maintain the same cooling performance. Configura-
tion of the front end sheet metal on a bus limits the radiator size,
but the sheet metal can be raised on the frame to accommodate a
larger radiator. This change impacts bus body mounting, tooling,
and driver visibility.
Fortunately, the cooling problem is not critical for conventional
school buses. School buses use the same sheet metal as medium-duty
trucks, but are seldom fitted with the largest engine that is available
in trucks of the same load capacity. This would indicate that larger
radiators are available than currently fitted to most school buses. Also,
since the majority of school buses do not operate during the hot summer
months, the design temperature can be lower for a school bus than for a
truck. On the other hand, cooling performance at idle cannot be com-
promised on a school bus.
Air emission control requirements for gasoline engines also need
to be taken into account. Current engine designs require highly retarded
5-16
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ignition timing which increases the exhaust temperatures and heat rejec-
tion to the cooling system. The reduced compression ratios and changes
in camshaft to delay exhaust valve opening and increase valve overlap
also increase the heat rejection. On the other hand, the use of higher
temperature thermostats gives some relief.
The chief differences between the diesel truck application and
conventional gasoline bus application are summarized in Table 5-1.
It should be noted that the cooling systems of forward control
buses require special attention. The technology in the DOT Quiet
Truck Program is not directly applicable for such buses.
b. Transit and Intercity Buses
Urban transit buses of current design employ a radiator and fan
for engine cooling on the left side of the engine compartment. The
arrangement results in uneven flow speeds through the radiator, and
thus little or no ram air is obtained from the forward motion of the
bus. CMC intercity buses also employ the same arrangement.
MCI intercity buses employ twin radiators with thermostatically
controlled centrifugal fans at the top of the engine compartment directly
above the engine. The fans are connected to the radiators by ducts.
This arrangement results in a quiet cooling system with evenly distrib-
uted sound levels on the two sides.
The three DOT Transbus prototypes use different cooling system
arrangements. (For a discussion of the DOT Transbus Program see
Appendix B.) None of the Transbuses use Detroit Diesel engines.
5-17
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Table 5-1
Comparison of Cooling Fan Parameters for Gasoline
and Diesel Engines
Diesel Engine
Truck
Conventional
Gasoline Engine
School Bus
Maximum engine rpm
Heat rejection at idle
Heat rejection at
maximum throttle
Load factor
Fan-on time (when on-off
clutches are used)
Coolant pressure
Shutters
Air conditioners
2100
2 Btu/hp/min
24 Btu/hp/min
Sustained opera-
tion at maximum
engine speed
Under 5%
Atmospheric
Employed
Available
3600-4000
7 Btu/hp/min
27.5 Btu/hp/min
Under 20% of
time at maximum
engine speed
23-40%
14-16 psig
Generally not
employed
Rarely employed
5-18
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The AM General Transbus uses a Caterpillar 3406 TAPC turbocharged and
aftercooled 6-cylinder in-line diesel for propulsion. The engine cooling
radiator and the air conditioning condenser are mounted in series
directly above the engine across the rear of the coach. The cooling
fan is hydraulically driven, with no speed modulation. The CM Transbus
used a gas turbine and hence does not require a water cooling radiator.
The oil coolers were on the right side of the engine compartment with a
squirrel cage type fan directly driven off the accessory drive system.
The evaporators, including the two-speed circulation fans, are mounted
in the air conditioning compartment above the engine. The Rohr Indus-
tries Transbus uses a Cummins VT-903, V8 turbocharged diesel engine for
2
propulsion. The 1300 in cooling radiator with the transmission
oil cooler was located between the left side of the bus and the front
of the engine, the conventional location for current design buses. The
fan was hydraulically driven with the speed modulated to meet cooling
demands by a sensor in the bottom tank of the radiator.
Although it is not certain where the future transit bus cooling
systems will be located, for this discussion, it shall be assumed that the
radiator and fan will be located in the left hand side rear portion
until space considerations dictate relocation.
The advantage of locating the side-facing radiator close to the
rear end of the bus is that the radiator air inlet is in the only high
pressure area at the rear of the bus. The disadvantage of the rear
side-facing placement of the fan is that the air near this section of the
bus is relatively dirty. As a result the fan draws this dirt through
5-19
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the radiator and usually deposits it in the engine compartment.
MCI reports that on their intercity buses with compromised radiator
positioning, during actual operating conditions on the highway, the
cooling fan air flow is only 50 percent of the air flow measured
during static bus tests.
Current transit bus cooling fan noise levels range from 77 to 85
dBA under acceleration conditions. The fan-on time with viscous fan
clutches is on the average higher than for trucks. It depends on the
operation cycle of the bus which may range from intermittent city opera-
tion to an occasional continuous highway cruise. The GM and Rohr quieted
buses used a fan clutch to lower noise levels on the left side of the bus
to 73 dBA. Even when the fan is engaged, it does not reach full engine
speed under normal operation.
(3) Air Intake Noise
Air intake noise of gasoline engines is included in the engine noise
for reasons discussed earlier. The following discussion will be limited
mainly to diesel engine intake systems.
Intake noise is produced by the opening and the closing of the
inlet valve. When the valve opens, the pressure in the cylinder is usually
above atmospheric and a sharp positive pressure pulse sets the air in the
inlet passage into oscillation at the natural frequency of the air column.
This oscillation is rapidly damped by the changing volume caused by the
piston's downward motion. When the inlet valve closes it produces similar
pressure oscillations, which are relatively undamped. In the diesel engine,
5-20
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air inlet noise is generally observed in the low to middle frequencies (up
to 1000 Hz). (On gasoline engine, this inlet noise may be inportant at
higher octave bands due to the flow noise produced in the carburetor.)
Typical unsilenced intake noise levels for truck diesel engines at
high idle vary between 70 dBA and 85 dBA, measured at 50 feet from
the engine inlet. Production air filters used on most trucks provide a
noise reduction (Insertion Loss) of from 9 to 22 dBA. In the case of
eleven trucks with Detroit Diesel Engines and production model intake
17
filters, intake noise exceeded the noise levels from the remaining
components in only one case. Six trucks had sufficiently quiet air
intake such that further reduction of the intake noise would not be of
any benefit to overall vehicle noise levels. The remaining trucks
showed overall noise reductions of 0.5 to 3 dBA for a 6 dBA reduction
of intake noise. If the noise from remaining components were lowered,
intake noise would assume greater importance for a great proportion
of trucks.
Intake filters act as silencers because of the sound absorption
properties of the filter element and because of the area changes.
Additional silencing may be provided by designing flow passages to
restrict line-of-sight transmission.
Heavy duty oil bath cleaners used in transit buses are good
noise suppressors. Cleaners that have large flat sections of sheet
metal can radiate significant amounts of noise from mechanical vibra-
tions. Use of rubber sections such as elbows, tubes or connectors
in the air intake piping should be avoided as much as possible. Most
5-21
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rubber sections are not good acoustic barriers and radiate excessive
amounts of noise because of their pulsating walls.
For maximum quieting, an additional intake silencer can be in-
stalled between the air cleaner and the engine inlet. These devices
are not particularly expensive, are easy to install, and will do a good
job of absorbing higher frequency noises. The silencer should be
installed as close to the engine inlet as possible. The additional
space requirement may be a problem in transit and forward control
school buses.
With the precautions outlined above, the attainment of intake
noise levels under 65 dBA is practicable with available intake
filters for diesel engines.
(5) Chassis and Accessory Noise
In the category of chassis noise, the coasting noise of the vehicle
with no propulsive power being applied to the vehicle and the noise from
the remaining minor sources such as air conditioning and air brake
compressors are included.
18
Motor Industries Research Association (MIRA) has collected
data on coasting noise levels for a broad range of vehicles. Coasting
rtoise depends on size or weight of vehicle, conditions of road surface,
and road speed. Variations might also be expected due to tire tread
pattern and construction, number of axles and tires, axle loadings,
and bus body surface area. A useful general relationship for the
5-22
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coasting noise of a vehicle at 30 mph (44 fps) on a smooth, dry surface
is given by the equation:
dBA = 65 + 7 log W
10
where:
W = gross vehicle weight in tons
dBA = sound level 7-1/2 meters from vehicle centerline.
A typical school bus of 23,000 Ib GVWR according to this formula will
produce 66 dBA at 50 feet while coasting at 30 mph. A vehicle of
10,000 Ibs GVWR will produce 64 dBA under the same conditions.
EPA conducted tests on the coasting levels of several school buses
25
of 17,400 Ib to 23,000 Ib GVW rating chassis. A 23,000 Ib GVWR bus
measured 65 dBA on the curbside and 69 dBA on the streetside while
coasting at 30 mph. A 17,400 Ib GVWR bus equipped with snow tires
measured 73 dBA on the curbside and 74 dBA on the streetside while
coasting at 30 mph. Both tests were conducted with the engine idling,
the transmission in neutral, and all accessories on. Hence the measured
levels reflect the total chassis noise levels to be expected rather than
the coast-by noise alone.
Current school bus chassis noise levels appear to be in the 65 to
74 dBA range at 30 mph with the engine shut off. Coast-by noise levels
for conventional school buses (without accessory noise) without snow tires
are approximately 64 to 68 dBA. Chassis noise levels can approach these
coast-by levels by lowering the contributions from accessories and body
vibrations.
5-23
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Chassis noise levels of current transit buses range from 65 to
16
76 dBA for 35 ft. and 40 ft coaches. It is felt that chassis noise
levels of 70 dBA are achievable on today's 40-foot transit coach.
In the case of integral design transit buses, the outer skin
panels are load-carrying members. Hence any road or engine vibrations
transmitted through the suspension or engine mounts will be transmitted
to the skin as stress and result in vibrations of the panels. These
panels are acoustically efficient radiators of sound at audible fre-
quencies. The mounting of accessories will need special care to avoid
excitation of the body panels into resonance. Ihe windows of the bus
should also receive attention. Apart from rattles, loose window panes
also result in large vibrating surfaces and hence chassis noise.
5-24
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Overall Noise Abatement
The abatement of bus noise is a systems problem. In the following
discussion, the classification of buses according to their noise com-
ponent configurations attempts to make the total universe of buses
into a manageable number of systems that are similar from the noise
abatement viewpoint. Total bus noise abatement is further broken down
into a number of steps or target noise levels. Each targeted noise
level may be achieved by combining component noise control measures
in a specific way. System compatibility is implicit in the selection
of such combinations.
In general, noise control strategy is determined by the source
levels of the noisiest and/or most difficult-to-control components. The
successive steps in noise reduction invariably require increasingly more
complex, and in most cases increasingly expensive, technologies.
(1) Conventional Gasoline-Powered School Buses
Five study levels have been identified for conventional gasoline-pow-
ered school buses. Component levels to achieve each study level are indic-
ated in Table 5-2. The production bus noise design levels should be 2 to
3 dBA under the targeted not to exceed noise levels, as shown.
Table 5-2
Component Noise Level Matrix for Gasoline-Powered Conventional School Buses
Sound Level, SAE J366b Test, dBA
Bus exterior study level 83 80 77 75 73
(Not to exceed level)
Bus design level 80.0 77.5 74.5 72.0 70.5
Engine and intake 77 74 71 68 65
Exhaust 73 69 65 65 64
Cooling fan 73 70 64 64 64
Chassis and accessories 70 70 70 65 65
Interior Study Level (at driver) 83 80 80 75 75
5-25
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83 dBA Exterior and Interior Study Levels
Engine
No special engine, intake or transmission treatments will be needed.
Exhaust System
The use of best available mufflers will be sufficient to obtain 73
dBA exhaust noise levels. The muffler will be located in an optimum
position for the school bus exhaust system after the tail pipe length
has been adjusted for the body length.
Cooling Fan
To obtain the 73 dBA fan noise level, careful sealing of the
shroud to the radiator along with optimization of fan coverage by the
shroud will be needed to maximize the air flow. In tests conducted by
International Harvester Company, the air flow rate was increased by
this method from 10.66 Ib/sec to 11.5 Ib/sec (see Figure 5-2). Optimum
fan coverage for the sealed shroud was obtained at 90 to 100 percent
coverage, while the original unsealed shroud gave maximum air flow rates
at 65 percent coverage. The increased air flow rate allowed a reduction
of fan speed to reduce overall noise level by as much as 5 dBA. Opti-
mization will help only to the extent of the actual departure in the
present system. The reduction in fan maximum speed can be obtained by
providing a viscous type fan clutch. The latter approach is recommended
because it has the advantage of minimizing the fan power requirements when
cooling loads are less than maximum. Because there is always some slippage
at fan speeds approaching maximum shift speed, the maximum fan speed will
be automatically lowered with the usage of a fan clutch.
5-26
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Figure 5-2
Effect of Fan Coverage on Air Flow
With Shroud Sealed to Radiator
pw
12 -
u
O
10 -
50
100
Fan coverage ( — ) percent
p w
Fan Speed 2520 rpm.
Source: International Harvester Company
5-27
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An on-off type clutch is not considered to be a feasible solution
because it will not lower the maximum fan speed, unless the engine to
fan pulley ratio is changed appropriately.
In those cases where the sealing of the shroud and optimizing fan
coverage does not result in sufficient noise reductions, flow rates may
be increased further by choosing a fan that will allow reduction in
shaft speed. This again is dependent on the present fan on the vehicle.
In most cases, increasing the number of blades and/or blade twist will
result in achieving the air flow at reduced speeds. A shaft speed reduc-
tion of ten percent will be sufficient.
Chassis
The required 70 dBA level for chassis and accessories is already
attained by most gasoline school buses on the road today.
With the above exterior technologies interior noise should be
reduced to the 83 dBA level.
80 dBA Exterior and Interior Study Levels
Engine
Some engines may require the inclusion of acoustic treatment of engine
hood. For this, acoustic barrier-cum-absorption material of the type
currently used for automobile hood insulation may be added.
To reach the interior noise level of 80 dBA at the driver's location,
2
one layer of barrier-type acoustic insulation weighing 1 Ib/ft should be
employed at the cowl face and under the floor extending about 5 feet as
shown in Figure 5-3. All holes in the firewall for pedal linkages, steering
column, etc., should be carefully sealed with heavy rubber boots.
5-28
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Figure 5-3
Engine Noise Abatement
by Shielding
Barrier Material
Attached to Firewall
Approximate Area of Barrier = 25 ft"
5-29
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Exhaust
To reduce exhaust noise to 69 dBA, larger, more advanced mufflers
will be needed. Careful design of the exhaust system to place the muffler
in the optimum position will be necessary. It will also be necessary for
the exhaust system designer to specify that the tail pipe length not be
altered by anyone adapting the chassis to school bus application.
19
In April 1973, CMC reported that by using a larger muffler, with
the pipes rerouted where possible to lie within the confines of any engine
compartment shielding and to avoid conflict with a belly pan installation,
the exhaust noise level of a CE 6500 gasoline engine truck was successfully
lowered from 83 dBA to 70 dBA.
Automotive mufflers are designed empirically by the muffler manufac-
turers who work with the engine manufacturers to achieve acceptable noise
11
reduction without loss in performance. For a simple expansion chamber
muffler, the transmission loss increases by a maximum of 7 dBA for a doubling
20
of expansion ratio. Increased expansion ratios can be obtained without
increasing the thickness of the mufflers by using elliptical cross sections.
It is estimated that almost a doubling of muffler volume will be needed to
achieve exhaust noise levels of under 69 dBA, which are 4 to 5 dBA below
those of currently available mufflers.
Special attention must be given to the support system for the exhaust
pipes and muffler under the bus floor to prevent the transmission of vibra-
tions to the chassis. Airborne noise could also excite the floor to radi-
ate noise to the bus interior. Current plywood floor designs appear
adequate in reducing floor transmitted exhaust noise to the bus interior.
5-30
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Cooling Fan
Two alternate approaches are possible for achieving fan noise
levels of under 70 dBA.
1. Contoured Shroud with 1/4-Inch Tip Clearance
This type of shroud is shown diagrammatically in Figure 5-4.
Tests by the International Harvester Company have shown that the use of this
shroud resulted in allowing fan speed to be reduced by 6 percent while
3 to 6 dBA noise reduction was obtained in comparison to the noise level
of the carefully sealed shroud. The shroud will need to be mounted in
such a way as to maintain the 1/4-inch clearance even when the engine
moves relative to the radiator. This can be achieved by mounting part
of the shroud to the engine and part to the radiator with the two sections
connected together by a flexible rubber boot. Recent road tests completed
on a truck equipped with such a shroud have demonstrated the practicality
21
of this design.
Total noise reduction expected from using the low tip clearance
shroud with careful seals, a viscous clutch and a seven-blade fan will
be between 10 and 13 dBA. The maximum fan speed has now been lowered to
79 percent of the original fan speed without sacrificing air flow and hence
cooling system performance. The radiator has not been altered in any way.
2. Increased Radiator and Fan Size
Increasing the radiator area can result in significant reduction in
1
fan rpm and noise. Estimates show that by using simple fan laws show
that increasing the radiator area by 20 percent and the fan diameter by
10 percent, fan rpm can be lowered by 37 percent without sacrificing
5-31
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Figure 5-4
Engine-Mounted 1/4 Inch Tip
Clearance Shroud
Radiator
— —D
Flexible
Rubber Seal
Mounting Strut
(one of three)
5-32
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cooling capacity. This would in turn result in lowering the fan noise
level by 8 <3BA. Additional noise reduction can be obtained by careful
fan and radiator sealing and increasing fan diameter (the larger radiator
will allow this).
Chassis and Accessories
Current chassis noise levels are sufficiently low and no treatment
will be required.
77 dBA Exterior and 80 dBA Interior Study Levels
Engine
To reach the 71 dBA required engine noise level/ additional en-
gine side shields will be required. These may be located as sketched in
Figure 5-5. The shield may be made from 20 gauge steel sheets lined on
the inside with a 2-inch layer of acoustical glass fiber. To keep the
glass fiber from losing its effectiveness from saturation with oil, gaso-
line, or water, a 2-mil nonflammable plastic barrier should be provided.
Finally, a perforated thin (22 gauge) metal cover should be added on the
inside to minimize mechanical wear and tear. This is sketched in Figure
5-6. Glass fiber materials are relatively inexpensive. The study of
currently available cowl and engine sizes for school buses indicates that
sufficient space is available for such shields and no alteration in cowl
design will be necessary.
The reduction in open area around the engine may result in some loss of
cooling air flow. Thus, in all probability/ cooling fan redesign would be
needed to achieve the 77 dBA bus regulated level.
5-33
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Figure 5-5
Engine Side Shields in Position For
77 dBA Overall Bus Noise Levels
Steel-Glass Fiber Side Shields
Details in Fig. 5_6
Chassis Rail
5-34
-------
Figure 5-6
Detail of Side Shield Construction
2-Inch Glass Fiber
Filling
20 Gauge
Steel Sheet
Fender
Side
Perforated 22-Gauge Steel
Sheet Over 2 mil Thick
Non-Flammable Plastic
Engine
Side
Approximate Dimensions:
30" x 22" x 2"
5-35
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The transmission noise at this level is expected to be sufficiently
below engine noise so as not to warrant any attention.
Engine accessibility will be somewhat reduced by the incorporation of
»
side shields.
Exhaust System
To reach exhaust noise levels of 65 dBA will require a carefully
designed advanced dual horizontal exhaust system with double walled
mufflers and premufflers or resonators to optimize the system under cruise
as well as high rpm conditions.
The use of a dual system allows greater expansion volume for the
exhaust gases and hence greater reduction of the pulsations which are
responsible for exhaust noise, The larger flow areas allowed by dual
pipes will also reduce the existing velocity of gases which is responsible
for the characteristic hiss of well-silenced exhaust systems of some of
the current luxury automobiles.
Heavier gauge exhaust and tail pipes with gastight exhaust joints will
be needed to minimize shell radiation and leaks.
The use of premufflers or resonators may not be necessary for all
engines. Since insertion loss data for mufflers and resonators designed
for the gasoline engines is not available, it is not possible to make any
judgments at this time as to which engines may need less treatment.
Double wall mufflers are currently being made available for diesel
truck applications by several manufacturers: Donaldson Co., Riker and
5-36
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Stemco. Donaldson markets the "Silent Partner" muffler wrap which
consists of an asbestos blanket held in place by a stainless steel
wrap together cover. Although current designs are for diesel truck
vertical stack mufflers, little development is expected to be
necessary to adapt these techniques to horizontal mufflers for school
bus applications.
Cooling Fan
For achieving overall bus noise levels of under 78 dBA, fan
design noise levels will need to be lowered to 64 dBA and under.
This is 13 to 18 dBA under current gasoline engine bus fan noise
levels. These levels have already been demonstrated by International
Harvester and Freightliner quiet trucks. International Harvester
Company was able to achieve a 66 dBA fan noise level by employing a
1/4-inch tip clearance fan shroud along with an engine enclosure which
reduces fan noise level by 2 dB and by replacing the original 4 row,
•
11 fin-per-inch, plate fin radiator by a 4 row, 14 fin-per-inch, serpen-
tine fin radiator. Freightliner Corporation achieved a 64 dBA estimated
fan noise level by replacing the standard 28 inch six-bladed fan with a
specially made 31 inch seven-bladed fan featuring staggered blade spacing
manufactured by Schwitzer Corporation. The fan speed was lowered from
2
2100 rpm to 1280 rpm and the standard 1200 in six-row radiator was
2
replaced by a 2000 in four-row radiator.
For current application to gasoline powered school buses, the
suggested method of achieving the 64 dBA level is to increase radiator
5-37
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frontal area by 20 percent and fan diameter by approximately 10 percent.
An engine-mounted close-fitting shroud should be used along with an
advanced serpentine-fin radiator with approximately 30 percent greater
heat transfer area than a comparable plate-fin type radiator. The
increased core thickness of the serpentine fin radiator will result in a
slightly greater pressure drop across the radiator resulting in somewhat
greater fan speed. However, the overall effect of all the improvements
will allow fan rpm to be lowered to almost 50 percent of the original
fan speed.
With this low fan speed, the fan shaft, pulley, and belt system
will need to be redesigned. The water pump could be mounted on a
separate shaft independent of the fan shaft so as to make its redesign
unnecessary.
Chassis and Accessories
No treatment is anticipated.
75 dBA Exterior and Interior Study Levels
Engine and Intake
To reach the 68 dBA source level, gasoline engines will require
the side shields shown in Figure 5-5 and an underpan between the radiator
and bell housing. Since gasoline engines require servicing from underneath
for regular oil changes, an underpan with small removable panels such as
that sketched in Figure 5-7 will be suitable. Some innovative provision
5-38
-------
Figure 5-7
Possible Underpan Configuration for
Achieving 75 dBA
Overall Noise Level
Barrier
n
i (
i
1
i
_, \
\
t=
\
<;
1
I
Underpan
Cross-Section
Under Engine
Rubber
Isolation
Material
Drainhole
Flange
Mounted to
Chassis Rails
Hinged Cover
5-39
-------
is necessary to ensure that the removable panels are always replaced after
the routine maintenance or servicing; otherwise, the benefit of the
underpan may be greatly reduced. One method to accomplish this would be
to hinge the panel so that it cannot be completely removed and discarded.
Warning labels could be attached to the panels to make maintenance personnel
aware of the purpose of these panels.
Hazards due bo fuel or oil collection in the underpan can be
minimized by careful design so that the liquid flows to a small drain
hole under all operating conditions. Again, the cooling capacity may
need to be increased to provide adequate ventilation and air flow rates.
This is not expected to increase fan noise since the side shields and
underpan will provide sound attenuation to fan noise also. This treat-
ment is expected to lower engine and air intake contribution from 2 to
5 dBA.
To achieve the interior noise levels, engine vibrations trans-
mitted through the chassis will need to be lowered by isolating the
engine or by isolating the body from the chassis.
Exhaust
The exhaust system will not need any alteration beyond that re-
quired for the previous study level.
»
Cooling Fan
The cooling system will need readjustment because of the presence
of the engine belly pan. The increased flow restriction will require
5-40
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the maximum fan speed to be increased. To maintain the fan source
level at 64 dBA, the engine side shield should be redesigned to give
some shielding to fan noise escaping from the sides of the cowl.
Chassis and Accessories
To meet the bus noise levels of 75 dBA, the chassis exterior
noise design levels will need to be at 65 dBA and under. To approach
this noise on buses over 23,000 GVWR will require careful body design
to minimize noise radiation from body panels. Some critical body panels
may need damping treatment or stiffening to make them inefficient radia-
tors of sound energy at the troublesome frequencies peculiar to the body-
chassis combination.
The isolation between the body and chassis will need improvement.
School buses employ truck chassis with stiffer suspensions than those
employed for automobiles. The number of isolation pads between the
chassis and the body should be kept at a minimum since each pad provides
a path for some of the chassis vibrations to the body. Doubling the
thickness and halving the stiffness of the rubber pads, for example,
will lower the critical frequency by a factor of 1.4 and improve the
isolation over a greater range of frequencies. Floor insulation in
the form of double flooring with isolation material in between has been
in use by Crown Coach for reducing road noise inside their diesel buses.
This technique will be very helpful in lowering engine contributed interior
levels also if the floor and body are carefully isolated from the chassis.
5-41
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Interior carpeting, fabric covering of roof, and safety padding
of seats and bus walls can reduce interior noise levels further if
necessary.
73 dBA Exterior and 75 dBA Interior Study Levels
Engine
To reach the 65 dBA engine noise level, side shields will need
to be extended to include the rerouted exhaust pipes which should be lagged
with thermal insulation. The cowl lid will need additional acoustical
treatment that will lock into the side shields. The engine will be virtually
encapsulated. This is conceptually shown in Figure 5-8.
Enclosure design technology has been demonstrated through experience
with the Quiet Truck Program. It should be noted that the enclosure will
provide shielding also to the fan noise. The greater heat buildup in the
engine compartment and increased restriction to the air-flow will require
cooling fan speeds to be increased, which will nullify some of the acousti-
cal benefits of shields. It is anticipated that in spite of this, the
enclosure will provide reductions of 5 to 8 dBA to the engine noise and
about 2 dBA to the fan noise.
The air intake noise will need further suppression by adding an
intake silencer between the carburetor and air filter.
The lowered engine and other component noise levels will require
some attention to the transmission casing, which may need to be redesigned.
5-42
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Figure 5-8
Engine Enclosure for Achieving
73 dBA Overall Bus Noise Level
Underhood
Insulation
Extended
Side Shield
Sealing
Arrangement
Underpan
5-43
-------
Approaches to reduce airborne noise radiation by the transmission
housing include the application of damping material to reduce resonant
amplification, the stiffening, or the weakening of housing areas to
shift resonance frequency components out of the range of excitation
forces; the decoupling housing areas by slotting or by adding mass
22
dampers, and the altering of panel geometries. Transmission manu-
facturers are already aware of these techniques and are anticipating
future noise reduction needs.
Exhaust System
The achievement of 73 dBA overall bus noise levels will require
the reduction of exhaust noise levels to 64 dBA or below. This is
only one decibel below the levels for the previous case and will not
require any major improvements in exhaust systems. It may be necessary
to lag some lengths of the exhaust pipes between the engine and the
mufflers to reduce pipe wall radiated noise and to minimize tempera-
tures in the engine enclosure. This section of the exhaust system
generally carries the largest pulsations from the engine exhaust.
Currently one of the bus exhaust system manufacturers, AP Parts Co.,
is working on the development of double walled exhaust pipes, and re-
ports promising results.
Cooling Fan System
The cooling system will need readjustment to maintain adequate
cooling in the presence of the sealed engine enclosure.
5-44
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(2) Conventional Diesel Powered School Buses
Based on data from diesel trucks, the attainable exterior noise
levels from conventional diesel school buses range from 83 dBA to
75 dBA, which is the lowest study level.
Allowing 2-3 dBA for variation among production buses, the design
levels would range from 80.5 dBA to 72.5 dBA. Table 5-3 shows the
targeted study "not to exceed" levels and design exterior noise levels
along with a set of possible combinations of component levels to achieve
the overall noise levels. Other component noise level combinations may
be used to achieve the same overall noise levels, but those shown in
Table 5-3 appear to be the most logical.
Interior levels ranging from 86 dBA to 75 dBA can be met using
similar techiques as discussed for conventional gasoline-powered
school buses.
The noise control packages are summarized below:
Table 5-3
Component Noise Level Matrix for Diesel-Powered Conventional School Buses
Sound Level, SAE J366b Test, dBA
Bus Exterior Study Level
(Not to exceed level)
Exterior Design Level
Engine
Exhaust
Fan
Intake
Chassis and Accessories
Interior Level at Driver
83
80.5
77
73
73
72
70
86
80
77.5
74
69
70
69
70
83
77
74.5
71
68
64
65
65
80
75
72.5
68
65
64
65
65
75
5-45
-------
83 dBA Exterior and 86 dBA Interior Study Levels
Engine
Diesel engine noise can be reduced to a source level of 77 dBA
by using engine quieting kits. Such kits include covers for the sides
of the engine block and oil pan, vibration isolation of the valve covers
or air intake manifolds, and cross-overs and possible damping treatment
on sheet metal covers.
The engine hood should be lined with acoustical material such as
non-flammable felt or glass wool.
No special treatment will be needed to reach the 86 dBA interior
level beyond the application of the exterior technology.
Exhaust System
Exhaust noise levels of 73 dBA will need available advanced double-
wrapped mufflers. A premuffler may be needed to obtain maximum attenua-
tion over the broad range of frequencies characteristic of engine opera-
tion over a wide speed range.
Cooling System
Cooling system design will be similar to that used to achieve 73
dBA source noise levels for gasoline engine buses.
Intake
Air intake noise from most current diesel engines is below 72 dBA
with available intake filters.
Chassis
No treatment will be necessary.
80 dBA Exterior and 83 dBA Interior Study Levels
Engine
In order to attain this level/ engine noise shields and an underpan
would be required. A sketch of side shields is shown in Figure 5-5,
5-46
-------
whereas a possible underpan configuration is shown in Figure 5-7. The
side shields and underpan have been described in detail for gasoline engine
buses. The dimensions of the shield will be somewhat larger than those
shown in Figure 5-5.
For the interior level technology refer to the 80 dBA interior tech-
nology of gasoline-powered conventional school buses.
Exhaust System
Mufflers with exhaust design levels of 70 dBA or lower are currently
not available. One way or reducing the exhaust noise is to use a turbo-
charged engine instead of a naturally aspirated engine. Because of addi-
tional expansion of exhaust gases through the turbocharger, the exhaust
noise levels should be significantly reduced. Alternately, diesel truck muffler
manufacturers currently have several experimental mufflers that could be
modified for bus applications to give source levels under 69 dBA.
Cooling System
The cooling system design will be similar to that for attaining 70
dBA source levels for gasoline engine buses described earlier.
Intake
In order to attain the design level of 69 dBA, some noise treat-
ment would be required. On the International Harvester Quiet Truck,
the intake noise was reduced from 72 dBA to 69 dBA by replacing
10
the intake rain cap with one with a better design. Thus, it is
possible to achieve the intake design level of 69 dBA by using better
designed parts for the intake system.
Chassis and Accessories
No treatment will be necessary.
5-47
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77 dBA Exterior and 80 dBA Interior Study Levels
Engine
Most medium duty truck engines can be quieted to a 71 dBA source
level by using side shields and an underpan as mentioned in the control
pcakage for 74 dBA. The noisiest engines may require a flow-through
engine enclosure with special engine mounts. Figure 5-8 shows such an
enclosed engine.
If a turbocharged engine has been substituted for meeting air emission
and exhaust noise levels a larger engine cab will be required.
For attaining the interior level refer to the technology for the
75 dBA interior level of conventional gasoline-powered school buses.
Exhaust System
In addition to the exhaust system modifications described for achiev-
ing the previous study level, exhaust pipes may need to be wrapped with
thermal/acoustical material.
Cooling System
The cooling system design will be the same as that for gasoline
engine buses for attaining the same source level.
Intake
An air intake silencer will be required.
Chassis and accessories
The same considerations for gasoline powered buses will be applicable
for attaining the 65 dBA chassis and accessory source level.
5-48
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75 dBA Exterior and Interior Study Levels
Engine
Attainment of 68 dBA source level for diesel engines will be
difficult. Engines will be turbocharged and a sealed tunnel type flow-
through enclosure will be mandatory. Major redesigns of engine cowl
and cooling system will be required.
For attaining the interior 75 dBA level, refer to the technology
for the 75 dBA interior level of conventional gasoline powered school
buses.
Exhaust System
In order to achieve this level, manifold mufflers or advanced
double-walled dual mufflers, double-wall exhaust piping, and pipe joint
seals would be required. Exhaust design levels of 65 dBA or lower have
been demonstrated on the Freightliner Quiet Truck and the Flxible quieted
bus. Quieting exhaust noise to this level would require additional lead
time beyond the normal development to productio.n lead times.
*
Cooling System
The system will be similar to that for gasoline engine buses. However,
due to the greater space limitations in engine cab, a redesign from the pre-
vious level cooling system will be required.
Chassis and Accessories
No additional treatment beyond the previous level will be required.
(3) Front-Engine Forward Control School Buses, Parcel Delivery Chassis
SchooX Buses and Motor Home Chassis Buses
The progression of noise levels and corresponding source levels
of these vehicles will be the same as those levels for school buses with
5-49
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conventional chassis powered by gasoline and diesel engines except for
the 73 dBA level for gasoline engine vehicles, which is not felt to be
applicable to the forward control school buses. The 73 dBA level and
its attendant technology is applicable, however, to parcel delivery
chassis and motor home chassis buses.
The methods for achieving these levels in forward control, parcel
delivery chassis and motor home chassis buses will be identical to
conventional school buses using similar engines, except that space
constraints will be more severe. Interior noise levels will be more
difficult to achieve, while the contribution of the engine to exterior
noise levels will be of a lesser extent.
(4) Mid-Engine School Buses
Exterior noise level reduction and component noise levels to achieve
the overall noise level reduction for mid-engine school buses are shown
in Table 5-4.
It is assumed that the bus will need to be designed to produce a
noise level on the average 2 to 3 dBA below the not to exceed
level because of the expected spread in production vehicle noise levels.
The noise control packages are summarized below.
86 dBA Exterior and 88 dBA Interior (Over Engine) Study Levels
Existing noise levels generated by this type of bus under
acceleration are expected to meet a 83.5 dBA design level without any
additional applied technology.
5-50
-------
Table 5-4
Component Noise Level Matrix for Mid-Engine School Buses
Sound Level, SAE J366b, dBA
Bus Exterior Study Level 86 83 80 77 75
(Not to exceed)
Exterior Design Level
Engine
Exhaust
Cooling Fan
Intake
Chassis
Interior (Over Engine)
83.5
79
79
77
65
70
88
80.5
75
75
76
65
70
86
77.5
71
70
73
65
70
83
75.0
71
65
70
65
65
80
72.5
67
65
65
65
65
78
83 dBA Exterior and 86 dBA Interior (Over Engine) Study Levels
To achieve this study noise level, damped engine covers and oil pan
will need to be incorporated and engine compartment treated to minimize
transmission of engine airborne noises.
Advanced double wall mufflers and premuffler compartments will be
needed. (These mufflers have been used in the DOT quiet truck program.)
All leaks between radiator, bus sidewall, and shroud should be
sealed and a thermostatically controlled fan clutch incorporated.
These treatments should result in lowering interior noise level
above the engine to 86 dBA.
5-51
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80 dBA Exterior and 83 dBA Interior (Over Engine) Study Levels
To achieve this study noise level, the engine compartment will
need belly pans.
The exhaust system will need improvement to achieve 70 dBA for
non-turbocharged engines. This can be obtained by adding a large
resonator in series with the main muffler. Leaks in exhaust system
become very important at this level and consequently must be sealed.
The engine mounts will need improvements to reduce transmission
of vibration to floor and body members.
77 dBA Exterior and 80 dBA Interior (Over Engine) Study Levels
To achieve this study level, the exhaust and cooling system will
need further improvement. The non-turbocharged engine would have to
be replaced with a turbocharged engine and a large resonator would be
needed.
Providing a 10 percent greater radiator area and engine mounted
contoured shroud with 1/4-inch tip clearance can be expected to reduce
the cooling fan noise to 70 dBA. To increase the radiator area, a
larger radiator would be required. To reduce the chassis noise to 65
dBA, the body panel design should consider the resonant modes of all
body panels. Damping treatment on the inside or outside of the panels
may be required. A floating slab floor may also need to be employed to
achieve the interior noise level.
75 dBA Exterior and 78 dBA Interior (Over Engine) Study Levels
The achievement of the 75 dBA level has been demonstrated for the
rear engine Scania CR HIM bus (see Appendix A).
5-52
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Total engine encapsulation would be required. To provide adequate
engine cooling, two radiators located on either side of the engine might
be necessary along with thermostatically controlled fans or blowers.
(5) Rear-Engine School Buses (Integral and Body-on-Chassis)
Exterior noise level reduction and component noise levels to
achieve the overall noise level reduction from rear-engine school buses
are shown in Table 5-5. Because of variation in noise levels among
production buses, the design noise levels are 2-3 dBA below the "not
to exceed" levels.
Table 5-5
Component Noise Level Matrix for Rear-Engine
School Buses (Integral and Body-on-Chassis)
J366b Sound Level, dBA
Bus Exterior Study Level
(Not to exceed level)
Bus Exterior 'Design Level
Engine and Transmission
Exhaust System
Cooling Fan
Intake
Chassis
Interior Level (Rear)
86 dBA Exterior and 84 dBA Interior
86
83.5
79
79
77
65
70
84
(Rear)
83
80.5
75
75
76
65
70
83
Study
81
78.5
75
70
73
65
70
83
Levels
80
77.5
71
70
73
65
70
80
77
75.0
71
65
68
65
68
80
75
72.5
65
65
65
65
68
78
Existing noise levels generated by this type of bus under acceleration
are expected to meet the proposed 83.5 dBA design level without any
additional applied technology.
5-53
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83 dBA Exterior and 83 dBA Interior (Rear) Study Levels
Damped engine covers and an oil pan should be incorporated. Engine
compartment should be treated to minimize transmission of engine and fan
airborne noises.
Double wall or wrapped body mufflers will be needed to produce
75 dBA exhaust noise levels. These mufflers are currently under develop-
ment by muffler manufacturers.
All leaks between the radiator, the bus sidewall and the fan shroud
should be sealed and a thermostatic control fan clutch incorporated.
81 dBA Exterior and 83 dBA Interior (Rear) Study Levels
The engine and transmission treatment remains the same as for previous
levels. The exhaust system will need improvement to achieve 70 dBA. This
can be obtained either by substituting a turbocharged engine or by adding
a large resonator in series with the main muffler. Leaks in the exhaust system
become iinportant.
Rectangular cooling fan shrouds should be replaced by contoured shrouds
and fan coverage reoptimized. This may need adjustment of fan to radiator
distance. Sealing and thermostatic fan speed control will be needed.
80 dBA Exterior and 80 dBA Interior (Rear) Study Levels
The exhaust system remains identical to the previous step. Engine
contributed level will be lowered to 71 dBA by providing a sealed belly
pan, an acoustically treated exit duct, and a line-of-sight shield between
the engine and the fan.
The fan will have to be replaced with one capable of delivering
the same airflow as before against a greater total head.
5-54
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Engine mounts will need improvement. Body panel vibrations in rear
area will need to be minimized by damping or isolation or by means of
barrier material. Interior reverberations should be minimized with acous-
tical material.
77 dBA Exterior and 80 dBA Interior (Rear) Study Levels
The exhaust and cooling systems will need further improvement. A
turbocharged engine with manifold mufflers or turbocharged engine with
improved resonators and a muffler with stack silencers will be needed.
Contoured or venturi shroud with 1/4-inch tip clearance will be required
along with 10 percent increase in radiator frontal area.
75 dBA Exterior and 78 dBA Interior (Rear) Study Levels
This level will need either total engine encapsulation or an improved
flow-through engine enclosure. Both concepts need development and extensive
testing. Some passenger seats will most probably be lost. Detailed discus-
sion given for urban transit buses will be applicable. A floating slab floor
may be required for attainment of the interior noise level.
(6) Urban Transit Buses
The lowest exterior noise level of integral transit buses studied was
75 dBA at 50 feet, measured according to the Section 8 (recommended)
procedure. Current transit bus noise levels with the cooling fan engaged
can be under 86 dBA with little difficulty. Step-by-step reduction of
noise levels of major contributors can result in four intermediate levels
as shown in Table 5-6.
5-55
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Table 5-6
Component Noise Level Matrix for Diesel
Powered Integral Transit Buses
J366b Sound
Bus Exterior Study Level
(Not to exceed level)
Bus Exterior Design Level
Engine and Transmission
Exhaust System
Cooling Fan
Intake
Chassis
Interior (Rear)
86
83.5
79
79
77
65
70
84
83
80.5
75
75
76
65
70
83
81
78.5
75
70
73
65
70
83
Level ,
80
77.5
71
70
73
65
70
80
dBA
77
74.5
71
65
68
65
68
80
75
72.5
65
65
65
65
68
78
With the application of the exterior noise abatement technologies
for transit buses outlined in the following discussion, the interior
noise levels at the rear of transit buses should be met. However, in
some cases additional treatment may be necessary. Refer to the discus-
sion of interior noise abatement technology for intercity buses for a
description of additional interior noise abatement technology which will
be applicable to transit buses.
86 dBA Exterior Study and 84 dBA Interior (Rear) Study Levels
Engine
No treatment to the engine or engine compartment is considered
necessary for achieving exterior engine source level of 79 dBA. The
blocking of all airborne engine noise from the passenger compartment will
be essential to achieve the interior level of 84 dBA at the rear seat
location.
5-56
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Exhaust System
No modification to current exhaust systems will be required. When
a vertical tail pipe is present, it should be resiliently mounted to
prevent transmitting vibrations to the bus body.
Cooling System
These levels will be achievable by installing a viscous clutch
between the engine and the fan without any modification to the cooling
system. All leaks between the engine compartment sidewall and radiator
and between the radiator and the shroud should be carefully sealed to
minimize fan-on time. An on-off type fan clutch will also be suitable
if the radiator grill is redesigned to minimize line-of-sight transmission
of sound.
Intake
Best available air cleaner with careful sealing of all leaks will be
adequate.
Chassis and Accessories
The mounting of accessories will need special care to avoid excita-
tion of the body panels into resonance. Air conditioner compressor area
may need some acoustical treatment.
83 dBA Exterior and Interior (Rear) Study Levels
Engine
For diesel transit buses, the attainment of 75 dBA engine contri-
buted noise levels will not require any major changes in the engine
5-57
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compartment. Rohr Corporation demonstrated a reduction of 3 dBA
on Detroit Diesel 6V-71 engine noise for a 35-foot transit bus by
using damped rocker arm covers and acoustical material on existing
parts of the hood, engine compartment sidewall, and forward bulkhead.
Detroit Diesel has developed such damped covers for retrofit
17
purposes. It is possible that such covers or similar improved covers
would be offered as standard equipment for future bus engines to comply
with 83 dBA exterior levels.
It is expected that sealed underpans will not be necessary to
reach this level.
The engine contributed level on the street side of the bus is
generally higher because of the radiator opening. Design of the
radiator grill to prevent line-of-sight sound transmission while
maintaining adequate cooling is one method of curbing streetside radi-
ated noise.
All other engine compartment holes should be carefully sealed,
and the entire compartment lined with sound absorbent material. Thin
metal panels such as hood and sidewalls will require sound barrier
type material, such as 1 Ib/sq foot lead-lined vinyl. Alternatively,
mylar-faced acoustical foam with lead septum and an insulation layer
between the septum and panel can be used for the entire area. This
treatment is illustrated in Figure 5-9.
Exhaust System
This level can be achieved by substituting single wall mufflers
with advanced double-wrapped body mufflers. These mufflers are
5-58
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Figure 5-9
Acoustic Treatment of Engine
Hood on a Flexible Busrd Bus
5-59
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already available for both 6V-71 and 8V-71 engines.* The design noise
level of this muffler with an MAM09—104 Wye connection is 75 dBA for
•t
5-inch systems on the 8V-71 engine, giving a back pressure of only 3.4-
inch Hg. Transit bus applications permit higher back pressures (up to
6-inch Hg.). The larger number of bends in the exhaust pipes will not
cause any penalty for naturally aspirated engines.
CMC achieved exhaust noise levels of under 75 dBA without exceed-
ing the back pressure limitation on their T8H5305 coach by replacing
the standard Nelson muffler with a Nelson T13680 muffler.
Exhaust noise should not present any difficulty for turbocharged
engines.
Cooling System, Intake, Chassis, and Accessories
The same treatments as for the previous level will be sufficient.
81 dBA Exterior Study and 83 dBA Interior (Rear) Study Levels
Engine
No treatment beyond the previous level is indicated, unless the
option of turbocharged engine is adopted for achieving lower exhaust
noise levels.
Exhaust System
70 dBA exhaust source noise level will be necessary to achieve
overall bus median noise levels of 78.5 and 77.5 dBA. It appears
that at present mufflers with exhaust design levels of 70 dBA are
not available for naturally aspirated two-stroke Detroit Diesel engines.
* Donaldson Co. Rart No. MCM 12-0189.
5-60
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There are two alternatives available to achieve 70 dBA exhaust noise
levels.
(1) Turbocharged Engine - A turbocharged six cylinder engine
may be substituted in place of a naturally aspirated eight
cylinder engine to obtain the same amount of power. Because
of the inherently low exhaust noise levels of turbocharged
engines, currently available mufflers or modifications
thereof to allow for the greater air flow rates can be em-
ployed to obtain the 70 dBA exhaust noise levels.
Stemco Mfg. Co. has currently available dual horizontal
mufflers, part No. 9428, producing 73.5 dBA which can
be treated to yield 70 dBA noise levels on the 8V-71T
engine.
(2) Adding a Resonator - Optimum exhaust system design to pro-
vide adequate muffling under low as well as high engine rpm
conditions requires the whole system to be designed with
a resonator (or premuffler) in series with the main muffler.
This allows a smaller size muffler than if the entire silenc-
ing were to be achieved from a single muffler.
Because of the allowable 6-inch Hg. back pressure at full
load for naturally aspirated engines, a single resonator and
muffler, with a vertical stack, should be sufficient. The
absence of any leaks in this type of exhaust system become
a necessity at the 70 dBA exhaust noise level.
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Gas-tight exhaust joints are available and should be used.
The muffler, if outside the engine enclosure, should be of
the double-walled type to minimize the noise entering the
passenger compartment.
8
Rohr Plxible bus retrofit noise reduction study resulted
in the development of such a resonator/muffler system in
cooperation with Donaldson Co. for which the estimated con-
tribution was only 65 dBA. This system may be used as a
guideline for a future 70 dBA exhaust system.
Cooling System
Noise levels of 73 dBA were reported by CMC and Rohr for their
quieted buses with optimized shrouds and thermostatic clutches. The
rectangular shrouds should be replaced by contoured shrouds with as
low a clearance as practical. The fan coverage should be optimized
after the new shroud is installed. The fan to radiator distance may
also have to be changed to ensure optimum air flow distribution across
the radiator.
An experimental fan with a U-shaped circular ring attached to the
23
blade tips has been tried by H. L. Blatchford Co. and QIC for the
RTS-2. This fan is designed to prevent tip recirculation without un-
usually small tip clearances. However, this is an experimental design
and to date no apparent advantage from the noise viewpoint has been
demonstrated.
5-62
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Intake, Chassis, and Accessories
No modifications will be required.
80 dBA Exterior and Interior (Rear) Study Levels
Engine
To reach engine contributed levels of 71 dBA, complete engine
belly pans and line-of-sight shielding between engine and radiator open-
ing will be required. The layout for this arrangement is shown in Figure
5-10.
It is important to provide an adequate outlet area for engine com-
partment ventilation and cooling air. Such an outlet can be provided
forward of the engine compartment between the floor and engine support
rails. The outlet opening should be designed to minimize the radiated
sound energy. This may be done by lining the inside of this duct with
two inches of glass fiber or open-cell foam and providing louvers at
the exit to minimize line-of-sight between the interior and the pavement.
The drive-shaft opening will need careful design to minimize sound
escape. It is not admissible to allow any other opening in the belly
pans, because that would render the belly pans ineffective. Refrigerant
and other fluid lines should be routed through holes sealed with asphalt
or rubber grommets.
The design of the outlet ahead of the belly pan, as shown in
Figure 5-10, is critical. Rroper aerodynamic shaping of the exit and
the louvers may be able to provide some suction when the bus is in motion.
The redesign of the cooling system will be a major undertaking.
5-63
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Figure 5-10
Engine Noise Reduction Package for
71 dBA Source Level
5-64
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The belly pans may be provided in two or three removable sections
for maintenance. Belly pans are currently available as optional items.
Suitable warning labels will be necessary to caution maintenance personnel
against discarding the belly pans.
The line-of-sight shield between engine and cooling fan can be
aerodynamically shaped to minimize restrictions. The shield should be
carefully matched with the cooling system to maximize the air flow through
the radiator. International Harvester Company used such shields to lower
the pressure head against which the fan must operate, allowing lower
14
fan speeds and lower fan noise levels.
Space limitations and added heat buildup in the engine compartment
for turbocharged engines will require auxiliary engine compartment ventila-
tion systems.
Exhaust System
The same two options as for the previous study level are applicable.
Cooling System
With the sealed engine belly pans, the cooling air will experience
some restriction, thereby affecting the cooling ability of the system.
This increased restriction has to be overcome by increasing the pressure
rise across the fan without decreasing the volumetric air flow rate.
Alternatively, the radiator and fan area may be increased to permit ade-
quate cooling at the reduced air flow velocity, again impacting the bus
5-65
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capacity. Since the latter approach requires increased engine compart-
ment space, the modification of fan design to produce greater pressure
rise across the fan appears more attractive.
Intake, Chassis, and Accessories
No modification will be required from the previous level.
77 dBA Exterior and 80 dBA Interior (Rear) Levels
Engine
The engine noise abatement methods for the previous level will be
sufficient. Turbocharged engines will be required.
Exhaust System
The achievement of 65 dBA exhaust source levels on production
model buses will be a major undertaking, although these levels have
been demonstrated on the Flxible quieted bus and the Freightliner
quiet truck.
The exhaust system for the previous study level, with some added
volume can be used.
The Freightliner quiet truck employed a manifold muffler along with
dual current production Donaldson mufflers and stack silencers. The
engine was a turbocharged Cummins NTC-350, which is an in-line six
cylinder engine. The experimental exhaust manifold muffler had a volume
4-1/2 times the volume of the standard manifold. For the V-form engines
used in transit buses, two manifold mufflers would be required.
5-66
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A turbocharged engine with large resonators as close to the mani-
folds as possible, followed by the exhaust pipe and muffler wrapped with
asbestos or mineral wool to provide acoustic as well as thermal insul-
ation will be needed.
Cooling System
To achieve fan noise levels of 68 dBA with the engine compart-
ment belly pan and line-of-sight shield in position, extremely low fan
tip to contoured shroud clearances and some increase in radiator
Erontal area will be required.
The incorporation of an engine-mounted contoured or venturi shroud
with 1/4-inch tip clearance can be expected to allow fan top speed
reductions oC approximately 6 percent, and noise reductions of 3 to 6
dBA. The mounting of such a shroud was explained for gasoline engine
school buses. The engine compartment area will probably need to be
increased slightly to accommodate a 10 percent larger radiator to assure
the achievement of 68 dBA noise levels in the case of high horsepower
turbocharged engines for air-conditioned buses operating on highways.
The increased radiator area will allow a further reduction in fan top
speed by 20 percent, resulting in an average noise reduction of 8 dBA.
Because of the lack of ram air and side-facing fan position in transit
bus applications, the achievement of 68 dBA will be somewhat more diffi-
cult than the achievement of 68 dBA levels for heavy duty diesel truck
applications. Increased engine compartment sizes suggested for the
previous level may become mandatory now.
5-67
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Intake/ Chassis and Accessories
Chassis and accessory noise will need to be lowered by about 2 dBA
by changes in basic body design such as acrylic panels bonded to the skin.
Improved accessory and engine isolation will be required.
75 dBA Exterior and 78 dBA Interior (Rear) Study Levels
Engine
Engine contributed levels of 65 dBA will require the engine to
be further enclosed and isolated from the bus framework. Itoo types
of enclosures are possible. Neither type of enclosure has been demon-
strated on a bus meeting the performance specifications of U.S. urban
transit buses.
In the first, the enclosure covers the cooling fan as well as the
engine. Openings for cooling air inlet and exit greatly reduce the
effectiveness of the enclosure. On the other hand, the enclosure provides
some shielding to fan noise. The cooling system generally has to be
adjusted to prevent overheating.
A flow-through type of enclosure may be incorporated. The square
radiator can be replaced by a rectangular radiator or twice the frontal
area. Two centrifugal blowers in the suction mode would draw air in.
Centrifugal blowers allow better isolation of engine noise. The radiator
and blowers will be enclosed in a duct. The seal between bus body sidewall
and radiator is particularly important.
The air from the engine compartment should be allowed to exit through
an acoustically treated opening on the curbside, at a height above normal
pedestrian head level. The flow-through concept is sketched in Figure 5-11.
5-68
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Figure 5-11
Flew Through Engine Compartment
Concept for Achieving 65 dBA
Engine Noise Level
5-69
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It is estimated that the bulkhead will have to be moved forward
approximately one foot, resulting in loss of passenger capacity. However,
the space above the engine need not be as large and probably the wall
can be shaped to provide some interior space. Another possibility is
that the floor can be inclined to provide more underfloor space in the
rear of the bus.
Such an enclosure will result in source levels of 65 dBA if the
future diesel engines are at least 4 dBA quieter than current engines
without any treatment.
The second type of enclosure places the cooling fan outside the
enclosure. This allows greater reduction of engine noise. The radiator
and fan will generally require relocation because of the restriction
presented by the engine enclosure. This type of enclosure is used on
production buses in Europe, such as the Scania CR111M.
In the Scania buses, the engine compartment is completely sealed
on all sides and is provided with a fan for ventilating of the engine
compartment. The air intake for ventilation is located on the roof
of the bus. The single radiator on the left side is replaced by two
radiators, one on each side of the bus located ahead of the closed
engine compartment. Cooling air is drawn in by individual electrically
operated fans at each radiator. The cooling system of the CR111M is
o
designed'for an air-to-boil temperature of 85-90 F. This would not
be acceptable for most climates in the United States.
5-70
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Air conditioning is not offered on the Scania bus, even as an
option. Exclusion of air conditioning reduces horsepower requirement
and engine cooling requirement significantly. Almost all transit coaches
in this country are air conditioned and noise reduction, at the expense
of eliminating air conditioning, would not be acceptable in our climate.
Further details of the Scania bus are given in Appendix A.
Exhaust System
Treatment remains the same as for the previous level, with the addi-
tion of water-cooled manifolds.
Cooling System
Cooling system design will have to be coupled with the achievement
of 65 dBA for all the major noise producing components of the bus. The
limiting factors at this stage will be the chassis and tire noises. The
engine will be either completely encapsulated, or a flow-through enclosure
provided with opening on both sides of the engine compartment.
(1) Totally Encapsulated Engine. - In this case, two radiators
will be remotely placed, forward of the engine enclosure,
with hydraulically or electrically driven thermostatically
controlled fans or blowers. This technique is currently
used in the Swedish Scania CR111M bus and its limitations
have been discussed earlier. New innovations to improve
the volumetric air flow rates without increasing fan speeds
will be required. These may include air scoops or larger
radiators. Another possibility would be to relocate the
5-71
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radiators on the roof of the bus to reduce sideline noise,
though this may result in excessive noise levels at second
story apartment levels.
The noise of the auxiliary fan to ventilate the engine
compartment has to be considered separately.
(2) Flow-Through Engine Enclosure - The principals of such flow-
through enclosures have been studied earlier for quiet trucks.
If the engine compartment area is increased to accommodate
the flow, and blowers substituted in place of fans, 65 dBA
cooling system noise levels appear achievable. By flowing
the cooling air through the enclosure, any heat radiated from
14
the engine and transmission is carried away. With proper
placement of acoustical material, much of the sound is
absorbed before it escapes from the inlet or outlet.
Multi-speed thermostatic speed controls will be required
to maintain optimized operation.
The substitution of the axial flow fan by multiple centri-
fugal blowers may be beneficial in minimizinng sound and
distributing the flow evenly over a rectangular radiator.
MCI buses have been using a dual radiator and centrifugal
fan system for engine cooling for the past twenty years.
5-72
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For transit bus application, the long rectangular radiator
may be located on the left side of the engine compartment
with the larger side parallel to the ground. Two blowers
in parallel would draw the air in, which would be directed
over the engine casing. The engine compartment ventilation
will be aided by another blower directing the air out on
the curbside through louvers located sufficiently high as
to direct air flow above by-stander head level. The design
of the louvers will be important to prevent leakage of engine
noise to the outside. Such a system is shown conceptually
in Figure 5-11.
This type of enclosure has not been demonstrated for transit
bus application. Current evaluation of feasibility is based
on experience with the IH quiet truck and on the assumption
that engine compartment temperatures can be maintained by
providing unrestricted cooling air flow rates.
Intake/ Chassis and Accessories
The comments for the previous level are applicable.
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(7) Intercity Buses
In view of the many similarities in construction and source levels
between urban transit and intercity buses, the progression of component
and overall noise reduction will be the same as that for urban transit
buses. However, due to the different mechanical layouts of intercity
buses, some details of noise reduction packages, will vary from one design
to another. These differences are analyzed during the discussion of the
various noise abatement study levels. The component and overall noise levels
are shown in Table 5-7.
Table 5-7
Component Noise Level Matrix for
Diesel Powered Integral Intercity Buses
J366b Sound Level, dBA
Bus Exterior Study Level
(Not to exceed level)
Bus Exterior Design Level
Engine and Transmission
Exhaust System
Cooling Fan
Intake
Chassis
Interior Level (Rear)
86
83.5
79
79
77
65
70
84
83
80.5
75
75
76
65
70
83
80
77.5
71
70
73
65
70
80
77
75.0
71
65
68
65
68
80
75
72.5
65
65
65
65
68
78
The three major manufacturers of intercity buses used in the United
States offer buses that look very similar from the outside with roughly
the same performance and ride qualities.
5-74
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Power Train Arrangements
The General Motors Corporation (CMC) intercity bus is identical in
many respects to their urban transit bus. The transverse rear engine
o
drives a 60 Vee-drive transmission. Motor Coach Industries (MCI) which
furnishes buses to Greyhound Lines, uses a T-drive arrangement, which
offers maximum utilization of truck components but results in a long rear
overhang and higher drive axle weight. Thus a third axle is needed aft
of the drive axle. The Eagle International design* circumvents this
problem by means of a drop back axle drive which allows the drive axle
to be under the transmission giving a larger wheelbase than the conven-
tional T-drive arrangement. Continental Trailways uses Eagle and Bus &
Car Co. buses. These three power train arrangements are shown in Figure
5-12.
The accepted power source is the Detroit Diesel 8V-71 engine.
Four-speed manual as well as automatic transmissions are available.
Engine Cooling Systems
The CMC bus uses an axial flow fan driven directly by the engine
crankshaft. The radiator is located in the left rear as in the case
of transit buses.
MCI buses use centrifugal fans located in ducts above the
engine. There are two radiators with shutters, one on each side of
the bus, and two fans drawing air in through the radiator and discharg-
ing it over the engine. The fans are driven from a gear-box located
between them and driven by a belt from the engine crankshaft. The
*0riginal design by Bus & Car Co., Belgium.
5-75
-------
Figure 5-12
Drive Train Arrangements
for Intercity Buses
60° V Drive
T Drive
(Standard)
T Drive With
Drop-Back Gear
5-76
-------
duct between the fan housing and the radiator is sealed off from the
engine compartment to maximize flow through the radiator. The engine
air cleaner intake is located in the left side radiator opening. The
relative locations of the system components are shown in Figure 5-13.
Eagle buses also utilize a longitudinal engine arrangement. A
standard 8-bladed 28-inch diameter axial flow fan located on the left
side of the bus is used for engine cooling. The fan is driven off a
o
90 gearbox located in the rear center of the engine compartment. A
6-bladed fan/ located on the right side of the engine compartment,
provides air flow through the air conditioning system condenser. There
is no thermostatic clutch arrangement for the fans. The layout is shown
in Figure 5-14.
Exhaust Systems
The exhaust system arrangement for the CMC intercity bus is similar
to CMC's transit bus. MCI uses an elliptical horizontal muffler with a
short tail-pipe located in the left rear corner. The two exhaust pipes
are connected together with a Wye before entering the muffler, as seen in
Figure 5-13.
Eagle uses a dual horizontal exhaust system with Donaldson MTM-08-5080
mufflers. These are standard truck-type mufflers. There are two
tail pipes located symmetrically in the rear, as seen in Figure 5-14.
5-77
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Figure 5-13
Layout for MCI Engine
Compartment
5-78
-------
Figure 5-14
Layout of Eagle (Bus & Car)
Engine Conpartment
5-79
-------
Noise Control Packages
The noise control study levels and technologies will be similar to
those for transit buses except in certain cases for MCI coaches. Moreover,
in the case of intercity buses, turbocharging of the engine appears more
justifiable than was the case with transit buses because of longer
sustained high-speed maximum power operation periods. The joint DOT-EE&
24
"Study of Potential for Motor Vehicle Fuel Economy Improvement" has
shown that the following fuel economy improvements may be obtained by
engine improvements in integral intercity buses.
Fuel Economy Improvement
Turbocharge Diesel 0-8%
Derate Horsepower 2-5%
Derate rpm 7-10%
All of the improvements are expected to lower engine noise levels.
To attain the engine source levels of under 71 dBA, Eagle buses
will need an additional shield between the engine and air-conditioner
condenser opening on the curbside. Since MCI buses use centrifugal
fans instead of axial flow fans, engine and fan noise will not escape
to the same extent as the transit buses through the radiator opening.
For the 65 dBA engine source level, the enclosure for MCI buses
will need an outlet near the axle. The enclosure will cover the entire
transmission casing. Additional suction fans may be needed at the en-
closure exit to minimize restriction to air flow through the radiators.
Exhaust noise reduction packages will be identical to the transit
bus exhaust noise packages. Differences in the exhaust systems of (MC,
5-80
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MCI, and Eagle buses were described earlier. Since all use the Detroit
Diesel 8V-71 engine, the treatments will be similar. A dual system,
already used by Eagle, will probably offer the most advantages. The
tail pipes will need to be rerouted to exit at the roof line for all
cases except the 79 dBA level.
The packages for cooling system noise abatement will be identical
to transit buses except for MCI buses.
Centrifugal fans which MCI buses already utilize, are inherently
quieter for the same mass flow delivered. Also, the ducts are amenable
to acoustic treatment to minimize the noise escaping through the radiator
opening. The air flow velocity is higher, and hence flow noise may
become audible if other sources are quieted.
Intercity bus radiators are larger than transit bus radiators
because of continous engine operation at high power factors, and heavier
bus loads due to baggage. However, the percentage changes in radiator
and fan sizes to achieve equivalent noise reductions for intercity and
transit buses will be similar.
For interior noise abatement, MCI has experimented with treatments
with no conclusive result. Eagle uses "Sorba-glass" which is a quilted
material with lead sheet between layers of glass fiber and aluminum foil.
In addition, the use of undercoating compounds to damp bulkhead panels
near the engine has been found to be effective.
Road noise is a problem for highway operations. To this end, the
baggage compartment under the passenger compartment offers a partial
barrier to tire noise transmitted to the interior.
5-81
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Air conditioning system noise, and especially evaporator noise,
may require attention.
For the achievement of 80 dBA interior rear section noise levels,
redesign of engine mounts and a careful analysis of the vibration trans-
mission paths from the engine to body panels and floor boards will be
required. If resonant vibrations are present in the panels, damping
treatment will be beneficial. Otherwise, sound radiation to interior
can be minimized by covering the interior surfaces with a limp heavy
acoustic material such as lead/vinyl sheeting. This will impose a
weight penalty which may be critical if legal restrictions on axle
loading exist. The floor boards may need sandwich construction with
an isolating layer of soft rubber between two boards.
Another approach to interior noise reduction would be to isolate
the rear section body panels from the main integral body framework.
This would mean a major redesign of the entire structure if these
panels were initially designed as load-bearing members.
The addition of sound absorbing linings in the interior, such as
pile carpeting and acoustic (and thermal) insulation on the roof, will
minimize reverberation and ensure low front seat noise levels.
The 78 dBA interior noise level at the rear seat for the 75 dBA
exterior noise level bus will be attained since the engine will be more
carefully isolated and completely encapsulated.
5-82
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DEGRADATION OF NOISE CONTROL TECHNOLOGY
The noise abatement methods described in Section 5 are based on
existing noise control techniques for the lowering of noise emitted
by currently designed buses. Many of these methods have been demon-
strated on prototype trucks and transit buses, while some of the
technology discussed (fan clutches, improved slower turning fans) has
been incorporated into production model vehicles. The durability of
these noise control technologies are of particular interest to the EPA.
If individual noise control components are not durable, total vehicle
noise emission characteristics may degrade (increase in measured vehicle
sound level) early after introduction into service. Such an increase in
noise level could significantly reduce the benefits expected as a result
of noise emission standards applicable at time of vehicle manufacture..
Thus, the Agency has considered in its technology assessment studies of
acoustical degradation potential of the total vehicle and its noise
control components. The following is a general discussion of EPA's
findings on acoustical degradation as it applies to bus noise control
technology.
(1) Engine Noise Control Degradation
Engine-mounted shields have been thoroughly tested by several diesel
engine manufacturers, such as Cummins Engine, General Motors, Detroit
Diesel Allison, and Catepillar. Degradation normally only occurs if
the panels are worked loose by vibration or if the acoustical materials
become saturated with oil.
Based on the above experience, engine side shields on conventional
school buses, which have been integrated into the engine cowl, can
5-83
-------
reduce the accessibility of the engine to servicing. As a result;
during servicing, care should be taken to avoid damage to the panels
from mechanic's tools, oil contamination and excessive vibration which
may loosen the shields themselves or the panels upon which they are
attached.
The use of belly pans on various types of heavy vehicles has
been unpopular with maintenance personnel because the pans can
collect oil, reduce engine accessibility from under the vehicle, and
are easily damaged by road hazards. However, rapid detachment systems
have been developed which have improved accessability for maintenance.
The removal of belly pans, when they have been designed specifically
for constant use on a vehicle, can cause certain vehicle systems not to
operate efficiently. For example, a cooling system designed for efficient
operation with belly pans in place may suffer if the pan is permanently
removed, since the air flow route through the engine compartment will be
changed. Increased air flow rates through the radiator, brought about
by the permanent removal of the pan, may not be advisable, especially
for diesel engines which are used in colder climates without radiator
shutters.
Degradation of noise levels from vehicles with totally encapsuated
engine compartments is unlikely if the shielding around the engine is
properly assembled.
(2) Exhaust Noise Control Degradation
If manufactured with comparable materials, the improved types of
mufflers, discussed in this section, should not deteriorate faster than
those mufflers being presently produced.
5-84
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(3) Cooling System Noise Degradation
Fans clutches and on/off fan devices are somewhat complicated
devices which can malfunction due to mechanical failure or failure of
the heat sensing elements. Any malfunction which causes the fan to be
on when not needed will result in higher average fan noise levels across
a vehicle's work cycle.
In conclusion, degradation appears to be a potential problem only
in the case of engine noise abatement measures. However, with proper
component design and maintenance procedures which incorporate checks on
critical noise abatement devices, degradation if any, should be kept to
a minimum. In support of this contention, the maxmium change in the
noise levels of four International Harvester (DOT) Quiet Trucks during
an average mileage of 157,000 miles was 2 dBA, with the final level of
21
all the trucks within 1 dBA of the initial level. This fact implies
that with the technology applied to these vehicles there were no signi-
ficant noise level changes in the noise emissions from the various
components during that mileage period.
5-85
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REFERENCES FOR SECTION 5
1. Kevala, R. J., Manning, J. E. and Lyon, R. H., "Noise Control
Handbook for Diesel Powered Vehicles," prepared for the U.S.
Department of Transportation, 1975. NTIS No. PB 2 6-382/AS.
2. Warnix, J. L. and Sharp, Ben H., "Cost Effectiveness Study of
Major Sources of Noise, Volume IV - Buses," Wyle Research Report
WR-73-10, prepared for the EPA Office of Noise Abatement and
Control, April 1974.
3. "Background Document for Medium and Heavy Truck Noise Regulations,"
U.S. Environmental Protection Agency, March 1976.
4. Jenkins, S. H. and Kuehner, H.K., "Diesel Engine Noise Reduction
Hardware for Vehicle Noise Control," SAE Paper No 73-681, Combined
Vehicle Engineering and Operations and Powerplant Meetings, Chicago
Illinois, June 1973.
5. Priede, T., "Noise Due to Combustion in Reciprocating Internal
Combustion Engines," The Institute of Sound and Vibration Research,
Southampton University.
6. Staadt, Richard L., "Truck Noise Control," SAE Special Publication
386.
7. "Diesel Engine Noise," SAE Special Publication SP-397, November 1975.
8. "Sound Attenuation Kit for Diesel Powered Buses," submitted by Rohr
Industries to the U.S. Department of Transportation, Report RII-SAK-
402-0101, February 1975.
9. Dunlap, T. A. and Halvorsen, W. G., "Transmission Noise Reduction,"
SAE Paper No. 720735, 1972.
5-86
-------
10. "Noise Control Retrofit of Pre-1970 General Motors Trucks and
Coaches," Report No. DOT-TSC-OST-75, U.S. Department of Trans-
portation, Office of the Secretary, Washington, B.C., October 1975.
11. Correspondence, Flxible Co. to Booz Allen Applied Research, dated
November 26, 1975.
12. Hunt, R. E., Kirkland, K. C. and Ryele, S.P., "Diesel Engine
Exhaust and Air Intake Noise," Truck Noise IVA, Report No. DOT-
TSC-OST-12, prepared for the U.S. Department of Transportation,
July 1973.
13. Ratering, E.G., written response to questions submitted by Booz,
Allen & Hamilton, dated January 23, 1976.
14. Shrader, J.T. and Page, W.H., "The Reduction of Cooling System
Noise on Heavy Duty Trucks," Truck Noise IV-C, Report No. DOT-
TST-74-22, prepared for the U.S Department of Transportation, 1974.
15. Bender, E. K. and Kaye, M. C., "Field Test of Freightliner Quieted
Truck," Truck Noise III-G, Report No. DOT-TST-76-29, prepared for
the U.S. Department of Transportation, 1975.
16. "Noise Control Retrofit of Pre-1970 General Motors Trucks and Coaches,"
Final Report, U.S. Department of Transportation, Office of Noise
Abatement, October 1975.
17. Law, R. M., "Diesel Engine and Highway Truck Noise Reduction,"
SAE Paper No. 730240, 1973.
18. Mills, C. H. G., "Noise Emitted by Coasting Vehicles," MIRA
Bulletin No. 3, May/June 1970.
19. Johnston, Laird E., "Technical Capabilities Relative to Truck
Noise Reduction," Proceedings of the Conference on Motor Vehicle
Noise, GM Desert Proving Ground, April 3-4, 1973.
5-87
-------
20. Noise and Vibration Control, edited by L. L. Beranek, McGraw Hill,
1971.
21. Shrader, J. T., "Truck Noise-IV G-Field Test Results on a Heavy
Duty, Diesel Truck Having Reduced Noise Emissions," prepared for
the U.S. Department of Transportation, Office of Noise Abatement,
December 1975.
22. Dunlap, T.A. and Halvorsen, W.G., "Transmission Noise Reduction,"
SAE Paper No. 720735, National Combined Farm, Construction &
Industrial Machinery and Powerplant Meetings, Milwaukee, Wisconsin,
September 11-14, 1972.
23. Baker, R.N., "Development of Noise Reduction Kits for the U.S.
Army 10,000 Ib. Rough Terrain Forklift Truck," prepared for U.S.
Army MERDC, June 1974.
24. "Study of Potential for Motor Vehicle Fuel Economy Improvement,"
Truck and Bus Panel Report, prepared by the U.S Department of
Transportation and the U.S. Environmental Protection Agency,
Jcxnuary 10, 1975.
25. "An Assessment of the Technology for Bus Noise Abatement," Draft
Final Report submitted by Booz-Allen Applied Research under EPA
Contract No. 68-01-3509, prepared for the Office of Noise Abatement
and Control, June 22, 1976.
5-88
-------
SECTION 6
POTENTIAL BENEFITS OF BUS NOISE REGULATION
SCHEDULES ON THE ENVIRONMENT
6.0 INTRODUCTION
Pursuant to the Noise Control Act of 1972, the Environmental
Protection Agency (EPA) has proposed noise emission regulations on newly
manufactured buses (EE). The proposed regulations specify levels not to
be exceeded as measured according to a modified SAE J366b test procedure,
and are intended to control all contributing components of bus noise.
In the analysis of this section, predictions of the potential health and
welfare benefits for a range of possible regulatory schedules of new bus
noise emissions are presented.
Because of inherent differences in individual responses to noise,
the wide range of traffic situations and environments encountered, and
the complexity of the associated noise fields, it is not possible to
examine all traffic situations precisely. Hence, in this predictive
analysis, certain stated assumptions have been made to approximate typical
or average situations. The approach taken to determine the benefits
associated with the noise regulation is, therefore, statistical in that
an effort is made to determine the order of magnitude of the population
that may be affected for each regulatory option. Some uncertainties
with respect to individual cases or situations may remain.
6-1
-------
6.1 HEALTH AND WELFARE BENEFITS OF BUS NOISE REGULATION
6.1.1 Measures of Benefits to Public Health and Welfare
The phrase "public health and welfare," as used here, includes
personal comfort and well-being as well as the absence of clinical
symptoms such as hearing damage. People are exposed to bus noise in a
variety of situations. Some examples are:
1. Inside a home or office
2. Around the home (outside)
3. As a pedestrian
4. As a bus operator
5. As a bus passenger
Reducing exterior noise emitted by buses should produce the following
benefits:
1. Reduction in average traffic noise levels and associated
cumulative long-term impact upon the exposed population.
2. Fewer activities disrupted by individual (single-event)
passby noise.
Furthermore, the reduction of noise levels inside buses should
result in reduced annoyance in terms of less interference with speech
communication, and reduced potential hearing damage risk to bus operators
and passengers in combination with non-bus noise exposures.
Predictions of vehicle noise levels under various regulatory
schedules are presented in terms of the noise levels associated with
typical vehicle passbys. These noise levels are weighted according to
traffic populations or mixes before averaging to determine traffic noise
levels. Reductions in average traffic noise levels from current condi-
tions (i.e., with no noise emission regulations) are presented for 15
6-2
-------
regulatory options on new buses both with and without noise emission
regulations on other traffic noise sources. Projections of the popula-
tion impacted as well as the relative reductions in impact from current
conditions are determined from reductions in average traffic noise levels.
The average noise level for traffic does not adequately describe
the annoyance produced by a single bus passby for all situations since
annoyance frequently depends on the activity and location of the indi-
vidual. In addition, the average noise level tends to average out the
disruptive and annoying peak noise level produced by a single bus passby.
As an additional measure of benefits, therefore, the undesirable effects
of intruding bus passby noise levels are evaluated in terms of sleep
disturbance, sleep awakening and speech interference.
6.1.2 Regulatory Schedules
This analysis predicts the impact of the reduction of bus noise
based upon the exterior and interior regulatory schedules shown in Tables
6-1 and 6-2. For predictions of health and welfare benefits with concur-
rent reductions in future emissions from new automobiles and motorcycles,
an effective date for the regulations of January 1979 is assumed. For
predictions of benefits concurrent with the regulation of new medium and
heavy duty trucks, effective dates of January 1978 for the limit of 83 dBA,
and January 1980 for the limit of 80 dBA are used. It should be noted
that regulatory schedule 15 for both exterior and interior bus noise were
examined in order to determine the maximum benefits achievable with the
virtual elimination of bus noise. Both schedule 15's are not under con-
sideration as a noise limit for newly manufactured buses.
6-3
-------
Table 6-1
Exter ior
Regulatory
Schedule
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Regulatory Schedules Considered
in the Health and Welfare Analysis of
Exterior Bus Noise
Not To Exceed Regulatory Level for All
Bus Types Unless Noted, (dBA)
Calendar Year
1979
-
83
-
-
-
83
83
83
83
83
83
83
83
83
55
1981
-
-
83
80
-
80
-
80
-
80
-
80
-
80
55
1983
-
-
-
-
80
-
80
-
80
-
80
-
80
-
55
1984
-
-
-
-
-
-
-
78
-
-
-
-
-
78
55
1985
-
-
-
-
-
-
-
-
78
77
77
-
-
-
55
1986
-
-
-
-
-
-
-
-
-
-
-
75
7h>
75
55
(1)
Gasoline Powered School buses 73 dBA
6-4
-------
Table 6-2
Interior
Regulatory
Schedule
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Regulatory Schedules Considered
in the Health and Welfare Analysis of
Interior Bus Noise
Not To Exceed Regulatory Level for All
Bus Types Unless Noted, (dBA) '
Calendar Year
1979
-
86
84
-
86
86
86
84
86
86
86
86
84
86
55
1981
-
-
-
83
83
83
83
-
-
-
-
83
-
83
55
1983
-
-
-
-
-
80
-
80
84
83
80
-
80
-
55
1984
-
-
-
-
-
-
80
-
-
-
-
80
~ (1)
80
55
1985
-
-
-
-
-
-
-
-
80
80
-
-
-
-
55
1986
-
-
-
-
-
-
-
-
-
-
78
78
78(D
78
55
(1)
Gasoline Powered School buses 75 dBA
6-5
-------
6.1.3 Outline of the Health and Welfare Analysis
The predictions of the reduction of the population impacted
within various land use categories due to the reduction of average
traffic noise levels by regulating buses are contained in Part 6.2. In
Part 6.3, predictions of relative potential changes in sleep disturbances,
sleep awakenings and speech interferences, due to single bus passbys are
estimated for different land uses for each of the regulatory schedules
under consideration. Related reductions in interior noise levels and the
resulting potential reduction in hearing damage risk and speech interfer-
ence to bus operators and passengers are presented and discussed in Part
6.4.
tn
•z.
0
1UU
90
60
70
ED
s
i ^
O
!•<• %O
20
10
93.4
I"""] URBAN TRAFFIC NOISL
%?/\ FHEC.WAY inAFFIC NOISE
59.0
4.9
24.3
G.9
JL^L
60
65
70
75
Figure 6-1. Estimated Number of People in Residential Areas
Currently Subjected to Traffic Noise Above L =55 dB.
dn
6-6
-------
6,2 REDUCTIONS IN THE IMPACT FROM TRAFFIC NOISE
Projections of reductions in average traffic passby noise levels
are presented for scenarios of both urban street traffic, where the aver-
age vehicle speed is assumed to be 30 mph} and highway traffic, where the
average vehicle speed is assumed to be 55 mph. Note that the benefits
accrued from the regulatory schedules considered for new buses will be
less for highway traffic than for urban street traffic for the following
reasons:
o The number of people exposed to highway traffic noise is
less than the number of people exposed to urban street
traffic noise.
o The reductions in traffic noise levels resulting from the
regulations on new buses will be less in freeway traffic
than in urban street traffic.
As depicted in Figure 6-1, the number of people currently
exposed to outdoor noise levels that are greater than L = 55 dB domi-
dn
nated by urban street traffic noise is significantly higher than the
number exposed to highway and freeway traffic noise (93.4 million as
opposed to 4.9 million). Thus, reducing urban street traffic noise will
benefit significantly more people than will similar reductions in high-
way traffic noise.
The bus regulation schedules considered in this analysis are based
on bus noise emission levels measured in accordance with a modified SAE
J366b test procedure. In the test procedure, bus noise emissions are
measured under maximum acceleration conditions with the bus traveling
at a speed less than 35 mph. Because, in general, engine-related noise
6-7
-------
emissions increase with engine speed and load, and noise generated by
tires increases with vehicle speed, the test procedure is designed so
that maximum engine-related noise emissions are the dominant noise
sources. The noise generated by tires under the proposed test conditions
is not expected to be significant.
At freeway speeds, bus tires contribute significantly to overall
bus passby noise levels. Therefore, the reduction of engine-related
noise brought about by bus noise regulation will be partially masked
by tire noise in freeway traffic. Because vehicle speeds are lower
in urban street traffic, tire noise contributes less to overall noise
emissions in urban areas. Thus, reductions in overall bus noise levels
by lowering engine-related noise emissions will be less affected by
tire noise in urban street areas.
6.2.1 Description of Traffic Noise Impact
In examining the reduction of traffic noise by regulating
buses, three steps must be followed (Figure 6-2). First, the average
noise level produced by each type of vehicle is determined. This
level is the average of the levels produced in each operational mode -
acceleration, deceleration, cruise, and idle which are weighted
according to the proportional time spent in each mode. In effect, it
is an energy average of the passby levels produced by all vehicles of
a given type during a typical operating cycle. From the point of view
of the observer, it is an average of the passby levels that would be
measured at random points along the vehicle's route of travel.
The average passby levels for each vehicle are combined in the
next step to form the average traffic noise level. This level is
6-8
-------
Vehicle
Levels
4-
1*
Present Levels
Regulated Levels
1 raffle
Levels
OoeraHonal Data
Impact
Population Data
Impact Criteria
Figure 6-2. Information Flow Involved in the
Calculation of the Impact of Bus Noise in Traffic
6-9
-------
computed by weighting the average passby level produced by each type
of vehicle by its relative frequency in typical traffic mixes. Composite
passby levels are determined for operation on both streets and free-
ways based on the different passby levels and proportions of vehicles
involved in each case.
The final step in determining traffic noise impact of which
buses are a component, utilizes a measure that condenses the infor-
mation contained in the noise environment into a simple indicator of
quantity and quality of noise which correlates well with the overall
34
long-term effects of noise on the public health and welfare. This
measure was adopted as a result of the Noise Control Act of 1972, which
required that EPA present information on noise levels that are "requisite
to protect the public health and welfare with an adequate margin
of safety". EPA has chosen the equivalent level in decibels L as its
8 ^
general measure for environmental noise; its basic definition is:
(1)
-eq "" XIJM"
where (^2 - t-j_) is the interval of time over which the levels are
evaluated, P(t) is the time-varying magnitude of the sound pressure, and
P is a reference pressure standardized at 20 micropascals.
When expressed in terms of A-weighted sound level, LA, the
equivalent A-weighted sound level, L__, is defined as:
Leq = 10
6-10
-------
In describing the impact of noise on people, a measure called
the day-night average sound level (L^) is used. This is a 24-hour measure
with a weighting applied to nighttime noise levels to account for the
increased sensitivity of people to intruding noise associated with the
decrease in background noise levels at night. The L^ is defined as
the equivalent noise level during a 24-hour period, with a 10 dB
weighting applied to the equivalent noise level during the nighttime
hours of 10 p.m. to 7 a.m. This may be expressed by the following
equation:
Ldn = 10
15
J+9
10(Ln+10)/10
(3)
where Ld is the "daytime" equivalent level obtained between 7 a.m.
and 10 p.m. , and L^ is the "nighttime" equivalent level obtained
between 10 p.m. and 7 a.m.
In order to assess the impact of traffic noise, a relation
between the changes in traffic noise and the responses of the people
exposed to the noise is needed. The responses may vary depending upon
previous exposure, age, socio-economic status, political cohesiveness,
and other social variables. In the aggregate, however, for residen-
tial locations, the average response of groups of people is related
to cumulative noise exposure as expressed in a measure such as L^.
For example, the different forms of response to noise such as hearing
damage, speech or other activity interference, and annoyance were
8
related to I or L^ in the EPA Levels Document. For the purposes
of this part of the study, criteria based on L-, presented in the
6-11
-------
EPA Levels Document are used. Furthermore, it is assumed that if the
outdoor level meets L^ £ 55 dB, which is identified in the EPA Levels
Document as requisite to protect the public health and welfare, no adverse
impact in terms of general annoyance and community response exists.
The community reaction data presented in Appendix D of the
8
EPA Levels Document show that the expected reaction to an identifiable
source of intruding noise changes from "none" to "vigorous" when the day-
night average sound level increases from 5 dB below the level existing
without the presence of the intruding noise to 19.5 dB above the level
before intrusion. For this reason, a level which is 20 dB above L =
55 dB is considered to result in a maximum impact on the people exposed.
Such a change in level would increase the percentage of the population
8
which is highly annoyed to 40 percent of the total exposed population.
Furthermore, the data in the Levels Document suggest that for environ-
mental noise levels which are intermediate between 0 and 20 dB above
L = 55 dB the impact varies linearly, that is, a 5 dB excess (L^ =
60 dB) constitutes a 25 percent impact, and a 10 dB (L, = 65 dB)
constitutes a 50 percent impact.
For convenience of calculation, percentages of impact may
be expressed as fractional impact (FI). An FI of 1.0 represents an
impact of 100 percent, in accordance with the following formula:
FI = <
0.5(L-55) for L > 55
for L < 55
(4)
6-12
-------
where L is the observed or measured L, for the environmental noise.
on
Note that FI can exceed unity for exposures greater than L, =75.
The impact of traffic noise may be described in terms of exten-
siveness (the number of people impacted) and intensiveness (the severity
of impact). The fractional impact method accounts for both the extent
and severity of impact.
The Equivalent Noise Impact (ENI) associated with a given level
of traffic noise (L-,1) may be assessed by multiplying the number of
people exposed to that level of traffic noise by the fractional impact
associated with this level as follows:
ENI1 = (FI.) P. (5)
where ENI1 is the magnitude of the impact on the population exposed to
traffic noise L x and is numerically equal to the number of people who
would all have a fractional impact equal to unity (100 percent impacted).
FI. is the fractional impact associated with an equivalent traffic noise
level of L-, and P. is the population exposed to that level of traffic
noise. To illustrate this concept, if there are 1,000 people living in
an area where the noise level exceeds the criterion level by 5 dB (and
thus are considered to be 25 percent impacted, FI = 0.25), the environ-
mental noise impact for this group is the same as the impact on 250 people
who are 100 percent impacted, FI = 1.0 (1000 x 0.25 = 250 x 1.0).
When assessing the total impact associated with traffic noise, the
observed levels of noise decrease as the distance between the source and
receiver increases. The magnitude of the total impact may be computed by
determining the partial impact at each level and summing over each of the
6-13
-------
levels. The total impact is given in terms of the equivalent number of
people impacted by the following formula:
ENI = I P ' FI (6)
i i i
i
where FI. is the fractional impact associated with L^ and P^ is the
population associated with L^. In this analysis, the mid-level of each
i
5 dB sector of levels above L^ = 55 dB is used for L^ in computing ENI.
The change in impact associated with regulations on the noise
emissions from traffic vehicles may be assessed by comparing the magni-
tude of the impacts with and without regulations. One useful measure
is the percent reduction in impact ( A) , which is calculated from the
following expression:
A = 100 ENI (before) - ENI (after) (7)
ENI (before)
The population figures (P.) in Eq (5) for urban street traffic
are based on a survey in which the total population exposed to outdoor
noise of L , above 55 dB was estimated from measurements taken at 100
dn 12
sites throughout the United States. The sites were selected far enough
from freeway traffic and airports so that these sources of noise were
not significant contributors to the measured outdoor noise levels. Thus,
urban street traffic was a dominant source of noise for each of the survey
sites. The results from this study are given in Table 6-3.
Using the data contained in Table 6-3, an ENI for existing
traffic conditions (without noise regulation of medium and heavy trucks)
of 34.6 million is calculated as shown in Table 6-4.
6-14
-------
Table 6-3
Distribution of Urban Population at or Greater Than a Specified L ,
12
Ldn
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
t
Cumulative
Number of People
(Millions)
134.09
133.94
133.76
133.46v
132.99
132.34
131.46
130.37
129.04
127.53
125.87
124.09
122.19
120.15
117.98
115.64.
113.01
110,12
106.80
102.98
98.544
93.427
87.665
81.237
74.222
Ldn
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
Cumulative
Number of People
(Millions)
66.738
58.997
51.234
43.668
36.542
30.061
24.320
19.352
15.200
11.791
9.046
6.853
5.155
3.826
2.776
1.963
K347
0.889
0.559
.332
.187
.093
..039
.012
.002
.0
6-15
-------
i
Si
0>
!
10
c
IP
Q)
t.
W
I
rH
3
*c
IO
O
.-i
O
I—
ID
r~
o
oo
6-16
-------
The ENI values associated with reductions in the average urban
street traffic noise levels are predicted by shifting (reducing) the
values of L in Table 6-3 by the traffic noise reduction of interest
dn
and performing computations similar to those shown in Table 6-4. In
following this procedure for estimating ENI, it is assumed that: (1)
reductions in urban street traffic noise levels produce equal reductions
in the L^ for the outdoor noise, and (2) the population in urban areas
will remain constant until the year 2000. The latter assumption is made
for convenience only. It does not affect the relative effectiveness
of the study regulation schedules. If population increases are somewhat
homogeneous within urban land use areas, only the absolute number of
people impacted will be different from the estimates. Furthermore, the
actual numbers can be approximated by multiplying the ENI estimated for a
given year by the fractional increase of population expected to occur in
that year.
While the exact value of present or future ENI's may not be known
precisely, the relative reduction of the ENI due to noise regulations—of
primary interest here—are known with much greater accuracy than the
absolute value of the ENI since the changes in the theoretical components
of ENI can be well defined. For instance, it may not be possible to
determine whether the present estimated ENI due to urban street traffic
noise, an absolute value, is actually 0.1 million too high. However, it
is possible to determine, for example, that the regulation of diesel-
powered school buses will not reduce the ENI by more than 0.1 million
(see Part 6.2.3 below). Extensive investigation of such small changes may
seem innocuous if it is not kept in mind that, although buses represent
6-17
-------
only a small part of traffic in the United States, their impacts may be
considerable when measured by metrics other than ENI. Thus, the changes
found to occur in ENI may help indicate what equivalent changes would
occur in impact measures which are not used in this analysis but whose
absolute values may reflect more accurately the effects of bus noise on
people.
As discussed above, the concept of fractional impact, expressed
in units of ENl, is most useful for describing relative changes in
impact from a specified baseline for the purpose of comparing benefits
of alternative regulatory schedules. In order to assess the absolute
impact or benefits correspnding to any regulatory schedule, information
on the distribution of population as a function of noise environment
is required. This information is included in this section and in
Appendix F in the form of graphs showing the number of people exposed
to different levels of traffic and/or bus noise. The anticipated
absolute impact of noise upon those individuals exposed to any given
noise level may be traced by referring to the various noise effects
8
criteria presented in the Levels Document as well as in this analysis
(see Figures 6-16, 6-17, 6-18 and 6-19).
6.2.2 Urban Street and Highway Traffic Noise
Two steps are employed to predict average noise levels from both
urban street and highway traffic. First, an energy average is taken of
the noise emissions from several passbys of each type of noise source.
Next, the average traffic noise level is then computed by energy averaging
the derived passby levels for each vehicular source, after appropriate
weighting for the proportion of each type of vehicle in the traffic flow.
6-18
-------
6.2.3 Vehicle Noise Levels in Urban Street and Highway Traffic
The following noise sources are considered in modeling urban street
and highway traffic noise:
o Automobile and motorcycle noise emissions that are unregu-
lated and regulated (assumed).
o Medium and heavy truck noise emissions that are unregulated
and regulated.
For a sample of instantaneous noise levels observed at equally
spaced time intervals that has a normal (Gaussian) distribution, the
58
energy-average of the noise levels over time (see equation 1) is given by:
Leq = L50 + 0.115 ^T2 (8)
where LCQ is the median noise level and o~T is the standard deviation.
It is assumed that the distribution of roadside passby noise levels for
each type of vehicle is approximated by a. normal (Gaussian) distribution
and that there is a steady stream of closely spaced passbys. This assump-
tion permits calculation of the energy-average of the passby noise levels
from median passby noise levels in a manner similar to the computation of
L in Equation 8; that is
La = L5Q + O.llScr2 (9)
where L is the energy-average of the passby levels, LKn is the median
3 DU
level and cr is the standard deviation of vehicle passby noise levels. As
Equation 9 demonstrates, vehicle passby noise depends on both median level
and the variability of these levels. The average passby noise levels
assumed to be produced by trucks, automobiles and motorcycles are shown
in Table 6-5 along with the references from which they were derived.
6-19
-------
Table 6-5
Passby Noise Levels for Non Bus Vehicles
Type of Vehicle
9
Medium and Heavy Trucks
(a) Unregulated
(b) EPA New Truck
Regulations
9
Automobiles
(a) Unregulated
(b) Assumed Regulation
Motorcycles
(a) Unregulated
- (b) Assumed Regulation
Urban Street
dBA
L50
85.0
74.6
65.0
61.0
76.0
72.0
cr
3.7
2.0
3.7
2.0
2.9
2.9
La
86.6
75.1
66.6
61.5
77.0
73.0
Highway
dBA
L50
85.5
81.7
75.0
71.0
80.6
76.5
or
3.5
2.0
3.5
2.0
2.8
2.8
La
86.9
82.2
76.4
71.5
81.5
77.5
6-20
-------
6.2.4 Bus Noise Levels
6.2.4.1 Levels for Unregulated jBuses
Bus passby noise levels are presented in Table 6-6. Bus
interior noise levels as measured near the driver and the rear seat are
presented in Tables 6-7 and 6-8.
Most of the bus noise research conducted to date has dealt with
only one bus type; transit buses. Thus, measurements have been made under
many operational conditions—acceleration, deceleration, cruise, passby,
etc. These measurements, when combined with the estimated percent of
time spent in each mode (Table 6-9), allow the computation of an energy
average noise level over a typical drive cycle. Where similar data was
found to be unavailable for particular operational modes of school and
intercity buses, levels were estimated as follows: The arithmetic dif-
ference between the acceleration level and each other operational mode
level was computed for transit buses. This difference was then applied to
the acceleration levels of the other bus types to derive their remaining
operational levels. The method was used in both the exterior and interior
cases. The measurement procedure used for obtaining most of the available
acceleration test level data is similar to one developed by the Society of
Automotive Engineers (SAE). The EPA proposed measurement procedures for
interior and exterior bus noise emissions are described in Section 8.
6.2.4.2 Levels for Regulated Buses
Vehicles which initially do not meet regulatory limits may be
modified in a variety of ways in order to do so. It is expected that
in order to comply with a given regulation, manufacturers will design
new vehicles to produce noise levels about 2.5 to 3 dB lower than the
6-21
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Table 6-9
Percentage of Time Spent in Each Operational Mode By
Buses on Streets and Highways
(Data from Reference 15 Unless Noted)
Bus Type
Transit
Street
Highway
School
Street
Highway
Intercity
Street*
Highway
Operational Mode
Acceleration
20
5
9
5
13
5
Deceleration
20
5
9
5
17
5
Cruise
26
85
21
85
56
85
Idle
34
5
61
5
14
5
*Data based on typical urban street cycle for automobiles,
Reference 33.
6-25
-------
regulatory limit (see Section 5, Bus Noise Reduction Technology). This
design level may be assumed to be the mean of what is actually a distri-
bution of noise levels for the redesigned buses. Since it is expected
that nearly all redesigned buses will comply with the regulation, the
upper tail of the distribution is assumed to terminate at the regulatory
limit. Thus all new production vehicles not initially complying with
a regulation are assumed to be redistributed in a normal distribution
with a width of 5 dB centered 2.5 dB below the regulatory limit (see
Figure 6-3).
By changing the distribution of new vehicle noise levels with
the implanentation of noise regulations, the fleet-average acceleration
test level is reduced over time as more and more old unregulated vehicles
are replaced by new regulated ones. Furthermore, regulating the noise
emissions from new vehicles lowers the median and average noise levels
as well as the variability of the noise levels within each vehicle class.
This is true because all the vehicles within each class are subject to
the same regulatory level, which tends to decrease the spread in noise
levels across all classes (see Figure 6-3).
For simplicity, the reduction of acceleration test levels can be
assumed to result in equal reductions in the noise levels produced by
buses under actual accelerating conditions. Actual reductions may be
somewhat smaller, but since data is not available to estimate how much
smaller, the reductions are assumed to be equal. The actual reduction
in noise levels produced under deceleration and cruise conditions can
be estimated, however, from measured data. Figure 6-4 demonstrates the
relationship between acceleration test levels and 30 mph cruise levels
that buses are expected to produce under regulatory conditions. Since
6-26
-------
25
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Old Complying
Vehicles
Newly Complying
Vehicles
Not-to-Exceed Limit for
New Vehicles, 83 dB
70 72
74
Would-be
Violators
76 78 80 82 84
Acceleration Test Level (dB)
90
Figure 6-3.
Illustrative Example of Redistribution
of New Vehicles Previously Exceeding
Regulatory Limit
6-27
-------
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Figure 6-4.
Average Relationship Between 30 mph Cruise
Maximum Passby Level and Acceleration Test
Level for Interior and Exterior Measure-
ments of All Types of Buses
6-28
-------
variations from this curve for different types of buses are extremely
small, the average curve is plotted and used for all bus types. Figure
6-4 is also used to find the reduction in deceleration levels. Noise
levels produced under idling conditions are not expected to be affected
by regulation of acceleration noise.
The reduction of cruise levels at high speed (55 mph) is less
than what can be obtained at low speed due to the fact that tire noise
creates a lower limit on the cruise-by noise level. This lower limit
is the "coast-by" or chassis noise level—the noise level measured when
the bus coasts by the measuring point with its engine off. This level
has been measured for twelve newly manufactured intercity buses at an
42, 54
average of 75 dB at 50 feet. Assuming the same level is valid for
transit buses, the reduction of cruise levels at high speed can be esti-
mated by applying the same reduction to the engine component of the high
speed levels as was presented in Figure 6-4 for low speed noise, and adding
the result to the tire noise floor. The result is shown in Figure 6-5.
80
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10 8 6 4 2
Reduction in Acceleration Test Level, dBA
Figure 6-5. Relationship Between 55 mph Cruise Maximum Passby Level
and Reduction in Acceleration Test Level Measured
at 50 Feet for Transit and Intercity Buses
6-29
-------
6.2.5 Traffic Noise Levels
Traffic noise levels at observer locations obviously depend on
the traffic settings and geometry. People living downtown may find that
a nearby high-rise completely blocks noise generated by a thoroughfare
located on the opposite side. On the other hand, buildings may enhance
the reverberation of traffic noise such that the resulting levels are
higher than what would occur in a rural setting devoid of barriers. In
addition to propagation factors, different traffic may have different
mixes of vehicles in the traffic flow, different average speeds, etc.,
each giving rise to different average traffic noise levels and, thus, to
different degrees of impact. To simplify the variety of cases in the
following analysis, the impact of traffic noise, and the contribution of
buses to that impact, is examined within four land use areas: high den-
sity urban; low density urban; suburban; and rural; as well as the total
urban case which is the summation of the high density urban, low density
urban, and suburban land use areas. In the urban and suburban land use
areas, the assessment is further divided into street and highway settings.
In rural areas, only highway and other main-road traffic are considered
for bus noise impact. Transit buses are assumed to operate in the urban
and suburban areas only, intercity buses and school buses are assumed to
operate in all four land use areas.
The estimated average mix of trucks, automobiles, motorcycles,
and buses within urban and rural traffic settings is shown in Table 6-10.
The estimates are primarily based on the number of vehicle miles traveled
1 19
by each bus type and by other vehicles. By using these traffic mixes
to weight the contribution of passby levels for each traffic vehicle within
6-30
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6-31
-------
the traffic stream (Table 6-5), an average traffic passby level was
computed for each land use area. Noise emission limits on new buses tend
to reduce these average traffic levels. Consequently, changes in urban
street traffic noise levels lead to changes in the distribution of peo-
ple exposed to day-night average sound levels (L^-J . As depicted in
Figures 6-6 through 6-9, however, the change in the number of people
exposed to various L^ levels is minor for the regulatory schedules con-
sidered. Figure 6-6 shows the shift expected in the year 2000 between
the "no regulation" case (regulation schedule number 1) and an ideally
protective regulation case (regulation schedule number 15) in high density
urban areas. Figure 6-7 shows similar but slightly smaller changes in
low density urban areas, and Figure 6-8 displays even smaller changes
in suburban areas. Figure 6-9 presents the sum of these changes for all
land use areas.
If noise regulations are applied to non-bus vehicles such as
trucks, there will already be an initial reduction in traffic noise,
depending on the severity of the regulation, the date of its implemen-
tation, and the turnover rate for the vehicle population involved. In
Appendix F, data (Tables F-5 through F-7) is presented which were used
to calculate average traffic passby levels for the following three
baseline cases:
(1) Regulation of new trucks, automobiles, and motorcycles
(2) Regulation of new trucks only
(3) No regulation of non-bus vehicles
The reductions of urban street traffic noise estimated by this method
for each land use area are shown in Tables 6-11 through 6-13 for the
6-32
-------
FIGURE 6-6.
HIGH DENSITY URBflN P0PULRTI0N VS OUTDOOR
TRRFFIC NOISE LEVEL IN 2000
WITH REGULflTION OF TRUCKS
RUTOS RND MOTORCYCLES
a
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DflY-NIGHT RVERRGE SOUND LEVEL (L
ON
60-85
) .08
6-33
-------
FIGURE 6-7
L0W DENSITY URBflN PQPULnTIQN VS OUTDOOR
TRPFFIC NQISE LEVEL IN 2000
WITH REGULRTIQN OF TRUCKS
RUTQS HND MOTORCYCLES
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6-34
-------
FIGURE 6-8
SUBURBRN PGPULRT1GN VS OUTDOOR
TRHFFIC N0ISE LEVEL IN 2000
WITH REGULRTIGN GF TRUCKS
HUTQS HND MOTORCYCLES
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(LDN),DB
6-35
-------
FIGURE 6-9
o
URBRN POPULflTIQN VS OUTDOOR
TRflFFIC NOISE LEVEL IN 2000
WITH -REGULflTIQN OF TRUCKS
RUTQS RNU MOTORCYCLES
3
15
55-60
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6-36
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first baseline case. Reductions in urban street traffic noise rela-
tive to the other baselines are presented in Appendix F (Table F-7).
Reductions in urban street traffic noise relative to the other two
baselines are presented in Appendix F (Tables F-8 through F-13).
From these tables, it should be noted that:
(1) Reducing bus noise emissions has little effect on overall
traffic noise for either urban highways or urban streets.
(2) The most stringent regulation schedule considered in
the analysis—a reduction of bus noise to an ideally
protective level of 55 dB at 50 feet (regulation sched-
ule 15)—results in a statistical change in the average
traffic passby level of less than 0.16 dB in the base-
line case most favorable for observation of measurable
differences due to bus regulation, i.e., baseline (1).
6.2.6 Reduction of Traffic Noise Impact
The equivalent noise impact in each land use area is calcu-
lated for each regulation schedule and study year by (1) applying the
traffic noise reduction for the land use to the present distribution
of people living in all urban areas with L^ greater than 55 dB (Table
6-3), (2) calculating the new total ENI, and then (3) taking the same
percent of the ENI as the percent of population contained in the given
land use. The results obtained by this method are presented in Tables
6-14 through 6-16 for the first baseline case. Summary tables show
the total ENI due to urban street traffic for all urban land uses (Table
6-17) and the percent reduction of this total ENI (Table 6-18) for each
regulation schedule and study year—for baseline (1). Results for base-
lines (2) and (3) are given in Appendix F (Tables F-14 through F-23).
6-40
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Upon inspection of Tables 6-17 and 6-18, it is clear that little
relative change in the impact of overall traffic noise is obtained through
the regulation of bus noise. In the most severe case (regulatory schedule
15), the equivalent of slightly less than half a million people would be
benefited by the implementation of bus noise regulation in the year 2000—
less than 2 percent of the present total ENI. Yet bus noise is perceived
21
by many as a major concern in comparison with noise from other vehicles.
To investigate the cause of these concerns, a more direct approach is
discussed in Part 6.3 for evaluating the impact attributable to bus noise
in isolated passby situations.
6.3 REDUCTION OF INDIVIDUAL PASSBY NOISE IMPACT
Up to this point, the analysis of bus noise impact has been con-
cerned with the contribution that buses make to day-night average traffic
levels (L, ). The impact contributions which are calculated in this way
are not wholly representative of the input attributable to bus noise,
for the calculations are relatively independent of the actual operating
conditions of the buses. For example, they do not reflect the fact that
almost the entire amount of hourly acoustical energy contributed by buses
in an area may be generated in only 10 seconds of noise during a single
acceleration near a bus stop. Yet this intrusive, short, intense event
may be the most annoying noise-related situation faced over the entire day
by a large number of pedestrians, residents, or people waiting near the
2, 21
bus stop.
On some occasions bus noise will be completely masked out by
other noises, making the conclusions reached by using L, essentially
correct. At other times or situations, one can expect that other noise
sources will not mask the noise of a passing bus, and thus the bus will
6-46
-------
cause a finite impact. The actual impact from buses is certainly due
to a combination of various levels of bus noise and other environmental
noise.
Annoyance is difficult to describe. It may pass rapidly and
the cause remain unnoticed. Or it may add to other agents causing stress
20
and lead to physiological problems. As measured from people's responses
in questionnaires, however, there is no doubt that annoyance to bus noise
does exist. In fact, in a recent survey of people's annoyance to motor
vehicles, it was found that, on the average, buses are perceived as the
21
loudest and the most intensely annoying of any of the motor vehicle noises."
A loud vehicle passby may also interrupt people's activities, such as
conversation or sleeping. The interruptions may again lead to annoyance,
but in themselves they may represent a degradation of health and welfare.
For instance, in a recent study of the annoyance caused by different levels
of simulated aircraft noise for people seated indoors watching television,
35
annoyance was seen to be mediated at least in part by speech interference.
Not only is the TV program, or other person speaking, more difficult to hear
during the time in which a noisy vehicle is passing by, but it has been ob-
served that the distraction which may occur from the conversation in which
35
the person is engaged may contribute in itself to annoyance. The speaker
may behaviorally attempt to cope with the noise intrusion either by increa-
sing his or her vocal effort, or in more severe cases, by ceasing to speak
altogether. Such behavioral reactions may be quite indicative of general
annoyance and disturbance with the intrusive noise event. Similarly, the
reaction to a noise intrusion during sleep may be in many cases a change
in sleep stage (from a "deeper" to a "lighter" stage) or, if the intrusive
6-47
-------
noise is intense or long enough, an actual awakening may result. In
either case, repeated disturbance of people's activities may be
expected to adversely affect their well-being. The covariance of ver-
balized annoyance with the interference of activities has been amply
8, 23, 56, 57
demonstrated in several investigations.
For these reasons it seems appropriate for the analysis of
passby impacts to examine the two activities of speech communication
and sleep in 'some detail, both in order to determine the direct effect
bus noise may have on them, as well as to aid in an estimation of the
total annoyance attributable to bus noise. These single event passby
noise intrusions become particularly important in light of other regu-
lations and efforts to reduce the noise from other motor vehicles and
urban noise sources, i.e., without a reduction in noise emissions for
buses, the bus may very well stand out as one of the most, if not the
most, intrusive noise source.
6.3.1 Sleep Disturbance
The sleep periods of humans are typically classified into five
stages. In Stages I and II, sleep is light and the sleeper is easily
awakened. Stages III and IV are states of deep sleep where a person is
not as easily awakened by a given noise, but the sleep may shift to a
lighter stage. An additional stage is termed rapid eye movement (REM)
.and corresponds to the dream state. When exposed to an intrusive noise,
a sleeper may (1) show response by a brief change in brainwave pattern,
without shifting sleep stages; (2) shift to a lighter sleep stage; or
(3) awaken. The greatest known impact occurs due to awakening, but
there are also indications that disruption of the sleep cycle can cause
34
(irritability, etc.) even though the sleeper may not awaken.
6-48
-------
36, 37
Two recent studies have summarized and analyzed sleep
disturbance data. These studies showed a linear relationship between
frequency of response (disturbance and awakening) and noise level, and
demonstrated that the duration of the noise stimulus was a critical para-
meter in predicting response. The studies also showed that the frequency
of sleep disruption is predicted by noise exposure better than is arousal
or behavioral awakening. An important fact is that sleep disturbance is
defined as any physiological change which occurs as a result of a stimu-
lus. The person undergoing such disturbance may be completely unaware
of being afflicted; however, the disturbance may adversely affect total
sleep quality. This effect on overall sleep quality may lead to, in
34
certain situations, behavioral or physiological consequences.
To determine the magnitude of sleep disturbance caused by
buses, some consideration must be made of the hours of bus operation.
Only two types of buses generally operate at night—transit buses and
intercity buses. School buses may be operating in the early morning
hours in some locales, but probably not nuch before 7:00 a.m. Transit
buses, too, have limited nighttime operation. For five major bus lines
in Los Angeles, for example, only 1/6 of the scheduled runs occur at
night, i.e., before 7:00 a.m. and after 10:00 p.m. (this ratio of day-
time to nighttime operation is not atypical throughout the nation).
Although some fraction of the population sleeps during the daytime,
it is assumed for the purposes of this analysis that sleep only occurs
during the nighttime hours. Therefore, the fraction of the total vehi-
cle miles traveled by transit buses which are likely to disturb sleep
is assumed to be 1/6 of the total.
6-49
-------
Official estimates of the portion of inter-city bus mileage
traveled at night are not available; however, some approximations may be
made. If there were no change between night and day operations, 37.5
percent (9/24) would occur at night and 62.5 percent (15/24) in the day.
For people taking short trips (a few hours long) on inter-city buses it
is assumed that somewhat less bus travel per hour actually occurs during
nighttime hours than during the day. A brief investigation of several
cross-country, inter-city bus schedules indicates that only a slightly
greater daytime biasing of the travel time is warranted for long trips
49
(37.1 percent night versus 62.9 percent day). In this analysis, a
35/65 percent split between intercity bus nighttime and daytime opera-
tions is used.
To find impact on sleep and the reduction in sleep disturbance
achievable with bus noise emission regulations, the following method
is utilized:
Step 1. Average passby levels at 50 feet are computed for both bus
types (transit and inter-city buses). These data are pre-
sented in Table 6-6.
Step 2. The distances from a typical bus passby at which these levels
are decreased in steps of 5 dB are calculated (Figure 6-10).
These distances are assumed to begin from the center of the
roadway since, on most roads, buses travel both directions
in equal frequency. .
Step 3. The number of people living in each 5 dB band from the 50-foot
passby level is calculated by multiplying the population
density of each land use in which the buses operate by the
6-50
-------
Attenuation Curve for
a Given Land Use
100 200 400
Distance from Source (Feet)
800
Figure 6-10. Illustrative Example of Calculation of Distances
Between Steps of 5 dB Attenuation from the 50-Foot
Average Bus Passby Noise Level
6-51
-------
width of the 5 dB bands (calculated in Step 2) and then by
the number of miles traveled within the given land use by
buses. Depending on the land use, the first 40 to 90 feet
on each side of the center line is assumed to be part of the
roadway and adjoining sidewalk, and thus it is assumed to
contain no people.
Step 4. The average sleep impact is calculated in each of the 5 dB
bands. The impact, expressed as a fraction, is found from
a curve relating sleep impact to passby noise level (Figure
6-16 and Figure 6-17). This procedure is analogus to the
fractional impact method presented in Part 6.2.
Step 5. The relative total impact is computed in each band by
multiplying the number of people living in each band (from
Step 3) by the associated fractional impact (from Step 4).
We shall now discuss in detail the steps outlined above, starting with
Step 2, since Step 1 has been previously defined.
Step 2 - For the purpose of analyzing bus passby noise in this
section, each of the four land uses discussed in Part 6.2 is assumed
to have a simplified mix of high-rise, low-rise, and open-space areas
51
(Table 6-19) which correspond to different propagation laws. The com-
putation of the distance between each 5 dB band of attenuation from the
bus roadway involves determining the noise attenuation characteristics
typical of each area. In urban high-rise areas the building density may
be so great that the noise from a point source, such as a bus, located
in the middle of an intersection, decays in the lateral direction as if
the vehicle were a line source: the acoustical waves have little chance
6-52
-------
Table 6-19
Assumed Mix of Building Types and Land Uses Impacted by Buses
Land Use
High Density Urban
Low Density Urban
Suburban
Rural
Percent of Different Types of Building Development
Corresponding to Different Propagation Laws*
High-Rise
100
50
0
0
Low- Rise
0
50
100
0
Open Space
0
0
0
100
See Figures 6-12 through 6-14
^53
-------
to dissipate in the direction parallel to the bus's line of travel
(Figure 6-11). In low-rise areas, the noise travels more radially
and the attenuation is correspondingly greater. In addition to these
two forms of laterally directed geometric spreading, building, ground,
and air absorption also contribute to attenuation. A recent review
of the literature on urban sound propagation produced the attenuation
22
values for traffic line sources shown in Figure 6-12. Applying the
same excess attenuation values to point source spreading losses yields
the curves of Figure 6-13. As a simplification, all low-rise areas
are assumed to have point source attenuation characteristics and all
high-rise areas are assumed to have line source characteristics.
The attenuation of noise in rural areas also involves many
factors (Figure 6-14). The low density of buildings in rural areas
allows the neglection of building reflection and absorption, so that
the distance computations are straightforward.
The build-up of reverberation in the longitudinal direction
(along the path of travel of the .bus) must also be considered as a
factor in the propagation of passby noise in high-rise areas. Figure
6-15 shows the apparent amplification of noise level due to reveberant
buildup on narrow streets completely, or nearly completely, bounded by
38
buildings. The amplification of the noise level will occur when buses
are traveling along streets bounded by buildings less than 78 feet apart.
39, 40
In a survey of twenty metropolitan areas, it was found that dis-
tances between building fronts vary widely within each city. In Boston,
for example, some building fronts are 50 feet apart, while others are 120
feet apart. Although there are thoroughfares in Eastern and Mid-western
6-54
-------
Distance Attenuation
from Relative to
Roadway 50-Foot
(ft) Level (dB)
Distance Between
5 dB Attenuation
Steps (ft) .
&.?••: ••::••& t>
High
Rise.
Point Source Attenuatior
(6 dB per Doubling
of Distance)
^ Line Source Attenuation
(3dB per Doubling of Distance)
Figure 6-11. Schematic of Attenuation of Bus Noise
by Low and High Rise Buildings
Note: Not drawn to scale.
6-55
-------
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6-56
-------
I I
i r
15-Foot Alley (No Building Setback)
o
o
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8
CO
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25-Foot Alley (No Setback)
10
36-Foot Local Street.
(50-Foot Right-of-Way)
44-Foot Collector
Street (64-Foot -
Right-of-Way)
56 20
Distance Between Building Fronts/ Meiers
Figure 6-15. Noise Amplification Factors
Bus Operation on Narrow Streets"
6-57
-------
cities with building fronts less than 78 feet apart, it is estimated
that these do not constitute the vast majority of public bus routes.
Western cities, as a rule, have constructed streets with building fronts
farther apart than Eastern and Mid-western cities. Thus, reverberant
amplification along bus routes was excluded from the analysis used in
this study.
Step 3 - Once the 5 dB band distances are known, the number of
people living within each band can be found by multiplying the bandwidth
area by the average population density of the locale. The three urban
densities and one rural density which have been selected are shown in
Table 6-20. The densities are converted to people per mile of road per
foot from the roadway. Thus, by multiplying by the appropriate distance
from the roadway, the total number of people per mile of roadway can be
found.
Step 4 - The fractional impact of the disruption of sleep by
noise is given in Figure 6-16 where the frequency of no sleep distur-
bance (as measured by changes in sleep state, including behavioral
awakening) is plotted as a function of the Sound Exposure Level (SEL) of
the intruding noise. Likewise, the frequency of behavioral awakening as
a function of SEL is shown in Figure 6-17. These relationships, adapted
from Figures 1 and 2 of reference 36, consist of data derived from a re-
view of most of the recent experimental sleep data as related to noise
exposure. The curves, which indicate the approximate degree of impact
(percent disruption or awakening) as a function of noise level, have
*
been modified somewhat from those contained in References 36. (Note that
*Personal Communication, J. S. Lukas, July 1976
6-58
-------
Table 6-20
Population Densities for Selected Areas of Bus Operation
Land Use Area
Type of Housing
Percent of the
1970 U.S. Urban
Populations 1
Average Popula-
uiation per Square
Mile24
Population per
Mile of Road per
Foot from Road-
way (Both Sides)
Urban
High Density
Dense and
Very Dense
Urban
Apartments
8.7
20,877
7.908
Low Density
Urban Row
Apartments
and Suburban
Dup! exes
24.9
8,473
3.209
Suburban
Suburban
Single Family
Detached
66.4
2,286
.866
Rural
Single
Family
Detached
-
20
.0076
6-59
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I
100
90
80
70
60
50
40
30
20
10
0
Sleep Disruption
FI = 0.0135 (SEL
- 37)
30 40 50 60 70 80 90
Sound Exposure Level (SEL), dB
100 110 120
Figure 6-16. Fractional Impact of Sleet Distruption^g
as a Function of Sound Exposure Level
(Regressions of Sleep Distruption on SEL, revised)
6-60
-------
100
*r so
9)
O}
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in Figure 6-17, the relationship beyond SEL = 95 dB is an extrapolation
of data. However, indoor SEL's from bus passbys rarely exceed SEL = 70
dB.) Furthermore, the noise data contained within these studies were
measured in terms of "effective perceived noise level" with a reference
duration of .5 second (EPNL>5 sec) . EPNL^ sec is converted to SEL by
the following approximate relationship:
SEL = EPNL ,- -16 dB (10)
• 3 S6C
The SEL is defined as:
SEL = login /
iu / 2 dt (11)
J o
where
t is the duration of the noise
P(t) is the A-^weighted sound pressure
and
P is the reference pressure (20 micropascals).
For triangular time histories such as vehicular passbys, an approximation
is
where
I, „ is the maximum A-weighted sound level
TO3X
and
t is the duration in seconds measured between the "10 dB down"
points where the sound level is equal to L_ax -10.
Based on the urban and rural attenuation curver (Figures 6-12 through
6-14), an observer located 50 feet from the roadway would find t = 8
5
seconds for an average bus speed of 15 mph. In rural bus operation on
6-62
-------
main roads where the average speed is likely to be twice this value
but the excess attenuation is less, it is found that t = 6 seconds.
These durations are increased to 17 and 14 seconds, respectively, at
distance of 100 feet from the road. The difference between the longer
and shorter durations shifts the SEL by 3 to 4 dB which changes the
fractional impact of sleep disruption by only 4 to 5 percent. It was
therefore decided to use an average value of 10 seconds as the passby
duration for all buses in the analysis. Selecting this duration sim-
plifies equation (12) to:
SEL = L + 7.0 (13)
Using the average passby levels given in Table 6-6 for
the SEL's were found for each bus type. To determine the resulting
SEL inside the home the following transmission losses were applied
to the propagated noise levels, depending on land use.
1. A noise level reduction of 20 dB was used for high and
low density urban areas to represent the case in which,
(because of the type of building construction) windows
of half of the homes are open and half of the homes are
6
closed.
2. A noise level reduction of 15 dB was used for suburban
and rural areas to represent the case in which the
6
windows of all homes are open.
Step 5 - The equivalent noise impact (ENI) for sleep disturbance was
derived for each of the regulatory schedules and study years under
investigation. The FI equations for sleep disturbance and sleep awak-
ening are included in Figures 6-16 and 6-17. Table 6-21 presents the
6-63
-------
total sleep disturbance ENI per night as a function of regulatory
schedule summed over all land use areas for various years. Table 6-22
shows the percent reduction in potential sleep disturbances brought about
by each regulation schedule with reference to the no regulation case.
Table 6-23 shows the total potential sleep awakening ENI occur-
ring per night as a function of regulatory schedule for all land uses.
Table 6-24 shows the percent reduction in potential sleep awakenings
brought about by each regulation schedule with reference to the no regu-
lation case.
In order to more fully explain the contents of Tables 6-23 and
6-24 an example follows. In Table 6-23, by consulting the year 2000
column, it is found that for regulation schedules 3 and 12 the sleep
awakening ENI due to buses are reduced to 27.88 million and 15.52
million per night respectively. Therefore, the relative difference in
ENI between the two schedules in the year 2000 is 12.36 million per
night. (Regulatory noise levels and dates of implementation for all
schedules are shown in Table 6-1.) Table 6-24 indicates the percent
reduction from the baseline level, 30.38 million (regulation schedule
1, 1979 shown in Table 6-23). Thus, the 27.88 million ENI value for
regulatory schedule 3 from Table 6-23 translates into a 8.23 per cent
reduction while the 15.52 million ENI value for regulation schedule 12
translates into a 48.91 per cent reduction from the baseline, a differ-
ence of 40.68 per cent between the two schedules. The above procedure
can be used to assess the relative differences among any group of regu-
latory schedules for any of the years shown in the tables. Furthermore,
the tables presented throughout this analysis (Section 6) follow the
6-64
-------
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6-68
-------
same general pattern as Tables 6-23 and 6-24 for all exterior bus noise
ENI calculations and all interior bus noise ENI calculations. The only
major difference is that in the case of interior bus noise ENI, Table
6-2 should be consulted for the interior bus noise regulatory levels
and their respective implementation dates.
The potential equivalent number of sleep disturbances and sleep
awakenings categorized by bus type (transit, intercity) and land use
are presented in Appendix F (Tables F-24 through F-35).
The data presented in this section and in Appendix F concerning
reductions in potential sleep disturbances and sleep awakenings are
measures of people times events. One person impacted (e.g., awakened)
10 times is equivalent to 10 people being impacted one time each.
It should also be noted that the individual bus passby noise
impact analysis examines the effects of reducing bus noise alone, and
hence does not take into account the presence of other noise sources in
the environment. .It is obvious that other environmental noise sources
create background noise over which in many situations bus noise will not
intrude. The benefits presented in this analysis represent the benefits
accrued during those times when the bus noise clearly intrudes over an
ambient level. The absolute sleep disturbance and sleep awakening impact
attributable to buses is dependent, of course, on the background level
assumed. However, the per cent reduction of ENI (Tables 6-22 and 6-24)
is representative of the relative reduction of bus noise impact over any
given ambient level. For a more precise description of the absolute
number of people impacted by nighttime bus noise, computer plots are
presented in Appendix F (Figures F-l through F-8) showing, for each of
6-69
-------
the study years, the number of people exposed to various bands of noise
measured in terms of the SEL inside their homes for each regulatory
schedule.
Additional analyses are underway to examine the absolute impact
of individual bus passbys assuming various background noise levels.
6.3.2 Speech Interference
Unlike the disruption of sleep, the interference of speech,
i.e., conversation, occurs when people are both indoors and outdoors.
For the purposes of this analysis, it was assumed that virtually all
conversation takes place during the daytime hours; thus, only "daytime"
(7 a.m. to 10 p.m.) bus operations were considered to contribute to
speech disruptions, whereas only "nighttime" operations were considered
to contribute to the disruption of sleep. This assumption pertains to
all types of buses in the speech impact analysis.
People can have their conversation disrupted by externally
propagating bus noise in at least three major settings during the day:
as pedestrians on the street, as residents inside their homes, or as
residents who are involved in leisurely activity just outside their
homes. Three different approaches are required to assess the impact
of these three different situations. Each approach will be examined
separately. In the discussions that follow, "inside the home" and
"outside the home" should be taken to mean, respectively, "inside any
building" and "outside any building but not along a street."
6.3.2.1 Pedestrian Speech Interference
Approximately 149 million people live in urban areas of the
24
United States according to the 1970 census. Extensive information on
pedestrian travel is not available to estimate the portion of the urban
6-70
-------
population which experiences bus noise as a pedestrian. However, for
the purposes of this discussion, a rough estimate of one-half mile of
travel per person per day may be assumed. A large fraction of the popu-
lation is probably too old or too young to walk even a tenth of this
value per day. Yet many healthy urbanites of young or middle age may
walk as much as a mile or more each day. Bus stops are typically spaced
45
1/2 mile apart. The average distance from a person's house stationed
along a bus route to the nearest bus stop is then about 1/8 mile. An
average bus passenger thus walks a total of 1/2 mile each day going to
and from the bus stop at which the passenger alights. For people who
do not ride buses, a 1/2 mile per day average walk would be equivalent
to driving to work in a car and walking two blocks (1/8 mile each) to
and from a restaurant for lunch. This walk may be assumed to take place
along main streets, and therefore these people are also exposed to bus
noise.
Table 6-25 gives the step-by-step rationale for the derivation
of the number of pedestrians exposed to bus noise used in this analysis.
From the point of view of the pedestrian, two average maximum
passby levels are considered to occur for each bus type: (1) the level
measured when the bus is passing by on the same side of the street as
the pedestrian (10 to 15 feet away), and (2) the level measured when
the bus passes by on the opposite side (60 to 75 feet away). The exposure
level occurring in the first case can be estimated from data on transit
52
bus levels at 3 feet. Under the acceleration mode a maximum passby
level of 97 dB is reported. This level represents approximately a 4
dB increase per halving of distance from the average acceleration level
6-71
-------
Table 6-25
Derivation of the Number of Equivalent Pedestrian-Impacts
Due to the Disruption of Speech by Bus Passby Noise
1. Daytime Vehicle Miles
Traveled on Urban
Streets (Millions per
Year, 1973)
2. Vehicle Miles Per Day
Per Street Mile
3. Pedestrian Miles
Traveled Per Day on
Urban Streets
4. Pedestrian/Street
Mile
5. - Pedestrian- Impact
Events Per Street
Mile Per Day
6. Average Fractional
Speech Impact^
7. Equivalent Impacts
(millions per day)
Transit
1450
8.28
School
478
2.73
Inter-City
25
.14
40,000,000
1.85
15.3
.68
5.0
5.05
.52
1.3
.26
.81
.1
Derivation
Reference 1 ,
(1) - (480,000 St. Miles)
•
- (365 Days)
•
(80 Million Workers)*
x (1/2 Mile/Day
Walk Per Worker)
(3) - (480,000 St. Miles)
•
- (3 mph Pedestrian
Velocity
- (15 Hours/Day
•
(2) x (4)
From Table 6-26
(5) x (6)
x (480,000 St. Miles)
24
*Employed non-agricultural civilians in 1973.
6-72
-------
15
at 50 feet of about 81 dB. Assuming the same attenuation figure can be
applied to the noise levels produced under other operational modes as
well, the average maximum passby levels can be computed for buses on
either side of the street. The estimated values are given in Table 6-26.
The criteria for outdoor speech interference is shown in Figure
6-18 as a function of the level of an interfering noise. (Note that
the appropriate noise metric for the criteria is an I^g occurring for
the duration of the passby, rather than the SEL of the event.) The
ENI speech for pedestrians is obtained by finding the fractional impact
produced by the average passby level of each bus type (Table 6-26) and
multiplying by the number of pedestrians impacted (Table 6-25). Reduc-
tions of bus levels measured at 50 feet were assumed to yield equal
reductions in levels measured at the distances from the bus at which
pedestrians are exposed. The effect of various regulations on the
predicted equivalent number of pedestrians impacted by bus noise inter-
fering with speech is given in Table 6-27. The percent reduction in
ENI is given in Table 6-28.
6.3.2.2 Residential Speech Interference
The interference of conversation between people located in or
near their homes involves both indoor and outdoor situations. For the
outdoor case, the same criteria used in the pedestrian impact analysis
was again utilized. In this case, however, disruptions only occur
beyond 40-90 feet from the bus, depending on land use, and they are
measured out to the point where the bus passby level is equal to the
background level. In this assessment, an outdoor cutoff background
level of 55 dB, and an indoor cutoff level of 45 dB are used. Although
6-73
-------
Table 6-26
Average Maximum Passby Levels to Which Pedestrians Are Exposed
and Fractional Speech Impact, by Bus Type and Location of Passby
Location of Passby
Bus on Same Side of Street
as Pedestrian
Bus on Opposite Side
of Street
Bus on Same Side of Street
Bus on Opposite Side
of Street
Arithmetic Average
Bus Type
Transit
School
Inter-City
Average Maximum Passby Level (dBA)
81.6
74.0
80.4*
71.3*
85.5
77.0
Fractional Speech Impact**
1.0
.35
.68
.94
.10
.52
1.0
.62
.81
*Levels weighted 97 percent gas-powered, 3 percent diesel-powered
14
school buses.
**From Figure 6-18. Six dB is added to the x-axis legend to account for
a halving of the speaker-listener distance to 1 meter.
6-74
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average urban ambient noise (LjJ tends to be about 5 dB greater than
the assumed outdoor background level, a concerted effort to reduce motor
vehicle noise in the future would make the 55 dB level a more appropriate
figure to use for this analysis.
Propagation loss is computed for each land use category in the
same manner as was discussed in Part 6.3.1. First, the distances from
the road at which the passby noise levels fall off in 5 dB steps are
computed. Then the number of "people" per mile living within each band
is derived. Finally, the relative impact is fractionally calculated
using the criteria shown in Figure 6-18. This number is multiplied by
the number of bus miles traveled during the time in which people are
estimated to be outdoors each day (.4 hours, i.e., 2.7 percent of the
33
day) to give the total ENI due to outdoor speech interference.
The potential ENI for outdoor speech interferences per day is
given in Table 6-29 for the 15 regulatory schedules. The reductions
in ENI obtained with these regulations are tabulated in Table 6-30.
It should be noted that "people outdoors" does not include pedestrians,
or people engaged in other forms of transportation during the day.
Rather it is intended to include those time-periods in which people are
relaxing outdoors - either outside a home, business, or cultural insti-
tution.
Indoor speech interference is assumed to occur when bus noise
propagates through walls of residences or buildings and remains above a
typical indoor background level of 45 dB. The criteria of impact for
indoor speech interference is given in Figure 6-19. The curve is based on
the reduction of sentence intelligibility relative to the intelligibility
6-78
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which would occur at 45 dB. If people are conversing indoors during
the time a bus is passing by, the probability of a disruption in com-
munication is given by Figure 6-19. Before the fractional impact is
computed, the same reductions in the passby levels due to transmission
through walls which were used in Part 6.3.1 must be taken into account.
During times when buses are not passing by, no bus-related speech inter-
ference occurs. It is estimated that people spend an average of 13
daytime hours inside each day, i.e., they spend about 86.7 percent of
33
the day inside. Taking this fraction of the daytime bus vehicle-miles,
we can compute the indoor speech impact. The estimated ENI for indoor
speech interference is given in Table 6-31, and the percent reduction
is given in Table 6-32. Adding these impacts to the pedestrian and
outdoor impacts described above gives the total estimated potential
ENI due to the interference of speech by bus passbys shown in Table
6-33. The associated percent reductions are shown in Table 6-34. In
Appendix F, Tables F-36 through F-38 present the reduction in speech
interference ENI categorized by the major bus types (transit, intercity
and school).
The actual levels to which people are exposed in the areas of
speech impact described above are of interest for analyzing the daytime
effects of bus passby noise. Appendix F contains figures (Figure F-9
through F-16) which show the average maximum passby levels to which the
daytime population of pedestrians, people indoors, and people located
outdoors are exposed. Each graph is a plot of the distribution of popu-
lation by exposure level for a given year. Again, the differences become
more noticeable as the years progress.
6-82
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6-86
-------
6.4 REDUCTION OF INTERIOR NOISE IMPACT
Interior bus noise affects primarily two population groups;
bus operators and bus passengers. Transit and inter-city bus operators
tend to spend more time each day driving their buses than school bus
operators since school transportation is usually only required during
the opening and closing hours of school. Typical passenger exposure
times are also different for each bus type. Inter-city passengers tend
to take infrequent but long trips, whereas short but recurrent trips
are characteristic of transit and school bus passengers. Two kinds of
impact may be associated with interior bus noise: the impact on hearing
for bus operators and passengers, and the disturbance of conversation
of bus passengers. These impacts are discussed in the following section
along with the reductions which are obtainable with the interior regula-
tion schedules (Table 6-2).
6.4.1 Hearing Loss Reduction
Average exposure levels measured in the driver's position and
in the rear of the bus have been given in Tables 6-7 and 6-8. Since
these levels are averages, an accurate description of the effects of
interior bus noise must include an assessment of those buses which are
much noisier than these levels may suggest. Based on data from EPA
studies, interior noise levels have a standard deviation of about 2 dB
15
for buses of the same bus type. If the distribution is normal, buses
producing an average interior noise level of L are distributed about
18
L as follows:
Level (dB) L-4 L-2 L L+2 L + 4
Percent (%) 6.6 24.2 38.4 24.2 6.6
6-87
-------
Although it is possible that some bus operators and passengers are
exposed to a variety of bus levels and therefore receive the average
noise exposure for a given type of bus over a long period of time, in
many cases passengers and operators may receive higher-than-average or
lower-than-average exposures. This would be the case if a school system
were to purchase only one type of bus for its operations, for instance,
or if bus operators were assigned particular buses for long periods of
time.
The distribution of people about an average interior bus noise
level may be estimated in this way for both front and rear seat loca-
tions. Lacking information to the contrary, it may be assumed that half
of the population riding buses of a given type (transit, school, etc.)
receive front seat exposure levels and half receive rear seat exposures,
i.e., half ride in the rear of the bus and half ride in the front. In
the case where the engine is located in the middle of the bus and middle
seats receive the loudest exposure levels, as occurs with mid-engine
diesel-powered school buses, the distribution of people by exposure level
will again be broken down into two equal groups - those receiving an
average middle seat exposure level and those receiving an average of the
front and rear seat exposure levels.
The reduction in the acceleration test interior noise levels
measured near the engine due to the regulation of interior noise is cal-
culated in much the same manner as the exterior noise situation, using
33
the HINCSAM program. These reductions are again assumed to yield equal
reductions in the acceleration levels measured under actual operating
conditions. The reduction of deceleration and cruise levels are taken
6-88
-------
from Figure 6-3. Interior noise levels produced in the idling mode are
again expected to remain constant and unaffected by the regulation.
With these assumptions, the calculations of the new average interior
noise levels are made for each regulation and study year for the front
and rear seat locations.
The total number of operators and passengers riding each type
of bus is given in Table 6-35. To find the equivalent noise impact on
hearing (ENIH) applicable to each population group the following frac-
13
tionalization equation is used:
FIH = 0.025 (1 ~70)2 (14)
where
FIH is the representative Noise Induced Permanent Hearing
Threshold Shift (NIPTS) expected over a 40-year exposure
period averaged over the .5, 1, 2, and 4 kilo hertz
frequency bands
and
L (24) is the equivalent continuous sound level experienced by
the bus operator or passenger over typical 24-hour periods.
To estimate the 1^/24) °f ^e bus-riding population it is necessary to
ascertain the exposure levels received while off the bus. While some
data has been collected in this regard for workers in manufacturing in-
dustries, very little data is available which would enable an accurate
prediction of the average daily exposures experienced by the great ma-
jority of the population. In order to proceed with the estimate of
L /24\ therefore, three non-bus exposures have been chosen in order to
6-89
-------
Table 6-35
Statistics of Bus Operators and Passengers
Estimated for Each Bus Type
Drivers Passengers
Bus Type (thousands) (miles/day)
(1) (4)
Transit 80 8.3
(2) (5)
School - Gas 290 23.0
(2) (5)
School - Diesel 10 .7
(3) (6)
Inter-city 24 1.1
9
(1) (1.545 x 10 vehicle mil.es/yr)
(15 miles/hr) x ((6 work nours/day) x <225 work
(2) Assuming approximately one driver per bus. Gas/Diesel breakdown from Ref. 14.
(3) Estimate based on extrapolation from Class I carrier data in Ref. 27.
(4) Assuming 2 trips per day. Total from Ref. 28.
(5) Ref. 28. Gas/Diesel breakdown from ^e£. 14.
(6) Ref. 27.
6-90
-------
cover the possible range of values which may occur: 60 dB, 70 dB, and
80 dB. The Leq(24) is then calculated using the following formula:
*b 10V10 + "-*!, .. V10 ....
Leg(24) • 10 log 2? 10 * 24— ' 10 (15)
where
tb is the time spend on the bus per day
24- tb is t^6 ti1116 spent off the bus per day
Lb is the average level of interior bus noise
Ln is the level of non-bus exposure
Exposure times for operators and passengers are derived in Table 6-36 for
each bus type.
Once Leg (24) is calculated for a given interior noise level
13
and FIH is thereby defined, the estimated ENIH is found by the formula:
ENIH =FIH • P
where
P is the population exposed
The impact of bus noise on potential hearing loss is estimated
for each regulation schedule and assumed non-bus exposure level. Table
6-37 shows the ENIH for bus operators assuming they are exposed to an
energy-average level of 60 dB during the time they are not driving buses.
Table 6-38 shows the percent reduction from the baseline case (regulatory
schedule 1) that each regulation would accomplish. Note that for regula-
tion 15, interior bus noise is set to an arbitrary health and welfare
level of 55 dB. Table 6-39 shows the ENIH for operators which would
occur if their non-bus driving exposure were 70 dB, and Table 6-40 shows
6-91
-------
Table 6-36
Duration of Daily Noise Exposure Experienced by
Operators and Passengers, by Bus Type
Exposure Per Day (Hours)
Operator
T
2
8
-
-
-
6
S
2
8
1-2
-
-
2
I
4
8
-
-
5-6
6
Passenger
T
2
-
-
-
-
2
S
2
-
1-2
-
-
2
I
4
-
-
1-2
-
2
Basis For Estimate
Reference 2
Assuming a full work day
Derived belcnr
Derived below
Derived below
Assumed for this report
Key
T
S
I
Transit
School
Inter-City
(1) (2 bil bus miles/yr i (15 - 30 mph)
330,000 buses) x (180 school days/yr)
=1-2 hours/operator or passenger/day
(2) (25.6 billioji revenue passenger miles/yr) _f (30 - 50 mph)
(0.4 billion revenue passengers/yr)
= 1-2 hours/passenger/day
(3) (1.2 billion bus miles/yr) 4 (40 mph)
(24,000 operators) x (225 work days/yr)
=5-6 hours/operator/day
6-92
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the resulting percent reduction. Tables 6-41 and 6-42 show the comparable
ENIH and percent reduction respectively, for an operator non-bus exposure
of 80 dB. Tables 6-43 through 6-48 show the ENIH and percent reduction
for the same three non-bus exposure levels for bus passengers. Appendix
F (Table F-39) contains a percentage breakdown of the contribution to
hearing loss impacts for each major bus type considered in the analysis.
The distribution of bus operators by interior bus exposure level
(level experienced independent of the time of exposure) is presented in
Appendix F (figures F-17 though F-34). From these figures it is clear
that in the year 1979 there is very little difference between the regula-
tions except for the ideally protective level (55 dBA) regulation number
15, which is assumed to be implemented and complied with immediately by
all buses. As the years progress, however, a shift is noticeable from
the higher to the lower noise bands. Appendix F also contains figures
(Figures F-25 thgough F-32) showing the distribution of bus passengers
by interior bus exposure level which display the noise band shift again
becoming more noticeable as the years progress.
6.4.2 Speech Interference Reduction
Interior bus noise has a second impact on people which must be
considered - the interference with speech. The implications of speech
interference for passengers are perhaps not too great. A conversation
may be interrupted for a few seconds as the bus accelerates, for instance,
or a few words may be missed. On the other hand, the interruption of
speech between passengers and the driver during an emergency situation
may have critical implications. A school bus driver should be able to
hear a child in need, for example, regardless of the loud commotion that
usually occurs on school buses.
6-97
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It has been suggested that the masking of speech between pas-
sengers not conversing with one another is a benefit of bus noise.
Passengers are often reluctant to have their conversation overheard by
others, and in cases where the bus level is quite low, they may compen-
sate by lowering their voices unnaturally or by not talking at all due
to the lack of privacy. This argument may be somewhat valid, however,
it cannot take precedence over a program to reduce the impact of in-
terior bus noise on hearing.
EPA has identified 72 dB as the intruding noise level at which
a conversation at .5 meters with normal voice projection is considered
to be satisfactorily intelligible (95% sentence intelligibiity) in
8
steady state noise. It has been suggested that 0.5 meters is a typical
2
speaker-to-listener distance for bus passenger. Thus, the outdoor speech
interference curve shown in Figure 6-18 was adjusted to 0.5 meters for
8
bus passengers by adding 6 dB per halving of distance, or a total of
12 dB, to the abscissa. The outdoor speech intelligibility criteria was
then used to assess the ENI for speech inside buses.
It was decided that outdoor speech criteria were better than
indoor speech criteria for estimating the impact of speech disturbance
inside buses because the background level assumed for the estimation of
outdoor speech disturbance is closer to the background level actually
experienced by bus riders and operators. A typical outdoor day-night
7
equivalent sound level in urban areas is 60 dB, which is the background
level assumed in the outdoor speech disruption criteria and is considered
comparable to actual background levels inside buses. The indoor criteria,
however, uses 45 dB as a background level. In addition to reasoning on
6-106
-------
the basis of background levels, it is also felt that outdoor criteria
should be applied to the case of bus passengers and operators because
the setting inside buses is not the typically relaxed environment one
experiences indoors.
Utilizing the values for the average interior front and rear
noise levels described in Part 6.4.1, the speech fractionalization method
described above, and the passenger population data of Table 6-35, the
equivalent number of people disturbed by interior noise as measured by
the potential disruption of speech can be estimated by the following
formula:
^speech = FIi speech x p
where
FI^ speech ^s snown by Figure 6-18 (as adjusted by the above discus-
sion) for each interior level and P-^ is the population exposed per day.
Table 6-49 shows the potential equivalent number of people esti-
mated for ENIspeech ^or eac^ °^ t^e samPle interior regulatory schedules
and study years. Table 6-50 shows the percent reduction which can be
accomplished with each regulation schedule.
Appendix F contains information (Table F-39) regarding the ENI
contributions by bus type to all interior ENI (hearing loss effects and
speech interference effects) discussed in this part.
6-107
-------
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-------
6.5.0 SUMMARY
The impacts from bus noise presented in Parts 6.2, 6.3, and 6.4
are based primarily on a single equation:
ENI = FI x P
where
ENI is the equivalent noise impact
FI is the fractional impact produced by the noise
and
P is the population impacted
This basic equation finds many forms as the investigated area of impact
changes from traffic noise to single passbys to interior noise. Table
6-51 summarizes the forms used in the preceding sections. Five areas of
impact are distinguished:
a. Annoyance from urban street traffic
b. Sleep disturbance from bus passbys
c. Speech disturbance from bus passbys
d. Hearing loss from interior bus noise
e. Speech disturbance from interior bus noise
The first three impact areas concern exterior bus noise, while the last
two areas concern interior bus noise.
6-110
-------
Table 6-51
Summary Equations Describing Calculation of Bus Noise Impacts
Basic Equation: Equivalent Noise Impact = Fractional Impact x Population
Ldn max
a. ENI „ = V ( FI x Pop.
traffic A ^ annoyance ri
i = 55 dB
0 "-an * 55dB
annoyance
Ldn>55dB
«
b« ENI i = SEL max /FI , x Pop DensiiyxBus Miles x Distance from Koad. \
sleep y / sleep r / , \
disturbance . ~ «7 I disturbance /
(awakening) ' ,,.^ (awakening)
where
FI, ,. t , =(1.35 SEL -50.0) x .01
sleep disturbance
FI. , . =(1.19 SEL -59.7) x .01
sleep awakening
• •
ENI , eq / Fl' , x Pop Density x Bus Miles xDistance from Road.
speech = \~» / speech r ' \
disturbance ) I outdoors
outdoors i = 55 dB \ (indoors)
(indoors) (45)
where Leq = Lmax - 10 log 2.3 (Lmax - Lb)/10
Lmax 1S the maximum level of a triangular time history passby
Lfc is the background level
^speech 1>s defined in reference 8,
6-111
-------
lable 6-51 (Continued)
Summary Equations Describing Calculation of Bus. Noise Impacts
max
d- I-NIHL__:__ = Y'"/ / FI, . x
hearing > ' ( '"'hearing
i = 70 dB \
\vhere
FI, . = .05 (L , -7Q
hearing •
L
i-k. ir max / _.i
ENIspeech = I ("speech
disturbance i ="55 outdoors
for passengers
where
FI , is defined in reference 8.
speech
6-112
-------
Section 6
REFERENCES
1. U.S. Department of Transportation, Federal Highway Administration,
Highway Statistics, Washington, D.C., Government Printing Office,
1975.
2. Wyle Laboratories, "Transportation Noise and Noise from Equipment
Powered by Internal Combustion Engines," for the EPA, ONAC, December
1971. NTID 300.3.
3. Booz/Allen, Inc., Memorandum to Wyle Research, February, 1976.
4. A.T. Kearney, Inc., "Cost and Economic Impact Analysis," Preliminary
Report for the EPA, ONAC, February 1976.
5. Transit Research Foundation of Los Angeles, "City and Suburban
Travel," Issue 123, August 1971.
6. House Noise — Reduction Measurements for Use in Studies of Aircraft
Noise, SAE Report AIR 1081, October 1971.
7. Wyle Laboratories, "Community Noise," Prepared for the EPA, Office of
Noise Abatement and Control, December, 1971. NTID 300.3.
8. U.S. EPA, "Information on Levels of Environmental Noise Requisite to
Protect Public Health and Welfare with an Adequate Margin of Safety."
March, 1974. 550/9-74-004.
9. C.B. Burroughs, "Public Health and Welfare Benefits from Regulations
on New Medium and Heavy Truck Noise Emissions," Report to EPA, ONAC,
August, 1975.
10. B. Sharp, Wyle Laboratories, "A Survey of Truck Noise Levels and the
Effect of Regulations," Wyle Research Report WR 74-8, for the Office
of Noise Abatement and Control, U.S. EPA, December, 1974.
11. K.E. Gould and R.H. Rowland, General Electric Tempo, "Health and
Welfare Benefits from the Reduction of Motorcycle Noise Levels,
"Draft Interim Report to EPA, ONAC, May, 1976.
12. W.J. Galloway, K.M. Eldred, and M.A. Simpson, "Population
Distribution of the United States as a Function of Outdoor Noise
Level," EPA Report 550/9-74-004, June, 1974.
13. D.L. Johnson, "The Impact of Levels Above 70 dB for Hearing Loss
Considerations," Memo from Aerospace Medical Research Laboratory,
Wright-Patterson Air Force Base to the EPA, ONAC, 1976.
6-113
-------
14. J. Brandhuber, A,T. Kearney Corp., Personal Communication, April 20,
1976.
15. "An Assessment of the Technology for Bus Noise Abatement," Booz/Allen
Applied Research, Draft final report submitted to U.S. Environmental
Protection Agency, Office of Noise Abatement and Control, EPA Contract
No. 68-01-3509, June 22, 1976.
16. U.S. Environmental Protection Agency, "Passenger Noise Environments
of Enclosed Transportation Systems," Report Number 550/9-75-025,
June 1975.
17. Booz/Allen Applied Research, memo to Wyle Research, March 12, 1976.
18. Games, P. and Klare, G., "Elementary Statistics." McGraw-Hill Book
Co., New York (1967), Appendix D.
19. Gould, K.E. and Rowland, R.H., "Environmental Impact of Noise Emission
Standards for Motorcycles," Draft interim report submitted to U.S.
Environmental Protection Agency, Office of Noise Abatement and Control,
June 1976.
20. Welch, B.L. and Welch, A.S. (Editors), "Physiological Effects of
Noise." New York, Plenum Press, 1970.
21. Bolt Beranek and Newman, Inc., "A Survey of Annoyance from Motor
Vehicle Noise." Report No. 2112, June 1971.
22. Rackl, R., Sutherland, L.C., and Swing, J., "Community Noise Counter-
measures Cost-Effectiveness Analysis," Wyle Research Report No.
WCR 75-2, prepared for the Motor Vehicle Manufacturers Association,
July 1975.
23. Noise-Final Report, "Cmnd. 2056, July 1963, Her Majesty's Stationary
Office, London.
24. U.S. Bureau of the Census, "Statistical Abstract of the United States:
1975" (96th Edition), Washington, D.C., 1975.
25. U.S. Department of Transportation, Bureau of Public Roads, "1970
National Highway Needs Report, with Supplement." December 1969.
26. Bolt Beranek and Newman, Inc., "Motor Vehicle Noise Identification
and Analysis of Situations Contributing to Annoyance." Report No.
2082, June 1972.
27. National Association of Motor Bus Owners, "Bus Facts" (39th Edition),
1972.
28. Warnix, J.L. and Sharp, B.H., "Cost-Effectiveness Study of Major
Sources of Noise. Vol. IV - Buses," Wyle Research Report WR 73-10,
April 1974.
6-114
-------
29. U.S. Environmental Protection Agency, Office of Noise Abatement
and Control, "Guidelines for Preparing Environmental Impact State-
ments on Noise," Second Draft, February 1976.
30. Plotkin, K., "Assessment of Noise at Community Development Sites.
Appendix A-Noise Models." Wyle Research Report WR75-6, October 1975.
31. Plotkin, K., "A Model for the Prediction of Highway Noise Assessment
of Strategies for its Abatement through Vehicular Noise Control,"
Wyle Research Report WR 74-5, September 1974.
32. Whitney, D., General Motors Corporation, verbal communication with
Wyle Research, July 23, 1976.
33. Sutherland, L., M. Braden, and R. Colman, "A Program for the Mea-
surement of Environmental Noise in the Community and its Associated
Human Response, Volume 1," Wyle Research Report WR-73-8 for the U.S.
Department of Transportation, December 1973.
34. U.S. Environmental Protection Agency, "Public Health and Welfare
Criteria for Noise." EPA Report 550/9-73-002, July 1973.
35. Gunn, W., T. Shighehisa, and W. Shepherd, "Relative Effectiveness of
Several Simulated Jet Engine Noise Spectral Treatments in Reducing
Annoyance in a TV-Viewing Situation." NASA Langley Research Center,
Draft Report, 1976.
36. Lukas, J., "Measures of Noise Level: Their Relative Accuracy in
Predicting Objective and Subjective Responses to Noise During Sleep."
UoS. Environmental Protection Agency, EPA-600/1-77-010, February 1977.
37. Lukas, J., "Noise and Sleep: A Literature Review and a Proposed
Criteria for Assessing Effect," J. Acous. Soc. Am., Vol. 58(6) p.
1232, Dec. 1975.
38. Organization for Economic Co-operation and Development, "Urban
Traffic Noise Strategy for an Improved Environment." Paris, 1971.
39. Southern California Rapid Transit District, "South Bay Improvement
Guide," effective June 27, 1976.
40. Department of Traffic, City of Los Angeles, "Traffic Counts," 1972.
41. Department of Public Works, City of Los Angeles, "Standard Street
Dimensions," Regional Plan Association Standard Plan D-22549,
effective September 23, 1969.
42. "Noise Levels of New MCI Buses," Booz-Allen Applied Research, a
report submitted to the U.S. Environmental Protection Agency°s
Office of Noise Abatement and Control, EPA Contract No. 68-01-3509,
October 7, 1976.
6-115
-------
43. U.S. Environmental Protection Agency Noise Enforcement Facility,
"Lima School Bus Test Report," Sandusky, Ohio, June, 1976.
44. U.S. Environmental Protection Agency, "Background Document for
Medium and Heavy Truck Noise Emission Regulations." EPA Report
550/9-76-008, March 1976.
45. Regional Plan News, "Where Transit Works," August, 1976, No. 99.
46. Wilbur Smith and Associates, "Transportation and Parking for
Tomorrow's Cities," New Haven, Conn., 1966.
47. Russ Kevala, Booz-Allen Applied Research, Personal Communication,
September 23, 1976.
48. Bolt, Beranek, and Newman, "Economic Impact Analysis of Proposed
Noise Control Regulation," Report No. 3246 for the U.S. Department
of Labor, Occupational Safety and Health Administration, April 21,
1976.
49. Continental Trailways, Schedule from Los Angeles to New York,
effective April 25, 1976, CW-2.
50. U.S. Environmental Protection Agency, "Comparison of Alternative
Strategies for Identification and Regulation of Major Sources of
Noise." EPA Report February 1975 (original reference reported by
reference 9).
51. Rowland, R.H., and K.E. Gould, "Environmental Impact of Noise
Emission Standards for Solid Waste Compaction Trucks: Health and
Welfare Benefits." Draft Interim Report to U.S. EPA, ONAC, June
1976.
52. Mitre Corporation, "Feasibiity Study of Noise Control Modifications
for an Urban Transit Bus." Prepared for Urban Mass Transportation
Administration, January 1973. PB-220 364.
53. U.S. Department of Transportation and the U.S. Environmental
Protection Agency, "Study of Potential for Motor Vehicle Economy
Improvement" Truck and Bus Panel Report, January 10, 1975.
54. "Noise Levels of New Eagle Buses," Booz-Allen Applied Research, a
report submitted to the U.S. Environmental Protection Agency's
Office of Noise Abatement, and Control, EPA Contract No. 68-01-3509,
November 16, 1976.
55. R. E. Burke, S. A. Bush, and J. W. Thompson, "Noise Emission Standards
for Buses - A Draft Environmental Impact Statement," Wyle Research
Report WR 76-21, submitted by Wyle Laboratories under EPA Contract No.
68-01-3512, prepared for the Office of Noise Abatement and Control,
October 19, 1976.
6-116
-------
56. Grandjean, E., Graf, P., Lauber, A., Meier, H.P., and Muller, R.,
A Survey of Aircraft Noise in Switzerland, Proceedings of the Inter-
national Congress on Noise as a Public Health Problem, Durbrovnik,
Yugoslavia, May 13-18, 1973, pp. 645-659.
57. Sorenson, S., Berglund, K., and Rylander, R., Reaction Patterns in
Annoyance Response to Aircraft Noise, Proceedings of the International
Congress on Noise as a Public Health Problem, Durbrovnik, Yugoslavia,
May 13-18, 1973, pp. 669-677.
58. Johnson, D.R. A note on the relationship between noise exposure
and noise probability distribution, NPL AEPD Report Ai40 (May 1969).
6-117
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SECTION 7
ECONOMIC IMPACT OF BUS NOISE CONTROL
I. OVERVIEW OF ECONOMIC IMPACT ANALYSIS
The purpose of this overview is to outline EPA's approach to the
economic impact analysis of bus noise regulation. Figure 7-1 describes the
conceptual format of the analysis in terms of a flow diagram, and the dis-
cussion that follows is essentially an elaboration of that diagram.
ECONOMIC IMPACT
ANALYSIS METHODOLOGY
This part describes the basic supply/demand model underlying the
analysis. For each of the major areas of bus noise abatement — inter-
city buses, urban transit buses, and school buses — two separate but highly
related markets are under analysis:
1. The market for fully equipped, finished buses, viewed as durable
capital goods input to producing transportation services.
2. The market for bus transportation, from the view point of final
consumers of bus services.
It should be noted that the market for school bus services in a consumer
sense differs from the market for other bus transportation in that it is
dictated more by the need to transport pupils and associated policy and legal
considerations than by individual consumer choice.
Bus transit firms, whether intercity carriers, urban transit authori-
ties, or public school districts, act as intermediaries, operating in both
of these markets.
7-1
-------
FIGURE 7-1. ECONOMIC IMPACT ANALYSIS OF NOISE REGULATION
INDUSTRY PROFILE;
o Industry Structure
o Components of Prime Cost,
Prime User Costs
o Age Distribution of capital
Stock, User Inventories
o International Trade
o Ongoing Regulatory Programs,
Government Subsidies, Etc.
o Baseline Forecast
DETERMINE
FEEDBACK EFFECT
ON SUPPLY;
ITERATE
ANALYSIS
T
DETERMINE EFFECT OF
REGULATION ON SHORT-RUN
INDUSTRY SUPPLY CURVE,
USER DEMAND CURVE
REGULATION PROFILE;
IDENTIFY CHANGES IN:
o Technology
o Production Costs
o Product Configurations
o Enforcement and
Compliance Costs
AS REQUIRED BY THE PROPOSED
REGULATIONS
I
USE DEMAND ELASTICITY
ESTIMATED AND COST
ANALYSES TO ASSESS EFFECT
ON EQUILIBRIUM QUANTITY
o Econometric
Studies
o Sensitivity
Analysis
EXAMINE LONG-RUN
EFFECTS ON INDUSTRY
STRUCTURE, EXPORTS/IMPORTS
INDIVIDUAL FIRMS
EXAMINE FINANCIAL IMPACT
ON USERS, CONSUMER GROUPS,
GOVERNMENT, INFLATION,
BALANCE OF BWMENTS
7-2
-------
The demand for buses as a capital good is a "derived" demand for a fac-
tor input, that is, derived from the demand for final consumption of bus
services by eventual end users. A large portion of the economic analysis
is devoted to describing the relationship between facts that can be ascer-
tained about final demand and the conditions under which that final demand
translates into a demand for buses as capital inputs.
The mix of regulatory and managerial incentives observed in the various
bus transportation markets implies a variety of potential responses to the
proposed regulations. A separation of the parallel analyses of the three
major categories (transit, intercity, and school buses) is maintained
throughout the Economic Impact Analysis.
SUPPLY AND DEMAND AT
THE CONSUMER LEVEL
(a) Urban and Intercity
Transportation Services
Figure 7-2 portrays a standard supply and demand model for urban and
intercity transportation services at the consumer level. Ideally, both
the supply and demand schedules could be estimated econometrically, and the
analysis conducted in precise, empirical terms. Realistically, however, we
know very little about either the supply or the demand curve, particularly
the former, and it is necessary to proceed in terms of heuristic arguments
combined with sensitivity tests of specific parametric assumptions.
The supply and demand curves of Figure 7-2 apply to the relevant market
or submarket in which the transit firm operates. For example, the relevant
market for an urban transit system is the appropriate urbanized area, while
the market for intercity bus carriers is nationwide.
7-3
-------
FIGURE 7-2
SUPPLY AND DEMAND AT THE CONSUMER LEVEL
Fare per '
Bus-mile'
So
•Si
Ql
Qo
Bus-miles per unit time
Consider the effect of a rise in the cost of transportation equipment.
Assume, to begin with, that the increased cost of equipment results in an
increase in the marginal cost of operating a bus transit firm, hence of the
supply curve facing bus passengers. The assumption can be verified subse-
quently in an analysis of transit firms.
Since the exact shape of the curve SS is not known in advance, a hori-
zontal supply curve S S is taken as a first approximation. This shape is
consistent with a long-run supply of an industry that does not experience
7-4
-------
economies or diseconomies of scale (Reference 1) in its bus operations, so
the initial analysis also has implications for long-term economic impacts.
(b) School Bus
Transportation Services
The demand for school transportation services are viewed as being signi-
ficantly different from that of urban and intercity transportation services.
Figure 7-3 is an approximation of the demand for school bus transportation.
FIGURE 7-3
TOTAL MARKET DEMAND FOR
SCHOOL BUS TRANSPORTATION
Price per
Pupil Mile
P =$0.009
0
Demand
0
Bus Miles
7-5
-------
Present conditions are approximated by the price/quantity relationship
1
of Q x P where P = $0.009 represents an approximation of the
present taxpayer burden per pupil mile for school bus transportation (cal-
culated in terms of numbers of students transported at public expense).
Price P, represents one of several alternative price levels per
pupil mile where other forms of transportation become visible alterna-
tives to school bus transportation. Depending upon individual circumstances,
prices around level P, can be viewed as the operating costs associated
with the following transportation alternatives:
— price of riding transit buses
to and from school
— car pool costs on a per pupil
basis
— cost of automobile transport
(if car pools are not a viable
alternative)
As the price per pupil mile for school bus transportation moves between
P and P-, very few parents would be rational if they chose to transport
their children on a personal basis due to the following conditions:
1. Pupil transportation is viewed as an essentially free commodity
due to the tax burden being shared by nearly all taxpayers in an
area.
2. If large numbers of publicly transported pupils chose alternative
forms of transportation, the public costs would remain essentially
unchanged in the short term with an additional burden being borne
by the individual transporting families.
1
For 1973-74, 267,704 school buses transported 21,347,039 pupils at an
average cost of $0.72 per bus mile. (National Center for Education
Statistics, Statistics of State School Systems, 1973-74, Table 41)
7-6
-------
If the individuals were the only interested parties, the demand curve
between P and P, would be perfectly inelastic such that no reduction
in school bus usage would be realized from price/cost increases. However,
state and local transportation coordinators and legislators feasibly have
options available to them such as changing policy to the extent that volume
of service offered as a free commodity would be reduced. Such policy con-
siderations might be in the following areas:
— reduction in the quantity and/or
length of field trips
— elimination of free transportation
to sporting events
— changing physical conditions which
presently preclude walking at
present (such as installing side-
walks and traffic lights where
necessary for safe walking)
Nevertheless, the section of the demand curve between P and P, is
viewed as being essentially inelastic.
As prices move above level P,, the likelihood of eliminating school
transportation services becomes much more viable, and we would view the curve
as being essentially elastic where it might be more attractive to eliminate
school transportation services entirely, with school districts possibly
offering payments to differentially impacted families.
INCREMENTAL
COST ANALYSIS
An estimate of the effect of the proposed noise regulations on the
supply curve SS (see Figure 7-2) can be formed by examining the expense
statement of a typical transit firm (or of U. S. transit firms in the aggre-
gate) . From economic theory, we know that the supply curve of an industry
7-7
-------
is the horizontal sum of individual firm supply curves, and individual firm
supply curves are the "marginal" or "incremental" cost schedules for oper-
ating transit fleets.
The transit firm's expense statement e is a sum of contributing expense
accounts, including labor (L), maintenance (M), fuel (F), capital expense
(X), stations (S), and other expenses (0):
Expense =L+M+F+X+S+0.
Imposition of noise control technology, as a first approximation,
affects only a subset of these expenses. (For the costs of bus noise tech-
nology, refer to Appendix C.) Since only incremental impact is relevant
to movements in the supply curve, consideration of many expense categories
can be eliminated.
Specifically, we determine (from Appendix C) the incremental effect
on E of imposition of regulatory level R:
dE/dR = oty/dR + dF/dR + dX/dR.
The derivatives with respect to other expense categories vanish,
since as a first approximation the technology has no effect on these items.
Note, however, that the full response to the regulation may change all
expense categories as different forms of bus and fleet management
technology are applied. The "first-round" approximation is an approach that
provides an upper bound to the predicted economic cost impact.
Analysis of incremental capital cost dX/dR deserves special attention.
If the firm's capital stock of buses is K dollars, then the relevant annual
carrying cost is X - (r + i) K dollars, where r is the rate of depreciation
per year and i is the rate of interest. Incremental capital cost there-
fore is:
dX/dR = (r + i) dK/dR,
7-8
-------
where dK/dR represents the additional cost of noise reduction equipment
installed on a newly-equipped bus.
(a) Effect on
Quantity Demanded
A rise in the supply curve to S, S, (see Figure 7-2) implies
a reduction in equilibrium quantity from Q to Q-,. The econometric
formula for estimating this relationship is given by the fare elasticity
of transit demand, EL-:
E_ = % Change in Quantity Demanded (B)
BF ~ % Change in Fare (F)
Appendix D reviews estimates of the fare elasticity of demand for
the urban bus transit market and the intercity bus transportation market;
adequate data for a similar estimate of the school bus market is unavail-
able, due to difficulties associated with defining the concept of a "fare"
in that market.
It is important to bear in mind certain cross-effects vis-a-vis other
modes of transportation. Empirical work in this area suggests that such
"cross elasticities" are indeed present to some extent, hence that a dif-
ferential rise in the price of bus services as compared with fares (or user
costs, in the case of private automobiles) of competing modes will have a non-
negligible impact on demand for the mode in question. A relevant consider-
ation in this regard is the possibility that simultaneous promulgation of
noise regulations on all modes of transit may have similar effects on fares
in all markets. To the extent that this phenomenon is true, the effect
of cross elasticities of demand is diminished.
7-9
-------
(b) Equilibrium
Quantity Impact
As a first approximation, the reduction of output to Q, translates
into a reduced long-run demand for bus capital as input to providing bus
services by the ratio (1 - Q-.Q ). To examine this impact further,
we consider the market for finished buses. In doing so, it is hoped that
some knowledge may be gained concerning the shape of the supply curve SS.
Analysis of the market for finished buses draws on the industry profile
section (Section 3). The aspects of the analysis can be distinguished as
one which is long-run and somewhat theoretical, and the other as which is
short-run and descriptive.
LONG RUN
ANALYSIS
The long-run analysis considers the effect of a long-run reduction in
output of buses by the ratio I - Qi/Ogf superimposed on the natural long-
term growth rate of the industry. Inasmuch as reduction in bus service is
predicted by movements along the demand curves in Figures 7-2 and 7-3,
reduction in long-run bus output will be forthcoming. (This assumption is
supported by an observed constant share of bus capital costs in the expense
accounts of bus fleet operators.)
The bus industry profile (Section 3) provides information concerning
the size distribution and profitability of bus manufacturers, the history and
growth of the industry, trade-in buses with foreign countries, life-cycle
characteristics of buses, and technical data concerning the manufacture and
design technology of buses. This information is examined to assess the
likelihood that reduced output levels result in a lower marginal cost of
newly produced buses (hence that the supply curve SS in Figure 7-2 is
7-10
-------
upward-sloping) and whether there are marginal firms in the industry, includ-
ing importers, who would be forced to cease operations due to the potential
reduction in equilibrium output. Note that this latter consideration properly
belongs to the normative phase of the overall impact analysis.
If so indicated, a rising supply schedule for bus production would
imply a rising supply curve SS in Figure 7-2, and a revision in the quan-
titative estimate of the impact Q^ /Q . An interative procedure {Fig-
ure 7-1) then leads to a determination of the long-run equilibrium.
SHORT-RUN
ANALYSIS
Although the long-run analysis is a reliable indicator on which to
base the overall study, some relevant short-run elements are worth consi-
dering, particularly in regard to assessing the possible costs of disrup-
tions following the initial promulgation of the regulations.
One such effect is the so-called "pre-buying" phenomenon wherein bus
fleet operators invest heavily in pre-regulation bus capital to avoid
the higher costs associated with the post-regulation equipment. In con-
trast to the effect on buyers of buses, the disruptive impact on manufac-
turers of buses is reduced by providing adequate lead times for the develop-
ment and introduction of noise abatement technology. A precise statement
as to the relative magnitude of these phenomenon is difficult to produce,
but the potential existence merits attention.
A second short-run phenomenon is the determination of the degree to
which higher equipment costs are passed through to eventual consumers and
end-users by the manufacturers and the bus fleet firms. Since most bus
fleets (except tourism, some charters, and private, non-revenue fleets)
7-11
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operate in a regulated or public ownership setting, immediate pass-through
of operating cost increases may not occur, particularly in the short-run.
Factors working against immediate operating cost pass-through include:
— government funding of bus
capital expenditures
— political decision-making
processes of regulatory bodies
— regulations relating to routes
and service requirements
— direct subsidies to mass
transit systems
— costs of record-keeping and
financial control
Since all of these factors serve to reduce or forestall the pass-through
of long-run incremental cost increases, the long-run analysis serves as
an "upper-bound" on the overall impact estimates.
SENSITIVITY
ANALYSIS
In complex numerical computations, the term "sensitivity analysis"
refers to tests concerning estimated values of certain key parameters by
varying their magnitude and by performing the calculations under the changed
assumptions to detect the significance of errors on the final results.
Such sensitivity tests are performed in two ways on the economic
analysis below. First, the estimate of technology costs (Appendix C) are
determined as a range of potential values and EE&'s independent estimate.
The three values (high, low, and the EEft. independent estimate) are carried
through the economic and financial impact analyses. Since the high estimate
generally corresponds to the highest estimate provided by industry sources,
7-12
-------
the calculations for this level also have implications for assessing the
"worst case" conditions envisioned by respondent industry firms.
A second use of sensitivity analysis is in examining the effect of
certain heuristic assumptions about demand elasticities, public funding
levels, and product costs. These tests are made routinely in the devel-
opment of the overall analysis.
FINANCIAL IMPACT
ANALYSIS
The positive economic analysis of what occurs after the regulations
are promulgated has implications for financial impacts on various special
interest groups. Since these normative aspects of the regulations may affect
the decision-maker's decisions, pertinent information is supplied.
Specific areas covered are the effects on exports and imports, impacts
on marginal producers, differential impacts on municipalities and consumer
groups, costs to government in the form of increased subsidies to transit
firms, inflationary impacts, and possible balance of payments repercussions.
The industry profile section (Section 3) presents projections for
industry output during the period 1976-90. The projections are combined
with the various technology cost estimates (Appendix C) and the assumptions
about the current capital stock of buses to produce a simulation of the
financial cost impact of the proposed regulations. The simulation permits
the assessment of alternative regulatory actions on the basis of an annual-
ized resource cost to the economy as a whole.
Because the intent of these projections is to obtain estimates of the
total resource cost, and not to predict economic behavior, incremental
capital cost is handled somewhat differently here than in the above economic
analysis. Here the objective is to measure the incremental capital cost
7-13
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actually expended in the aggregate, as opposed to the effect of a change in
marginal capital costs on pricing decisions of bus fleet operators.
Actual incremental capital expenditures in any given year are estimated
by multiplying the sum of depreciation and interest (r + i) times the value
of the stock of additional outstanding equipment, net of reserves for depre-
ciation, that has been committed for the purpose of noise abatement. If,
for example,Ak. additional equipment is installed in year t for noise
abatement, then the capital cost related to that investment in year t + s
is given by:
(r + i) (1 - r)s Akt,
a
where the term (1 - r) reflects depreciation at annual rate r for s years.
Alternatively, if straight line depreciation is employed, this cost is
estimated by:
k /n + i (1 - s/n)s Ak ,
where n is the depreciable life of the equipment installed.
7-14
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II. ECONOMIC IMPACT OF NOISE REGULATIONS ON USERS AND MANUFACTURERS
INTRODUCTION
This part of the analysis deals with the economic impact of the
promulgation of noise abatement regulations on bus manufacturers, industry
suppliers, end-users and other affected groups as have been identified.
The industry has been divided into three separate product groups —
intercity, transit, and school buses — due to the following considerations.
1. The products are dissimilar with respect to
their end-use characteristics.
2. Operating entities in each category are
structured and regulated differently.
The three economic impact assessments appear in the following order:
A. Economic Impact of Noise
Regulations on Intercity Motor
Bus Carriers and manufacturers
B. Economic Impact of Noise Regulations
on Urban Transit Motor Bus Carriers
and Manufacturers
C. Economic Impact of Noise Regulations
on School Bus Carriers and Manufacturers
A. ECONOMIC IMPACT OF NOISE REGULATIONS ON INTERCITY MOTOR
BUS CARRIERS AND MANUFACTURERS
Appendix C indicates three major effects of bus noise reduction tech-
nology:
o Additional noise-abatement equipment
installed on newly-produced buses
o Increased maintenance costs for new
buses
o Reduced fuel efficiency of new buses
7-15
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Since the primary impact of these costs is on bus users — fleet operators,
intercity cariers, and, ultimately, consumers — the analysis below concen-
trates attention initially on the user end of the industry. Induced impacts on
manufacturers and financing authorities is studied subsequently.
ANALYSIS OF
USER COSTS
By way of introduction, Table 7-A-l summarizes operating expense accounts
2
of the Class 1 intercity motor bus carrier during the years 1939-75. An
important result from economic theory (reference 2) states that as the demand
for an intermediate product (like buses) is less sensitive (elastic) to changes
in its own price, the smaller is the share of that intermediate product in the
composition of the final product demanded (bus transportation). The reason is
that for a given elasticity of demand for the final product, bus transportation,
the smaller the share of the intermediate input, buses, the smaller will be the
percentage impact of a change in bus prices on the total cost and price of the
final product. A relatively small change in the price of the final product,
transportation, implies a relatively small effect on quantity demanded of both
the final product and the intermediate good.
2
Class designations are formed using annual revenue dollars.
Class 1 carriers have revenues of $1,000,000 ore more.
Class 2 carriers have revenues of $300,000 or more but less than $1,000,000.
Class 3 carriers have revenues less than $300,000.
7-16
-------
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Using this theorem, Table 7-A-l lends insight into the probable
results of the economic impact analysis. Bus capital, the major component
of the "Depreciation and Amortization" account in the ICC reporting format,
represents a small fraction of total operating expenses, say five percent
of less. Hence, a given regulation-induced change in the price of new
buses has only a small effect on the "derived" demand for new buses, and
the ability of the bus manufacturing industry to pass through the additional
equipment costs without severely reducing their sales is thereby enhanced.
Expenses for fuel and maintenance, are relatively important compon-
ents of the operating expense accounts, but here the potential for adverse
economic economic impacts on the suppliers of these inputs — the petroleum
industry and the supply of skilled mechanic labor, respectively — is
negligible due to the overwhelming size of these markets relative to the
bus service industry.
COST ESTIMATES
FROM APPENDIX C
Table 7-A-2 summarizes the pertinent estimates of technology cost from
Appendix C. Expense estimates are in terms of 1976 dollars. It should be
noted that the various proposed technology levels are cost independent of one
another.
The estimates in Table 7-A-2 are "incremental" expenses, that is, addi-
tional expenses over and above the costs in 1976 of purchasing and operating a
typical bus that has no noise abatement equipment installed. Incremental fuel
costs are computed on the basis of midpoint mileage estimates, as described in
the footnote to the table.
7-18
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7-19
-------
For Technology Level 5, an additional consideration not reflected in
Table 7-A-2 is the fact that noise abatement equipment required to attain
the 75 dBA exterior level and the 78 dBA interior level also entails a
reduction in seating capacity by two seats (four passengers) from the
standard 43-seat bus. Reduced seating capacity clearly imposes costs on
the intercity carrier, but the magnitude of these costs is difficult to
assess. The average passenger load on intercity trips is 20 passengers,
or less than half-full, so a large proportion of current service would be
unaffected by the loss of these seats, except to the extent that increased
crowding of remaining capacity adversely affects customer demand.
3
Industry sources have indicated to EPA that the price differential for
similarly-equipped 41 and 49 passenger-rated buses is $12,000 in 1976.
The implied differential for estimating the cost of losing two seats (four
passengers) is $6,000. No measurable difference is indicated in the opera-
ting and maintenance costs between the two buses.
The only adjustment called for in Table 7-A-2 is the addition of $6,000
to the equipment cost for Technology Level 5. This adjustment is included
in^ all subsequent calculat ions of the economic impact^ analysiis.
The $6,000 estimate is substantiated by some evidence collected in 1973
by Greyhound Lines, Inc., in connection with their discussion at that time
to make the 43-seat bus standard equipment in preference to the 38-seat bus.
Greyhound's study involved a survey of departure loads for twelve different
U.S. locations. For a sample of 2,179 scheduled bus departures, 45, or 2.07
3
Housman Bus Sales; Chicago, Illinois (a major distributor)
7-20
-------
percent, had passenger loads of 39 to 43 passengers. Since Greyhound
has a legal obligation to provide service for all paying customers, the
implication is that a reduction in bus seating capacity from 43 to 38
seats would raise total operating costs by roughly two percent.
In the analysis set forth below, an increase of $6,000 in equipment
costs implies a maximum 1.40 percent increase (see Table 7-A-8) in total
operating costs. After adjusting this estimate to reflect five lost seats
instead of four, the agreement with Greyhound's measure is apparent,
particularly in light of the fact that the $6,000 estimate reflects full
adjustment of schedules to fleet capacity whereas Greyhound's test held
schedules constant.
ESTIMATES OF INCREMENTAL
CAPITAL COSTS
The formula for estimating incremental capital costs is
dX/dR = (r + i) dK/dR,
where dX/dR is the incremental capital cost associated with regulatory
level R, dK/dR is the dollar value of noise abatement equipment installed
on new buses, r is the rate of depreciation, and i is the rate of interest.
A major difficulty arises in providing accurate estimates of the rate
of depreciation r.
Three alternatives for estimating r are discussed: estimates based
1 on observations of prices of used equipment, life cycle estimates, and
analysis of carriers' accounting statements. Each of these methods en-
counters difficulties which are examined in turn.
7-21
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(a) Estimates Based on Observed
Used Equipment Prices
The major difficulty in this case is the lack of meaningful data
on which to base estimates. For time periods of ten years or more, the
difference in quality and design of used buses versus newly produced buses
makes price comparisons highly difficult. The used market itself is not
well organized, thus pure quotations are not easily obtained or necessarily
representative.
One major dealer did provide EPA with a pair of prices of standard
intercity buses for the years 1976 and 1964. The price for the 1964 bus
includes expenses incurred by the dealer for equipment overhaul and refur-
bishing (as much as $10,000 per bus), so the extent to which the price
reflects true "depreciation" is not certain:
1976 new intercity bus $85,000 - $95,000
1964 good condition used intercity bus $31,000 - $32,000
The implied rate of depreciation over the 12-year period is estimated
as follows:
1/12
1 - (31,500/90,000) = 8.4%
(b) " Estimates Based on
Life Cycle Assumptions
Tables 7-A-3 and 7-A-4 demonstrate that the total U.S. population of
intercity buses has remained relatively constant during the past two decades,
and that new bus production has amounted to five-to-ten percent of total
stocks. The difference between the two tables in the ratio of new bus pro-
duction to total stocks is explained by the fact that Table 7-A-4 records
only Class I bus inventories, whereas Table 7-A-3 gives estimates of Class I,
II and III inventories.
7-22
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TABLE 7-A-3
INTERCITY BUS FLEET VEHICLE
INVENTORY AND PRODUCTION
1970-75
Calendar
Year
1970
1971
1972
1973
1974
1975p
Bus
Inventory5
22,000
21,900
21,400
20,800
20,600
20,500
Bus
Shipments
1,064
977
1,353
1,276
1,350
Shipments as
of Existing
4.84%
4.46
6.32
6.13
6.55
Percent
Stock
Source:
National Association of Motor Bus Owners (NAMBO).
Note:
Bus inventory refers to estimated inventories of all
operating companies, including Class I, Class II and
Class III Carriers, from NAMBO, One-half Century of
Service to America, Table 1. p: preliminary.
7-23
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TABLE 7-A-4
SELECTED BALANCE SHEET AND OPERATING STATISTICS,
CLASS I INTERCITY MOTOR BOS CARRIERS,
1941-73
Calendar
Year
Total Revenue
Passenger
Equipment
(millions)
Net Revenue
Passenger
Equipment5
[uipmei
dllioi
(millions)
Depreciation
of Revenue
Equipment
(millions)
Equipmen t
Acquired
During Year
(Buses)
Equipment
Owned At
Year-End
(Buses)
1941
1950
1955
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
$ 75.0
214.
264.
319.8
332.
402.
408.
428.
376.0
,7
,1
394
424
450.0
415.9
418.7
439.5
454.0
464.2
$ 42.4
88.7
112.1
119.4
127.8
178.
184.
205.
194
250
256
171.8
186.1
199.0
,3
.2
,6
255.9
249.5
226.3
$ 12.1
24.4
25.0
27.6
26.7
32.6
32.0
37.7
34.8
37.4
38.9
40.7
34.3
32.8
32.9
31.3
34.9
1,358
697
1,344
1,639
1,057
1,329
1,102
1,543
1,084
1,376
1,411
1,205
743
1,042
893
972
1,000
7,891
13,200
11,547
11,093
11,036
13,873
13,608
14,274
11,295
11,749
12,307
12,257
10,063
10,158
9,900
9,711
9,300
Source: Interstate Commerce Commission, Transport Statistics in the United
States (annual).
Note: Net of Reserves for Depreciation. Coverage varies from year
year according to ICC definition of Class I carriers.
to
7-24
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A large portion of the supply of buses to Class II and Class III fleet
operators is in the form of second-hand, used buses from Class I operators,
and only a small part of this supply is in the form of newly-produced buses.
Hence, the total supply of new buses, around 1,200 per year, more properly
represents replacement service to the entire population of carriers and not
just to Class I Carriers.
On the assumption that the age distribution and technology of buses is
roughly uniform over time, these numbers indicate a lower bound on the rate
of depreciation of five percent per year.
(c) Estimates Based on
Carriers' Financial Statements
An upper bound on the rate of depreciation may be obtained by examining
the pertinent accounting statements from ICC Class I annual complications.
These statistics are provided in Table 7-A-4 for the period 1941 through 1973.
ICC accounting rules permit a variety of depreciation formulas for
reporting purposes, including depreciation by number of miles driven, but the
industry norm is eight-year, straight-line depreciation. The ICC Class I
motor bus statistics are dominated by the major carriers (Greyhound, Conti-
nental Trailways, Bluebird, etc.) and the numbers in Table 7-A-4 undoubtedly
reflect this method of accounting in large part.
The eight-year figure is well below the true economic life of intercity
buses: actual service life is at least fifteen and potentially thirty years
or more. But due to the significantly greater intensity with which new inter-
city buses are driven during the initial two years of operation (250,000 miles
7-25
-------
per year as compared with an average annual mileage of 86,000 miles per year
for all Class I intercity buses), the official depreciation life of eight
years represents a compromise between straight-line method and true economic
loss-of-value.
The question remains as to whether to use the "total equipment" or "net
equipment" accounts as the basis for estimating the rate of annual depreciation.
Use of the "total" depreciation (Column 2 of Table 7-A-4) results in an under-
statement of depreciation, since it includes equipment still owned but older
than eight years and therefore no longer depreciated. Net equipment, on
the other hand, results in an overstatement of depreciation because the eight-
years straight-line formula results in an understatement of the total capital
stock.
Note, however, that estimates of the rate of depreciation based on these
accounting summaries are not biased due to price inflation: both the numerator
(stated depreciation) and the denominator (total or net assets) are increased
each year by equally inflated increments.
Using the net equipment definition of depreciable assets, an upper bound
for the annual rate of depreciation r is estimated from the years 1964 through
1973 as 16.65% per year.
(d) Summary of Pate of
Depreciation Estimates
Intercity buses have potentially long service lives, and the concept of a
"rate of depreciation" is not necessarily well-defined or applicable. Depre-
ciation is itself an economic variable, subject to variation according to the
maintenance and route decisions of the fleet operator.
7-26
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Historically, however, the size of the total U.S. fleet and production
of new equipment have maintained relatively constant levels through the past
two decades. On the assumption that this record is representative of the type
of depreciation that buses do in fact experience, EPA estimates an annual rate
of depreciation of five to fifteen percent, with a best midrange estimate of
ten percent per annum.
ESTIMATES OF INCREMENTAL
PRIME COST
The technology cost estimates from Table 7-A-2 for incremental equipment,
fuel, and maintenance costs can be combined into single estimates of incre-
mental cost per vehicle mile. This is accomplished by converting equipment
cost increments from Table 7-A-2 into per annum capital costs (depreciation
plus interest), and then by dividing the sum of annual capital, fuel, and
maintenance cost by 250,000 miles per year.
The relatively high figure of 250,000 vehicle miles per year is used
rather than the average 86,000 miles per year, because the purpose of the
analysis is to estimate the effect of marginal prime cost. The results of
using the alternative 86,000 miles per year figure are indicated below in
Table 7-A-8.
Tables 7-A-5 and 7-A-6 provide results of the calculation for assumptions
of 5% and 15% annual rate of depreciation. It is clear that the calculated
numbers are relatively insensitive to both the assumption about the annual
rate of depreciation and the incremental capital cost from Table 7-A-2. In
the following analysis, only the midrange estimate of these numbers (i.e.,
10% depreciation and EPA's independent estimate of incremental capital costs)
is considered.
7-27
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TABLE 7-A-5
INCREMENTAL PRIME COST PER BUS-MILE OF SERVICE
ASSOCIATED WITH PROPOSED LEVELS OF NOISE
ABATEMENT TECHNOLOGY, DIESEL POWERED
INTEGRAL INTERCITY BUSES
Technology Exterior
Level dBA
1 86
2 83
3 80
4 77
5 75
Interior
dBA
84
83
80
80
78
Incremental Cost — Cents per Vehi<
High Low EPA Estimate
0.012
0.058
0.522
1.055
2.561b
0.000
0.028
0.459
0.969
2.361b
0.003
0.040
0.491
1.030
2.512b
Source: Table 7-A-2. Interest and depreciation are calculated as 15%
of incremental capital cost (5% depreciation from Table 7-A-3
plus 10% interest). Estimates reflect an assumption of 250,000-
vehicle-miles per bus year. (See Source note to Table 7-A-2.)
a
Note: 1976 dollars.
b
Includes adjustment for seat loss.
7-28
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TABLE 7-A-6
INCREMENTAL PRIME COST PER BUS-MILE OF SERVICE
DIESEL POWERED INTEGRAL INTERCITY BUSES
ASSUMING 15 PERCENT RATE OF
DEPRECIATION IN EQUIPMENT
Incremental Cost — Cents per Veh
Technology
Level
1
2
3
4
5
Exterior
dBA
86
83
80
77
75
Interior
dBA
84
83
80
80
78
High
0.021
0.079
0.578
1.139
b
2.965
Low
0.000
0.028
0.473
0.995
b
2.631
EPA Estimate
0.005
0.048
0.526
1.097
b
2.883
a
Source: Same as Table 7-A-5 but with interest and depreciation computed as
25% of incremental captial cost (i.e., 15% depreciation plus
10% interest).
a
Note: :\976 dollars.
b
Includes adjustment for seat loss.
7-29
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IMPACT ON QUANTITY OF
BUS SERVICE DEMANDED
On the assumption that increments to prime cost are passed through
fully, to consumers, results of the sort provided in Tables 7-A-5 and 7-A-6
can be combined with average revenue statistics to estimate the potential
increase in average fare per mile that results from the various levels of
noise abatement technology.
Statistics on average revenues per vehicle mile are provided in Table
7-A-7. Comparison of these numbers with expenses per revenue mile, Table
7-A-l, indicates that profit margins in this regulated industry are moderate
and relatively constant over time. The average fare in 1976 dollars can be
estimated by applying the percentage increase in the Consumer Price Index
2
(transportation) for 1975 to June 1976:
(165.9/150.6) X 93.20 = 102.67c per vehicle mile.
Midrange calculations for the estimated percentage increase in average
fares are given in Table 7-A-8. These numbers are multiplied by the demand
elasticity estimate of -0.5 from Appendix D to compute the expected change
in quantity of service demanded.
IMPACT ON EQUILIBRIUM
BUS PRODUCTION
The foregoing analysis, and Table 7-A-8, indicates that for all tech-
nology levels proposed, the impact on equilibrium bus service demanded is
quite small, and in most cases virtually imperceptible. Since it is unlikely
that the technology of bus fleet management permits substantial substitution
2
Survey of Current Business, July 1976; page S-8.
7-30
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TABLE 7-A-7
OPERATING REVENUE PER PASSENGER AND PER
VEHICLE MILE, 1939-75, U.S.
CLASS I INTERCITY BUS OPERATIONS
Calendar
Year
1939
1950
1960
1965
1968
1969
1970
1971
1972
1973
1974p
1975p
Source:
Passenger
Revenue
(millions)
$113.9
321.4
354.8
453.2
463.7
483.2
510.9
540.1
540.3
562.4
643.3
638.2
Operating Revenue
per Passenger
$ 0.83
0.97
2.12
2.73
3.18
3.55
3.81
4.19
4.25
4.73
5.27
5.45
National Association of Motor Bus Owners
of Service to America, Tables 3 and 4:
Operating Revenue
per Vehicle Mile
22.35$
34.32
48.68
55.36
60.93
65.25
68.84
74.32
76.45
79.91
89.09
93.20
, One-Half Century
Regular route inter-
city service, p: preliminary.
7-31
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7-32
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between buses and other inputs in the production of bus service, it is
probable that reduced patronage of one or two percent resulting from noise
abatement technology will translate into an equivalent reduction in long-run
5
demand for new buses.
To buttress this argument further, note in Table 7-A-2 that the noise
abatement technology in Levels 3 through 5 simultaneously affects maintenance
and fuel costs each to a greater extent than interest and depreciation
expense on incremental equipment.
Fluctuations in annual bus output of one or two percent are well below
the normal variation experienced from year to year by the bus industry as a
whole (Table 7-A-3). Any attempt to refine the analysis further along the
lines of an aggregate demand model would prove fruitless. The remainder of
Subsection 7-A addresses secondary financial impacts and the baseline pro-
jections.
FINANCIAL IMPACTS
ON USERS
The proposed regulations may have adverse economic impacts not recorded
above in the "long-run" analysis if they cause short-run financial disruptions
or have adverse distributional effects. Consider first the impact on the
consumer and fleet operators.
5
Passengers per bus (average load) have remained remarkably constant on
intercity bus service. 1950: 18.2 passengers per bus; 1960: 18.0;
1965: 19.2; 1970: 19.1; 1975: 19.3. (Source: NAMBO, One-half Century
of Service to America.)
7-33
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Since motor bus intercity travel is typically somewhat slower and less
convenient than travel by alternative modes (especially air and auto), a
larger portion of intercity bus patronage is from lower income groups than
for other modes. Increases in the costs of intercity bus transportation will,
therefore, affect lower income groups more adversely than others. The magni-
tude of this distributional effect is likely to be quite small, however. An
increase in fare revenues by 4.62 percent (Table 7-A-8) and a resulting
predicted loss'in demand of 2.31 would increase the total revenue of all U.S.
carriers by about $25.7 million (in 1976).
Fleet operators would be disadvantaged by the noise abatement technology
if the increased equipment costs could not be met without incurring sub-
stantial additional financing. The relatively small share of equipment
replacement costs (Table 7-A-l) in total operating expenditures makes this
an unlikely possibility, however. Moreover, the increased responsiveness of
regulatory bodies to permitting cost-justified fare increases will help firms
to maintain satisfactory profit margins.
FINANCIAL IMPACTS ON
PRODUCERS, INCLUDING
EXPORTERS AND IMPORTERS
As indicated in the above economic analysis, the long-run impact on
equilibrium industry output is likely to be small in percentage terms, so
that given the current growth rate of industry output no actual reductions
in output are projected from one year to the next as a result of reduced
demand for bus services. There remains, however, the possibility of
adverse impact on specific supplies if their product or technology differs
significantly from the industry norm.
7-34
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For U.S. producers of intercity buses, Figure 3-16 (Section 3) indicates
that the market is dominated by three large producers: Motor Coach Industries
(Greyhound), General Motors, and Eagle International, who together account
for virtually 100 percent of U.S. production. The production of these bus-
makers is highly standardized (Figure 3-6), and no differential impact on
producers is envisaged.
U.S. International trade in intercity buses involves two major foreign
countries: Canada and Belgium. Canadian production, trade, and regulation
of buses are so completely integrated with U.S. production (under the Auto-
motive Pact Trade Agreement) that virtually no differential impacts vis-a-vis
Canadian imports is expected. Imports of buses from Belgium, which have
amounted to approximately 62 percent of annual U.S. production during 1970-
75, are almost exclusively production of a subsidiary of Eagle International;
currency devaluation by the U.S. has led Eagle to shift its manufacturing
facilities back to the United States, and beginning in 1976 this "import"
source is largely eliminated.
ANNUALIZED COSTS FOR
INTERCITY BUS NOISE ABATEMENT
Annualized cost calculations projected to the year 2000 for 15
regulatory schedules are presented in Appendix E. Input variables for
intercity buses are listed in Table 7-A-9.
7-35
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TABLE 7-A-9
DATA INPUT AND PARAMETER VALUES
FOR ANNUALIZED COST CALCULATIONS
DIESEL POWERED INTEGRAL INTERCITY BUSES
Variable Description Source or
Baseline Production Rate Figure 3-23
Projected Production Rate Figure 3-23
Incremental Operating Cost Table 7-A-2
Incremental Maintenance Cost Table 7-A-2
a
Incremental Equipment Cost Table 7-A-2
Depreciable Life (years) 15
Price Elasticity of Demand -0.50
Rate of Discount 0.10
a
Note: Incremental equipment costs in Table 7-A-2 for Technology Level 6
are increased by $6,000 to reflect seat loss.
7-36
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B. ECONOMIC IMPACT OP NOISE REGULATIONS ON
URBAN TRANSIT MOTOR BUS CARRIERS AND MANUFACTURERS
Appendix C indicates three major effects of bus noise reduction tech-
nology, as applied to the standard diesel powered integral urban transit bus:
o Additional noise-abatement equipment
installed on newly-equipped buses
o Increased maintenance costs for new
buses
o Reduced fuel efficiency of new buses
The primary impact of these costs is on bus users — fleet operators,
transit authorities, and consumers. The analysis below concentrates atten-
tion initially on the user end of the industry. Subsequently, induced
impacts on manufacturers and financing authorities are studied.
ANALYSIS OF
USER COSTS
Tables 7-B-l and 7-B-2 summarize operating expense accounts of a sample
of urban bus transit systems which are also members of the American Public
Transit Association. The tables demonstrate that bus capital, the major
component of the "Depreciation and Amortization" account, represents a small
fraction of total operating expense, about seven percent or less.
An important result from economic theory (reference 2) states that the
demand for an intermediate product (like buses) is less sensitive (elastic)
to changes in its own price, the smaller is the share of that intermediate
product in the composition of the final product demanded (bus transportation)
The reason is that for a given elasticity of demand for the final product,
7-37
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TABLE 7-B-l
PERCENTAGE DISTRIBUTION OF EXPENSES BY EXPENSE
CATEGORY, APTA BUS TRANSIT SYSTEM
RESPONDENTS, 1960 AND 1969
Expense Category
Total Operating Expenses
Operation and Maintenance - Total
Equipment Maintenance and Garage
Transportation
Station
Traffic, Solicitation, and Advertising
Insurance and Safety
Administrative and General
Depreciation and Amortization
Operating Taxes and Licenses
Operating Rents, Net
Percent
1960
100.00
85.56
19.26
49.42
0.60
0.90
5.31
10.07
6.06
7.92
0.46
of Total
1969
100.00
86.72
16.37
52.68
1.04
1.29
4.41
10.93
6.98
5.81
0.46
Note: Numbers are compiles from American Transit Association,
Transit Operating Report, 1960 and 1969, as aggregates
of respondent-firm data. The sample contains 107 firms
in 1960 and 76 firms in 1969.
Source: John D. Wells, et. al., Economic Characteristics of the
Public Transportation Industry, Table 3.5 Washington, D.C.
U.S. Government Printing Office, 1972.
7-38
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TABLE 7-B-2
EXPENSES PER BUS-MILE BY EXPENSE CATEGORY,
AGGREGATE FOR 48 BUS TRANSIT SYSTEMS,
AND PERCENTAGE DISTRIBUTION, 1974
EXPENSE CATEGORY
Total Operating Expenses
Operation and Maintenance — Total
Equipment Maintenance and Garage
Transportation
Station
Traffic, Solicitation,
and Advertising
Insurance and Safety
Administrative and General
Depreciation and Amortization
Depreciation of Revenue Equipment
Operating Taxes and Licenses
CENTS PER
BUS-MILE
116.65
106.18
20.68
63.31
0.25
1.93
4.65
15.36
5.27
4.60
5.20
Source: American Public Transit Association, Transit
Report for Calendar/Fiscal Year
PERCENT
OF TOTAL
100.00
91.02
17.73
54.27
0.21
1.65
3.99
13.17
4.52
3.94
4.46
Operating
1974, Section D. The
sample consists of all APTA respondent systems in
locations where buses are the sole public transit mode
and for which either ICC or APTA format of accounts are
provided.
7-39
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transportation, the smaller the share of the intermediate input, buses,
the smaller will be the percentage impact of a change in bus prices on
the total cost and price of the final product. A relatively small change
in the price of the final product, transportation, implies a relatively
small effect on quantity demanded of both the final product and the
intermediate good.
Using this theorem, Tables 7-B-l and 7-B-2 lend insight into the
probable results of the economic impact analysis. Since bus capital has
a small share in total factor cost, a given regulation-induced change in
the price of new buses has only a small effect on the "derived" demand
for new buses. The ability of the bus manufacturing industry to pass
through the additional equipment costs without severely reducing sales
is thereby enhanced.
Expenses for fuel and maintenance are relatively important components
of the operating expense accounts, but here the potential for adverse
economic impacts on the suppliers of these inputs — the petroleum industry
and the supply of skilled mechanic labor, respectively, — is negligible
due to the overwhelming size of these markets relative to the bus service
industry.
COST ESTIMATES
FROM APPENDIX C
TafrLe 7-B-3 summarizes the pertinent estimates of technology cost
from Appendix C. Expense estimates are in terms of 1976 dollars. It
should be noted that the various proposed technology levels are cost
independent of one another.
7-40
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The estimates in Table 7-B-3 are "incremental" expenses, that is,
additional expenses over and above the costs in 1976 of purchasing and
operating a typical bus that has no noise abatement equipment installed.
Incremental fuel costs are computed on the basis of midpoint mileage
estimates, as described in the footnote to the table.
For Technology Level 6, an additional consideration not reflected in
Table 7-B-3 is the fact that noise abatement equipment required to attain
the 75 dBA exterior level and the 78 dBA interior level also entails a
reduction in seating capacity by two seats (four passengers) from the
standard 45 or 53 passenger bus. Reduced seating capacity clearly imposes
costs on the transit firm, but the magnitude of these costs is difficult
to assess in the absence of accurate information on capacity utilization
of existing buses.
An indirect estimate of the cost of reduced seating capacity is avail-
able by comparing the costs of constructing and operating buses of
different sizes. Currently, two sizes of urban transit buses are pro-
duced, with passenger ratings and specification as follows:
Standard
Passenger Wheelbase Length Weight Engine
Rating (Inches) (Feet) (1,000 Ibs.) Make and Model
45 225 35 17.6-22.7 Det D 6V-71N
- or -
53 285 40 19.3-23.8 Det D 8V-71N
Industry sources have indicated to EEA that the two bus types are
priced in 1976 as follows:
35 foot $58,000 - $68,000
40 foot $64,000 - $75,000
7-42
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A comparison of midpoint price estimates indicates a price differential
of $6,500 for eight passengers, hence an implied differential of $3,250
for four passengers.
Bus industry sources have also indicated to EE& that there is no
measurable difference in operating and maintenance costs between the
two buses. Hence, the only adjustment called for in Table 7-B-3 is the
addition of $3,250 to the equipment cost for Technology Level 6. This
alteration is included in all subsequent calculations of the economic
impact analysis.
ESTIMATES OF INCREMENTAL
CAPITAL COSTS
The formula for estimating incremental capital costs is:
dX/dR = (r + i) dK/dR,
where dX/dR is the incremental capital (equipment) cost associated with
regulatory level R, dK/dR is the dollar value of noise abatement equip-
ment installed on new buses, r is the rate of depreciation, and i is
the rate of interest. A major difficulty arises in providing accurate
estimates of the rate of depreciation r.
In the absence of satisfactory price information on used urban
transit buses, two alternatives for estimating r are discussed:
(1) estimates based on life cycle assumptions, and (2) analysis of
fleet operators' accounting statements. Both of these methods encounter
difficulties, which are examined in turn.
(a) Estimates Based on
Life-Cycle Assumptions
Table 7-B-4 demonstrates that the total U.S. population of transit
buses has remained virtually constant at roughly 50,000 units during the
7-43
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TABLE 7-B-4
URBAN BUS TRANSIT VEHICLE INVENTORY
AND PRODUCTION, 1940-75
Calender Motor Bus New Bassenger Deliveries as Percent
Year Inventory Buses Delivered of Existing Stock
1940 35,000 3,984 11.38%
1945 49,670 4,441 8.94
1950 56,820 2,668 4.70
1955 52,400 2,098 4.00
1960 49,600 2,806 5.66
1961 49,000 2,415 4.93
1962 48,800 2,000 4.10
1963 49,400 3,200 6.48
1964 49,200 2,500 5.08
1965 49,600 3,000 6.05
1966 50,130 3,100 6.18
1967 50,180 2,500 4.98
1968 50,000 2,228 4.46
1969 49,600 2,230 4.50
1970 49,700 1,442 2.90
1971 49,150 2,514 5.11
1972 49,075 2,904 5.92
1973 48,286 3,200 6.63
1974 48,700 4,818 9.89
1975p 50,811 5,261 10.35
Source: American Riblic Transit Association, Transit Fact Book
'75-'76, Tables 12 and 14. p: preliminary.
7-44
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post World War II period. New production has averaged roughly six percent
of total inventories during this period.
On the assumption that the age distribution and technology of buses is
roughly uniform over time, these numbers indicate a lower bound on the rate of
depreciation of six percent per year. Some caution should be exercised,
however, in accepting this figure as an unbiased estimate of depreciation,
because of the likely possibility that inventory figures represent an
increasing proportion of relatively inactive buses. Such buses serve as
capital reserves to meet contingencies and periods of peak demand. Ihe
accretion of such reserves during the post-war period implies a downward
bias in the above estimate of the actual annual rate of depreciation.
A comparable estimate of the rate of depreciation based on life cycle
data was recently undertaken using fleet inventory characteristics
collected by the American Public Transit Association (Reference 3). Using
survivor curve techniques applied to the age distribution of current
bus fleet inventories, the study concluded that transit buses have an
average life of 19 years, implying a depreciation rate of roughly six per-
cent per annum. As with the above estimate, however, the 19-year age may be
biased (upwards) due to the existence of significant stocks of old, low-
use buses.
(b) Estimates Based on Fleet
Operators' Financial Statements
An upper bound on the rate of depreciation may be obtained by examining
the pertinent accounting statements from ICC annual compilations for
Class I carriers engaged primarily in local or suburban service. Since
7-45
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the coverage is limited to the large carriers, and hence to the larger
urban areas, the rate of depreciation is probably somewhat higher than that
experienced on a nationwide basis.
ICC accounting rules permit a variety of depreciation formulas for
reporting purposes, but the industry norm (and the rule of the Internal
Revenue Service) is eight year, straight-line depreciation. Eight years is
well below the true economic life of urban transit buses; actual service life
can extend to fifteen or twenty years or longer. Table 7-B-5 records the
pertinent statistics from the ICC Annual Statistics. A question remains
as to whether to use the "total equipment" or "net equipment" accounts as
the basis for estimating the rate of annual depreciation. Use of the "total"
definition (Column 2 in Table 7-B-5) results in an understatement or
depreciation, since it includes equipment still owned but older than eight
years and therefore no longer depreciated. Net equipment (Column 3 in
Table 7-B-5), on the other hand, overstates depreciation because the eight-
year formula understates the total capital stock.
Note, however, that estimates of the rate of depreciation based on
these accounting summaries are not biased due to price inflation; both the
numerator (stated depreciation) and the denominator (total or net assets)
are increased each year by equally inflated increments.
Using the net equipment definition of depreciable assets, an upper bound
on the annual race of depreciation r is estimated for the years 1960-73 as
14.3% per annum.
7-46
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7-47
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(c) Summary of Rate of
Depreciation Estimates
Urban transit buses have potentially long service lives, and the concept
of a single "rate" of depreciation is not obviously well-defined or appli-
cable. Depreciation is itself an economic variable, subject to variation
according to the maintenance and route decisions of the fleet operator.
Historically, however, the size of the total U.S. fleet and production
of new urban transit buses have maintained relatively constant levels over
the past three decades. On the assumption that this record is representative
of the type of depreciation that buses do, in fact, experience, EPA estimates
an annual rate of depreciation of six to fourteen percent, with a best mid-
range estimate of ten percent per annum.
ESTIMATES OF INCREMENTAL
HOME COST
The technology cost estimates from Table 7-B-3 for incremental equip-
ment, fuel, and maintenance cost can be combined into single estimates of
incremental cost per vehicle mile. This is accomplished by converting
equipment cost increments from Table 7-B-3 into per annum capital costs
(depreciation plus interest), and then by dividing the sum of annual capital,
6
fuel, and maintenance cost by 30,000 vehicle miles per year.
Table 7-B-6 provides results of the calculations for the assumption of
a 10% annual rate of depreciation. The calculated numbers are relatively
insensitive to the assumption about incremental capital cost from Table
7-B-3 (i.e., low versus medium versus high).
6
American Public Transit Association, Transit Fact Book '75-'76, pp.
23-24.
7-48
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TABLE 7-B-6
INCREMENTAL PRIME COST PER BUS-MILE OF SERVICE
ASSOCIATED WITH PROPOSED LEVELS OF NOISE
ABATEMENT TECHNOLOGY, DIESEL POWERED
INTEGRAL URBAN TRANSIT BUSES
a
Incremental Cost—Cents per Vehicle-Mile
Technology
Level
1
2
3
4
5
6
Exterior
dBA
86
83
81
80
77
75
In ter ior
dBA
84
83
83
80
80
78
High
0.137
0.570
1.589
3.433
5.533
11.567b
Low
0.000
0.233
0.467
1.733
3.167
8.533b
EPA Estimate
0.033
0.363
0.720
2.083
3.847
10.080b
Source: Tables 7-B-3 and 7-B-4. Interest and depreciation are calculated
as 20% of incremental capital cost (10% depreciation plus 10%
interest). Estimates reflect an assumption of 30,000 vehicle-miles
per bus-year (American Public Transit Association, Transit Fact
Book '75-'76f pp. 23-24).
a
1976 dollars.
b
Includes adjustment for seat loss.
7-49
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EFFECT OF IMTA SUBSIDIES
FOR EQUIPMENT PURCHASES
Qualified urban transit authorities receive a subsidy of up to 80%
of the cost of new equipment purchases from the Urban Mass Transit
Administration (UMTA). Since the urban transit firm has no incentive to
pass on costs borne by the Federal Government to its customers, the effect
of UMTA subsidies is to reduce the effective capital cost by 80%. Table
7-B-7 reproduces the calculations of Table 7-B-6 on the assumption that
incremental equipment costs have an annual value equal to 20% that assumed
in Table 7-B-6.
The calculations also constitute a sensitivity analysis with respect to
the assumption about the rate of depreciation. In effect, Table 7-B-7
assumes an annual rate of depreciation of 2.0% in place of 10% in Table
7-B-6. The difference in the resulting numbers is not substantial, and one
may conclude that the economic impact analysis is relatively insensitive to
the assumption about the annual rate of depreciation.
IME&CT ON QUANTITY OF
BUS SERVICE DEMANDED
On the assmption that increments to price cost are passed through to
consumers, at least in part, results of the sort provided in Table 7-B-7
can be combined with average revenue statistics to estimate the potential
increase in average fare per mile that results from various levels of noise
abatement technology.
Statistics on average revenue per vehicle mile are provided in Table
7-B-8. The average fare in terms of 1976 dollars can be estimated by applying
7-50
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TABLE 7-B-7
INCREMENTAL PRIME COST PER BUS-MILE OF SERVICE
DIESEL POWERED INTEGRAL URBAN TRANSIT BUSES
ASSUMING 80 PERCENT FUNDING OF CAPITAL
EXPENDITURES BY THE URBAN MASS
TRANSPORTATION ADMINISTRATION
Technology Exterior
Level dBA
1 86
2 83
3 81
4 80
5 77
6 75
Interior
dBA
84
83
83
80
80
78
a
Incremental Cost — Cents per Vehicle-Mile
High Low EPA Estimate
0.027
0.301
0.691
1.887
3.293
6.90013
0.000
0.233
0.467
1.547
2.820
6.293^
0.007
0.259
0.517
1.617
2.956
6. 60^
Source: Same as Table 7-B-6, but with interest and depreciation
computed as 4.0% of incremental capital cost (i.e.,
1/5 x 20%).
a
Note: 1976 dollars.
b
Includes adjustment for seat loss.
7-51
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TABLE 7-B-8
OPERATING REVENUE PER PASSENGER AND PER
VEHICLE MIIB, 1940-75, U.S.
MOTOR BUS TRANSIT SYSTEMS
Calendar Passenger Operating Revenue Operating Revenue
Year Revenue per Passenger per Vehicle Mile
(millions)
1940 $248.8 6.87$ 20.83$
1945 590.0 7.07 34.26
1950 734.2 9.56 38.74
1955 826.3 14.41 48.32
1960 910.3 17.17 57.75
1961 897.8 18.57 58.69
1962 910.1 19.07 60.06
1963 932.2 19.62 61.20
1964 950.4 20.10 62.20
1965 971.9 20.55 63.59
1966 998.1 21.23 65.59
1967 1037.3 22.39 67.98
1968 1049.7 23.20 69.60
1969 1114.8 25.71 75.41
1970 1193.6 29.41 84.69
1971 1226.8 32.23 89.19
1972 1177.8 33.07 90.05
1973 1183.8 32.40 86.38
1974 1269.6 31.76 88.72
1975p 1310.1 32.10 85.74
Source: American Public Transit Association, Transit Fact Book
*75-'76, Tables 7, 9, and 10. p: preliminary.
7-52
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7
the percentage increase in the Consumer Price Index (transportation) from
1975 to June 1976:
(165.9/150.6) X 85.74 « 94.45 per vehicle mile.
Examination of the cost/revenue ratio of U.S. urban mass transit
systems (Table 7-B-9) indicates that an assumption of full cost pass-through
of incremental expenses is unwarranted. Not only do urban transit systems
enjoy significant subsidies in the purchase of new equipment (a relatively
small proportion of total operating costs), but subsidies by federal (UMTA),
state and municipal financing authorities has brought about a condition
of costs in excess of revenues by a ratio approaching two-to-one in 1976.
A reasonable assumption is that such subsidization will continue at
present levels. The calculations of Table 7-B-10 assume, therefore, that
only one-half of regulation induced cost increments are passed on to consumers
in the form of higher fares.
Percentage increase in fares as computed in Table 7-B-10 translates
into estimates of the corresponding decrease in ridership demanded by apply-
ing demand elasticity estimates from Appendix D. The calculations of regu-
lation-induced reductions in quantity demanded in Table 7-B-10 assume the
relatively high elasticity of -0.5: actual percentage decreases in quantity
will probably be less than those computed in the table.
7
Survey of Current Business, July 1976; page S-8.
7-53
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TABLE 7-B-9
TREND OF
Operating
Revenue
(millions)
$ 737.0
1,380.4
1,452.1
1,426.4
1,407.2
1,443.8
1,478.5
1,556.0
1,562.7
1,625.6
1,707.4
1,740.7
1,728.5
1,797.6
1,939.7
2,002.4
TRANSIT OPERATIONS, 1940-1975
Operating
Expense
(millions)
$ 660.7
1,231.7
1,385.7
1,370.7
1,376.5
1,454.4
1,515.6
1,622.6
1,723.8
1,846.1
1,995.6
2,152.1
2,241.6
2,536.1
3,239.4
3,705.9
Cost-Revenue
Ratio
0.896
0.892
0.954
0.961
0.978
1.007
1.025
1.043
1.103
1.136
1.169
1.236
1.297
1.411
1.670
1.851
Calendar
Year
1940
1945
1950
1955
1960
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975p
Source: American Public Transit Association, Transit Fact
Book '75-'76 Table 4. p: preliminary.
7-54
-------
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7-55
-------
ON EQUILIBRIUM
BUS PRODUCTION
The foregoing analysis, and Table 7-B-10, indicates that for all Technology
Levels proposed, the impact on equilibrium bus service demanded is quite small,
and in most cases virtually imperceptible. Since it is unlikely that the tech-
nology of bus fleet management permits substantial substitution between buses
and other inputs in the production of bus service, it is probable that reduced
patronage of one or two percent resulting from noise abatement technology will
8
translate into an equivalent reduction in long-run demand for new buses.
To buttress this argument further, note in Table 7-B-3 that the noise
abatement technology in Levels 4 through 6 simultaneously affects maintenance
and fuel costs each to a greater extent than interest and depreciation expense
on incremental equipment.
Fluctuations in annual bus output of one or two percent are well below the
normal variation experienced from year to year by the bus industry as a whole
(Table 7-B-4). The remainder of this analysis for transit buses addresses
secondary financial impacts and baseline projections.
FINANCIAL IMEACT
ON USERS
The proposed regulations may have adverse economic impacts not recorded
above in the "long-run" analysis if they cause short-run financial dislocations
8
Motor bus passengers per vehicle have declined steadily since World War
II, despite fluctuations in relative operating costs. 1945; 5.74 passen-
gers per vehicle; 1950: 4.74; 1955: 4.24; 1960: 4.08; 1965: 3.80;
1970: 3.57; 1975: 3.32. (Source: ARTA, Transit Fact Book '75-76,
Tables 6 and 10.)
7-56
-------
or have distributional effects. Consider first the impact on consumers and
fleet operators.
Since urban transit by motor bus is typically somewhat slower and less
convenient than travel by alternate modes, especially auto, a larger portion
9
of urban bus patronage is from lower income groups than for other modes.
Increases in the costs of urban transit will therefore effect lower income
groups more adversely than others. The magnitude of this distributional
effect is likely to be quite small, however. A maximum predicted increase in
fare revenues of 3.65 percent (Table 7-B-10) and a corresponding decrease in
demand of 1.83 percent would increase the total revenue of U.S. bus transit
systems by $35.1 million (in 1976).
Fleet operators would be disadvantaged by the noise abatement technology
if the increased equipment costs could not be met without incurring substan-
tial additional financing. The relatively small share of equipment replace-
ment costs (Tables 7-B-l and 7-B-2) in total operating expenses makes this an
unlikely possibility, however, particularly when consideration is taken of
the UMTA equipment subsidy program.
The annual survey by the American Public Transit Association of urban
transit fleet inventories makes possible a statement of the likely replace-
ment needs of various municipalities. Table 7-B-ll presents such a summary,
«
broken down by size of city fleet. It is apparent from Table 7-B-ll that
9
The Federal Highway Administrations's Nationwide Personal Transportation
Study, 1973, shows that for 1969-70, ridership on bus and street car
transportation is distributed as follows (by annual household income):
$0-3,000: 12.7%; $3,000-3,999: 10.8%; $4,000-4,999: 9.2%; $5,000-5,999:
8.8%; $6,000-7,499: 12.3%; $7,500-9,999: 15.4%; $10,000-14,999: 16.3%;
$15,000 and over: 7.9%; Not applicable: 6.6%.
7-57
-------
larger cities do not differ significantly from smaller cities in terms of
median fleet age.
Table 7-B-12 identifies major municipalities with median fleet age in
excess of ten years as of June 10, 1975. Municipalities that are especially
prone to replacement needs appear to be distributed evenly by geographical
region and city type.
FINANCIAL IME&CTS ON
PRODUCERS, INCLUDING
EXPORTERS AND IMPORTERS
As indicated in the above economic analysis, the long-run impact on
industry output equilibrim is likely to be small in percentage terms.
Thus, given the current growth rate of industry output (in recent years), no
actual reductions in output are projected from one year to the next as a
result of reduced demand for bus services. There remains, however, the
possibility of adverse impact on specific suppliers if their product or
technology differs significantly from the industry norm.
Figure 3-17, section 3, indicates that the market is dominated by three
large producers: General Motors, Flexible, and AM General, who together
account for virtually 100 percent of U.S. production. The production of these
bus-makers is highly standardized (Figure 3-7), in fact virtually inter-
changeable, and no differential impact on producers is envisaged.
Since the noise abatement technology involves mostly minor additions
and modifications to existing equipment, the potential for impacting U.S.
export production to non-regulated countries is minimal. The only,
importer of consequence of urban transit buses is Mercedes-Benz, whose
marketing activities are devoted exclusively to the airport-hotel and muni-
cipal "feeder route" markets.
7-58
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TABLE 7-B-ll
MEDIAN AGE OF FLEET BY FLEET SIZE,
U.S. MOTOR BUS TRANSIT SYSTEMS,
AS OF JUNE 30, 1975
Fleet Size (Buses) Number of Cities Mean Median Age Standard Deviation
500 or more
100 to 499
50 to 99
3 to 49
17
43
41
104
Source: American Public Transit
Vehicle Fleet Inventory
9.82 years
b.23
9.54
8.64
Association, Transit Passenger
as of June 30, 1975.
4.14
4.48
7.23
6.68
7-59
-------
TABLE 7-B-12
MAJOR BUS TRANSIT SYSTEMS WITH MEDIAN
FLEET AGE IN EXCESS OF TEN YEARS
AS OF JUNE 30, 1975
City
Maplewood, New Jersey
Boston, Massachusetts
Oakland, California
Seattle, Washington
Buffalo, New York
Milwaukee, Wisconsin
Cincinnati, Ohio
Houston, Texas
Norfolk, Virginia
Richmond, Virginia
Sacramento, California
Jacksonville, Florida
Louisville, Kentucky
Fleet Size (Buses) Median Fleet £
1847
1149
878
559
556
523
444
421
285
233
204
193
179
Charlotte, North Carolina 132
Hampton, Virginia
Holyoke, Massachusetts
Dayton, Ohio
Des Moines, Iowa
Des Plaines, Illinois
106
98
93
90
88
Source: American Public Transit Association, Transit
Vehicle Fleet
Inventory as of June 30, 1975.
12
13
12
20
12
13
11
13
18
14
13
13
14
14
19
23
27
17
20
Passenger
7-60
-------
The Mercedes-Benz buses sold in the U.S. are small (passenger rating:
19), limited use vehicles which do not compete with the industry standard
U.S. urban transit model. Annual average sales amount to 200 units, with
a base price of $26,111. Sales to municipalities are primarily to service
"feeder" routes, and some further penetration of this market is anticipated
in future years.
Noise levels of the Mercedes bus are currently high (84 dBA) at 75%
of maximum throttle at 45 mph). Mercedes-Benz has engaged in research to
reduce these levels, including the development of optional equipment to
reduce exterior noise to 80 dBA. Information on their ability or the cost
of attaining noise levels below 80 dBA is not available at present. Some
adverse impact on Mercedes-Benz imports to the U.S. market does appear
possible at this point.
ANNUALIZED COSTS FOR
URBAN TRANSIT BUS NOISE ABATEMENT
Annualized cost calculations projected to the year 2000 for 15 regu-
latory schedules are presented in Appendix E. Input variables for urban
transit buses are listed in Table 7-B-13.
7-61
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TABLE 7-B-13
DATA INPUT AND PARAMETER VALUES
FOR ANNUALIZED COST CALCULATIONS
DIESEL POWERED INTEGRAL URBAN TRANSIT BUSES
Variable Description Source or Value
Baseline Production Rate Figure 3-24
Projected Production Rate Figure 3-24
Incremental Operating Cost Table 7-B-3
Incremental Maintenance Cost Table 7-B-3
a
Incremental Equipment Cost Table 7-B-3
Depreciable Life (years) 12
Price Elasticity of Demand -0.50
Rate of Discount 0.10
a
Note: Incremental equipment costs in Table 7-B-3 for Technology Level 6 are
increased by $3,250 to reflect seat loss.
7-62
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C. ECONOMIC IMPACT OF NOISE REGULATIONS ON
SCHOOL BUS CARRIERS AND MANUFACTURERS
INTRODUCTION
The school bus industry is a highly complex entity consisting of several
manufacturers producing an almost infinite number of variations to the basic
product - a vehicle designed to transport pupils to and from schools. Almost
any combination of the following characteristic variables can be specified
by the school bus customer:
1. Engine Type - Gasoline or diesel of various horsepower ratings.
2. Construction - Body-on-chassis or integral.
3. Engine Placement - Forward, mid-unit, or rear.
4- Make - Chassis (3 primary manufacturers), body (6 primary
manufacturers), integral (2 manufacturers).
5. Size (seating capacity) - as many as 97 passengers.
6- Options - Air conditioning, interior quality, transmissions
(various speeds; standard or automatic), etc.
The production of school buses is, therefore, of a customizing nature with
differing costs and prices associated with each of the variables described
above.
Due to the impracticality of assessing the economics impact of noise
abatement regulations on all possible variations in the product, the
analysis has been limited in the following manner:
Small buses (under 10,000 pound gross vehicle
weight rating (GVWR) have been eliminated from
consideration.
Size of buses (in terms of passenger capacity)
and optional equipment have been considered
only with respect to their contribution to the
price range of the final product.
7-63
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The outgrowth of these limiting factors are the following school bus
"product" types:
1. Gasoline powered conventional
2. Gasoline powered forward control
3. Parcel delivery and motor home chassis
4. Diesel powered conventional
5. Diesel powered forward control
6. Diesel powered integral mid-engine
7. Diesel powered integral rear-engine
The proposed noise abatement schedules differ by type of power unit (gas
and diesel), and costs of meeting the proposed regulations differ by each of
the seven product types defined above. Furthermore, consideration has been
given to differential noise abatement costs associated with individual manu-
facturers insofar as these costs can be identified.
The primary economic areas affected by the noise abatement requisitions
are shown schematically in Figure 7-C-l. Each of the following economic
impact areas are given consideration in the analysis:
1. Manufacturers
2. End users
3. Suppliers
The economic impact analysis assumes a quantitative posture where
possible, and the discussion is ordered in the following manner:
Timing of the regulation
Costs of noise abatement
Industry considerations
— Analysis of User Costs
Estimates of Incremental Capital Costs
Estimates of Incremental Prime Costs
— Impact on Quantity of Bus Production
Financial Impacts
Baseline Projections
TIMING OF THE
REGULATION
The point in time when regulations are to be imposed on the industry is
important in several respects.
7-64
-------
FIGURE 7-C-l
ECONOMIC IMPACT FLOW CHAKT-
"SCHOOL BUSES
/NOISE \
&EGULATIONST
PUBLIC
SCHOOLS
SUPPLIERS
MANUFACTURER-
CHASSIS
MANUFACTURER-
BODIES
PRIVATE
SCHOOLS
FIRM
IMPACTS
OTHER
USERS
1
r
1
r
OPERATIONAL/
FINANCIAL
IMPACTS
COMMUNITY/
INDIVIDUAL
IMPACTS
7-65
-------
1. Technology considerations. The development of the technology
associated with quieting vehicles to the noise level allowed
by the requisitions can take several years of effort on the
part of manufacturers. If the lead time given to the industry
is sufficiently long, the opportunity exists to develop and
implement less costly emission control equipment for the
vehicles. Furthermore, the potential for technology
advancements to be realized by all industry groups
increases with time.
2. Planning horizon. The promulgation of regulatory constraints
has the potential of producing disruptive effects on an industry
and its market if the effective date and level of regulation
are known only a short time before regulation occurs. The
longer the time that industry has to gauge the effects of the
regulation on its markets, the more intelligently it is able
to react to those effects.
Thus, the economic impact of the various regulatory levels as recommended
by EPA and presented in this analysis assumes that sufficient time will have
elapsed between announcement and promulgation of the regulations such that:
1. Technology will be adequately developed when regulations
are effective.
2. The planning horizon for industry adjustment to any discernable
market reactions is sufficiently lengthy.
7-66
-------
COSTS OF NOISE
ABATEMENT
After the assessment of the noise abatement technology presently .
available to the school bus industry was made by EPA an analysis of the
costs associated with applying that technology to the various types of
school buses was undertaken. EPA's estimates of those costs and discussions
concerning the required manufacturing processes are included in the text
and figures of Appendix C of this report.
Note that each dBA level has three costs associated therewith —
low, high, and one called the EPA independent estimate. The low and
high estimates in most cases refer to cost estimates which were provided
to EPA by industry representatives who responded to requests for cost
information. The independent estimates were developed by EPA and con-
sulting firms utilizing all available information. Although all three
estimates are utilized in developing the economic impact analysis, it
is felt that the independent estimate more adequately reflects the actual
costs which can be expected to be expended in the process of meeting the
regulations.
In order to analyze the costs of quieting school buses in the
proper context, it is appropriate to relate the post-regulatory costs
of manufacture to the present costs. Cost data of this nature in con-
sidered by most companies to be proprietary and confidential. Therefore,
the post-regulatory price (assuming a full cost pass-through) related to
the pre-regulatory price will serve as a best available approximation of
the estimated cost increase.
7-67
-------
(a) Present School
Bus Prices
Due to the variance in model types available to the consumer (as desc-
ribed in the introduction of this section), there is no one price which can
be pinpointed as being representative of all school bus prices. However,
Table 7-C-l attempts to identify the range of prices a consumer could expect
to pay for each type of bus.
Note in Table 7-C-l the wide range of prices quoted within bus type
category and between different categories of bus. The range within categories
is primarily due to the variance in specifications required by bus purchasers
rather than any discernible differences of manufacturing companies. With
respect to the wide variance between prices paid for different school bus
types, it should be noted that diesel powered units cost from $3,000 to $4,000
more than comparably equipped gasoline powered units. Also, the nature of
construction and special characteristics of the integral units account for
the large price difference, in terms of the average price, between all other
bus types.
(b) Estimated Cost
Increases
The percent cost increase due to the proposed regulatory scenarios is
calculated by applying the manufacturing cost increases expressed in Appendix
C to the prices of respective units presented in Table 7-C-l.
IMPORTANT INDUSTRY
CONSIDERATIONS
In addition to the following industry considerations, Section 3 contains
a profile of the school bus industry. Certain major points are detailed here
as they are important factors to be considered for analyzing the economic
impact of proposed noise emission regulations.
7-68
-------
TABLE 7-C-l
August, 1976 Prices for
Completed School Buses, by Type of Bus
Type of Bus
Gasoline Powered:
Conventional
Forward Control
Parcel Delivery
Diesel Powered:
Conventional
Forward Control
Integral Mid-engine
Integral Rear-engine
Range of Prices
$11,000-18,000
$26,000-30,000
$10,000-11,500
$17,000-25,000
$28,000-30,000
$37,000-90,000
$37,000-75,000
Average Price
$14,500
$27,000
$11,000
$19,000
$30,000
$50,000
$50,000
Note: itie average price expressed here is the price given
by respondents as closely approximately the mean price
paid for units of the respective type.
Source: Telephone interviews conducted between EPA consultants
and manufacturers and school bus distributors.
7-69
-------
(a) Competition Nature of
the Industry
Due to the complex nature of the channels of distribution operating in
the school bus market, it is important to highlight some salient points
relative to industry competition.
The market for integrally constructed buses is distinctly different
from that of body-on-chassis models both in terms of market interactions
and marketability. The principle difference are as follows:
1. The sale of the integrally constructed bus is generally
conducted by the manufacturer of the unit, whereas the body-on-
chassis bus is normally sold through a distributor representing
a particular body builder. The body builder, in turn, obtains the
driveable chassis from the chassis manufacturers (with the
chassis make and specifications being indicated in the bid
document).
2. The integrally constructed unit contains physical characteristics
which make it more appropriate for use in a particular region and for
specific functions where the body-on-chassis type of bus is
physically unsuitable or economically unjustified. Integral
units appear to be particularly well-suited for use in mountain-
ous terrain and when high speed highway driving is necessary.
Also, integral units all well-suited for such special purposes
as the transportation for college football teams to and from
games.
7-70
-------
Due to these important considerations, among others, body-on-chassis
school buses are not thought of as being substitutes for integrally
constructed buses. Rather, they are in a class more like that of intercity
buses although they are neither as heavily constructed nor as costly in
terms of purchase price.
As far as competition between buses other than the integrally con-
tructed types, a high degree of competition appears to exist at least within
bus categories. For example, gasoline powered conventional buses of dif-
ferent makes compete directly, as readily substitutable goods. Any make of
bus body can be constructed on any one of the four major chasses makes, and
sales are typically made on the basis of competitive bids by several pro-
ducers. Domestic market share data for the four major chassis manufacturers
(Table 7-C-2) shows that a great deal of brand switching does occur from
year-to-year — further a priori information indicating a high degree of
competition.
At the assembly stage of manufacture, diesel and gasoline body-on-
chassis school buses are highly substitutable, and the assembler can switch
easily from production of one to the other. This is a significant consi-
deration in connection with the differential lead times envisaged for
attainment of the various levels of noise attenuation. Should an
industry-wide noise standard be promulgated, say, one year in advance
of compliance capability by diesel chassis maufacturers but not so
for gasoline chassis, the assemblers could shift production entirely to
gasoline chassis with minimal hardship. Advance notice of the forth-
coming regulations would enable bus purchasers with strong preference
for the diesel mode to advance or delay their buying.
7-71
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TABLE 7-C-2
SHARES OF DOMESTIC MARKET
FOR SCHOOL BUS CHASSIS — 1973-1975
Make
Chevrolet
CMC
Ford
International Harvester
100.0% 100.0% 100.0%
Source: Motor Vehicle Manufacturers Association
1973
.et 11.9%
8.2%
29.6%
itional Harvester 50.3%
1974
12.8%
9.2%
35.0%
43.9%
1975
15.0%
8.2%
22.7%
54.1%
7-72
-------
(b) Price
Movements
No information has been found during the course of this study to express,
in a quantitative manner, the way in which manufacturers of school buses per se
have reacted to increased production costs in the past. However, if the
Wholesale Price Index for all buses is a representative measure of school bus
price movements, we find that bus prices have lagged behind the WPI for all
manufactured goods since 1973 when prices jumped from an index of 117.9
(1967 base) for 1972 to 129.2 for 1973 (Table 7-C-3). In 1975, bus prices
showed an extraordinary increase from 128.6 in 1974 to 156.4 in 1975. The
margin of difference has narrowed again by June of 1976, possibly due in
part to cost increases associated with brake system regulations.
Irrespective of the behavior of manufacturers to other associated cost
increases, industry sources indicate that cost increases caused by regulatory
actions are passed through to consumers in full. Such is the expectation
relative to safety regulations to be effective in early 1977 and thereafter.
(c) Differential
Impacts
Differential impact on the school bus industry are discussed in the
following paragraphs in the context of differing costs, by firms manufactur-
ing the same product type, and of differing costs associated with
quieting different types of buses.
1. Differential costs, by manufacturer, for producing the same
product. As discussed previously, it is felt that the
regulatory levels under analysis here will cause no
differential costs which will put one firm in a less favorable
competitive position than may be the case at present.
7-73
-------
TABLE 7-C-3
WHOLESALE PRICE COMPARISON -
ALL MANUFACTURERS VS. BUSES
(1967=100)
YEAR WPI - BUSES WPI - ALL MANUFACTURED GOODS
100.0
102.6
106.3
110.2
113.8
117.9
129.2
154.1
171.1
178.7
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
100.0
103.6
106.9
111.2
115.0
116.8
117.7
128.6
156.4
167.8
Source: U.S. Department of Labor, Bureau of Labor Statistics
7-74
-------
2. Differential costs associated with quieting different product
types. Here it is necessary to analyze the pre-and-post-regulatory
prices of different product types relative to competitive product
types.
It can be concluded from inspection of the price differential movements
for the various regulatory levels that little change in the relative competi-
tive positions of competing units will derive from the regulatory levels
under study.
This result is of importance because it demonstrates that differential
impacts on the demand for various construction categories of school buses
10
will be minimal under the proposed regulatory level. In the following
analysis cross-effects on demand, as between the different categories will
not be considered in detail.
For purposes of the overall microeconomic analysis, there is little
loss in generality by proceeding to terms of the two principal construction
categories: conventional gasoline and conventional diesel school buses.
Table 7-C-4 shows that in percentage terms, this simplification sacrifices
coverage only to a very limited extent.
10
Integrally constructed mid-engine and rear-engine buses built by Crown
Coach and Gillig Bros, are an exception to this statement, but as
mentioned earlier, they are considered specialized products not
competing directly with other school bus types.
7-75
-------
TABLE 7-C-4
PERCENT DISTRIBUTION
OF ALL SCHOOL BUS TYPES
Percent of
Type of Bus Total Buses
Gasoline Powered:
-Conventional 84.8%
-Forward Control 0.7%
-Parcel Delivery and
Motor Home Chassis 4.4%
Subtotal Gasoline 89.9%
Diesel Powered:
-Convent ional 4.9%
-Forward Control 3.9%
-Integral Mid-Engine 1.0%
-Integral Rear-Engine 0.3%
Subtotal Diesel 11.1%
TOTAL ALL TYPES 100.0%
Source: Based on market share information from
Motor Vehicle Manufactures Association,
School Bus Fleet, industry interviews,
and EPA estimates.
7-76
-------
ANALYSIS OF
USER COSTS
To assess the economic impact of noise abatement technology on the over-
all market for school buses, an examination of user costs parallel to that
in Subsections 7-A and 7-B is appropriate, despite the fact that no "fare",
as such, is generally charged to riders of school buses. Instead, pupil trans-
portation expenses are funded out of general school system revenues. Route
service decisions are determined in part by local school boards and in part
by requirements of state and federal law to provide adequate transporta-
tion for all pupils.
Just under half of the pupils attending schools travel to their
11
destination by means other than school buses, either on foot, by public
conveyance, or in private automobiles. Since the allocation of school
system revenues is in part at the discretion of local government, service
decisions — and by implication, the demand for transportation equipment
— will respond to changes in the cost of providing transportation service.
Figure 7-C-2 demonstrates that during the period 1963-74 expenditures
by school systems for replacement and new vehicles was a relatively small
percentage of total transportation expenditures. Since total bus inventories
were also rising significantly during this period (Table 7-C-7), annual capital
replacement costs were at most ten percent of total transportation expen-
ditures.
11
In 1971-72, 46.1 percent, and in 1973-74, 51.5 percent, of average daily
attendance was transported at public expense. (National Center for
Educational Statistics, Statistics of State School Systems.)
7-77
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Figure 7-C-2
HISTORICAL REVIEW OF EXPENDITURES BY ELEMENTARY AND
SECONDARY SCHDOLS BY MAJOR ACCOUNT AND BY TRANSPORTATION
RELATED ACCOUNTS
(Dollar figures in thousands)
School Years
Total Expenditures'1'
Total Current Expenditures for
Elementary and Secondary Schools
Capital Outlays
Interest on School Debt
Total Pupil Transportation
Expenditures
Capital Outlays for Transportation
Vehicles and Equipment
Current Transportation Expenditures
Salaries'2'
Replacement of Vehicles'2'
Supplies & Maintenance for'2'
Buses and Garages
Other Transportation Expenses'2"3'
Total Pupil Transportation Expenditures
As % of Total Expenditures
Total Pupil Transportation Expenditures
As % of Total Current Expenditures
Salaries as % of Total Pupil Transportation Expenditures
Vehicle Replacement t, Capital Outlays for
Vehicles and Equipment as % of Total
Transportation Expenditures
Supplies and Maintenance as % of Total Transportation
Expenditures
Other Expenses as t of Total Transportation
Expenditures
1963-1964
$20,897
17,218
2,978
701
723
49
674
245
72
121
236
3.5%
4.2%
33.9%
16.7%
16.7%
32.6%
1965-1966
$25,600
21,053
3,755
792
812
25
787
310
77
137
263
3.2%
3.9%
38.2%
12.6%
16.9%
32.4%
1967-1968
$32,111
26,877
4,256
978
1,021
40
981
348
82
143
408
3.2%
3.8%
34.1%
11.9%
14.0%
40.0%
1969-1970
$40,048
34,218
4,659
1,171
1,268
49
1,219
445
88
185
501
3.2%
3.7%
35.1%
10.8%
14.6%
39.5%
1971-1972
$47,655
41,818
4,459
1,378
1,607
99
1,508
532
104
208
664
3.4%
3.8%
33.1%
12.6%
12.9%
41.3%
1973-1974
$56,518
50,025
4,979
1,514
1,955
97
1,858
625
132
271
830
3.5%
3.9%
32.0%
11.6%
13.9%
42.5%
Notes: (1) Excluding current expenditures for services not related to elementary and secondary
education.
(2) Calculated on the basis of expense distribution of states which were consistent
in their reporting methodology. TJie following nine states were inconsistent for
itost years of the analysis: Alabama, Alaska, Arizona, California, Hawaii, Iowa,
Montana, Ohio, and Texas.
(3) Includes constracted services, fares for public transportation, and payments in
lieu of transportation.
Sources: Digest of Educational Statistics, 1975 Edition, U.S. Department of Health, Education,
and Welfare, Education Division, Table 69.
Statistics of State School Systems, various editions, U.S. Department of Health,
Education, and Welfare, National Center for Education Statics, various tables.
7-78
-------
Following the analysis of the previous subsections, the fact that bus
capital is a small fraction of total factor cost in the production of bus
service implies that a given regulation induced change in the price of new
buses has only a small effect on the total cost of transportation and there-
fore, on the "derived demand" for new buses. The ability of the bus manufac-
turing industry to pass through the additional equipment costs without
severely reducing sales is thereby enhanced.
COST ESTIMATES
FROM APPENDIX C
Tables 7-C-5 and 7-C-6 summarize the pertinent estimates of technology
cost from Appendix C. Expense estimates are in terms of 1976 dollars. The
various proposed technology levels are also independent of one another.
The estimates in the tables are "incremental" expenses, that is, addi-
tional expenses over and above the costs in 1976 of purchasing and operating
a typical bus that has no noise abatement equipment installed. Incremental
fuel costs, a negative quantity in the case of gasoline powered conventional
school buses, are computed on the basis of a midpoint mileage estimate, as
described in the note for Table 7-C-5.
ESTIMATES OF INCREMENTAL
CAPITAL COSTS
The formula for estimating incremental capital costs is:
dX/dR = (r + i) dK/dR,
7-79
-------
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7-81
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where dX/dR is the incremental capital (equipment) cost associated with
regulatory level R, dK/dR is the dollar value of noise abatement equipment
installed on new buses, r is the rate of depreciation, and i is the rate of
interest. , A major difficulty arises in providing accurate estimates of the
rate of depreciation r.
In the absence of satisfactory data summarizing fleet operators'
balance sheets and annual depreciation charges, two alternatives for estima-
ting r are discussed: (1) estimates based on life cycle assumptions; (2)
estimates based on observed used equipment prices.
(a) Estimates Based on
Life Cycle Assumptions
Table 7-C-7 demonstrates that the total population of school buses in
the United States has grown dramatically in the last decade. Replacement
requirements, as indicated in the last column of the table, have constituted
a relatively modest proportion of the total population, roughly five percent
per year.
This five percent figure is lower than the actual rate of depreciation
experienced, however, for two reasons. First, a significant portion of the
observed population of school buses consists of relatively inactive, reserve
inventories that are used only occasionally during the year for emergency
purposes or special events. Such buses, which have outlived their normal
lives as useful working capital, do not properly belong in the denominator
of the depreciation estimate. Secondly, the fact that the bus population
has experienced growth means that production from previous years was smaller
than in recent years, hence that the rate of obsolescence of past years is
lower than the rate of depreciation of the total stock.
7-82
-------
TABLE 7-C-7
Calendar Bus
Year Inventory
1968
1969
1970
1971
1972
1973
1974
262,204
273,973
288,750
307,285
316,421
333,892
354,634
UNITED STATES SCHOOL BUS
INVENTORY AND PRODUCTION
1968-74
Bus
Shipments
29,015
28,064
27,408
28,358
30,635
30,039
29,561
Shipments as Percent
of Existing Stock
11.07%
10.24
9.51
9.23
9.68
9.00
8.34
a
Net Shipments
as Percent of
Existing Stock
6.58%
4.85
3.09
6.26
4.16
2.78
—
Source: Industry Sources.
Note: Net shipments are defined as gross shipments less
replacement requirements to keep inventory at a constant
level.
7-83
-------
A somewhat cruder estimate based on life cycle assumptions is the
industry estimate of an average useful life of 9-10 years for gasoline
powered conventional school buses (which comprise 85% of the total stock).
(See Table 7-C-4.) The implied depreciation rate is 10-11% per year.
(b) Estimates Based on
Observed Used
Equipment Prices
One major dealer in used school buses provided EPA with a repre-
sentative pair of prices for good condition conventional gasoline-powered
school buses built in the years 1976 and 1970. Both buses are equipped
with five-speed transmissions:
1976 new conventional school bus $14,100
1970 good condition used conventional school bus $ 5,500
The implied rate of depreciation over the 6-year period is estimated as
follows:
1/6
1 - (5,500/14,100) = 14.52%
*
(c) Summary of Rate of
Depreciation Estimates
As with intercity and urban transit buses, conventional school buses
have potentially long service lives depending on routes traveled, main-
tenance, and mileage figures. Estimates based on life cycle assumptions
indicate a minimum rate of depreciation of at least six percent per annum,
whereas observed market prices of old versus new buses imply a depreci-
ation rate as high as fifteen percent. EPA's independent estimate for
conventional gasoline-powered school buses is twelve percent, somewhat
above the ten percent figure for transit and intercity buses. For con-
ventional diesel powered school buses, EPA's estimate is ten percent
per annum.
7-84
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ESTIMATES OF INCREMENTAL
PRIME COST
The technology cost estimates from Tables 7-C-5 and 7-C-6 for incre-
mental equipment, fuel, and maintenance costs can be combined into single
estimates of incremental cost per vehicle mile. This is accomplished by con-
verting equipment cost increments into per annum capital costs (depreciation
plus interest), and then by dividing the sum of annual capital, fuel, and
maintenance cost by 10,000 vehicle miles per year.
Tables 7-C-8 and 7-C-9 provide results of the calculations for conven-
tional gasoline-powered and conventional diesel-powered school buses,
respectively. Sensitivity tests with respect to the assumption concerning
depreciation demonstrate relatively low sensitivity, and they are not repro-
duced here.
IMPACT ON QUANTITY
OF BUS SERVICE DEMANDED
On the premise that increments to prime cost are transmitted to tax-
payers, the political decision-making process will respond to increased
transportation costs by reducing service, by lengthening pupil riding times,
and by increasing the number of pupils riding in each bus. Given that the
decision-making process is performing optionally, the equilibrium response
of ridership, equipment, and routes will be precisely the same as the res-
ponse that would occur in a market environment where a fare equal to average
expense including normal profit was charged to each pupil.
The correspondence of market and non-market equilibria enables us to
obtain predictions concerning the effect of increments to prime cost on
equilibrium school bus ridership and the demand for school buses.
7-85
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TABLE 7-C-8
INCREMENTAL PRIME COST PER BUS-MILE OF SERVICE
ASSOCIATED WITH PROPOSED LEVELS OF NOISE
ABATEMENT TECHNOLOGY, GASOLINE POWERED
a
Incremental Cost—Cents per Vehicle-Mile
Technology Exterior Interior
Level dBA dBA High Low EPA Estimate
0.805 0.200 0.310
3.190 1.342 1.430
3.649 1.812 1.977
5.751 2.341 3.309
9.068 5.790 6.769
Source: Table 7-C-5. Interest and depreciation are calculated as 22%
of incremental capital cost (12% depreciation plus 10% interest)
Estimates reflect an assumption of 10,000 vehicle miles per bus
year.
a
Note: 1976 dollars.
1
2
3
4
5
83
80
77
75
73
83
80
80
75
75
7-86
-------
TABLE 7-C-9
INCREMENTAL PRIME COST PER BUS-MILE OF SERVICE
ASSOCIATED WITH PROPOSED LEVELS OF NOISE
ABATEMENT TECHNOLOGY, DIESEL POWERED
CONVENTIONAL SCHOOL BUSES
a
Incremental Cost—Cents per Vehicle-Mile
Technology Exterior Interior
Level dBA dBA High Low EPA Estimate
1 83 86 1.500 0.530 1.460
2 80 84 5.800 2.070 3.010
3 77 80 8.160 3.950 5.110
4 75 75 11.320 6.520 7.660
Source: Table 7-C-5. Interest and depreciation are calculated as 20%
of incremental capital cost (10% depreciation plus 10% interest).
Estimates reflect an assumption of 10,000 vehicle miles per year.
a
Note: 1976 dollars.
7-87
-------
Statistics on average expense per vehicle mile for the United States
are provided in Table 7-C-10. Average expense for 1974 may be adjusted to
12
1976 dollars by applying the percentage increase in the Consumer Price Index
(transportation) for 1974 to June 1976:
(165.9/137.7) x .72 = 86.75$ per vehicle mile
Calculations for the estimated percentage increase in average expense
are given in Tables 7-C-ll and 7-C-12. These numbers are multiplied by the
demand elasticity estimate of -0.50 to compute the expected change in the
quantity of service demanded. This elasticity is the same as that estimated
in Appendix D for urban transit. It is probably high in absolute terms due to
imperfections in the political process, but the fact that pupils' marginal
cost of time is relatively low implies less sensitivity to service charges.
IMPACT ON QUANTITY
OF BUS PR3DUCTION
The foregoing analysis, and Tables 7-C-ll and 7-C-12, indicate that
the impact on equilibrium bus service is relatively small, particularly
compared to the three percent per annum projected growth rate of (baseline)
industry production. Since it is unlikely that the technology of bus fleet
management permits substantial substitution between buses and other inputs
in the production of bus service, reduced ridership of three to five per-
cent resulting from noise abatement technology translates into a similar
reduction in long-run demand for new buses.
Table 7-C-13 demonstrates the fact that school buses are utilized at
near capacity levels. The ability of school bus fleet managers to reduce
equipment expenditures for a given level of pupil service is severely
limited, and it is doubtful that substantial factor substitution will occur
in response to a change in the relative price of bus capital.
7-88
-------
TABLE 7-C-10
TRANSPORTATION EXPENDITURES PER PUPIL
AND PER BUS MILE, 1963-74,
U.S. PUBLIC SCHOOLS
School Average Cost Per
Year Pupil Transported
1963-64
1965-66
1967-68
1969-70
1971-72
1973-74
$46.53
50.68
57.27
66.96
77.43
87.04
Average Cost per
Bus Mile
$0.40
0.42
0.50
0.54
0.63
0.72
Vehicle Replacement and
Capital Outlays as % of
Transport Expenses
16.7%
12.6
11.9
10.8
12.6
11.6
Source: Statistics of State School Systems, various editions. U.S.
Department of Health, Education, and Welfare, National Center
for Education Statistics, Table 41.
7-89
-------
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7-91
-------
TABLE 7-C-13
AVERAGE RIDERSHIP PER SCHOOL BUS, 1963-74
Average Daily Attendance
Transported/Total Number
School Year of Vehicles
1963-64 72.06
1965-66 84.09
1967-68 80.67
1969-70 76.77
1971-72 76.75
1973-74 82.07
Source: National Center for Education Statistics,
Statistics of State School Systems, Table 25.
7-9?
-------
FINANCIAL IMPACT ON
SCHOOL BUS USERS
The proposed regulations may have adverse economic impacts not recorded
above in the "long-run" analysis if they prompt short-run financial disloca-
tions or have distributional effects. Consider first the impact on tax-
payers and municipal and state financing authorities.
The preceding analysis (Tables 7-C-ll and 7-C-12) demonstrates that
increases of no more than ten-to-twelve percent (across all school bus types)
in pupil transportation expenditures are anticipated even at the most stringent
level of proposed noise attenuation. This estimate can be combined with
statistics on public school finance to assess the extent of financial impact.
Table 7-C-14 demonstrates the fact that total pupil transportation
accounts for only a small percentage of public school system expenditures,
and that this percentage increases significantly in smaller, non-metropolitan
systems. For the purposes of estimation, a ten percent increase in total
pupil transportation expenditures translates into a 0.24 percent increase
in total pupil expenditures in central metropolitan areas as compared with
a 0.57 percent increase in non-metropolitan areas.
Public school system finances are shared by local, state, and federal
sources as shown in Table 7-C-15.
FINANCIAL IMPACTS ON
PRODUCERS, INCLUDING
EXPORTERS AND IMPORTERS
1
The above economic analysis puts an upper bound on the aggregate
percentage reduction in equilibrium demand for school buses at 5.4 percent
7-93
-------
TABLE 7-C-14
PUPIL TRANSPORTATION SERVICES EXPENDITURES
BY ENROLLMENT SIZE AND
METROPOLITAN STATUS, 1970-71
(Dollar Figures in Millions)
(1)
Total
Current
Expenditures
(2)
Pupil
Transportation
Expenditures
(3)
Pupil
Transportation
As % of Total
Expenditures
All U.S. Public
School Systems
$25,827.3
$1,376.7
3.84%
System Enrollment Size:
5,000 and Over
Less than 5,000
Metropolitan Status:
Central Metropolitan
Metropolitan, Other
Non-Metropolitan
Source: Statistics of
$23
$12
$10
$15
$10
,746.
,080.
,193.
,178.
,455.
Local Public
4
9
8
3
2
School
$
$
$
707.
668.
249.
523.
603.
Systems,
9
8
3
7
8
Finance,
2
5
2
3
5
.98%
.54%
.45%
.45%
.78%
1970-71.
U.S. Department of Health, Education and Welfare,
Of ice of Education
7-94
-------
TABLE 7-C-15
REVENUE AND NONREVENUE RECEIPTS OF LOCAL PUBLIC
SCHOOL'SYSTEMS BY SOURCE OF FUNDS:
UNITED STATES, 1970-71
Total Receipts
Revenue Receipts
Local
Intermediate
State
Federal
(Millions)
$45,511
$42,424
22,851
504
15,784
3,285
(Percent)
100.0%
93.2%
50.2
1.1
34.7
7.2
Nonrevenue Receipts (Bonds) $ 3,087 6.8%
Source: National Center for Educational Statistics,
Statistics of Local Public School Systems,
Finance 1970-71, Table A-l.
7-95
-------
from baseline levels, with an independent estimate of 3.9 percent at the
13
most stringent level of noise abatement.
Figure 3-25, (Section 3) indicates a growth rate in baseline produc-
tion of 3.0 percent per year through the year 1990. Given proposed lead
times of sufficient length for the various noise abatement levels studied,
no reduction in existing manufacturing capacity will be required, and at the
aggregate level no financial impacts on producers are foreseen.
Two individual cases have been identified, however, for which the
estimated incremental cost impact of the noise abatement technology is
substantial. These are the transit-style integral construction school buses
produced in relatively small numbers by Gillig Bros, and Crown Coach
Corporation in California.
EPA's attempts to assess the cost impact on these producers has been
hampered by a lack of substantial information provided by the companies
involved. Differentially higher costs of noise abatement do appear likely,
however, and further investigation by EPA of the specific problems involved
appears warranted.
An important mitigating factor, not capable of accurate estimation from
an econometric viewpoint based on available data, is the fact that these
buses serve a significantly different market than the conventional school
bus market.
13
These figures are computed as a weighted average from Tables 7-C-ll
(85%) and 7-C-12 (15%).
7-96
-------
They are long-lived (20-30 years as opposed to 9-10 years), expensive
($50,000 as opposed to $14,000-$19,000), and intended primarily for
long-route, intensive use typical of the west-coast region in which
they are marketed. It is clear that the "cross-elasticity" of demand
for these buses vis-a-vis conventional buses is substantially below
infinity, but the precise elasticity is not possible to estimate from
available data.
Section 3 indicates that the vast majority of school bus chassis
and bodies are produced domestically and in Canada (which is virtually
equivalent, given the Automotive Pact Trade Agreement). Finished school
buses are generally built according to customer specifications, so that
the producers already possess the necessary flexibility to treat the
noise reduction package as an optional item, not included on exports to
nonregulated countries.
Since school buses are not imported in significant quantities to the
United States, no balance of trade or balance of payments effects are fore-
seen for the proposed technologies under consideration for regulation.
ANNUALIZED COSTS FOR
SCHOOL BUS NOISE ABATEMENT
Annualized cost calculations projected to the year 2000 for 15
regulatory schedules are presented in Appendix E. Input variables for
school buses are listed in Table 7-C-16.
7-97
-------
TABLE 7-C-16
DATA INPUT AND PARAMETER VALUES
FOR ANNUALIZED COST CALCULATIONS
SCHOOL BUSES
Variable Description
Baseline Production Rate
Projected Production Rate
Incremental Operating Cost
Incremental Maintenance Cost
Incremental Equipment Cost
Depreciable Life (years)
Price Elasticity of Demand
Rate of Discount
Source or Value
Figure 3-25
Figure 3-25
Appendix C
Appendix C
Appendix C
10
-0.50
0.10
7-98
-------
GENERAL REFERENCES
SECTION 7
1. "An Econometric Model of Urban Bus Operations," Chapter IV
of John D. Wells et al, Econometric Characteristics of the
Urban Public Transportation Industry (Washington, D.C.:
Government Printing Office, 1972).
2. Hicks, John R., The Theory of Wages. London: MacMillan, 1932.
3. Heightchew, Robert E., United States Transit Bus Demand.
Highway Users Federation, Washington, D.C.: June, 1975.
4 "A Study to Determine the Economic Impact of Noise Emission
Standards in the Bus Manufacturing Industry," Draft Final
Report submitted by A. T. Kearney, Inc. under EPA Contract
No. 68-01-3512, prepared for the Office of Noise Abatement
and Control, September, 1976.
7-99
-------
Section 8
MEASUREMENT METHODOLOGY
The choice of a procedure for measuring the noise emitted by buses
was based on several considerations:
o Existing bus noise measurement procedures
o Bus noise characteristics
o Work cycle of buses
o Enforcement requirements
- Repeatability of measurement
1. EXISTING PROCEDURES
A number of existing and proposed noise measurement procedures
for buses and trucks were examined for applicability.
For a number of years U.S. industry has been using the SAE J366b
measurement procedure (full throttle acceleration) for measuring the
exterior sound levels for heavy trucks and buses. ISO recommendation,
1
R362, which follows a similar procedure, is the basis for noise
measurement in some European countries. Table 8-1 compares the main
features of these two procedures.
8-1
-------
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8-2
-------
Both procedures require the use of high quality (Type I or "Pre-
cision") sound measuring equipment, background noise levels at least
10 dBA below the level produced by the test vehicle, and a flat, open
space free of reflecting surfaces. The recommended test sites for per-
forming measurements are shown in Figure 8-1.
The ISO recommendation includes a procedure for measurements with
stationary vehicles, with the engine operating at governed speed, or at
three-quarters of maximum rated speed if the engine is ungoverned.
The MITRE Corporation, under contract to the U. S. DOT Urban Mass
Transit Administration, has developed a standard procedure specifically
2
directed at urban transit buses. For exterior noise, two microphones
are required, one at a 15.2 m (50 feet) distance and a 1.2 m (4 feet)
height and another at a 10.8 m (35.4 feet) distance and 12.0 m (39.4
feet) height. The latter position corresponds to a slant distance of
15.2 m (50 feet) from the bus lane along a line 45 degrees to the road
surface, and is designed to insure controlled noise levels to apartment
dwellers. A recommended test site area is shown in Figure 8-2. A sta-
tionary starting point ahead of the microphone reference line is selected
such that, when the vehicle is accelerated from that point with rapid
application at wide open throttle, the chief vehicle noise source of
the test coach shall fall within a 32.8 ft. (10 m) region on either
side of the microphone reference lines when the vehicle reaches maximum
8-3
-------
FIGURE 8-1
Recommended Test Sites for
ISO and SAE Procedures
ISO R362 Procedure
Microphone o>
7.5/77
7.5 m
Microphone
Test area
perimeter
CAR WITH OR WITHOUT
TRAILER
— Measuring positions for measurement with vehicles in motion — Measuring positions for measurement with stationary vehicles
SAE J366b Procedure
Microphone Point
Measurement
Area
Dimensions in
Meters (Feet)
8-4
-------
FIGURE 8-2
Minimum Acceptable Test Area for Urban Transit
Buses, MITRE Recommendation^ '
NO LARGE REFLECTING
SURFACES PERMITTED
WITHIN THIS PERIMETER •
CENTERLINE OF
VEHICLE PATH
10.8M (35.4 ft.)—
MICROPHONE REFERENCE LINE
8-5
-------
governed speed for manual transmission models or shift point for auto-
matic transmission models. Maximum vehicle speed during the test is
limited to 31 mph (50 km/hr). Interior noise levels are measured at
the forwardmost passenger seat, the seat nearest the center of the bus,
and the rearmost seat.
The Coach Noise Subcommittee of the SAE Vehicle Sound Level
Committee has also been preparing recommended procedures for exterior
and interior sound levels of motor coaches which include school,
transit, and intercity buses. This subcommittee feels that for buses,
the "pull-away" or standing start mode of operation normally produces
maximum exterior noise levels. They are also considering a shortened
end zone where the bus reaches maximum rated or governed speed between
tests. Test conditions have also been established for interior noise
measurements.
2. BUS NOISE CHARACTERISTICS
If the noise characteristics are similar while the vehicle is
stationary and moving, stationary test procedures are to be pre-
ferred because of the resultant ease of testing. Other considerations
are the consistency of noise levels between tests and the ease of
extrapolation of the measured level to actual noise levels experienced
in the community. One of the difficulties with stationary procedures
is that if the engine is ungoverned, the maximum engine speed cannot
8-6
-------
be precisely controlled. In addition, sudden acceleration of gasoline
engines without load is considered damaging since excessively high engine
speeds would result. The stationary procedure does offer the advantage
of removing one of the unwanted sound sources, namely tires, from the
overall sound measured.
Existing bus noise level data (Section 4) include stationary
and acceleration noise levels. The SAE Vehicle Sound Level Committee
has collected and analyzed noise data on various vehicle types using
stationary and acceleration procedures. The data indicate that while each
of the procedures gives repeatable measurements for a given vehicle, and
about equal spread in levels between different vehicles, the correlation
between the two procedures is poor. In other words, vehicles may or may
not emit higher levels during acceleration tests as opposed to stationary
tests. Thus, there does not appear to be a simple method to predict which
of the two levels would be higher for a given vehicle. Because of this
problem, most bus manufacturers have adopted the J366b procedure as the
standard procedure.
Interior noise has not received much attention from bus manu-
facturers, except for intercity bus manufacturers. They have dis-
covered mainly that the noisiest section of the bus is generally
around the seat nearest the engine.
8-7
-------
3. WORK CYCLES
Buses are used for a wide variety of applications under different
road and traffic conditions. The proportions of operating time spent
under acceleration, deceleration, cruise, and idle conditions vary
accordingly. The work or duty cycles of buses are important considera-
tions in the development of a noise measurement procedure because the
measured level should be representative of one or more of the prominent
modes of operation of the bus.
The school bus generally operates in a suburban environment as
opposed to the urban environment of the transit bus. Metropolitan
transit buses generally operate in an urban environment picking up
and discharging passengers frequently along their daily runs. As a
result work cycles consist mainly of accelerations and decelerations
with minimum cruise time at constant speeds. The work cycle of an
intercity bus is comprised mainly of cruise time at high speed with
stops occurring only near bus terminal locations.
A representative work cycle for school buses was estimated from
data obtained from the Radnor School District near Philadelphia,
6
Pennsylvania.
Number of Routes 25
Number of Stops 541
Total Time 1263 min.
Total Distance Covered 129 miles
8-8
-------
Assuming an average cruise speed of 27 mph and acceleration/deceleration
rate of 3.22 ft/sec/sec, the percentage of time under different conditions
was obtained:
9% of time under acceleration
9% of time under deceleration
21% of time at cruise
61% of time at engine idle
A representative work cycle for urban transit buses was estimated from
data furnished by the EPA Mobile Source Air Pollution Laboratory, Ann
3
Arbor, and from the report on the California Steam Bus Project. Urban
drive cycles vary widely. An average work cycle for buses making seven
to ten stops per mile would be as follows:
20% of time under acceleration
20% of time under deceleration
26% of time at cruise
34% of time at engine idle
Eagle International Inc., has furnished the following data for inter-
city buses:
Average cruise speed of intercity buses - 60 mph
Average acceleration and deceleration rates - 1.5 to 3,0 mph/sec
Average cruise distances - 50 miles
Average number of stops and starts per year - 5,000
Typical drive cycles: Acceleration - 5%
Deceleration - 5%
Cruise - 85%
Idle - 5%
8-9
-------
4. MEASUREMENT DISTANCE
The location of the receptors of bus noise vary widely.
Pedestrians are possibly subjected to the loudest noise levels from
buses because of their close proximity to the bus. CMC has reported
the existance of data showing that transit buses contribute measurably
to the background noise levels in downtown Detroit. They argue that
urban transit bus noise should, therefore, be measured at a distance
4
of 15 to 25 feet from the curbside of the bus. Extrapolation to 50 ft.
measurements from closer distances than 50 ft., however, using the
standard 6 dB loss per doubling of distance would suggest levels lower
than those actually existing at 50 ft. In addition, because buses can
be up to 40 ft. long, measurement distances shorter than 50 ft. place
the microphone in a closer proximity to the acoustic nearfield of the
bus, an undesirable position for repeatable results.
5. ENFORCEMENT REQUIREMENTS
All available bus noise level data are in A-weighted decibel units.
All standard and recommended test procedures also recommend that measure-
ments be iriade in A-weighted decibel units. Available equipment for
measurement of sound directly in these units is reliable and readily
available. Since sound levels measured in these units also approximate
human subjective response to noise, the A-weighted decibel unit is
recommended for any test procedure.
The procedure should be such that repeatable test conditions can
be easily obtained. Repeatability can be ensured by specifying engine
speeds, engine rpm, and test site surface and surrounding conditions.
8-10
-------
6. TEST MEASUREMENTS
Noise measurements from 65 school, transit and intercity buses were
taken under various test procedures. Exterior as well as interior noise
levels were measured during each test.
The SAE J366b Standard procedure was used for measuring exterior
and interior noise for all buses with manual transmissions and for
those buses with automatic transmissions which could be manually held
in gear. In addition, stationary noise measurement procedures were
also employed for all buses tested.
A modified J366b procedure was used in the case of buses with
automatic transmission which could not be manually held in gear. The
modified J366b procedure consisted of the bus accelerated under wide
open throttle from a predetermined stationary position. The starting
position was selected to assure that the bus reached maximum governed
speed (i.e., upshift) in the end zone defined by the SAE J366b proce-
dure.
A full throttle pull-away procedure was also examined for all bus
types with microphones in line with the front and rear bumpers of the
bus. This test is not suitable for vehicles with manual transmissions
because of the non-repeatablity of the bus pull-aways.
It should be noted that all interior bus noise measurements were
taken with all bus windows and doors closed and all interior fan
accessories (including air conditioner fans and/or heating fans)
operating. Windscreens were utilized during all the interior measure-
ments to assure that no variation in sound level due to the movement
of air throughout the bus would occur. In addition, in order to assure
that the interior microphone did not receive acoustic standing wave
8-11
-------
sound propagation from any bus wall (i.e., the ceiling), the microphone
was tilted towards the front of the bus at a 20-30 degree angle from
the vertical for all interior bus measurements made.
SCHOOL BUSES
The principal noise sources on conventional school buses, the
cooling fan, the engine, and the exhaust outlet, are separated by the
length of the bus. Thus, two microphones, separated by the length of
the bus, were used simultaneously on one side of the bus as shown in
Figure 8-3.
Two stationary test procedures were examined for school buses.
The IMI (Idle-Max. Governed Speed-Idle) procedure requires the engine
throttle to be opened at a rapid rate from idling condition to its
maximum governed speed and then closed to return it to idle speed. The
maximum governed speed test requires the maximum governed speed to be
maintained for approximately ten seconds. This test is not recommended
for ungoverned engines as engine damage might result.
Measured noise levels for 29 new and in-use conventional gasoline
school buses under the stationary, pull-away and acceleration procedures
may be found in Section 4, Tables 4-1 and 4-2. Maximum interior noise
levels were obtained during the J366b procedure at the seat (driver)
nearest the engine.
Since microphones were used to record maximum noise exterior levels
with the front and the rear of the school bus as reference points, the
tests revealed which of the two ends of each bus was noisier. Figure
8-4 shows that on the average, the front of the bus is louder by 3
decibels on the curbside. Both ends of the bus are about equally loud
on the streetside.
8-12
-------
FIGURE 8-3
Bidirectional Test Site for
School Bus Noise Measurement
Curbside
Starting
Point,
Automatic
Transmission
Buses
-50'-
-40'
END ZONE
50'
Curbside
Acceleration —'
Point
10'
-20'-
^20'*
10'
MIC 1
40'-
ENDZONE
Streetside
Starting
Point,
Automatic
Transmission
Buses
50'-
Variable
Streetside
1—Acceleration
Point
8-13
-------
FIGURE 8-4
Differences in Sound Levels of
Conventional School Buses with
the front and rear
used for reference
EXHAUST
\
I
-40'-
MIC.
ENGINE
TEST NO.
1
2
3
4
5
6
10
AVERAGE
M2)-L(1)
CURBSIDE
2 dB
3
3.25
3.67
3.5
3.0
3.0
3.06 dB
L(2)-L(1)
DRIVERSIDE
0.75 dB
0.25
-1.25
0
•0.25
-0.33
-1.0
-0.167 dB
8-14
-------
TRANSIT BUSES
Exterior and interior noise levels for 24 diesel powered transit
buses are summarized in Table 4-10 (Section 4). During the testing,
difficulty was encountered in maintaining uniformity of procedure when
performing maximum acceleration (modified J366b) and pull-away testing.
In the case of the maximum acceleration procedure the buses would not
always shift at the same point in the end zone. In the case of the pull-
away procedure, although the buses were accelerated at wide-open throttle
the run-up of the engines to the maximum governed rpm was not always
consistent. Most of the variation in the bus operations was felt to be
due to the age of the buses tested.
It is interesting to note that in correcting for the variability in
the bus operation, it was found that it was easier to correct for the
variation in the shift point location by changing the starting point
location than for the variation in the engine run-up.
INTERCITY BUSES
Tables 4-19 and 4-21 (Section 4) display summaries of exterior and
interior noise level data measured from 12 newly manufactured intercity
buses. Data was recorded using a modified J366b sound measurement proce-
dure (both acceleration and deceleration modes were tested), a pull-away
procedure (for automatic transmission vehicles) and a stationary IMI
procedure. Interior noise level data was taken using all procedures.
7. SUMMARY
Exterior Procedures
The standard SAE J366b procedure was found acceptable for school
buses and intercity buses with standard transmissions and automatic
8-15
-------
transmissions that can be manually locked in gear to prevent upshifting
above desired gears.
For transit buses with automatic transmissions which cannot be
manually locked in gear, the modified J366b procedure was found acceptable
for exterior sound measurement testing.
Interior Procedure
The selection of an interior measurement procedure is closely
linked to the selection of an exterior procedure. This leaves the
location of the microphone as the most salient question. To this end,
it has been found that in all EPA bus noise measurements, as displayed
in Section 4, the noisiest location in the bus is the seat location
nearest the main body of the engine. Thus, it may be concluded that
measurements at this seat location (nearest the main body of the engine)
characterize the loud extreme of the noise environment inside a bus.
8-16
-------
8. RECOMMENDED TEST PROCEDURE FOR MEASUREMENT OF EXTERIOR SOUND LEVELS
(a) Instrumentation. The following instrumentation shall be used,
where applicable.
(1) A sound level system which meets the Type 1 requirements
of ANSI SI.4-1971, Specification for Sound Level Meters or a
sound level system with a magnetic tape recorder and/or a
graphic level recorder or indicating meter, may be used providing
the system meets the Type I performance requirements of ANSI
SI.4-1971, Specification for Sound Level Meters.
(2) A sound level calibrator. The calibrator shall produce
a sound pressure level, at the microphone diaphragm that is
known to within an accuracy of _+ 0.5 dB. The calibrator shall
be checked annually to verify that its output has not changed.
(3) An engine-speed tachometer which is accurate within +2
percent of meter reading.
(4) An anemometer or other device for measurement of ambient
wind speed accurate within +10 percent at 19.3 km/hr (12 mph).
(5) A thermometer for measurement of ambient temperature
o
accurate within 4-1C .
(6) A barometer for measurement of ambient pressure accurate
within +1 percent.
(7) A windowscreen must be employed with the microphone during
all sound measurements. The windscreen shall not affect the
A-weighted sound levels from the vehicle in excess of +_ 0.5 dB.
(b) (1) The test site shall be such that the bus radiates sound
into a free field over a reflecting plane. This condition
8-17
-------
may be considered fulfilled if the test site consists of
an open space free of large reflecting surfaces, such as
parked vehicles, signboards, buildings or hillsides, located
within 30.4 meters (100 feet) of either the vehicle path
or the microphone.
(2) The microphone shall be located 15.2 + 0.1 meter (50 feet +
4 inches) from the centerline of vehicle travel and 1.2 + 0.1
meters (4 feet + 4 inches) above the ground plane. The micro-
phone point is defined as the point of intersection of the
vehicle path and the normal to the vehicle path drawn from
the microphone.
The microphone shall be oriented with respect to the
source in a fixed position so as to minimize the deviation
from the flattest frequency response characteristic over the
frequency range 100 Hz to 10 kHz for an accelerating vehicle
traversing through the end zone.
(3) For vehicles with manual transmissions or with automatic
transmissions which can manually be held in gear, an acceleration
point shall be established on the vehicle path 15.2 meters (50
feet) before the microphone point.
(4) For vehicles with automatic transmissions, which cannot
be manually held in gear, a starting point shall be established
as described in paragraph (c) (2).
(5) An end point shall be established on the vehicle path
30.5 meters (100 feet) from the acceleration point and 15.2
meters (50 feet) from the microphone point.
8-18
-------
(6) The end zone is the last 12.2 meters (40 feet) of
vehicle path prior to the end.
(7) The measurement area shall be the triangular-paved
(concrete or sealed asphalt) area formed by the accelera-
tion point, the end point, and the microphone location.
(8) The reference point on the vehicle, used to indicate
when the vehicle is at any of the points on the vehicle
path,shall be the front of the vehicle except as follows:
N,
o If the engine is front-mounted and the horizontal
distance from the front of the vehicle to the
exhaust outlet is more than 5.1 meters (200 inches),
tests shall be run using both the front and rear
of the vehicle as reference points. The two
measurements may be made simultaneously by placing
two microphones, the distance of the vehicle apart,
as shown in Figure 8-3.
o If the engine is located rearward to the
center of the chassis or at the approximate
center (+1.5 meters + 5 feet) of the chasis,
the rear of the vehicle shall be used as the
reference point.
(9) The plane containing the vehicle path and the micro-
phone location (plane ABCDE in Figure 8-1) shall be flat
within + .05 meters (+2 inches)
(10) Measurements shall not be made when the road surface
or the measurement area is wet, covered with snow, or
during precipitation.
(11) Bystanders have an appreciable influence on sound
level meter readings when they are in the vicinity of the
vehicle or microphone; therefore, not more than one person,
other than the observer reading the meter, shall be within
8-19
-------
15.2 meters (50 feet) of the vehicle path or measuring
instrument and the person shall be directly behind the
observer reading the meter, on a line through the micro-
phone and observer. To minimize the effect of the observer
and the container of the sound level meter electronics on
the measurements, cable should be used between the
microphone and the sound level meter. No observer shall be
located within 1 meter (3.3 feet) in any direction of the
microphone location.
(12) The maximum A-weighted fast response sound level
observed at the test site immediately before and after the
test shall be at least 10 dB below the regulated level.
(13) The road surface within the test site upon which the
vehicle travels, and, at a minimum, the measurement area
(BCD in Figure 8-1) shall be smooth concrete or smooth
scaled asphalt, free of extraneous material such as gravel.
(14) Vehicles with diesel engines shall be tested using
Number ID or Number 2D diesel fuel possessing a cetane
rating from 42 to 50 inclusive.
(15) Vehicles with gasoline engines shall use the grade
of gasoline recommended by the manufacturer for use by
the purchaser.
(16) Vehicles equipped with thermostatically controlled
radiator fans (fan clutches) will be tested with the fan
engaged in a "lock up" mode such that the fan drive hub
and the fan are turning at the same speed or as near the
8-20
-------
same speed as is possible within the design limits of the
particular fan clutch design.
(c) Procedure
(1) Buses equipped with manual (standard) transmissions
or buses with automatic transmissions which can be manually
held in gear (governed or ungoverned engines.). Full
throttle acceleration and closed throttle deceleration tests
shall to be used. A beginning engine speed and proper gear
ratio must be determined for use during measurements.
o Select the highest rear axle and/or transmission
gear ("highest gear" is used in the usual sense;
it is synonymous to the lowest numerical ratio)
and an initial vehicle speed such that at wide-
open throttle the vehicle will accelerate from
the acceleration point:
Starting at no more than two-thirds
(66 percent) of maximum rated engine
speed, if the vehicle is not equipped
with an engine governor, or of
governed engine speed, if the vehicle
is equipped with an engine governor.
Reaching maximum rated or governed
engine speed within the end zone.
Without exceeding 35 mph (56 k/h)
before reaching the end point.
o Should maximum rated or governed rpm be attained
before reaching the end zone, decrease the approach
rpm in 100 rpm increments until maximum rpm is
attained within the end zone.
8-21
-------
o Should maximum rated or governed rpm be attained
before reaching the end zone, decrease the approach
rpm in 100 rpm increments until maximum rpm is
attained within the end zone.
o Should maximum rated or governed rpm not be
attained until beyond the end zone, select the
next lower gear until maximum rated or governed
rpm is attained within the end zone.
o Should the lowest gear still result in reaching
maximum rated or governed rpm beyond the permis-
sible end zone, unload the vehicle and/or increase
the approach rpm in 100 rpm increments until the
maximum rated or governed rpm is reached within
the end zone.
o For the acceleration test, approach the accelera-
tion point using the engine speed and gear ratio
selected in paragraph (c)(1) of this procedure and
at the acceleration point rapidly establish wide-
open throttle. The vehicle reference shall be as
indicated in paragraph (b)(8) of the recommended
exterior noise measurement procedure.
Acceleration shall continue until the entire vehicle
has vacated the end zone.
o Buses equipped with governed engines must be held
at wide open throttle until the entire vehicle is
out of the end zone. Buses equipped with ungoverned
engines must not be allowed to drop more than 100
8-22
-------
rpm below maximum rated engine speed until the
vehicle is out of the end zone.
o Wheel slip which affects maximum sound level
must be avoided.
o If the vehicle being tested is equipped with an
engine brake, it must also be tested as follows:
Approach the microphone point at maximum rated
or governed engine speed in the gear selected
for the acceleration test. When the vehicle
reference point reaches the microphone point,
close the throttle and immediately apply the
engine brake fully and allow the vehicle to
decelerate to one-half of maximum rated or of
governed engine speed. The vehicle reference
shall be as indicated in paragraph (b)(8) of
the recommended exterior measurement proce-
dure. The engine brake must be full on during
this test.
(2) Buses equipped with automatic transmissions which cannot
be manually held in any gear. Full throttle acceleration
tests are to be employed.
o Select the highest rear axle and/or transmission
gear (highest gear is used in the usual sense;
it is synonymous to the lowest numerical ratio)
to accelerate the bus under wide open throttle
from a stationary position.
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o A starting point along the test path at which the
vehicle shall begin the acceleration test shall be
determined by the following procedure:
- The vehicle's reference point shall be placed
at the midpoint (+0.3 meters, +_ 1 foot) of
the end zone with the front end of the vehicle
facing back along the test path in the opposite
direction of travel that is used for the sound
measurement tests.
- The vehicle shall then be accelerated as rapidly
as possible to establish a wide open throttle,
until the first transmission shift point is
reached.
- The location along the test path at which the
front end of the vehicle is passing when the
first transmission shift point occurs shall be
the designated starting point.
- The vehicle's direction of travel shall then
be reversed for sound testing.
o For the acceleration test, accelerate the vehicle
from a standing position with the front of the
vehicle at the selected stationary starting point,
obtained by using the procedure outline above,
as rapidly as possible to establish a wide open
throttle. The acceleration shall continue until
the entire vehicle has vacated the end zone.
o Wheel slip which affects maximum sound level
must be avoided.
;
o If the vehicle being tested is equipped with an
engine brake, it must also be tested as follows:
Approach the microphone point at maximum rated
or governed engine speed, in the gear utilized
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during the acceleration test. When the vehicle's
reference point reaches the microphone point,
close the throttle, immediately apply the engine
brake fully and allow the vehicle to decelerate
to one-half: of governed engine speed. The vehicle
reference shall be as indicated in paragraph (b)(8)
of the recommended exterior measurement procedure.
The engine brake must be full on during the test.
(3) Measurements.
o The meter shall be set for "fast response" and the
A-weighted network.
o The sound .meter shall be observed during the period
while the vehicle is accelerating. The applicable
reading shall be the highest sound level obtained for
the run. The test is to be rerun if unrelated peaks
should occur due to extraneous ambient noises.
o Sound level measurements shall be taken on both sides
of the vehicle. The sound level associated with a side
shall be the average of the first two pass-by measure-
ments for that side, if they are within 2 dBA of each
other. Average of measurements on each side shall be
computed separately. If the first two measurements
for a given side differs by more than 2 dBA, two
additional measurements shall be made on each side,
and the average of the two highest measurements on
each side, within 2 dBA of each other, shall be
8-25
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taken as the measured vehicle sound level for that
side. The reported measured vehicle sound level
shall be the higher of the two averages.
(d) General Requirements
(1) Measurements shall be made only when wind velocity
is below 19.3 km/hr (12 mph).
(2) Proper usage of all test instrumentation is essential
to obtain valid measurements. Operating manuals or other
literature furnished by the instrument manufacturer shall
be referred to for both recommended operation of the instru-
ment and precautions to be observed. Specific items to be
adequately considered are:
o The effects of ambient weather conditons on the
performance of the instruments; (for example, tempera-
ture, humidity, and barometric: pressure).
o Proper signal levels, terminated impedances, and
cable lengths on multi-instrument measurement systems.
o Proper acoustical calibration procedure, to include
the influence of extension cables, etc. Field calibra-
tion shall be made immediately before and after each
test sequence. Internal calibration means is acceptable
for field use, provided that external calibration is
accomplished immediately before or after field use.
(3) A complete calibration of the instrumentation and external acous-
tical calibrator over the entire frequency range of interest shall be
performed at least annually and as frequently as necessary during the
8-26
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yearly period to insure compliance with the standards cited in
American National Standard SI.4-1971 "Specifications for Sound
Level Meters" for a Type 1 instrument over the frequency range
100 Hz - 10,000 Hz.
o If calibration devices are utilized which are not
independent of ambient pressure (e.g., a pistonphone)
corrections must be made for barometric or altimetric
changes according to the recommendation of the instru-
ment manufacturer,
(4) The vehicle shall be brought to its normal operating tempera-
ture prior to commencement of testing. During testing appropriate
caution shall be taken to maintain the engine at temperatures
within the normal operating range.
8. RECOMMENDED PROCEDURE FOR MEASUREMENT OF INTERIOR SOUND LEVELS
Interior sound levels shall be measured using the same vehicle operation
and measuring equipment as described in the Recommended Procedure for Measure-
ment of Exterior Sound Levels.
(a) Instrumentation. The following instrumentation shall be used,
where applicable.
(1) A sound level system which meets the Type I requirements of
ANSI SI.4-1971, Specifications for Sound Level Meters.
(2) A windscreen must be employed along with the microphone
during all measurements. The windscreen shall not affect
the A-weighted sound levels from the bus in excess of j^ 0.5 dB.
(3) A sound calibrator. The calibrator shall produce a
sound pressure level, at the microphone diaphragm, that is
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known to within an accuracy of + 0.5 dB. The calibrator shall
be checked annually to verify that its output has not changed.
(4) An engine speed tachometer which is accurate to
within + 2 percent of the meter reading.
(5) A thermometer for measurement of ambient temperature
o
accurate within + 1C.
(6) A barometer for measurement of ambient pressure accurate
within +1 percent.
(b) Microphone placement.
o The microphone shall be located next to the seat location
closest to the main body of the engine at a height of 1.25
meters (4.1 ft.) from the bus floor. In addition, the
microphone shall be placed at least 0.5 meters (1.6 ft.)
from the nearest vehicle wall.
o For front engine buses the microphone shall be placed
next to the vehicle operator's seat, at a height of
1.25 meters (4.1 ft.) from the floor and at least 0.5
meters (1.6 ft) from the nearest vehicle wall.
o The microphone shall be tilted towards the front of
o o
the vehicle at an angle of 20 - 30 from the vertical.
o The test site shall be such that the bus radiates sound
in a free field over a reflecting plane. This condition
may be considered fulfilled if the test site consists of
an open space free from reflecting surfaces, such as
parked vehicles, signboards, buildings or hillsides,
located within 30.4 meters (100 ft) of the vehicle.
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(c) Vehicle operation.
o The vehicle shall be operated in the same manner as
stated in the recommended exterior noise measurement
procedure. The same axle ratios, gear ratios, along
with the same procedure as modified by transmission
type shall be utilized.
o All windows and doors shall be closed on the vehicle
and all interior fan accessories (including air con-
ditioning fans and/or heating fans) turned on.
(d) Measurements.
o The meter shall be set for "fast response" and the
A-weighted network,
o The meter shall be observed during the period while
the vehicle is accelerating. The applicable reading
shall be the highest sound level obtained for the
run. The observer is cautioned to rerun the test if
unrelated peaks should occur due to extraneous ambient
noises.
o The average of the two highest levels within 2 dB
of each other shall be reported as the interior
level of the bus.
(e) General requirements.
(1) Bystanders have an appreciable influence on sound level
meter readings when they are in the vicinity of the microphone;
therefore, not more than one person, other than the observer
reading the meter and the driver shall be in the vehicle at
the time of measurement.
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(2) The maximum A-weighted fast response sound level observed
in the test vehicle immediately before and after the test
shall be at least 10 dB below the regulatory level.
(3) Proper usage of all test instrumentation is essential to
obtain valid measurements. Operating manuals or other literature
furnished by the instrument manufacturer shall be referred to
for both recommended operation of the instrument and precautions
to be observed. Specific items to be adequately considered are:
o The effects of ambient weather conditions on the
performance of the instruments (for example, tempera-
ture, humidity, and barometric pressure).
o Proper signal levels, terminating impedances, and
cable lengths on multi-instrument measurement systems.
o Proper acoustical calibration procedure, to include
the influence of extension cables, etc. Field calibra-
tion shall be made immediately before and after each
test sequence. Internal calibration means is acceptable
for field use, provided that external calbration is
accomplished immediately before or after field use.
(4) o A complete calibration of the instrumentation and
external acoustical calibrator over the entire frequency
range of interest shall be performed at least annually
and as frequently as necessary during the yearly period
to insure compliance with the standards cited in
American National Standard Si.4-1971 "Specifications
for Sound Level Meters" for a Type 1 instrument over
the frequency range 100-Hz - 10,000 Hz.
8-30
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o If calibration devices are utilized which are not
independent of ambient pressure (e.g., a pistonphone)
corrections must be made for barometric or altimetric
changes according to the recommendation of the instru-
ment manufacturer.
(5) The vehicle shall be brought to a temperature within
its normal operating range prior to the commencement
of testing. During appropriate caution shall be taken
to maintain the engine temperature within the normal
operating range.
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REFERENCES
SECTION 8
1. ISO Recommendation R362-1967 (E), "Measurement of Noise
Emitted by Vehicles," February, 1964.
2. Swetnam, G. W. and Murray, W.S., "Proposed Standard Noise
Measurement Procedure for Diesel Transit Buses," Report
No. UMTA-VA-06-0028-75-1, Prepared by MITRE Corp., for
U. S. Dept. of Transportation, Washington, D.C., July
1975.
3. "California Steam Bus Project Final Report," Prepared by
The Assembly Office of Research , Sacramento, Calif.,
January 1973.
4. "A Status Report of an Environmental Noise Study of Transit
Buses," by the Environmental Activities Staff (Vehicular
Noise Control), General Motors Corp., December 1975.
5. Oswald, L. J. and Hickling, R., "An Overhead Microphone
Facility for Recording Vertically-Radiated Vehicle Noise,"
Research Publication GMR-1944, GM Research Laboratories,
November 1975.
6. "An Assessment of the Technology for Bus Noise Abatement,"
Draft Final Report submitted by Booz-Allen Applied Research,
under EPA Contract No. 68-01-3509, prepared for the Office
of Noise Abatement and Control, June 22, 1976.
8-32
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Section 9
ENFORCEMENT
A. GENERAL. The EPA enforcement strategy will place a major
share of the responsibility on the manufacturers for pre-sale testing
to determine the compliance of buses with the regulation. This approach,
besides relieving EPA of an administrative burden benefits the manufac-
turers by leaving their personnel in control of many aspects of the
compliance program and imposing only a minimum burden on their business.
Therefore, monitoring by EPA personnel of the tests and manufacturers'
actions taken in compliance with the regulation is advisable to insure
that the Administrator is provided with the accurate test data necessary
to determine whether the vehicles distributed in commerce by manufacturers
are in compliance with the regulation. Accordingly, the proposed regul-
ation provides that EPA enforcement officers may be present to observe any
testing required by the regulation. In addition, enforcement officers
under previously promulgated regulations [40 CFR Part 205 Subpart A] are
empowered to inspect records and facilities in order to assure that manu-
facturers are carrying out their responsibilities properly.
The enforcement strategy in the proposed regulation, applicable
to both exterior and interior standards consists of three parts: (1)
Production Verification (PV), (2) Selective Enforcement Auditing (SEA),
and (3) In-Use Compliance Provisions.
9-1
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The manufacturer who assembles the completed bus, as in the case
of intercity and transit buses, is responsible for satisfying the PV,
SEA and in-use requirements of the regulation for both the interior
and exterior standards. In the case of vehicles which are assembled by
two manufacturers, such as many Type I school buses, the chassis manu-
facturer must comply with the PV, SEA and in-use provisions of this
regulation with respect to the vehicle exterior noise emission standard.
The body assembler/mounter of such a bus which is assembled by two manu-
facturers is responsible for compliance with the provisions with respect
to the vehicle interior standard. In addition, the body assembler is
prohibited from causing the vehicle exterior noise emissions to exceed
the standard and is subject to SEA provisions of the regulation for the
exterior standard.
B. Production Veritiicatign. Production verification is testing
by a manufacturer of selected early production models of a configuration
intended for sale, to verify a manufacturer has the requisite noise con-
trol technology in hand to comply with the standard at the time of sale
and during the Acoustical Assurance Period (AAP), and is capable of
applying the technology to the manufacturing process. The first pro-
duction models of a configuration tested must not exceed the level of
the standard minus that configuration's expected sound level degradation
(Sound Level Degradation Factor, SLDF) before any models in that config-
uration may be distributed in commerce. Any testing shall be done in
accordance with the proposed test procedures.
Production verification does not involve any formal EPA approval
or issuance of certificates subsequent to manufacturer testing, nor is
9-2
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any extensive testing required of EPA. The proposed regulation would
require that prior to distribution in commerce of any model of a config-
uration, as defined within the regulation, the configuration must undergo
production verification. All testing is performed by the manufacturer.
However, the Administrator reserves the right to be present to monitor
any test (including simultaneous testing with his equipment) or to require
that a manufacturer supply him with vehicles for testing at EPA's Noise
Enforcement Facility in in Sandusky, Ohio, or at any other site the
Administrator may find appropriate.
The production unit selected for testing is a vehicle configuration.
A vehicle configuration is defined on the basis of various parameters
including the exhaust system, the air induction system, the cooling fan
type, horsepower, and, where applicable, certain interior design charac-
teristics, and any additional parameters that a manufacturer may select.
A manufacturer shall verify production vehicles prior to sale by
one of two methods. The first method will involve testing any early
production vehicle intended for sale of each configuration.
A vehicle configuration is considered to be production verified
after the manufacturer has shown, based on the application of the sound
measurement tests, that a configuration does not exceed a sound level
defined by the new product standard minus that configuration's expected
sound level degradation during its defined acoustical assurance period.
The second method allows a manufacturer, in lieu of testing vehicles
of every configuration, to group configurations into categories. A
category will be defined by basic parameters such as engine and fuel
9-3
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type, engine manufacturers, engine displacement, engine configuration,
manufacturers, engine displacement, engine configuration, engine
location, and bus body style. Again, the manufacturer may designate
additional categories based on additional parameters of its choice.
Within a category, the configuration estimated by the manufacturer to
be emitting the greatest A-weighted sound pressure level at the end of
the Acoustical Assurance Period is determined either by testing or good
engineering judgment. The manufacturer can then satisfy the production
verification requirements for all configurations within that category
by demonstrating that that configuration complies with the applicable
standards. This can eliminate the need for a substantial amount of
testing. However, it must be emphasized that the loudest configuration
at the end of the acoustical assurance period must be clearly identified.
The proposed regulation also provides that the Administrator may
test vehicles at a manufacturer's test facility using either his own
equipment or the manufacturer's equipment. This will provide the
Administrator an opportunity to determine that the manufacturer's test
facility and equipment are technically qualified for conducting the
required tests. If it is determined that the equipment and/or facil-
ities are not technically qualified, he may disqualify them from fur-
ther use for bus testing. Procedures that are available to the manufac-
turer, subsequent to disqualification are delineated in the proposed
regulation.
A production verification report must be filed by the manufacturer
performing the required production verification test before any vehicles
of the configuration represented are distributed in commerce.
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A vehicle configuration is considered to be production verified
when the manufacturer has shown, based on the application of the noise
measurement test, that a configuration does not exceed a level defined
by the standard minus the SLDF, and a timely report indicating such
compliance has been mailed to EPA.
If a manufacturer is unable to test due to weather conditions, the
production verification of a configuration is automatically waived by
the Administrator for a period of up to 45 consecutive days without the
manufacturer's request provided that he tests on the first day that he
is able. This procedure will minimize disruptions to manufacturing
facilities. The manufacturer may request an additional extension of up
to 45 days if it is demonstrated that weather or other uncontrollable
conditions prohibited testing during the first 45 days. However, to
avoid any penalties under the proposed regulation, the manufacturer
must test for purposes of production verification on the first day that
he is able.
If a manufacturer plans to add a new configuration to his product
line or change or deviate from an existing configuration with respect
to any of the parameters which define a configuration, the manufacturer
must verify the new configuration either by testing a vehicle and sub-
mitting data or by filing a report which demonstrates verification on
the basis of previously submitted data.
Production verification is an annual requirement. However, the
Administrator, upon request by a manufacturer, may permit the use of
data from previous production verification reports for specific vehicle
configurations and/or categories. The considerations that are cited in
9-5
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the proposed regulation as being relevant to the Administrator's deci-
sion are illustrative and not exclusive. The manufacturer can submit
all data and information that he believes will enable the Administrator
to make a proper decision. It must be again emphasized that the manu-
facturer must request the use of previous data. If he fails to do so,
then he must production verify all categories and configurations for
each subsequent year.
The manufacturer need not verify configurations at any particular
point in a year. The only requirement is that he verify a configuration
prior to distribution in commerce. The inherent flexibility in the scheme
of categorization in many instances will allow a manufacturer to either
verify a configuration that he may not produce until late in a year based
on representation or else wait until actual production of that configura-
tion to verify it.
If a manufacturer fails to properly verify and a configuration is
found to be in non-conformity with the regulations, the Administrator
may issue an order requiring the manufacturer to cease the distribution
in commerce of vehicles of that configuration. The Administrator will
provide the manufacturer the opportunity for a hearing prior to the
issuance of such an order.
Production verification performed on the early production models
provides EPA with confidence that production models will conform to the
standards and limits the possibility that non-conforming products will
be distributed in commerce. Because the possibility still exists that
subsequent models may not conform, selective enforcement audit testing
of assembly line vehicles is made a part of this enforcement strategy
9-6
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in order to determine whether production vehicles continue to comply with
the standards.
C. Selective Enforcement^ Auditing. Selective Enforcement Auditing
(SEA) is the term used in the proposed regulation to describe the testing
of a statistical sample of production vehicles from a specified vehicle
category or configuration selected from a particular assembly plant in
order to determine whether production vehicles comply with the noise
emission standards including the in use standard and to provide the basis
for further action in the case of non-compliance.
Testing is initiated by a test request which will be issued to
the manufacturer by the Assistant Administrator for Enforcement or his
authorized representative. A test request will address itself to either
a category or a configuration. The test request will require the manu-
facturer to test a sample of vehicles of the specified category or
configuration produced at a specified plant. An alternative category
or configuration may be designated in the test request in the event
vehicles of the first category or configuration are not available.
Upon receipt of the test request the manufacturer will select the
sample as specified in the test request in one of the following ways:
(1) Random selection from the first batch of vehicles of the
specified category or configuration by sequentially numbering all vehicles
in the batch and using a table of random numbers to select the proper
number of vehicles or;
(2) Selection by the manufacturer using his own random selection
plan, if it is approved by the Administrator; or
9-7
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(3) Consecutive selection from the batch, if the test request
does not specify random selection; or
(4) Selection of vehicles from the batch in a manner specified
by the EPA Enforcement Officer.
Generally, a batch will be defined as the number of vehicles produced
durinij a time period specified in the test request. A batch defined in
this manner will allow the Administrator to select batch sizes small enough
to keep the number of vehicles to be tested at a minimum and still enable:
EPA to eventually draw statistically valid conclusions about the noise
emission performance of all vehicles of the category or configuration which
is the subject of the test request.
One important factor that will influence the decisions of the
Administrator not to issue a test request to a manufacturer is the evidence
that a manufacturer has to demonstrate that his vehicles comply to the
applicable standard. If a manufacturer can provide evidence that his
vehicles are meeting the noise emission standards based on testing results,
the issuance of a test request may not be necessary.
The Selective Enforcement Audit plan is designed to determine the
acceptability of a batch of items for which one or more inspection criteria
have been established. As applied to vehicle noise emissions, the items
being inspected are buses and the inspection criterion is the noise emission
standard, taking into consideration the sound level degradation estimated
to occur during the acoustical assurance period (See Part G., In Use
Compliance of this section)
Once the sample of a batch has been selected, each item is tested
to determine whether it meets the prescribed criterion; this is generally
9-8
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referred to as inspection by attributes. The basic criteria for accep-
tance or rejection of a batch is the nurabe-r of sample vehicles whose
parameters meet specification rather than the average value of some
parameter.
The particular type of inspection plan which has been adopted for
SEA of buses is known as sequential b;atch sampling. Sequential batch
sampling differs from single sampling in that small test samples are
drawn from sequential batches rather than one large sample being drawn
from a single batch.
This sampling offers the advantage of keeping the number of
vehicles tested to a minimum whe-n the majority of products are meeting
the standards.
The sampling plans are arranged according to the size of the batch
from which a sample is to be drawn. Each plan specifies the sample size
and acceptance and rejection number for the established acceptance quality
level (AQL). As applied t.o bus noise emissions, this AQL is the maximum
percentage of failing vehicles that for purposes of sampling inspection
can be considered .satisfactory. A vehicle is considered a failure if it
exceeds the noise emission standard minus its SLDF. An AQL of 10% was
chosen to take into account some test variability. The; number of failing
vehicles in a sample is compared to the acceptance and rejection numbers
for the appropriate; sanpling plan. If the number of failing vehicles in
the sample is grea,ter than or equal to the rejection number, then there
is a high probability that the percentage of non-complying vehicles in
the batch is greater than the AQL and the batch fails. On the other
hand, if the number of failures is less than or equal to the acceptance
9-9
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number, then there is insufficient evidence to conclude that the per-
centage of non-complying vehic.les in the batch is greater than the
AQL, and the batch is accepted.
Since the sampling strategy involves a sequential batch sampling
plan, in some instances the number' of failures in a test sample may not
allow acceptance or rejection of a batch so that continued testing may
be required until a decision can be imade to either accept or reject a
batch.
Regardless of whether a batch is .accepted or rejected, failed
vehicles would have to be repaired and/or adjusted and pass a retest
before they can be distributed in commerce.,
The proposed regulation establish two types of inspection criteria.
These are normal inspection and 100% testing,. Normal inspection is used
until a decision can be made as to whether a batch sequence is accepted
or rejected. When a batch sequence is tested and accepted in response
to a test request, the manufacturer will not hx= required at that time
to do any further testing pursuant to that test request. When a batch
sequence is tested and rejected, the Administrates may then require 100
per cent testing of the vehicles of that category or configuration pro-
duced at that plant. The Administrator will notify the manufacturer of
the intent to require 100 per cent testing. The manufacturer can request
a h'earing on the issue of non-compliance of the rejected category or con-
figuration.
The proposed regulation also discusses the situation where batches
consist of four or less vehicles. The proposed regulation requires
that each vehicle in that batch be tested and comply with the noise
9-10
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emission standards. This will allow testing to take place within a more
reasonable period of time when a test request is issued for particular
categories or configurations which are not produced in a sufficiently
high volume for the normal SEA scheme to be applicable.
Since the number of vehicles tested in response to a test order may
vary considerably, a fixed time limit cannot be placed on completing all
testing. The proposed approach is to establish the time limit on a test
time per vehicle basis, taking transportation requirements, if any, into
consideration. The manufacturer would be allowed a reasonable amount of
time for transport of vehicles to a test facility if one were not avail-
able at the assembly plant.
The Administrator estimates that the manufacturers can test a
minimum of five (5) vehicles per day. However, manufacturers are
requested to present any data or information that may affect a revision
of this estimate.
D. Adjninistratiye 0_rder_s. Section ll(d)(l) of the Noise Control
Act of 1972 provides that:
"Whenever any person is in violation of section 10(a) of this Act,
the Administrator may issue an order specifying such relief as he deter-
mines is necessary to protect the public health and welfare."
-Clearly, this provision of the Act is intended to grant to the
Administrator discretionary authority to issue administrative orders to
supplement the criminal penalties of section ll(a). If vehicles which
were not designed, built, and equipped so as to comply with the noise
emission standard, including the in-use requirement, at the time of sale
to the ultimate purchaser were distributed in commerce, such act would
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be a violation of section 10(a) and remedy of such non-compliance would
be appropriate. Remedy of the affected vehicles shall be carried out
pursuant to an administrative order.
The proposed regulation provides for the issuance of such orders
in the following circumstances: (1) recall for the failure of a vehicle
or group of vehicles to comply with the applicable noise emission stan-
dard, (2) cease to distribute vehicles not properly production verified,
and (3) cease to distribute vehicles for failure to test.
In addition, the proposed regulation provides for cease to distribute
orders for substantial infractions of the regulation requiring entry to
manufacturers' facilities and reasonable assistance. These provisions do
not limit the Administrator's authority to issue orders, but give notice
of cases where such orders would in his judgment be appropriate. In all
such cases, notice and opportunity for a hearing will be given.
E. Compliance Labeling. The proposed regulation requires that buses
subject to it shall be labeled to provide notice that the product complies
with the exterior and/or interior noise emission standards. The label
shall contain a notice of tampering prohibitions.
F. Applicability of Previously Promulgated Regulations. Manufac-
turers who will be subject to the proposed regulation must also comply
with the the general provisions of 40 CFR Part 205 Subpart A. These
include the provisions for inspection and monitoring by EPA enforcement
officers of manufacturers' actions taken in compliance with the proposed
regulation and for granting exemptions from the proposed regulation
for testing, pre-verification vehicles, national security reasons,
and export vehicles.
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G. In-Use Compliance. The manufacturer is required to design,
build, and equip vehicles subject to the regulation so that the degra-
dation of emitted noise levels is minimized provided that they are properly
maintained, used, and repaired.
In-use compliance provisions are included in the proposed regulation
to insure that this obligation is satisfied.
EPA does not specify what testing or analysis a manufacturer must
conduct to determine that his vehicles will meet the standard during the
Acoustical Assurance Period (AAP) of the regulation. However, the pro-
posed regulation requires the manufacturer to make such determination and
maintain records of the test data and other information upon which the
determination was based. This determination may be based on information
such as tests of critical noise producing or abatement components, rates
of noise control deterioration, engineering judgements based on previous
experience, and physical durability characteristics of the product.
An SLDF is the degradation (sound level increase in A-weighted
decibels) which the manufacturer expects will occur on a configuration
during the period of the one year in-use standard. The manufactuer must
determine an SLDF for each of his vehicle configurations.
To ensure that the vehicles will meet the noise standard throughout
the acoustical assurance period, they must emit a sound level at the time
of sale less than or equal to the standard minus the SLDF. A vehicle is
in compliance only if its measured dBA level, is less than or equal to
the applicable standard minus the SLDF. Production verification and
selective enforcement audit testing both embody this principle.
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All vehicles must emit a sound level that is less than or equal to
the standard at the time of sale, so a negative SLDF cannot be used.
A vehicle that becomes quieter during Acoustical Assurance Period must
still meet the standard on the day of sale; an SLDF of 0 must be used
for that configuration.
As stated above, the Agency is not requiring durability testing as
a matter of course, however, should it be necessary, section 13(a) of
the Noise Control Act authorizes EPA to require the manufacturer to run
such tests on selected vehicles.
These provisions also include a requirement that the manufacturer
provide a warranty to purchasers [required by section 6(d)], assist the
Administrator in fully defining those acts which constitute tampering
[under section 10(a) (2)(A)], and provide retail purchasers with instruc-
tions specifying the maintenance, use, and repair required to minimize
degradation during the life of the bus, and with a log book to record
maintenance and repairs performed.
In the case of a bus which is assembled by two manufacturers such
as the Type I School Bus, the manufacturer who assembles the chassis must
satisfy these requirements with respect to the exterior standard. The
manufacturer who then assembles the body must satisfy these requirements
as they relate to the interior noise emissions standard.
Section 6(d)(1) of the Act requires the manufacturer to warrant to
the ultimate and subsequent purchasers that the buses subject to the
proposed regulation are designed, built, and equipped to conform at the
time of sale with the applicable Federal noise emission standards. The
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proposed regulation requires that the manufacturer furnish this time-of-
sale warranty to the ultimate purchaser in a prescribed written form.
The proposed regulation also provides for EPA review of the written
warranty and related information furnished to purchasers, dealers, zone
representatives, etc., in order that the Agency can determine whether
the manufacturer's warranty policy is consistent with the intent of the
Act.
The tampering regulations require the manufacturer furnish the
Agency a list of those acts which in the manufacturer's estimation might
be done to a vehicle and result in that vehicle emitting sound levels
above the standards. The Administrator will respond to the manufacturer's
list within 30 days by developing a list of specific tampering acts that
the manufacturer must include in the owner's manual for each product.
It is stressed that the Administrator's list is not all inclusive; any
act of tampering is unlawful and subject to Federal penalty.
The provisions dealing with instructions for proper operation, use,
and repair are intended to assure that purchasers know exactly what is
required to minimize any degradation of the vehicle's emitted noise level
during use. The instructions are necessary to minimize degradation and
also must be reasonable in the burden placed on the purchaser. A record
or log book must be provided to the ultimate purchaser to assist pur-
chasers in demonstrating proper maintenance should a record be necessary
at any time during the life of the vehicle. The instructions may not
contain language which tends to give manufacturers or their dealers an
9-15
-------
unfair competitive advantage over the after-market manufacturers.
Finally, the proposed regulation provides for Agency review of the
instructions and related language.
9-16
-------
SECTION 10
EXISTING NOISE REGULATIONS APPLICABLE
TO BUSES
A. INTRODUCTION
Federal noise regulations applied to any particular product
are developed primarily on the basis of the assessment of available
technology together with associated economic and health and welfare
impacts as required by Section 6 of the Noise Control Act of 1972. In
most cases, actions by the EPA in proposing and finalizing new product
noise regulations will not be the first cases of regulatory action, but
will have been preceded by various state and local regulations. These
state and local regulations refer, in some cases, to the noise emissions
of the product at the time of sale, and in others cases to the control
of noise produced during the product's operation. It may be expected
that the scope and stringency of state and local noise standards will
differ from place to place in a way that is dependent on the degree of
annoyance, local citizen pressures and the amount of work put into the
development of the regulation. The results of these regulations will
also probably differ considerably based on the degree of enforcement
and compliance.
B. REVIEW OF EXISTING NOISE ORDINANCES
The increased interest in noise brought about in recent years
by the wider understanding of its potential effects on people has resulted
in the development of a large number of state and local noise ordinances.
Many of these ordinances can be classified as "nuisance" laws that make
10-1
-------
it unlawful to conduct certain acts that would disturb the peace of "a
reasonable person of normal sensitivity." However, there are an increasing
number of state laws and local ordinances that refer quantitatively to
specific noise sources in the community.
The first motor vehicle noise regulations were introduced in
the State of California in 1967, which established noise standards for dif-
ferent types of vehicles, including trucks and buses with a Gross Vehicle
Weight Rating (GVWR) in excess of 10,000 Ibs. The regulations were appli-
cable both to the sale of new vehicles and the operation of vehicles on the
highway. Since 1967, a number of other states and cities have introduced
such regulations, many of them identical to regulations applicable to trucks
and buses operated by interstate motor carriers. Again, the lower limit on
the GVWR was 10,000 Ibs.
In each of the many regulations applicable to medium and heavy
vehicles described above, there is no distinction in noise standards be-
tween the various classes. Thus the category of vehicles having a GVWR
in excess of 10,000 Ibs. includes not only trucks but inter-city buses,
transit buses and school buses. In other words, buses are combined with
trucks in every case. There are therefore no separate noise regulations
for buses in the United States. A summary of state and local noise
standards applicable to buses and trucks is given in Reference 10-1.
Since the publication of this referenced document, many of these regula-
tions have been preempted in part by the issuance of federal regulations
for new medium and heavy trucks and for new and in-service interstate
10-2
-------
motor carriers, the latter also including in-service inter-city buses.
However, there has been no federal preemption of newly manufactured
inter-city, transit, or school buses, so these standards remain as
stated in Reference 10-1.
The situation concerning the nonspecificity of buses in noise
regulations is similar in the vehicle noise regulations of many other
countries. A distinction between buses and trucks is made in Australia,
Sweden, and the United Kingdom, as well as by ECE (Geneva) and EEC
(Brussels), but in each case the noise standards are identical. It appears
that only one country, Portugal, has a different set of noise standards for
new buses and trucks. A summary of the foreign noise standards applicable
to buses is given in Table 10-1.
C. ANALYSIS OF EXISTING REGULATIONS
In view of the fairly uniform approach taken towards the
regulation of medium and heavy vehicles, it is interesting to determine
the reasons for not separating buses from trucks. A review of the deci-
«
sion criteria for noise regulations adopted at the state and local level
reveals the following information:
o Many considered that buses and trucks exhibit very similar
noise characteristics. It is true that the two vehicles
use the same type of engines—whether diesel or gasoline—
and some of the same auxiliary components, but the
conclusion that their noise emissions are the same must
be taken advisedly because of the lack of available data.
o Whereas there was a considerable amount of data on the
noise characteristics of heavy trucks, the same was not
10-3
-------
Table 10-1
Summary of Noise Standards*
Applicable to Buses in Foreign Countries
Country
Australia
Sweden
W. Germany
Yugoslavia
Belgium
Canada
Czechoslovakia
Denmark
ECE (Geneva)
EEC (Brussels)
Type of Regulation
and Effective Date
• New vehicles manuf'd
after 1975
• New vehicles manuf'd
after 1968
• Operation
• New vehicles manuf'd
after 1970
• New vehicles manuf'd
after 1969
• Operation
• New vehicles
• Operation
• New vehicles
• New vehicles
Applicability
• > 3.5 Mg w/engine
< 200 HP
• > 3.5 Mg w/engine
< 200 HP
• diesel engine
> 200 HP DIN
• Heavy Duty Vehicles
• >3.5Mg
• >220BHP
engine power
• > 3.5 Mg
• > 200 HP DIN
• >3.5Mg
> 9 Seats
• > 200 HP DIN
> 9 Seats
As for ECE
Max. Noise
Level (dBA)
89
92
92
2 dB greater
than above
88
88
89
2 dB greater
than above
89
92
3 dB greater
than above
89
91
"Measured according to ISO R362 at 25 feet.
10-4
-------
Table 10-1 (cont.)
Country
Finland
France
Italy
Luxembourg
Netherlands
Portugal
Great Britain
Type of Regulation
and Effective Date
• New vehicles
• New vehicles
• Operation
• New vehicles manuf d
after 1968
• New vehicles manuf d
after 1973
• Operation
• New vehicles
• New vehicles
• Operation
Applicability
• > 200 DIN HP
• Public Service
Vehicles
• >1500cc
• >3.5Mg
• > 200 HP DIN
• <5Mg
• >5Mg
• > 12 passengers,
excluding
driver
Max. Noise
Level (dBA)
92
90
2 dB greater
than above
93
88
92
2 dB greater
than above
85
88
89
92
10-5
-------
true of buses. Hence, the two vehicles were combined into
one category in the absence of reasons to do otherwise.
o Some states not having the resources to perform their own
background studies have incorporated the results of testing
done in other states.
o As an aid to enforcement, it was considered unwise to have
a large number of vehicle categories with different noise
standards.
o At the state level, the enforcement activities are often
restricted to highways outside of the cities. In these
areas, buses were not considered to pose significant
problems.
o There are indications that some agencies did not consider
buses at all, but were mainly concerned with heavy trucks.
In no case has there been reported any impetus to treat buses separately
from heavy trucks. Furthermore, many State and local officials have
indicated they do not now believe that such a separation is required,
although some indicate that a special case might be made for transit
buses.
10-6
-------
REFERENCES
SECTION 10
1. U.S. Environmental Protection Agency, "Noise Source Regulation
in State and Local Noise Ordinances," Report No. 550/9-75-020,
February 1975.
2. Society of Automotive Engineers, "Exterior Sound Leveil for Heavy
Trucks and Buses," SAE Standard J366b.
3. "Interstate Motor Carrier Noise Emission Standards," Federal
Register, Vol. 38, No. 144, July 27, 1973.
4. "Interstate Motor Carrier Noise Emission Standards—Final
Regulations on Compliance," Federal Register, Vol. 40, No. 178,
September 12, 1975.
5. "Existing Noise Regulations Applicable to Buses," Draft Fina.l
Report submitted by Wyle Laboratories under EPA Contract No.
68-01-3516, prepared for the Office of Noise Abatement and
Control, June 24, 1976.
10-7
-------
APPENDIX A
FOREIGN TECHNOLOGY BUSES
Two European bus manufacturers currently produce urban transit
buses that claim to be considerably quieter than any available in
the United States.
1. SAAB SCANIA CRlllM BUSES
In 1971, Scania-Bussar AB, Katrineholm (Sweden) presented a bus
in which the noise level had been effectively reduced. The bus is
an integrally constructed city bus, the Scania CRlllM, with a suburban
version, the CRlllMF.
Scania CRlllM and CRlllMF, the "quiet buses," have a reduced noise
level as low as 77 dBA for buses with automatic transmission and 80 dBA
for buses with standard transmission when measured in accordance with
the ISO R362 procedure for noise measurement. Other non-quieted modern
Swedish buses (CRllO) generate noise levels of 86 to 87 dBA (ISO R362).
The reduction in noise level on the Scania CRlllM (see Figure A-l)
has been achieved primarily by insulating the engine compartment and
relocating the cooling system. The engine compartment is lined with
sound-insulating materials attached directly to the exterior panels.
Within this sound-insulating wall is a thicker covering of sound-
absorbent glass fiber which in turn is covered with perforated aluminum
sheet. Insulated belly pans are mounted underneath the engine. The
engine, consequently, is almost entirely encased in sound-absorbent
material.
A-l
-------
Figure A-l
Comparison of Scania CR111M City Bus
and the CR1110M Standard Bus
1. Insulated Engine Compartment
2. Fan for Engine Compartment Ventilation
3. Belly Pan
4. Air Intake for Radiators, One on Each Side
5. Engine Air Intake
6. Ventilation Air Intake
7. Radiator Air Intake (Standard Version)
8. Bottom Opening
A-2
-------
As a result of this insulation, problems arise in disposing of
the heat generated by the engine. The bus has, therefore, been equipped
with a water-cooled exhaust manifold and heat-insulated exhaust pipe
up to the silencer. A special fan located on the roof provides the
engine compartment, by way of a channel through the bus rear section,
with effective ventilation.
2
The CRlllM has two radiators (each 0.42 m in area), instead of
the one as is normal on U.S. transit buses. The radiators are mounted
in front of the insulated engine compartment to cope with the increased
cooling requirements caused by the insulation. By using two fans of
480 mm diameter, a lower peripheral speed is achieved than if only one
fan was used for cooling. The fans are thermostatically controlled
in three steps up to 1400 rpm. If required, the fans can run at full
speed even while the engine is working at a minimum speed. For cross-
country operation, 10 to 15 percent larger radiators are employed.
Noise levels within the bus vary in relation to the distance
from the engine. The noise level at the driver's seat is as low as
68 dBA under acceleration. Levels of 78 dBA are reported at the rear
seat. Further reductions are expected from development work currently
in progress.
Due to the relocation of the radiators and a change in design
of the rear overhang, the number of seats has been increased by four
in comparison with other versions of the same bus type. The number
of seats in the "quiet bus" is 36 to 41 depending on the type of
bus.
A-3
-------
The Scania CR111M is designed specifically as a city bus and is
equipped with air suspension and power steering. The engine is a
transversely mounted diesel providing 151 KW (205 hp), ISO 2534 gross.
The Scania CRlllM is 11.55 m long (37.9 feet) and carries 36
seated and 45 standing passengers. As a comparison, the 35-foot CMC
45 series transit bus seats 45 passengers and the 40-foot CMC 53 series
seats 53 passengers. It is not known whether the reduced seating capa-
city of the CRlllM is due to compromises made for noise reduction, such
as the fully encapsulated engine and remote cooling packages, or for
other reasons. The cost increase due to engine encapsulation for noise
reduction purposes is given to be 2% by Scania Engineers.
The CRlllM engine is derated for urban operation on request. This
is a compromise in performance that may not be acceptable in the U.S.
On the other hand, derating the engine may cut down on maintenance and
increase the life of the engine.
The cooling system of the CRlllM is designed for an air-to-boil
temperature of 85-90 F. This would not be acceptable for buses oper-
ating in the U.S.
Air-conditioning is not offered on Scania Buses, even as an option.
Exclusion of air-conditioning reduces horsepower requirements and engine
cooling requirements significantly. In contrast, almost all transit
coaches in this country are air-conditioned.
There are a total of 360 single-decker and 300 double-decker CRlllM
Buses operating in the following:
Sweden: Stockholm, Gothenburg, Malmo, Vasteras, Orebro, and
Uppsala
Norway: Oslo
A-4
-------
Finland: Helsingfors
England: London, Leeds, Glasgow, New Castle, and Liverpool
2. BRITISH LEYLAND SUPER QUIET BUS
Research versions of a Super Quiet Leyland National were shown in
December 1972 and April 1974. work on developing this bus centers around
modifications to the bus interior with prime advantage to the passengers,
backed up by exterior modifications aimed at improving the acceptance of
the bus in-quiet suburban environments where background noise is vastly
lower than in typical city centers.
These changes combine to obtain an external noise level of 76 dBA
on a British standard 3425 "pass-by" test. Alteration of the torque
characteristics of the turbocharged 510 engine to an alternative form
achieves a more silent running power unit without detriment to avail-
able torque. A reworked engine air intake and exhaust system further
contribute to noise attenuation.
A major item of the noise reduction treatment of the Super Quiet
Leyland National is the structural enclosure around the engine, which
is of laminated sheet metal construction spot welded in a way that
permits the inner skin to reflect noise back to the engine. The outer
skin of the bus is designed with an air gap to reduce the transmission
of noise. Fitting of this enclosure involves the provision of an
electric fan mounted in an aluminum duct on the left hand rear valance
i
door with cooling air exiting around the flywheel housing. The radiator
cooling fan features a fluid drive coupling effecting a maximum fan speed
reduction and hence a lowering of fan noise. As a safety requirement, a
A-5
-------
thermostatically controlled fire extinguishing system is a safety
measure incorporated in the specification of the engine enclosure.
Noise generated by the transmission of the bus has also been
reduced by the specification of final drive gears designed to minimize
whine on drive and over-run. The hot shift pneumocyclic gearbox is
replaced by a fully automatic transmission involving reduced gear noise
and jerk-free up-changing.
Reduction of "road noise" entering the structure is achieved
by a more compliantly mounted Vee-frame rear axle location assembly
tuned to isolate road vibration inputs.
Hatches to the engine compartment feature improved sealing. To
this end, the hatches and the vehicle floor are lined with Revertex
noise insulant.
Regarding the maintenance difficulties generally encountered with
engine enclosure technology the semi-monocoque construction of the engine
enclosure allows for acoustic panel suspension from brackets welded onto
the engine support longitudinals. Panels are secured with quick-release
fasteners for easy service access to the engine; a single panel gives
access to inner and outer sump drain plugs and the oil filter. Vertical
walls (panels) of the enclosure are fitted where possible with sheets
of glass fiber "wool" held in position by perforated sheet aluminum.
Toward interior noise reduction, seats are fully upholstered and
have squab backs trimmed in foam based moquette in the interests of
covering any large reflective surface. The seat squab upper rails are
shrouded by an enveloping safety crash pad and the vertical "grab"
stanchions in the bus are nylon covered. Another aspect of interior
A-6
-------
noise control applies to the redesigned heater recirculation duct which
has provided a "spin-off" of considerably improved air circulation.
The noise reduction achieved on the vehicle is so considerable that
"canned music" is provided in the vehicle to alay the uncanny feeling
of sitting in what has been stated as virtually an anechoic chamber.
Subtle changes to the interior specification include stapling
of a 25-mm closed cell pvc foam to the top of the floor over the rear
saloon only; at the edges this is compressed between the lower stain-
less cover panel and the body side. Beneath the whole floor, aluminum
trays enclosing glass wool insulant are suspended between floor support
members. Teroform sheeting is bonded to the front of the saloon access
step riser channel; similar treatment applies to the rear wheel arches
and rear seat box. Interior trim panels have their 25 mm polyether
heat insulating backing panels replaced by 66.5 mm expanded polyethylene
foam with heat and very adequate noise insulation. Backing the rear
corner cove panels are Teroform moulded shapes around the heater piping
and air ducting entry points; these are overlaid with flexible polyether
foam to a depth of 6 inches.
A-7
-------
REFERENCES
Appendix A
1. "An Assessment of the Technology for Bus Noise Abatement," Draft
Final Report submitted by Booz-Allen Applied Research, under EPA
Contract No. 68-01-3509, prepared for the Office of Noise Abate-
ment and Control, June 22, 1976.
A-8
-------
APPENDIX B
NEW TECHNOLOGY BUSES
1. TRANSBUS
The Transbus program is a federally funded competitive development
project aimed at the next generation of transit buses. The final
Transbus design specification vehicle was intended to replace currently
produced, 40 ft transit buses. The first prototype vehicles from each
of three bus manufacturers were delivered in mid-1973. The final Trans-
bus design was to enter full production in the last half of this decade
as part of a program to reduce urban traffic congestion, improve urban
air quality, and revitalize urban mass transportation.
The Transbus program is a major element of UMTA's (DOT) overall
bus technology effort. Competitive prototype vehicle development sub-
contracts were awarded to three bus manufacturers: AM General Corp.,
Rohr Industries, and General Motors Truck and Coach Division. Each
manufacturer developed a prototype bus. At the conclusion of testing
and evaluation, a final design was to be selected for further develop-
ment. The standard design was to be the property of the government,
but the bus itself could be built by any qualified bus manufacturer.
The three prototype bus designs currently built were selected from ten
proposed designs.
B-l
-------
(A) Transbus Specification
It was an objective of the Transbus program to develop an
advanced bus design that can be used to stimulate an increase
in bus ridership. Consequently, the specifications change many
of the traditional priorities in bus design.
Some of the features required by the Transbus specifica-
tion are listed for five key areas in Table B-l. The require-
ments shown were selected primarily on the basis of appealing
to the passenger, while maintaining total vehicle cost/mile
consistent with the increased benefits. This reverses tradi-
tional priorities on vehicle operating economy factors, such
as fuel economy and low maintenance costs, which often result
in a reduced level of passenger amenities.
(B) Transbus Sound Levels
The sound levels for Transbus were specified as follows:
1) Interior Noise Level
The vehicle-generated noise level experienced by
a passenger at any seat location in the bus shall not
exceed 75 dBA, and shall be designed to not exceed
75 dBA, under the following operating conditions:
o Acceleration of O.lOg (3.2 ft/sec/sec) at vehicle
G.V.w.R.
o Constant speed of 65 mph on level road at vehicle
G.V.w.R.
o Constant speed of 10 mph on level road at vehicle
G.V.w.R.
o Deceleration at O.lOg (3.2 ft/sec/sec) at vehicle
G.V.W.R. engine operating and engaged.
B-2
-------
Table B-l
Original Transbus Specifications
Performance
Design Factor
Top speed
Acceleration
Gradeability
Boarding Time
Design Improvement Required
Increased from 60 to 70 mph to be comparable with freeway traffic
Increased to 2.2 mph/s for greater maneuverability, the greatest
desirable without sacrificing passenger comfort
Increased from 40 to 55 mph on a 2-1/2% grade for increased travel
rates in hilly terrain
Halved from 3 to 1.5 s/passenger for expeditious ingress and egress
Passenger Comfort and Convenience
Design Factor
Interior noise level
Air conditioning
Ventilation
Interior lighting
Seat width
Knee room
Passenger information
Window area
Jerk
Emissions
Design Factor
Gases and smoke
Design Improvement Required
Odor
Exterior noise
Reduced to a maximum of 75 dBA under all operating conditions
and at all passenger locations, 30% of the level of current vehicles
To be standard equipment on all vehicles
Circulated air will consist of 25% fresh outside air, an increase over
present vehicles in order to improve interior environmental quality
A 100% increase in intensity at reading position over presently used
lighting systems
Increased from 16 to 18 in/passenger
Increased from 8 to 10 in
Destination sign letter height increased from 4 to 5 in.vvith a mini-
mum of three intermediate destinations per sign and 200 sign
storage capability
A 100% increase in side window area for increased visibility for
both seated and standing passengers
Kept to a maximum of 3 mph/s^ to provide smoothness of accel-
eration comparable to modern rail transit
Design Improvement Required
Compliance with proposed 1973 California heavy-duty standards,
and 1974 Federal standards. A target of the 1975 California
standards.
Reduced by 50%
Reduced over 30% of noise levels from present vehicles
Service Life and Maintenance
Design Factor
Interior cleaning
Glazing material
Bumper impact
Exterior panel replace-
ment
Design Improvement Required
Interior cleaning costs reduced with conversion from supported to
cantilever seating
High-strength tempered glass and acrylic materials increase impact
strength in order to reduce breakage caused by vandalism
Withstand a 5 mph impact by a 4000 Ib automobile without incurr-
ing damage to bus
Exterior panels to be quickly repairable or replaceable within 30 min
B-3
-------
Table B-l (Continued)
Original Transbus Specifications
Service Life and Maintenance
Design Factor
Design Improvement Required
Brake friction material
Safety
Design Factor
Floor height
Boarding steps
Passenger windows
Crashworthmess
Emergency egress
A 100% increase in friction material life from an average 50,000 to
100,000 miles for a reduction in brake maintenance costs
Design Improvement Required
Reduced 50% from 34 to 17 in. above road surface to reduce
boarding accidents, especially involving the aged
Step from street reduced from 14 to 10 in, with interior step
height reduced from 10 to 7 in, and number of interior steps
reduced from two to one
Converted from operable type to permanently fixed and sealed to
insure that passenger limbs do not protrude from bus envelope
and to protect passengers from flying objects
Interior dimensions to be altered by no more than 6 in in typical
rollover and 3 in in side impact crashes for improved passenger
protection
Hatches in roof and side windows which can be opened in an
emergency for rapid egress in event of rollover and fire
B-4
-------
2) Sound Insulation
The combination of inner and outer panels and any material
used between shall provide sufficient sound insulation such that
a sound source with a level of 80 dBA measured at the outside
skin of the bus will have sound level of 65 dBA or less at any
point inside the bus with the doors closed, engine and auxiliaries
switched off. The use of sound deadening materials within the bus
may contribute to this.
3) Exterior Noise
Bus airborne noise shall not exceed 75 dBA under the following
conditions when operated at or below 30 mph at G.V.W.R.:
o Acceleration of O.lOg (3.2 ft/sec/sec)
o Deceleration of O.lOg (3.2 ft/sec/sec)
o Constant speed at 30 mph and full accessory load
o Constant speed at 10 mph and full accessory load
The maximum noise level at a constant 65 mph shall not be
greater than 3 dBA higher than the noise level under coast-by con-
ditions with none of the operational equipment in operation. All
noise readings shall be taken at 50 feet from, and parallel to, the
center line of the bus.
4. Exhaust Location
The exhaust gases and waste heat shall not be discharged
on the right-hand side of the bus, and shall be directed so
that it may not cause discomfort to pedestrians.
The actual measured noise levels for the three prototype
Transbuses and a present day CMC Coach are summarized in Tables
B-2 and B-3.
B-5
-------
Table B-2
Interior Noise Test Summary
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B-6
-------
Table B-3
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B-7
-------
2. GAS TURBINE ENGINE APPLICATIONS
Gas turbine engines are currently being field tested as the prime
power source for such applications as on-highway trucks, urban transit
and intercity buses, and industrial and marine electrical generator sets.
The heaviest concentration of these engines is in trucks and buses.
Turbine engine sizes, shapes, and weights, (such as the GT-404 engine)
have ideal envelope dimensions for installation in a space that is
designed for a diesel engine.
Only a few companies manufacture turbine engines with a rating below
500 brake horsepower (bhp) suitable for city and intercity bus and coach
application. The turbine engine is higher in cost than a comparable
diesel engine. However, it burns almost any type fuel, requires less
maintenance and will have an extremely long life expectancy.
The gas turbine uses very little oil compared to a diesel engine.
This difference is on the order of magnitude of a thousand to one;
or 0.3 quarts for turbines to 300 quarts for diesels per 1000 hours of
operation. Gas turbine engines are lighter and smaller than diesel
engines. This is offset somewhat, however, by the requirement of the air
or a filtration system and a regenerator unit in the turbine installation.
The gas turbine requires less maintenance than a diesel engine
because of fewer wear parts and less vibration. The precise amount
has not been established in commercial vehicles; however, under military
conditions, the gas turbine engine costs approximately 25 to 40 percent
less to maintain than a comparable diesel engine where the cost reflects
labor, oil, repair parts, minor accessories, but not overhaul. Signifi-
cant technological improvements in terms of reliability and life-cycle
ownership costs are expected during the next three years.
B-8
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The favorable influencing factors for the gas turbine engine are:
o Cleaner exhaust emissions. Major pollution elements
are minimized because of the turbine's highly effi-
cient, low-pressure, continuous combustion.
o Good serviceability. Gas turbines are simple in
design. Cast iron one-piece blocks have the char-
,acteristics of a traditional industrial configur-
ation. Engine components can be easily handled,
maintained or replaced because of their modular design.
o Smooth-power—high torque rise. The two-shaft
turbine produces a torque curve that increases as
output speed decreases—like a torque converter.
The result is a high performance engine with high
torque for load starting and fast acceleration. The
two-shaft turbine torque characteristic provides a
broad power curve in the operating speed range.
o Effective engine-dynamic braking. Outstanding
engine-dynamic braking is achieved in the GT404/
505 design because of the unique Power Transfer
feature. Braking effort equal to full rated
engine output can be achieved by the automatic
engagement of the Power Transfer clutch, which
causes the compressor to act as a dynamic brake.
This results in major cost saving in service brake
maintenance in vehicles and—more important—gives
the inherent safety of controlled engine braking.
B-9
-------
o Simplified transmission requirements. Turbine
equipped vehicles can utilize either a standard or
an automatic transmission. A fewer number of gear
ranges are required because of the inherent torque
characteristics of the turbine and its broad power
ranges.
o Superior cold weather starting. The gas turbine's
ability to start at low temperatures quickly is
superior to any conventional power plant. The
engine has demonstrated the ability to start
without aid in temperatures well below freezing.
o Lower weight. The gas turbine provides a 25 percent to
45 percent reduction in installation weight as compared
to diesel engines in the 250 to 300 bhp power class.
o Simple cooling system. Gas turbines do not require
a water jacket cooling system. Only lubricating oil
requires cooling through a simple oil heat exchanger.
This contributes to less maintenance and downtime.
The diesel engine with its ancillary components (cooling system,
exhaust system, converter) weighs approximately 50 percent more than
the comparable gas turbine and is 75 percent larger in cubic feet of
volume. The favorable influencing factors for the diesel engine are:
o Lower fuel costs
o High reliability
o Lower mean time to overhaul
o Lower skill required to overhaul
o High altitude performance
o High durability
o Heat source (at no additional cost) for coach heating
o Lower fuel consumption when idling.
B-10
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Pilot models of the gas turbine engine began going into service
in 1972 for extensive field evaluation. The test engines have logged
nearly two million miles in 24 trucks from 10 manufacturers; eight motor
coaches from MCI-Greyhound and CMC Truck and Coach Division, and various
watercraft and industrial applications.
Consignment engines currently are operational with Greyhound on the
East and West Coasts; Binswanger Trucking in Los Angeles, California;
Freightliner Corporation and Consolidated Freightways in Portland, Oregon;
Acadian Marine Rentals in New Orleans, Louisiana; Terminal Transport in
Atlanta, Georgia; Gardner-Denver in Quincy, Illinois; CMC Truck & Coach
Division of General Motors in Pontiac, Michigan; and Detroit Diesel
Allison in Indianapolis, Indiana.
The turbine is quiet and virtually vibration-free, and offers the
added advantages of low air emissions, reduced maintenance costs, and
excellent cold-weather starting performance. It appears to be a likely
power source of future intercity buses if target reductions in fuel
consumption and improvements in durability are realized.
3. BATTERY POWERED BUSES
This type of bus has seen several applications for urban revenue
transit service as well as demonstration services in the United States,
Canada, and France. These buses claim as their principal advantage low
air emissions and noise levels.
In the U.S., Electrobus Division of Otis Elevator Co. and its
successors are marketing a bus with two models. Model 20 has a curb
weight of 13,500 Ibs., is 25 ft. in length and seats 21 passengers.
Model 26 has a curb weight of 14,300 Ibs., is 30 ft. in length and
seats 30 passengers.
B-ll
-------
The bus is driven by a single, separately ventilated 50 HP, 72 volt
DC traction motor, mounted under the floor ahead of the rear axle. The
motor was specifically developed for this bus with a long, small diameter
(14") frame to provide adequate road clearance with an unusually low
floor height (22").
The application of motor power is controlled by low voltage electro-
mechanical switching in an eight step contactor controller designed for
maximum simplicity and reliability with quiet operation. A timed sequence
of battery and motor field switching in response to power pedal position
regulates motor power and speed. No transmission or clutch is used.
A single unit, 72 volt, 36 cell, 880 AH at 6h, 4,250 Ib. lead acid
storage battery is used for propulsion power. The battery is fitted
with fork lift slots. Rapid battery exchange is aided by a quick dis-
connect feature, allowing full transfer in five minutes or less. Re-
charging is done on or off the bus by automatic charging equipment.
A separate 150^AH, 12 volt battery provides' power for accessories
and controller. This battery is recharged from the traction battery
by a dynamotor, which also drives the motor cooling and coach body
ventilation blower.
The foot controlled service brake initially reconnects the DC
traction motor as a three phase AC generator to provide dynamic braking.
Secondarily, the brake pedal applies air-assisted tandem hydraulic drum
service brakes. Even if the air supply should fail completely, a mechani-
cal override would still operate these service brakes. A separate,
mechanically actuated disc parking brake is also furnished.
B-12
-------
Dashboard instruments, in addition to the conventional speedometer
and air pressure gauge, include a voltmeter, ammeter and battery condi-
tion meter.
Outside of the electric traction motor and controller, the elec-
tric bus running gear and mechanical components are standard heavy
service truck and bus types.
The electric traction motor and control system are similar to
trolley coach or railway types except for being designed for lower
voltages to suit storage battery operation rather than higher voltages
needed for distribution efficiency on wire fed, fixed power systems.
4. ARTICULATED AND DOUBLE DECK BUSES
Articulated and double deck buses have been and are being used in
transit bus applications to maximize the capacity of a public service
vehicle suitable for use on existing roadways. In the United States,
double deck buses were in use through the mid 1950's in New York and
Chicago while articulated buses have been only used experimentally.
Declining bus ridership since the 1920's has discouraged use and
development of these unique forms of road transport, leaving the 40 ft.
rigid single deck vehicle as the backbone of the North American transit
fleet.
Now with the growing importance of economic and environmental
pressures and concerns about energy consumption, the use of larger
public service vehicles is being seriously considered. Negotiations
for the joint purchase of at least 300 such vehicles is currently under-
way by a consortium of operators representing several large American
cities. This bus will be a single operator, articulated vehicle having
B-13
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at least one and one half times the capacity of the 40 ft. standard
coach with greater maneuverability and equal fuel consumption. The
vehicle will undoubtedly be based on current European designs which
have a pancake engine under the floor of the front section. There are
significant drawbacks to this arrangement in considering its use in
transit fleets in America. An upright engine at the rear has become
established as the industry standard regardless of vehicle manufacturer.
In addition, the present design trend is to lower the coach floor which
is a major goal of the principal funding agent, the U.S. Department of
Transportation.
Some development work (notably that which took place in Germany)
with a low floor, rear engine, articulated vehicle is currently being
undertaken, but production of such a vehicle is far in the future.
Research in the U.S. has been conducted in areas that might benefit from
the use of the larger buses. A recent study indicated that at least seven
major U.S. cities had specific routes that could effectively now use
articulated vehicles. With further development of priority bus lanes,
greater acceptance by the ridership, and more improved accommodations, the
number of articulated vehicles in the U.S. Transit fleet can be expected
to increase rapidly in the not to distant future.
B-14
-------
REFERENCES
APPENDIX B
1. "An Assessment of the Technology for Bus Noise Abatement," Draft
Final Report submitted by Booz-Allen Applied Research, under
EPA Contract No. 68-01-3509, prepared for the Office of Noise
Abatement and Control, June 22, 1976.
B-15
-------
APPENDIX C
BUS NOISE ABATEMENT COSTS
Presented in this appendix are the estimated cost increases
(decreases) required to manufacture quieter buses as compared to cur-
rently produced buses for the various technology levels discussed in
Section 5. This appendix is organized as follows:
I. Introduction
. Methodology
. Bus Classification
II. Gasoline Powered Conventional School Buses
. Manufacturing Process
. Estimated Costs
III. Diesel Powered Conventional SchooJ Buses
. Manufacturing Process
. Estimated Costs
IV. Forward Engine Forward Control School Buses
.. Manufacturing Process
. Estimated Costs
V. Diesel Powered Integral Urban Transit Buses
. Manufacturing Process
. Estimated Costs
VI. Diesel Powered Integral Mid-Engine Buses
. Manufacturing Process
. Estimated Costs
C-l
-------
VII. Diesel Powered Integral Rear Engine School Buses
. Manufacturing Process
. Estimated Costs
VIII. Diesel Powered Integral Intercity Buses
. Manufacturing Process
. Estimated Costs
IX. Parcel Delivery and Motor Home Chassis Buses
. Manufacturing Process
. Estimated Costs
X. Enforcement Costs
. Introduction
. Methodology
. Estimated Costs
C-2
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I - INTRODUCTION
METHODOLOGY
Using information developed by Booz-Allen Applied Research under
EPA contract number 68-01-3509, technology packages were developed and
distributed to bus manufacturers and bus component suppliers. These
packages described study levels of bus noise abatement and recommended
approaches to achieve those study levels.
Bus manufacturers were asked to provide on a level-by-level basis,
cost estimates to achieve the proposed levels of bus noise abatement.
In addition to the technology packages each manufacturer received:
. Cost estimating forms
. Lead time estimating forms, and
. Enforcement scenarios necessary for assessing costs attributable
to compliance testing by manufacturers
Telephone contacts were made with all manufacturers receiving the
technology packages. In addition, visits were made by EPA personnel and
EPA consultants to various manufacturers in order to gain a better under-
standing of the .different manufacturing processes used throughout the
bus industry.
Component manufacturers were contacted and supplied with a copy of
the technology packages that pertained to their product. These manufac-
turers were asked to furnish cost information for their products based
on the recommendations in the technology package.
Cost information requested from the manufacturers was based on a
manufacturing tolerance of 2 1/2 - 3 dBA. For example, if the proposed
study level was 83 dBA, the design level for manufacturing would be
80-80.5 dBA.
When submitting cost estimates, the manufacturers were asked to
break the costs into:
C-3
-------
. Product cost
. Channel Cost
. End-user cost
For each bus category, manufacturers were asked to identify each
type of cost. The different types of costs were used to determine the
impact on labor, material, quality control, investment and burden cost.
No manufacturer supplied this information totally. A.M. General was the
only manufacturer that provided some information on end-user costs, chan-
nel costs and product costs for transit buses.
Quality control and testing procedure costs were not broken out by
any responding manufacturer. These costs were said to be built into
their responses. For the automotive-truck industry, costs related to
quality control and testing normally represent 5% - 8% of product cost.
The estimated costs in this report include quality control and testing
procedure costs.
A.M. General was the only responding company to indicate the addi-
tional investment required to meet the proposed study levels of noise.
On a level-by-level basis the investment required 3% - 21% of total esti-
mate cost. Typically, for the automotive-truck industry, for every dol-
lar of investment three dollars of revenue are generated on an annual
basis. The estimated costs in this report include investment cost.
The school bus body builders visited, except for Wayne Corp., have
equipment and tooling that lend themselves to high flexibility. Many
operations on different part configurations are possible. Wayne by using
roll forming equipment have, to some extent, limited their flexibility.
Integral bus builders (intercity, transit, and school) have flexi-
bility in their assembly process. No information was supplied by any
integral bus manufacturers as to the impact of engine encapsulation on
bus design.
Operation and maintenance estimated costs were based on interviews
of end-users, industry supplied information and component vendors.
C-4
-------
Estimated costs in this report are associated with levels of bus
noise abatement. By initiating the actions outlined in the technology
study, the corresponding level of noise was assumed to be achieved. The
first study level for each bus type is designated as Level 1, the second
study level is Level 2, etc. Levels do not mean years.
The development of the EPA estimated costs was based, as much as
possible, on manufacturers' knowledge of the industry, cost structure
and technology. Component costs received from vendors were used to cross-
check manufacturers' data and to provide a basis for estimating costs
when required.
Guidelines followed in the construction of EPA cost estimates were:
. Manufacturers' data was used as much as possible.
. Final costs were rounded to the nearest five dollars.
. An hourly rate of $15 per hour was used to cover direct labor and
all burden charges.
. Labor hour changes were estimates.
Low and high estimated costs were, in most cases, based on manufac-
turer-supplied data. The basis for EPA cost estimates were outlined
above.
Response to requests for cost estimates were slow with varying levels
of participation by the companies. Companies that had chosen not to
respond at all were:
. Chrysler Corporation
Detroit, Michigan
. Blue Bird Body Company
Fort Valley, Georgia
. Thomas Built Buses, Inc.
High Point, North Carolina
. Gillig Brothers
Hayward, California
C-5
-------
. Ward School Bus Manufacturing, Inc.
Conway, Arkansas
The remaining companies provided some information.
BUS CLASSIFICATION
Buses are normally classified into three major categories:
. School Buses
. Transit Buses
. Intercity Buses
Within each category various configurations of buses are possible.
To estimate the cost impact of bus noise abatement buses were classified
as follows:
. Gasoline Powered Conventional School Buses
. Diesel Powered Conventional School Buses
. Forward Engine Forward Control School Buses
. Diesel Powered Integral Urban Transit Buses
. Diesel Powered Integral Mid-Engine School Buses
. Diesel Powered Integral Rear-Engine School Buses
. Diesel Powered Integral Intercity Buses
. Parcel Delivery and Motor Home Chassis Buses
The definition of a bus used in this study was a vehicle with a
Gross Vehicle Weight Rating (GVWR) in excess of 10,000 Ibs. and a capa-
city of transporting 10 passengers or more, other than the driver. The
vehicle's primary design is to transport passengers, not material,
driver, etc.
C-6
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II - GASOLINE POWERED CONVENTIONAL SCHOOL BUSES
MANUFACTURING PROCESS
A completed conventional school bus is assembled by mounting a body
onto a chassis. The chassis and the body are produced by two separate
manufactures. The school bus chassis is equipped vith an engine located
forward of the driver and passengers, a completed drive train, a com-
pleted steering mechanism and an engine cowl. The chassis itself is not
a completed vehicle, per Federal specifications, that can be driven on a
street or highway.
A conventional school bus chassis is similar to a medium duty truck
chassis. As a result, school bus and truck chassis are/can be manufac-
tured on the same assembly line utilizing many of the same components
and manufacturing equipment. The primary differences between conventional
school bus and truck chassis are the locations of the fuel and air tanks,
the chassis rail configurations, the brake systems and the vehicle oper-
ator enclosures.
A typical assembly sequence for a bus chassis is:
. assemble frame and braces
. install front and rear axles
. mpunt engine and transmission
. locate chassis wire
. locate fluid lines
. bleed and test hydraulic system and air check
. paint frame
, install exhaust system
. mount tires
. hook up chassis wiring to lights and engine
, connect all chassis lines
. mount and hook up cowls
, install radiator
C-7
-------
, mount front end and bumper
. mount temporary driver seat
. install steering wheel
. add coolant to radiator
. add gas
. inspect
. deliver to shipping lot
Normally the front and rear axles, engine and transmission, tires,
cab trim, and front end are off line assemblies. Conveyor systems move
these subassemblies to the main line to match the chassis used.
This assembly sequence is the same as truck assembly. An individual
not familiar with the two chassis configurations or standing away from
the assembly line cannot differentiate between the two.
After assembly the chassis is shipped to a body builder. Each
chassis is accompanied by an incomplete vehicle document which states
the Federal Standards to which the vehicles comply as built by the
chassis builder,
The body builder mounts the body shell to the chassis and completes
the interior of the shell. Body builders do not alter or change the
chassis as received. Chassis builders maintain service representatives
at the body builder's location to inspect the chassis after the body is
mounted and to make repairs if required.
A typical assembly sequence for body builders is:
, fabricate, build and mate
- floor
- backend
- side frames
- front end
- roof
- interior side panels
- exterior side panels
- ceiling
C-8
-------
. undercoat
. mount exterior trim
. paint exterior and interior
. install floor coverings
. mount shell to chassis
. install
- seats
- windows
- lights
- heater, etc,
. letter
. inspect
. road test
. deliver to shipping lot
Normal subassembly operations are: seats, lights, flooring, and
frames. Subassembly operations are as close to the assembly line as
practical.
High flexibility is present due to the variation in bus lengths,
in chassis designs between manufacturers and in specifications from
each buyer. Normally no two buses are identical on the assembly line.
Federal Certification tags are placed on the completed bus by the
body builder. Chassis builders furnish tags and specification sheets
listing what standards the chassis will meet as long as components are
not changed.
Both chassis and body manufacturers have a high degree of flexi-
bility in their assembly sequence primarily due to the various require-
ments for a bus. Federal, State and local governments plus each school
district and school have individual standards that a school bus must
meet. These standards can and do vary from state to state, local
government to local government and school district to school district.
C-9
-------
ESTIMATED COSTS
The estimated costs to achieve the proposed study levels of noise
abatement for gasoline conventional school buses are shown in Figure C-l.
These costs are for a typical conventional school bus with a 60-66
passenger capacity. The costs are based on information supplied by
chassis builders, body builders, component vendors and estimates.
Table C-l summarizes the estimated costs to reduce bus noise. Note
that all costs are rounded to the nearest 5 dollars.
Table C-l
Estimated Cost to Achieve
Bus Noise Abatement for Gasoline
Powered Conventional School Buses
Level
1
2
3
4
5
Source: Figure C-l
Exterior
dBA
83
80
77
75
73
Interior
dBA
83
80
80
75
75
EPA
Estimated Cost
$ 50
150
285
845
1,145
These costs are typical and variation between engine, transmission,
drive train and shell construction will change the cost, For example,
the CMC 350-V8 engine currently meets the 83 dBA level. The CMC 366-V8
and International Harvester MV442 engine do not. In order to meet an
83 dBA standard for school buses using these engines, CMC will add a
viscous fan drive and International Harvester will add a wrapped muffler,
fan spacer and absorption material for the splasher panels. Both
actions, while different, cost approximately the same.
Body builders Thomas, Carpenter, Wayne and Superior have indicated
that chassis changes will not increase their costs or change their
C-10
-------
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methods of assembly. They feel interior noise is directly related to
chassis noise, and as chassis noise is reduced, interior noise will be
reduced.
The cost increase estimates for body builders are for installing
an acoustical barrier between the engine compartment and driver for
about $25. The change in body mounting to the chassis for this installa-
tion is estimated at $150. This cost is comparable to the installation
of a plywood floor.
The'introduction of a viscous fan clutch will have the positive
impact of increasing gas mileage by an estimated 5%. Current miles per
gallon average 3-5 miles or with viscous fan clutch 3.2-5.3 for an
average increase of 0.25 miles per gallon.
Maintenance costs will increase with the changes suggested in each
study level, The cost increases are due to more parts and increased
labor. The labor costs are impacted not only by the parts increase but
decreased access to the engine due to the installation of shielding for
noise control.
The dollar amount of maintenance costs is dependent on bus usage,
manpower costs and component costs. Each bus system's cost varies from
another system. Based on information supplied by bus manufacturers and
users, cost increases for maintenance are shown in Table C-2.
Table C-2
Maintenance Cost for
Gasoline Powered Conventional School Buses
EPA
Level Estimated Cost Per Year
1 $ 20
2 135
3 160
4 170
5 450
Source: User Interviews
CMC
C-12
-------
Based on industry interviews, lead time for noise levels should
correspond to the truck regulation. International Harvester has
indicated that a level could be reached every 20-24 months as an ongoing
process to the 73 dBA study level.
C-13
-------
Ill - DIESEL POWERED CONVENTIONAL SCHOOL BUSES
MANUFACTURING PROCESS
Diesel Powered Conventional School Buses are basically the same as
Gasoline Powered Conventional School Buses except for the engine. The
same definitons of conventional school bus, chassis and body assembly
methods can be used for the diesel bus. For the descriptions refer to
Gasoline Powered Conventional School Buses.
Diesel and gasoline engine chassis are mixed on the chassis assembly
line. Differences between the two engines normally impact the subassembly
area of engine and transmission. Work content may vary on the assembly
line, but production lines are balanced to account for these variations.
Body builders, as in gasoline powered buses, mount the body to the
chassis. The type of engine does not impact their work methods.
Vehicle certification procedures are the same as gasoline powered
buses.
ESTIMATED COSTS
The estimated costs to achieve the proposed study levels of noise
are shown in Figure C-2. These costs are for a typical conventional
diesel school bus with a 60-66 passenger capacity. The costs are based
on information supplied by chassis builders, body builders, component
vendors and EPA estimates.
Table C-3 summarizes the estimated costs to reduce Diesel Powered
Conventional School Bus noise.
C-14
-------
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C-15
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Table C-3
Estimated Cost to Achieve
Bus Noise Abatement for Diesel
Powered Conventional School Buses
Level
1
2
3
4
Source: Figure C-2
Exterior
dBA
83
80
77
75
Interior
dBA
86
83
80
80
EPA
Estimated Cost
$ 630
730
1,480
1,580
These costs are typical costs. Thus, variations of the type of
engine, transmission drive train and shell construction can change costs.
For example, concerning shell construction, Wayne uses a roll forming
method to produce the panels for a bus. These panels are interlocked
and fasten to the frame with "huckbolts." Carpenter fabricates each
panel and fastens it to the frame by riveting and/or welding.
Body builders Thomas, Wayne, Carpenter and Superior have indicated
that chassis changes will not increase their costs or change methods of
assembly. They feel interior noise is directly related to chassis noise
and as chassis noise is reduced interior noise will be reduced. Actions
taken by the body builders to reduce noise will be based on the interior
noise level at the exterior level.
At present diesel powered buses represent 3% - 4% of the school bus
market. The market share is increasing. To offset the higher initial
purchase price of diesel buses versus savings in operating costs, the
bus must be driven an estimated 40,000 miles per year. The operating
savings result primarily from increased fuel mileage and longer life.
Estimated fuel mileage for diesels ±s 5 - 6 miles per gallon as compared
to the 3-5 miles per gallon for gasoline engines.
No increase or decrease in fuel costs is expected with the addition
of noise control technology to diesel powered conventional school buses.
C-16
-------
The cost of maintenance affected by changes outlined in the tech-
nology packages. As with the gasoline powered conventional school bus,
the cost changes are due to material and labor changes.
Based on information supplied by manufacturers and users, cost
increases for maintenance are shown in Table C-4.
Table C-4
Maintenance Cost for Diesel
Powered Conventional School Buses
Level Estimated Cost
1 $ 20
2 155
3 215
4 450
Source: Industry Interviews
The sharp jump in maintenance costs after Level 1 is caused by
the use of noise shields and belly pans causing increased labor time to
gain access to the engine.
Based on industry interviews, the lead time for noise levels should
correspond to the truck regulation. International Harvester has indi-
cated that a level could be reached every 20 - 24 months in an ongoing
process to tlie 75 dBA study level.
C-17
-------
IV FORWARD ENGINE FORWARD CONTROL SCHOOL BUSES
MANUFACTURING PROCESS
Diesel Powered Forward Engine Forward Control School Buses,
Gasoline Powered Forward Engine Forward Control School Buses and Forward
Control Buses, gasoline and diesel, are being combined for cost estimat-
ing purposes. These types of buses have many of the same characteristics,
construction methods and technology packages for noise abatement. A
primary difference between these buses is the interior layout of the
bus. The layout changes with the use, such as a transit coach, school
bus, luxury bus, etc.
These types of buses are not of integral construction. A body
shell is mounted onto a chassis with two manufacturers involved. The
buses are produced by companies that manufacture school buses. For
descriptions of the assembly sequence, refer to the Gasoline Powered
Conventional School Bus.
It is important to remember that this type of bus is normally built
on the same body assembly line as the conventional school bus. Extra
work required is performed off the assembly line. Flexibility is present
in the assembly process.
Federal Certification procedures are the same as for the conventional
school bus.
Both manufacturers must be able to meet not only the Federal require-
ments but also State and local government as well as school district
requirements. The State and local government and school district require-
ments can and do vary among themselves.
ESTIMATED COSTS
The estimated costs to achieve the proposed study levels of noise
are shown in Figures C-3, C-4, and C-5. These costs are for a typical
bus. The costs are based on information from component vendors and
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estimates. The chassis builders and body builders contacted did not
respond.
Table C-5 and Table C-6 summarize the estimated costs for both
gasoline and diesel buses.
Table C-5
Estimated Cost to Achieve Bus Noise Abatement for
Diesel Powered Forward Engine Forward Control School
Buses and Diesel Powered Forward Control Buses
Exterior Interior EPA
Level dBA dBA Estimated Cost
1 83 86 $ 255
2 80 83 340
3 77 80 1,090
4 75 75 1,580
Source: Figure C-3 and C-4
Maintenance costs, operating costs and technology lead times are
estimated to be the same as shown for Diesel Powered Conventional School
Buses.
Table C-6
Estimated Cost to Achieve Bus Noise
Abatement for Gasoline Powered Forward Control Buses
EPA
Level Estimated Cost Per Year
1 $ 75
2 145
3 285
4 995
Source: Figure C-5
Maintenance, lead times and operating costs changes are estimated
to be the same as shown for Gasoline Powered Conventional School Buses.
C-22
-------
V - DIESEL POWERED INTEGRAL URBAN TRANSIT BUSES
MANUFACTURING PROCESS
Transit buses differ in their manufacture from conventional school
buses. While conventional school buses are manufactured in a two-stage
process (body on chassis) by two separate manufacturers, transit buses
are manufactured by a single manufacturer who performs the entire assembly.
For transit buses the floor, sides, ends and roof are joined into a one-
piece construction to form the bus shell. The advantage to this type of
construction is more efficient use of material and space. Intercity
buses, rear and mid-engine diesel school buses also employ this type of
construction.
A typical assembly sequence for an integral transit bus is:
. fabricate and assemble
- understructure
- right and left sides
- front and back end
- roof
. join sections together
. assemble exterior skin
. assemble interior floor base and rubber covering
. install interior wires, controls, etc.
. mount undercarriage items
. paint interior and exterior
. mount wheels
. install windows and doors
. test for water leaks
. complete interior
- seats
- lights
- controls
C-23
-------
- flooring
- trim, etc.
. install engine, transmission and drive train
- heating and cooling system
- gas lines
- air and hydraulic lines, etc.
. inspect bus
. road test
. deliver to shipping lot
Typical subassembly operations are: seats, windows, engine and
transmission, front and rear axles, lights and air conditioners. The
assembly sequency can overlap and many components not listed above are
installed throughout the process.
High flexibility is present in the assembly process. Every bus
order represents the specifications of that purchaser. As with the
school buses, transit buses must meet Federal, State and local govern-
ment standards. These standards can and do vary from state to state
and local government to local government.
ESTIMATED COSTS
The estimated costs to achieve the proposed study levels of noise
abatement are shown in Figure C-6. These costs are for a typical tran-
sit bus either 35' or 40' long. The costs are based on information
supplied by integral bus manufacturers, component vendors and EPA
estimates.
Table C-7 summarizes the estimated costs to reduce bus noise.
C-24
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C-25
-------
Table C-7
Estimated Cost to Achieve
Bus Noise Abatement for Diesel
Powered Integral Urban Transit Buses
Exterior Interior EPA
Level dBA dBA Estimated Cost
1 86 84 $ 50
2 83 83 195
3 81 83 380
4 80 80 875
5 77 80 1,670
6 75 78 3,270
Source: Figure C-3
Rohr Industries has found that the maintenance of a bus plays a
significant part in noise control. While performing tests for the Sound
Attenuation Kit for Diesel Powered Buses (reference 1), a 35' bus powered
by a Detroit Diesel 6V-71 engine was able to meet the first three study
levels with no modification. Actions taken by Rohr were to tighten all
loose bolts, nuts, clamps, etc.; to insure the specified parts were
used; and that these parts were functional.
Rohr was able to meet Level 4 by using:
. double wrapped muffler
. two 3-inch diameter pipes into the muffler
. one 4-inch diameter pipe out of the muffler
. resonator
. 4-inch diameter tail pipe pointing down to the left center rear
of the bus
. acoustical absorption material on inside of hood
. isolated valve rocker covers on engine
This bus was also tested with a vertical, roof-level exhaust.
C-26
-------
In addition to the above, to meet Level 5, the following technology
was used:
. contoured cooling fan shroud
. partition on left-hand side of the engine
These actions differ significantly from the technology study for
those levels as costed by A.M. General and by CMC.
Level 4 was achieved by using parts of the technology from the
Sound Attenuation Kit for Diesel Powered^ Buses and a new radiator grill.
The costs associated with bringing the bus to the indicated Level 4 is
estimated at $350. Using the Rohr Sound Attenuation Kit technology, an
estimated cost of $650 for Level 5 appears to be a reasonable
extrapolation.
Two major impacts on operating costs for transit buses in reducing
bus noise will be reduced fuel mileage and reduced passenger capacity.
Table C-8 shows the estimated impact for fuel usage by level.
Table C-8
Transit Bus Miles Per Gallon
EPA
Level Estimated MPG
Current 3.8 - 4.8
1 3.8 - 4.8
2 3.8 - 4.8
3 3.8 - 4.8
4 3.6 - 4.6
5 3.4 - 4.4
6 2.8 - 3.8
Source: A.M. General
Industry Interviews
C-27
-------
Passenger capacity should not be affected until study Level 6 is
reached. At this level an estimated one row, or two seats, will be lost.
This loss can vary by seating arrangement, bus length, and Federal Speci-
fications. It is possible that buses, depending on the changes in design
at Level 6, could absorb the increased engine compartment size and still
maintain the same seating capacity.
Maintenance costs will be impacted with the changes suggested in the
technology study levels. The cost increases are due to increased labor
and some additional parts. Labor costs are affected by decreased access
to the engine and replacement of additional parts.
The dollar amount of maintenance will vary between transit companies.
Maintenance costs shown in Table C-9 are estimated costs for a typical
bus and transit system.
Table C-9
Maintenance Cost for Diesel Powered
Integral Urban Transit Buses
EPA Estimated Cost
Level Per Year
1 $-0-
2 70
3 140
4 305
5 520
6 830
Source: A.M. General
Industry Interviews
Based on industry interviews and on a continuous integrated program,
the six levels can be achieved in an estimated 30 months, or one level
every 5 months.
C-28
-------
VI - DIESEL POWERED INTEGRAL MID-ENGINE SCHOOL BUSES
MANUFACTURING PROCESS
Diesel Powered Integral Mid-Engine School Buses are constructed with
the same principles as the Urban Transit Bus. The entire bus supports
the bus weight and provides strength.
A typical assembly sequence for this type of bus is:
. Chassis assembly
- drill side rails
- weld cross bars to the side rails
- mount front end and front axle
- mount rear axle and rear suspension
- install engine, transmission, exhaust, controls, cooling
system, electrical system, etc.
. Body assembly
- build roof, both exterior and interior
- build left side
- build right side
- build rear end
. mate body and chassis
. weld outriggers
. assemble exterior skin on all sides
. run engine
. paint
. complete interior
C-29
-------
- skin
- seats
- floors
- windows
- steering
- lights, etc.
. complete mechanical hookup
. final inspect
. road test
. deliver to shipping lot
Typical subassemblies are: seats, windows, engine and transmission,
axles, and lights.
Flexibility is present in the assembly process. Each bus order is
built to the individual state specifications and individual local school
district specifications. In all cases Federal specifications must be
met.
ESTIMATED COSTS
The estimated cost to achieve the proposed study levels of noise
are shown in Figure C-7. These costs should be considered costs for a
typical bus. Costs are based on component vendors and estimates.
Table C-10 summarizes the estimated costs to reduce bus noise.
C-30
-------
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C-31
-------
Table O10
Estimated Cost to Achieve Bus Noise
Abatement for Diesel Powered
Integral Mid-Engine School Buses
Exterior Interior EPA
Level dBA dBA Estimated Cost
1 86 88 -0-
2 83 86 $ 248
3 80 83 3,027
4 77 80 4,417
5 75 78 7,200
Source: Figure C-4
A major cost impact for this type of bus is reduced fuel mileage
for the various levels. Table C-ll, shows the estimated impact for fuel
usage by level.
Table C-ll
Fuel Mileage
EPA
Estimated MPG
7
7
7
6.7
6.3
5.6
- 9
- 9
- 9
- 8.6
- 8.1
- 7.2
Source: Crown Coach
A.M. General
Industry Interviews
For the impact on maintenance refer to Diesel Powered Integral
Urban Transit Bus.
C-32
-------
Based on industry data and a continuous integrated program, lead
time requirements for each level are:
EPA
Level Estimated Lead Time
1 Current
2 18 Months
3 18 Months
4 24 Months
5 36 Months
C-33
-------
VII ~ DIESEL POWERED INTEGRAL REAR ENGINE SCHOOL BUSES
MANUFACTURING PROCESS
Diesel powered integral rear engine school buses have the same type
of construction as urban transit buses. The floor, sides, ends and roof
are joined together into a one piece construction.
As with the urban transit bus, the advantage to this type of con-
struction is more efficient use of material and space.
A typical assembly sequence for this type of bus is:
. assemble side rails and cross members
. assemble to frame assembly
- front and rear axles
- suspension
- side rails
- fire wall
- air piping
- engine and transmission
- radiator and fan
. mount front platform for driver
. install long half sections across frame
. install flooring
. mount side posts
. assemble roof
. assemble side panels
. hook up connections
- from engine
- electrical
- gauges
. undercoat
. remove temporary tires and mount permanent
. paint bus
C-34
-------
. install
- windows
- finished floors
- seats
- final trim, etc.
. final inspection
. road test
. delivery to shipping lot
Typical subassemblies are: seats, windows, engine and transmissions,
roof exterior and interior, axles and lights.
Flexibility is present in the assembly process. Each bus order is
built to the Federal, State and local government specifications. The
specifications can and do vary from state to state and locality to
locality. In addition, each school district can and does have their
own additional specifications.
ESTIMATED COSTS
The estimated costs to achieve the proposed study levels of noise
are shown in Figure C-8. These costs should be considered costs for a
typical bus. Costs were based on component vendors and estimates.
Gillig Bros, Inc., the builder of this bus, chose not to participate in
the study.
Table C-12 summarizes the estimated costs to reduce bus noise.
C-35
-------
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Table CXL2
Estimated Cost to Achieve Bus Noise
Abatement for Diesel Powered Integral Rear
Engine School Buses
Exterior
Level dBA
1 86
2 83
3 81
4 80
5 77
6 75
Source: Figure C-8
Interior EPA
dBA Estimated Cost
84 Currently building to
83 $ 195
83 380
80 875
80 1,670
78 3,270
For the impact on operating costs, maintenance costs and lead times
refer to the Diesel Powered Integral Urban Transit Bus.
C-37
-------
VIII - DIESEL POWERED INTEGRAL INTERCITY BUSES
MANUFACTURING PROCESS
Diesel Powered Integral Intercity Buses utilize the same type of
construction as the Diesel Powered Integral Urban Transit Buses. The
complete structure is load bearing and is a more efficient use of
material and space as compared to a conventional school bus.
A typical assembly sequence for integral intercity buses is:
. fabricate component parts
. assemble floor structure
. assemble front and back ends
. assemble sides
. assemble roof
. joint floor, ends, sides and roof
. install air lines, electrical interior
. install insulation
. paint
. letter
. complete interior of bus
- lavatory
- inside side panels
- inside roof panels
. install front and rear axles
. install air conditioning
. install cooling system
. complete steering
. complete instrumentation
. install engine and transmission
. install seats
. install windows
. complete air and electrical hookups
CX38
-------
. inspect
. road test
. delivery to shipping lot
Typical subassemblies are; seats, windows, engine and transmission,
axles, air conditioning, parts of cooling system, air lines and lights.
Quality control checks are maintained throughout the manufacturing
process. Before a bus is moved to the next work station the production
foreman and inspector must sign a check list.
The CMC intercity coach is assembled on the same production line as
the CMC transit bus, starting with the paint operation,
Flexibility is present in the assembly process. Each bus is indi-
vidually ordered and normally unique to that purchaser. The types of
assembly lines employed lend themselves to variety in production and
changes in mid-production.
ESTIMATED COSTS
The estimated costs to achieve the proposed study levels of noise
are shown in Figure C-9. These costs should be considered costs for a
typical bus. Costs are based on information from component vendors and
estimates.
CMC, MCI, and Eagle International have not provided any cost
information.
Table C-13 summarizes the estimated costs to reduce bus noise.
C-39
-------
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C-40
-------
Table C-13
Estimated Cost to Achieve Bus Noise
Abatement for Diesel Powered Integral
Intercity Buses
Level
1
2
3
4
5
Source: Figure C-9
Exterior
dBA
86
83
80
77
75
Interior
dBA
84
83
80
80
78
EPA
Estimated Cost
$
50
195
875
1,670
3,270
Table C-14 presents estimated impact for fuel mileage.
Table C-14
Fuel Mileage
Level
Current
1
2
3
4
5
Source:
MCI Ltd.
A.M. General
EPA
Estimated MPG
6
6
6
5.7
5.4
4.8
- 7
- 7
- 7
- 6.7
- 6.3
- 5.6
Maintenance, lead times and passenger capacity changes are
estimated to be the same as shown for Diesel Powered Integral Urban
Transit Buses.
C-41
-------
IX - PARCEL DELIVERY, MOTOR HOME CHASSIS BUSES
MANUFACTURING PROCESS
These buses are similar to conventional school buses in that they
are not of integral construction. The Parcel Delivery and some Motor
Home chassis are produced using a two-stage manufacturing process.
The chassis may not be built on the same assembly line as conven-
tional school bus chassis, but the sequence of assembly would be the
same. For a description of this sequence, refer to Gasoline Powered
Conventional School Buses.
The body builder mounts the body shell onto the chassis and com-
pletes the interor of the shell. Body builders do not alter or change
the chassis as received. Typically this size bus is produced on the
same assembly line as the conventional school bus. For a description
of this sequence, refer to Gasoline Powered Conventional School Buses.
The CMC Transmode chassis is offered as a conversion of the CMC
Motor Home. The Transmode chassis can be converted into a bus. This
chassis includes the shell. GMC currently does not have plans to offer
a bus built on this chassis.
The actions required to reduce noise for the Parcel Delivery
chassis are considered identical to Conventional Gasoline Powered School
Buses except for some small details.
ESTIMATED COSTS
The estimated costs to achieve the proposed study levels of noise
for Parcel Delivery chassis and motorhome chassis vehicles are shown in
Figure C-10. These costs are for a typical bus. The costs are based on
information from component vendors and estimates. The chassis builders
and body builders contacted did not respond.
Table C-15 summarizes the estimated costs for this type of bus.
C-42
-------
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Table C-15
Estimated Cost to Achieve Bus Noise
Abatement For Parcel Delivery and
Motor Home Chassis Buses
Exterior Interior EPA
Level dBA dBA Estimated Cost
1 83 83 $ 50
2 80 80 135
3 77 80 360
4 75 75 820
5 73 75 1,055
Source: Figure C-10
The primary differences in costs between this bus and the gasoline
conventional school bus are: this type of bus incorporates a mixture of
technology packages from the school bus and transit bus, and different
component noise level requirements.
Maintenance cost, lead times and operating cost changes are esti-
mated to be the same as shown for the Gasoline Powered Conventional
School Bus.
C-44
-------
X - ENFORCEMENT COSTS
INTRODUCTION
Estimated costs for enforcement are included.in the cost estimates
presented in the preceding sections. Manufacturers contacted would not
provide detailed information concerning enforcement costs, other than to
say they are included in their cost estimates.
To understand the potential cost/impact of enforcement requirements
the bus industry was divided into four segments:
. non-integral school buses
. integral school buses
. transit buses
. intercity buses
An estimated cost per bus was developed for each segment. Since
some companies produce buses in more than one segment, each segment has
been treated separately.
METHODOLOGY
The estimated costs have been based on the following points:
. Test requirements are based on an Enforcement Scenario developed
by EPA, summarized in Figure C-ll.
. Tests are conducted for compliance testing only, and not for
gathering engineering data.
. When chassis and body tests are required, each test is considered
a separate test.
. Construction of a test facility is not required.
. Cost per test for Product Verification or Selective Enforcement
Auditing is $95 (Figure C-12).
. Equipment cost per year is $600 (Figure C-12).
C-45
-------
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FIGURE C-12
ESTIMATED COST PER TEST (EXTERIOR OR INTERIOR)
1976 DOLLARS
I. Manpower:
2 Technicians @ $35/day each $70
1 Engineer @ $50/day each 50
$120
II. Time required to set up, run, record and file
necessary data 4 Hours
III. Average miles driven: 20 @ cost of $1.75/mile
which includes:
- Driver
- Gas and oil
Other expenses related to a test, e.g.,
test site, etc.
IV. Cost per test:
($120 v 2) + $35 = $95
V. Equipment cost $6,000 with a useful life of
10 years or a cost per year of $600.
Source: General Motors Corporation
A. M. General
International Harvester
General Radio
C-47
-------
Based on the above points, a weighted average for each segment of
the bus industry was made to develop an estimated cost per bus for
enforcement purposes.
ESTIMATED COSTS
The estimated costs per bus for enforcement are shown in Figures
C-14, C-16, C-18, and C-20. These costs should be considered as typical
for a bus of that type.
Table C-16 summarizes the estimated costs for non-integral school
buses.
Table C-16
Estimated Enforcement Cost for
Non-Integral School Buses
EPA
Test Estimated Cost
Exterior (Chassis) $ .46
Interior (Body) .73
$1.19
Source: Figures 14 and 16
Table C-17 summarizes the estimated costs for integral school buses.
Table C-17
Estimated Enforcement Cost for Integral
School Levels for All Study Levels
Test Estimated Cost/Test
Exterior and
Interior $8.70
Source: Figure C-16
C-48
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Table C-18 summarizes the estimated cost for transit buses.
Table C-18
Estimated Enforcement Cost for Transit
Buses for All Study Levels
Test Estimated Cost/Test
Exterior and
Interior $3.00
Source: Figure C-18
Table C-19 summarizes the estimated cost for Intercity buses.
Table C-19
Estimated Enforcement Cost for Intercity
Buses for All Study Levels
Test Estimated Cost/Test
Interior and
Exterior $11.00
Source: Figure C-20
Figures C-13, C-15, C-17, and C-19 provide backup information for
the Summary Tables.
C-57
-------
Appendix C
References
1. "Sound Attenuation Kit for Diesel Powered Buses," submitted by
Rohr Industries, Inc., to the U.S. Department of Transportation,
Report RII-SAK-402-0101, February 1975.
2. "A Study to Determine the Economic Impact of Noise Emission
Standards in the Bus Manufacturing Industry," Draft Final Report
submitted by A. T. Kearney, Inc., under EPA Contract No. 68-01-3512,
prepared for the Office of Noise Abatement and Control, September
1976.
C-58
-------
APPENDIX D
ESTIMATES OF DEMAND ELASTICITIES FOR URBAN
BUS TRANSIT AND INTERCITY BUS TRANSPORTATION
This Appendix reviews some of the pertinent econometric literature
and reports estimates made of the fare-elasticity of demand for both
intracity and intercity bus transit. The estimating model is based on
one developed by Nelson. The cross-sectional test of intra-urban
transit demand in a sample of U.S. metropolitan areas used in Nelson's
model is repeated for the year 1974. Results are compared with Nelson's
estimates for the years 1960 and 1968, and some tentative explanations
for the observed lower fare elasticity in 1974 are offered.
For intercity bus travel demand, the same model is applied to time
series of annual aggregate U.S. data. The fits are generally quite
satisfactory, subject to the caveat that the time series sample may
overstate the significance of the results when substantial autocorrela-
tion is present.
Both time series and cross-section estimates reveal fare-elasticities
of demand that are of the same order of magnitude, ranging from -0.20 to
-0.80. This range is somewhat above the industry rule-of-thumb of -0.30,
but is by no means contradictory, given the nature of the approximations and
data involved. The data also exhibit positive cross-elasticities with
respect to competing modes (auto and rail), though the precision of the
estimates is not adequate for predictive purposes.
D-l
-------
Part 1 of Appendix D reviews the econometric model and describes
the notation. Parts 2 and 3 record the results of the statistical tests
for urban transit demand and intercity bus travel demand, respectively.
These results are applied in Parts 7-A and 7-B of the Economic Impact
Analysis (Section 7).
D - I ECONOMETRIC MODEL OF TRANSIT DEMAND
Consider a given geographical area, such as an urban center or the
United States intercity highway network. Bus service B, defined as
vehicle miles of service provided per year, may be thought of as a factor
input in the production of transportation services to the population of
the given region. Since passengers are to some extent flexible as to
trip schedules and destination points, but not perfectly so, bus service
B encounters diminishing returns in the production of transportation
services as saturation of the potential market increases.
Demand D for bus service, defined as revenue passenger miles of
service obtained per year, depends both upon the quantity B of service
provided and upon other demand characteristics of the market served:
the age and income of the population, the availability of auto, rail,
and other competing modes of transportation, the fare per mile F charged
to revenue passengers (and fares on competing modes), and other exogenous
factors which may differentiate one urbanized area from another or which
reflect changes in the demand for bus transit over time.
D-2
-------
EQUILIBRIUM IN THE TRANSIT MARKET
Transit firms experience total revenue equal to FD and total costs
equal to CB, where C is the average cost per mile of vehicle operation.
Nelson's paper provides evidence that there are no scale economies in the
operations of bus transit firms, hence that a linear approximation of the
cost function does not misrepresent the empirical evidence.
Since transit firms operate in a regulated environment, equilibrium
is not necessarily determined by the "competitive" condition that total
revenues less total costs (FD-CB) yield profits just sufficient to give
the firm a competitive return on its total invested capital. Rather,
the regulatory authority imposes on the transit firm a constraint, such
as a rate of return criterion or a set ratio of revenues to costs, and
the firm responds accordingly. Nelson summarizes the action of the
regulatory authority in terms of a target cost-revenue ratio k:
k = CB /FD.
If k is treated as an exogenous, predetermined component of the
model, then equilibrium is determined by the condition CB = kFD.
The full model may be written:
Supply: B = B (POP, AREA, D,C,k) + u
Demand: D = D (B, POP, F,F', Area, Auto, Hway, GNI) + v
Equilibrium: CB = kFD
Here POP is the population of the given geographical region, AREA
its area, HWAY its highway capacity per capita, F1 the fare per passenger
mile on competing modes of transportation, and GNI the level of real per
D-3
-------
capita income. B (bus service supplied), D (ridership demanded), and F
(fare per passenger mile) are endogenous, jointly determined variables,
while the remaining quantities, including C (cost per vehicle mile) and
k (cost/revenue criterion), are exogenous (predetermined). The symbols
u and v represent random, independent error terms.
DETERMINANTS OF THE COST/REVENUE RATIO K
Urban bus transit systems have undergone a significant revolution
in ownership and profitability during the post World War II period, and
a general perspective is useful to understanding the nature of the
regulatory constraint, k. Tables D-l and D-2 record some pertinent
statistics. As indicated in Table D-l, there has been a persistent
decline in the operational profitability of bus transit operations, both
at a local level and in terms of national aggregates. The assumption
that k is exogenous to the transit system is at best a crude approximation,
since other regulatory constraints on service B and the fare F certainly
come into play.
Nelson finds that for the 1960 and 1968 cross-section samples of
urban bus transit systems, the variable k is better "explained" in terms
of regulatory variables such as private-versus-public ownership and the
locality of regulatory control than by the various operating character-
istics such as costs of operation, highway capacity, etc. His finding
justifies treatment of k as exogenous, but it also suggests that conclusions
D-4
-------
TABLE D-l
TREND OF TRANSIT OPERATIONS, 1940-1975
Calendar
Year
1940
1945
1950
1955
1960
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
197 5p
Operating
Revenue
(millions)
$ 737.0
1,380.4
1,452.1
1,426.4
1,407.2
1,443.8
1,478.5
1,556.0
1,562.7
1,625.6
1,707.4
1,740.7
1,728.5
1,797.6
1,939.7
2,002.4
Operating
Expense
(millions)
$ 660.7
1,231.7
1,385.7
1,370.7
1,376.5
1,454.4
1,515.6
1,622.6
1,723.8
1,846.1
1,995.6
2,152.1
2,241.6
2,536.1
3,239.4
3,705.9
Cost-Revenue
Ratio
0.896
0.892
0.954
0.961
0.978
1.007
1.025
1.043
1.103
1.136
1.169
1.236
1.297
1.411
1.670
1.851
Source: American*Public Transit Association, Transit Fact Book '75-'76
Table 4. p:preliminary.
D-5
-------
of the empirical tests may be affected by the rapid increase in public
ownership of transit systems that has occurred during the past two decades
(Tables D-2 and D-3).
ESTIMATION OF THE ECONOMETRIC MODEL
The above model is an example of an (over-) identified simultaneous
equations model with endogenous variables B, D, and F, and exogenous
variables POP, HWAY, C, k, AUTO,F', and GNI. The standard technique for
estimating such models is two-stage least squares (2SLS), an adaptation
of ordinary least squares (OLS) wherein correlations between jointly
determined endogenous variables and the error terms u and v are eliminated
prior to estimation of the structural relationships.
It should be noted, however, that the 2SLS technique is not neces-
sarily preferable to OLS, particularly where specification error is
2
involved. For this reason both methods of estimation are reported below.
REVIEW OF RECENT STUDIES OF URBAN TRANSIT DEMAND
Two significant studies have examined urban bus transit demand within
a given locale instead of for aggregate cross-section or time-series data.
Kraft and Domencich use an origin-and-destination survey from the Boston
area to estimate travel demand elasticities with respect to both service
(time) and fare. What small effects they determine fall mainly on the
D-6
-------
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D-7
-------
TABLE D-3
DATE OF INITIAL PUBLIC OWNERSHIP:
MAJOR U.S. MASS TRANSIT SYSTEMS
Urbanized Population of Date of
Area Urbanized Area Public Ownership
Seattle-Everett, WA 1,238.107 1911
San Francisco, CA 2,987,850 1912
New York, NY 16,206,841 1922
Cleveland, OH 1,959,880 1935
Boston, MA 2,652,575 1947
Chicago, IL 6,714,578 1947
Kalamazoo, MI 152,083 1957
Los Angeles, CA 8,351,266 1958
San Antonio, TX 772,513 1959
Dallas, TX 1,338,684 1960
Memphis, TN 663,976 1961
Grand Rapids, MI 352,703 1964
Wichita, KS 302,334 1966
San Diego, CA 1,198,323 1967
Source: American Public Transit Association
Dr8
-------
service variable, and their estimates of the fare elasticity are low,
between -0.09 and -0.33. Notably, cross elasticities with respect to
automobile operating costs are neglible.
4
A more recent study by Schmenner analyzes patronage data on a
route-by-route basis for the cities of Hartford, New Haven, and Stamford,
Connecticut. Time series regressions for data provided by a local
bus company indicate an elasticity of demand with respect to fare per
mile of between -0.80 and -1.03. Schmenner attributes his higher
estimates of fare elasticity to reduced error due to aggregation in his
sample. His data also exhibit a positive cross-elasticity with respect
to automobile operating costs.
The Nelson study (1972) is subject to Schmenner"s criticism that
the estimates are probably biased towards zero due to aggregation, since
the unit of observation is the transit system for an entire urbanized
area. Information on a cross-section of transit systems (e.g., Table
D-4) is published annually by the American Public Transit Association
in its Transit Operating Report. The sample each year consists of member
firms whose transit operations are devoted solely to bus transportation,
without competition from rail or trolley. While the total sample size
(number of firms) has stayed relatively constant over the years, it is
subject to relatively high turnover from one year to the next, so that
cross-sectional comparisons for different years are not strictly
equivalent. The 1974 sample for the present study contains 19 (of 52)
firms that were not present in either the 1960 or 1968 (Nelson) samples.
D-9
-------
TABLE D-4
1974 Sample of Bus Firms and Urbanized Areas
Location
Akron, OH
Albany, NY
Albuquerque, MM
Amarillo, TX
Atlanta, GA
Baltimore, MD
Binghamton, NY
Charleston, SC
Charleston, WV
Charlotte, NC
Chattanooga, TN
Cincinnati, OH
Columbia, SC
Columbus, OH
Corpus Christi, TX
Dallas, TX
Duluth, MN
El Paso, TX
Fort Worth, TX
Greenville, SC
Harrisburg, PA
Hunt ing ton, WV
Houston, TX
Jacksonville, FL
Kansas City, MO
Lewiston, ME
Lincoln, NE
Madison, WI
Memphis, TN
Miami, FL
Milwaukee, WI
Minneapolis-St. Paul,
MN
Monterey, CA
Muskegon, MI
Nashville, TN
Norfolk, VA
Omaha, NE
Portland, OR
Company Name
Metro Regional Transit Authority
Capital District Transportation Authority
Albuquerque Transit System
Amarillo Transit System
Metropolitan Atlanta Rapid Transit Authority
Maryland Department of Transportation Mass Transit
District
Broome County Transit
South Carolina Electric and Gas Company
Karawha Valley Regional Transportation Authority
Charlotte City Coach Lines, Inc.
Chattanooga Area Regional Transportation
Authority
Southwest Ohio Regional Transit Authority
South Carolina Electric and Gas Company
Central Ohio Transit Authority
Corpus Christi Transit System
Dallas Transit System
Duluth Transit Authority
Country Club Bus Lines, Inc.
McDonald Transit, Inc. dba CITRAN
Greenville City Coach Lines, Inc.
Cumberland-Dauphin-Harrisburg Transit Authority
Tri-State Transit Authority
Houston Transit System/Rapid Transit Lines, Inc.
Jacksonville Transportation Authority
Kansas City Area Transportation Authority
Hudson Bus Lines
Lincoln Transportation System
City of Madison Department of Transportation
Memphis Area Transit Authority
Metropolitan Dade County Transit Agency
Milwaukee & Suburban Transport Corporation
Twin Cities Area Metropolitan Transit Commission
Monterey Peninsula Transit
Muskegon Area Transit System
Metropolitan Transit Authority
Tidewater Metro Transit
Transit Authority of the City of Omaha
Tri-County Metropolitan Transportation District
of Oregon
D-10
-------
TABLE D-4 (Continued)
Location Company Name
Raleigh, NC Raleigh City Coach Lines, Inc.
Rochester, NY Regional Transit Service, Inc.
St. Louis, MO Bi-State Transit System
San Diego, CA San Diego Transit Corporation
Savannah, GA Savannah Transit Authority
Springfield, MO City Utilities of Springfield
Stockton, CA Stockton Metropolitan Transit District
Syracuse, NY CNY Centre, Inc.
Toledo, OH Toledo Area Regional Transit Authority
Tulsa, OK Metropolitan Tulsa Transit Authority
Waco, TX Waco Transit System
Wichita, KS Wichita Metropolitan Transit Authority
Wilmington, DE Delaware Authority for Regional Transportation
Winston-Salem, NC Winston-Salem Transit Authority
-------
D-II CROSS SECTION ESTIMATES OF URBAN
BUS TRANSIT MODEL
Nelson's results for 1960 and 1968 are presented in Tables D-6 and
D-7, along with parallel regression results for 1974. Data sources
for the 1974 regressions are reviewed in Tables D-8 and D-9 for the
Urban Transit Bus model.
SUPPLY EQUATION ESTIMATES
The supply equations for 1974 conform well to Nelson's previous
estimates, with the significant exception of variables C and k, both
related to the cost of operations. As indicated in Table D-2, the last
decade has witnessed a significant increase in the number of publicly
owned and subsidized urban mass transit systems, particularly in
connection with the Urban Mass Transportation Act of 1964, which
subsidized both purchases of new equipment and conversion of private
transit firms to private ownership.
Whereas the cost/revenue ratio k is negatively associated with
supply of service in 1960, the reverse appears to be true in 1974:
firms with greater service B, holding constant population, demand,
etc., experience higher ratios of cost to revenue. This change
highlights the importance of the shift from private to public ownership.
D-12
-------
TABLE D-6
Estimates of the Supply Equation
For Urban Bus Transit Service
Statistic
Dependent Variable
Independent Variable
Constant
(t-statistic)
In POP
In AREA
In D
In C
In R
R2
Standard Error
Number of Observations
Note: From Gary R. Nelson
Operations." Table
Characteristics of
1960a
(2SLS)
In B
-1.05
(-1.75)
.055
(0.42)
.008
(0.13)
.927
(7.08)
-.446
(-2.70)
-.511
(-2.09)
.971
.133
44
1968a
(2SLS)
In B
1.42
(1.41)
.248
(1.75)
.055
(0.76)
.727
(7.08)
-.601
(-3.66)
-.065
(-0.34)
.982
.170
51
1974
(OLS)
In B
.448
(1.68)
.193
(1.54)
.142
(1.36)
.648
(14.13)
-.043
(-0.26)
.230
(2.06)
.972
.217
52
1974
(2SLS)
In B
.359
(1.00)
.406
(1.73)
.151
(1.14)
-.007
(-0.03)
.490
(3.64)
.575
(2.03)
.958
.268
52
, "An Econometric Model of Urban Transit
4.5 of John D. Wells, et al, Economic
the Urban Transportation
Industry
(Washington ,
D.C.: U.S. Government Printing Office, 1972).
D-13
-------
TABLE D-7
Estimates of the Demand Equation
For Urban Bus Transit Service
Statistic
Dependent Variable
Independent Variables
Constant
(t-statistic)
-(B/POP)"0'3
F
In POP
In AREA
In AUTOS
In HWAY
POURTYb
INC 15°
AGE 18d
AGE 65S
1960a
(2SLS)
In D
NR
6.54
(5.84)
-4.52
(-3.70)
1.11
(17.34)
.002
(0.03)
-.106
(-0.96)
—
-1.61
(-1.49)
-0.40
(-0.33)
-1.74
(-1.53)
-0.87
(-0.54)
1968a
(2SLS)
In D
NR
8.81
(4.41)
-3.06
(-1.91)
1.10
(8.46)
.0208
(0.19)
-.175
(-0.44)
.156
(0.98)
-3.02
(-2.93)
-3.57
(-1.81)
-5.95
(-2.44)
-8.17
(-2.39)
1974
(OLS)
In D
7.412
(6.94)
6.81
(14.19)
-.669
(-1.25)
1.037
(6.51)
.0809
(0.52)
-.175
(-.51)
.784
(4.12)
1.215
(0.65)
.0798
(0.05)
-4.149
(-2.02)
-3.607
(-1.33)
1974
(2SLS)
In D
9.485
(3.31)
9.458
(2.91)
-0.183
(-0.20)
0.974
(4.36)
-.0069
(-0.03)
.0691
(0.13)
1.022
(2.68)
-.743
(-0.22)
-2.393
(-0.63)
-1.029
(-0.22)
-5.623
(-1.30)
D-14
-------
TABLE D-7 (Continued)
Statistic
R2
Standard Error
Number of Observations
Fare Elasticity Evaluated
At Mean Fare
I9603
(2SLS)
.986
.113
44
-0.81
(-3.70)
1968a
(2SLS)
.976
.227
51
-0.67
(-1.91)
1974
(OLS)
.974
.270
52
-0.20
(-1.25)
1974
(2SLS)
.954
.356
52
-0.05
(-0.20)
Notes: E"rom Gary R. Nelson, "An Econometric Model of Urban Transit
Operations." Table 4.6 of John D. Wells et al, Economic
Characteristics of the Urban Transportation Industry (Washington,
D.C.: U.S. Government Printing Office, 1972).
Percent of households below poverty level ($3,000 for 1960 and
1968).
Percent of households with income above $15,000 ($10,000 in
1960 & 1968).
Percent of population under 18 years of age.
Percent of population over 65 years of age.
D-15
-------
TABLE D-8
Calendar
Year
1940
1945
1950
1955
1960
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975p
Source: America
Table 13. p: preliminary
TREND OF AVERAGE FARE, MOTOR
BUS URBAN TRANSIT, 1940 - 75
Average
Fare
6.87$
7.07
9.56
14.41
17.96
20.55
21.23
22.39
23.20
25.71
29.41
32.23
33.07
32.40
31.70
32.10
5ublic Transit
Consumer Price
Index (1967=100)
42.0
53.9
72.1
80.2
88.7
94.5
97.2
100.0
104.2
109.8
116.3
121.3
125.3
133.1
147.7
161.2
Association, Transit Fact
Average
Real Fare
16.36C
13.12
13.26
17.97
20.25
21.75
21.84
22.39
22.26
23.42
25.29
26.57
26.39
24.34
21.50
19.91
Book '75-'76,
D-16
-------
TABLE D-9
Cross-Section Urban Transit Regressions:
Definition of Variables and Their Sources
Variable
Definition and Source
AGE 18 Fraction of Population Under Age 18 years in 1970. U.S.
Census of Population (1970), Vol. I, Part 1, Table 66
(Urbanized Areas).
AGE 65 Fraction of Population over Age 65 years in 1970. U.S.
Census of Population (1970), Vol. I, Part 1, Table 66
(Urbanized Areas).
AREA Land Area of Urbanized Area. U.S. Census of Population
(1970), Vol. I, Part A, Section 1, Table 20.
AUTOS Automobiles per Capita, by County, 1973. Rand McNally & Co.,
Commercial Atlas and Marketing Guide, 107th edition. (New
York, 1976).
B Line Service Bus Miles. American Public Transit Association,
Transit Operating Report (1974): Section D, Operating
Statistics, Item 3.
CPM Operating Expense per Total Bus Mile. American Public
Transit Association, Transit Operating Report (1974):
Section D, Derived Statistics, Item 2.
D Total Re'venue Passengers. American Public Transit Associa-
tion. Transit Operating Report (1974): Section D, Operating
Statistics, Item 27.
F Revenue per Revenue Passenger. American Public Transit
Association, Transit Operating Report (1974): Section D,
Operating Statistics, Item 27 and Operating Revenues and
Operating Expenses, Item 1.
HWAY 68 Population Per Unit of Highway Capacity, 1968. Highway
capacity estimated by the formula:
8720x + 2500y,
where x is miles of freeways and expressways and y is all
other road miles. Federal Highway Administration, National
Highway Needs Report, 1970 (91st Congress). Washington,
D.C., U.S. Government Printing Office: 49-840-0.
D-17
-------
TABLE D-9 (Continued)
Variable Definition and Source
INC15 Fraction of Households with Income in Excess of $15,000 per
year in 1970. U.S. Census of Population (1970), Vol. I,
Part 1, Table 183.
k Ratio of Expenses to Revenues. American Public Transit
Association, Transit Operating Report (1974): Section D,
Income Statement, Items 1 and 2.
MPH Bus Miles per Bus Hour (Line Service). American Public
Transit Association, Transit Operating Report (1974):
Section D, Derived Statistics, Item 4.
POP Population of Urbanized Area. American Public Transit
Association, Transit Operating Report (1974): Section D,
Operating Statistics, Item 1.
POVRTY Fraction of Households Below Poverty Level in 1970. U.S.
Census of Population (1970), Vol. I, Part 1, Table 183.
D-18
-------
DEMAND EQUATION ESTIMATES
The same phenomenon may explain the relatively poor performance of
the two-stage least squares fits for the demand equation in 1974.
Apparently, Nelson's sophisticated model is misspecified as applied to
the 1974 urban setting, and ordinary least squares estimation is probably
preferable (that is, treating service B and average fare F as exogenous,
predetermined variables).
The following results may be concluded from Table D-7:
1) Improved service levels B relative to population POP hold-
ing constant the fare per mile F and highway capacity per
capita HWAY, attract greater ridership. This result has
been found in virtually all empirical studies of urban
transit.
2) Demand D is inelastic with respect to the fare F, and the
fare elasticity has declined in absolute value since 1968.
In part, this decline may be attributed to a fall in the
real fare (Table D-8) relative to rising real wages (which
measure the opportunity cost of travel time). In the
economic impact analysis covering transit buses (Section 7,
Part B) an average (-0.5) of the three 2SLS point estimates
(1960, 1968, 1974) in Table D-7 was used for the demand (fare)
elasticity estimate.
3) Bus patronage is unresponsive to measures of income dispersion
(PVRTY and INC15), but is significantly increased in cities
D-19
-------
where the population in the 19 to 64 age group is greater.
This result is consistent with Nelson's finding that bus
transit demand is determined primarily by trips to and from
people's places of employment.
4) The coefficients on per-capita automobile ownership are not
significantly different from zero, but they are mostly
negative, indicating a very slight positive cross elasticity
with respect to the automobile mode of travel.
D-III TIME SERIES ESTIMATES OF INTERCITY
BUS TRANSPORTATION DEMAND
Table D-10 records regression coefficients for the demand model as
applied to time series of intercity bus transportation statistics. Data
sources are reviewed in Table D-ll for the Intercity Bus Model.
The fits are generally satisfactory. Due to the presence of signi-
ficant autocorrelation in the residuals of the log-log form of the regres-
sions (Durbin-Watson statistic = 1.31), a first-difference formulation was
tried with somewhat better results (Durbin-Watson statistic = 1.77).
The following results are concluded from Table D-10:
1) Intercity bus patronage D is responsive to service B, as
with urban transit.
2) The fare elasticity of intercity bus travel demand is
about -0.50, holding constant the availability and fare
D-20
-------
TABLE D-10
ESTIMATES OF THE DEMAND EQUATION
FOR INTERCITY BUS TRANSPORTATION,
1948 - 73
Statistic
Dependent Variable
Independent Variables
Constant
(t-statistic)
In B
In POP
In F
F/FRAIL
In AUTO
In GNI
In HWAY
R2
Standard Error
Durbin-Watson
Number of Observations
OLS
In D
-16.14
(-3.25)
.953
(10.95)
.493
(2.08)
-.448
(-3.10)
-.026
(-1.14)
-.693
(-3.25)
.207
(1.30)
-.142
.985
.015
1.31
26
2SLS
In D
OLS
A In D
-16.03
(-2.99)
.959
(6.90)
.501
(1.78)
-.446
(-3.00)
-.026
(-1.13)
-.685
(-2.61)
.201
(1.03)
-.135
.985
.015
1.31
26
.044
(1.72)
1.003
(8.12)
-.143
(-.13)
-17.47
(-3.30)
-.030
(-1.46)
-2.283
(-2.37)
.332
(2.34)
—
.919
.017
1.77
25
Note: The 2SLS estimates treat In B as a jointly determined dependent
variable, identified by the excluded variables In C and In K.
aFirst-difference form of the demand equation: the constant reflects
a trend coefficient; In F is replaced by the first difference in F;
F/FRAIL is replaced by the first difference in F/FRAIL; all other
variables are replaced by the first differences in natural logarithms.
The coefficient AF implies a fare elasticity of -0.497, evaluated at
the mean fare.
D-21
-------
TABLE D-ll
INTERCITY BUS TRANSIT TIME SERIES REGRESSIONS:
DEFINITION OF VARIABLES AND THEIR SOURCES
VARIABLE
AUTO
B
DEFINITION AND SOURCE
Passenger Car and Taxi Registrations, U.S., per
capita. Department of Transportation,
Summary of Transportation Statistics, Table 9.
Vehicle Miles Operated. Regular-Route Inter-
city Service, Class I Carriers. National
Association of Motor Bus Owners, Fact Book,
Table 4.
Cost per mile of bus service. Regular Route
Intercity Service, Class I Carriers. Estimated as:
C = CPMB = (E-(TR-R))/B, where TR is total
operating revenues, R is passenger revenues on
intercity regular routes, E is total operating
expenses, and B is vehicle miles operated.
National Association of Motor Bus Owners, Fact
Book, Tables 3 and 4. Deflated by the Consumer
Price Index (1967=1.00).
CPI
D
FRAIL=FPMR
GNI
Consumer Price Index, 1967=1.00. U.S. Department
of Commerce, Bureau of Economic Analysis.
Revenue Passenger Miles, Regular-Route Intercity
Service, Class I Carriers. National Association
of Motor Bus Owners, Fact Book, Table 4.
Revenue per Passenger Mile, Regular-Route Intercity
Service, Class I Carriers. F=R/D, where R is
passenger revenue on intercity routes and D is
revenue passenger miles. National Association of
Motor Bus Owners, Fact Book, Tables 3 and 4.
Deflated by the Consumer Price Index (1967=1.00).
Rail Fare Per Passenger Mile. Class I rail, other
than commutation. Department of Transportation,
Summary of Transportation Statistics, Table 1.
Real per Capita U.S. National Income. U.S. Depart-
ment of Commerce, Bureau of Economic Analysis.
-------
TABLE D-ll (Continued)
VARIABLE DEFINITION AND SOURCE
HWAY U.S. Intercity Highway Mileage per Capita. Depart-
ment of Transportation, Summary of Transportation
Statistics, Table 8.
k Cost/Revenue, Intercity Buses. Regular Route
Intercity Service, Class I Carriers:
k = CPMB/RPMB.
POP U.S. Total Population. U.S. Department of Commerce,
Bureau of the Census.
RPMB Revenue per Mile, Buses. Regular-route intercity
service: revenue from Table 3 of National Associa-
tion of Motor Bus Owners, Fact Book, Miles Operated
= B.
D-23
-------
on competing modes (auto and rail). A one percent
increase in bus fares relative to rail fares results in
an additional 0.03 percent decrease in bus patronage.
Automobile ownership per capita is significantly related,
in a negative direction, to bus patronage.
3) The income elasticity of intercity bus demand is small
but positive (around 0.20), indicating that distributional
impacts of fare increases do not necessarily affect only
lower income groups.
D-24
-------
REFERENCES
Appendix D
1. Gary R. Nelson, "An Econometric Model of Urban Bus Transit Operations".
Chapter IV of John D. Wells et al, Economic Characteristics of the
Urban Public Transportation Industry (Washington, D.C.: U.S. Govern-
ment Printing Office, 1972).
2. J. Johnston, Econometric Methods, Chapter 10 (New York, 1963).
3. G. Kraft and T. Domencich, Free Transit, Boston, Mass.: D. C. Heath
and Company, 1971.
4. R. Schmenner, "The Demand for Urban Bus Transit", Journal of Transport
Economics and Policy (January, 1976) 9:68-66.
5. "A Study to Determine the Economic Impact of Noise Emission Standards
in the Bus Manufacturing Industry", Draft Final Report submitted by
A. T. Kearney, Inc. under Contract No. 68-01-3512, prepared for the
Office of Noise Abatement and Control, September, 1976.
D-25
-------
APPENDIX E
UNIFORM ANNUALIZED COSTS OF BUS NOISE ABATEMENT
Equivalent annual cost or annualized cost as applied to the bus noise
regulation was calculated as the sum of the incremental operating and
maintenance 'costs due to the usage of additional noise abatement equip-
ment, the annual amortization of noise abating equipment, and the annual
cost of capital for this equipment as calculated using the prevailing
discount rate.
Uniform annualized cost is precisely defined by the following formula:
where A = uniform annualized cost
Ci = actual cost incurred in the i year
r = annual discount rate
n = number of years which have elapsed from the
start to the end of the entire transaction
The uniform annualized costs presented in this Appendix utilized a discount
rate of 0.10 and the year 2000 as the end year of calculation. The other
inputs, (projected changes in the number of buses produced and changes in
operating, maintenance and equipment costs) may be found either in Section 3,
Section 7, or in Appendix C for the various types of buses considered.
Uniform annualized costs for 15 exterior and 15 interior bus noise
abatement regulatory schedules are presented in this Appendix. Tables E-l
E-l
-------
and E-2 present the 30 exterior and interior regulatory schedules (respect-
ively) considered in these calculations. It should be noted that Tables E-l
and E-2 are identical to Tables 6-1 and 6-2 respectively, which were used
as keys to the presentation of Health and Welfare data in Section 6.
Table E-3 shows the annualized cost figures across all buses for the
15 exterior noise regulatory schedules. Table E-3 also presents the contri-
butions of operating, maintenance, and equipment costs to the total cost
figures. Tables E-4 to E-6 show the annualized cost figures regarding the
15 exterior schedules for the three main bus types: intercity buses,
transit buses and school buses, respectively.
Table E-7 presents annualized cost figures for the 15 interior noise
regulatory schedules across all buses. Table E-7 also indicates the break-
down of the interior schedule costs by bus type. Note that only increased
equipment costs were considered for the interior regulatory schedules.
No increases in operating or maintenance costs were projected as a result
of the implementation of any interior regulatory schedule.
Regulation 15 for both the exterior and interior regulation schedules
(Tables E-l and E-2, respectively) do not have increased costs associated
with them. These schedules were used for assessing the maximum health
and welfare benefits associated with bus noise abatement. Since these
two schedules were never under real consideration as regulatory schedules,
except in a theoretical vein, no attempt was made to attribute costs to
them.
E-2
-------
Table E-l
Regulatory Schedules Considered
in the Health and Welfare Analysis of
Exterior Bus Noise
Exterior
Regulatory
Schedule
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Not to Exceed Regulatory Level for All
Bus Types Unless Noted, (dBA)
Calendar Year
1979
—
83
—
—
—
83
83
83
83
83
83
83
83
83
55
1981
—
—
83
80
—
80
—
80
—
80
—
80
__
80
55
1983
—
—
—
—
80
—
80
—
80
—
80
--
80
—
55
1984
—
—
—
—
—
—
78
—
—
-_
78
55
1985
—
—
—
—
—
—
—
—
78
77
77
—
--
—
55
1986
—
—
—
—
—
—
—
—
—
—
—
75
75
75CD
55
(1)
Gasoline Powered School Buses 73 dBA
E-3
-------
Table E-2
Regulatory Schedules Considered
In the Health and Welfare Impact Analysis of
Interior Bus Noise
Interior
Regulatory
Schedule
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Not To Exceed Regulatory Level For All
Bus Types Unless Noted, (dBA)
Calendar Year
1979
—
86
84
—
86
86
86
84
86
86
86
86
84
86
55
1981
—
—
—
83
83
83
83
—
—
—
83
83
83
55
1983
—
—
—
—
—
80
—
80
84
83
80
—
80
55
1984
—
—
—
—
—
—
80
—
—
—
—
80
80(1)
55
1985
—
—
—
—
—
—
—
80
80
—
—
— —
55
1986
—
—
—
—
—
—
—
—
—
—
78
78
78
78C1)
55
(1)
Gasoline Powered School Buses 75 dBA
E-4
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-------
APPENDIX F
ADDITIONAL SUPPORTING INFOFMATION
FOR
HEALTH AND WELFARE ANALYSES
(SECTION 6)
-------
Table F-l
Exterior Bus Noise Levels, by Operational Mode and Bus Type
(Data from Reference 1 Unless Noted)
Bus Type
Transit
Range
Mean
School-Gas
Range
Mean
School-Diesel
Front Range
Engine Mean
Middle Range
Engine Mean
Rear Range
Engine Mean
Inter-City
Range
Mean
50 Ft. Maximum Passby Levels, dBA*
Acceleration
76-83
80
74-S42
80
83-92
87
81-84
83
81-84
83
81-86
84
Deceleration
and Cruise
30 mph
70-72
72
(72)
783
78
(75)
(75)
73-774'5
75
55 mph
78
78
(78)
(85)
(81)
(81)
79-804'5
80
Idle
6612
66
(66)
663
66
(66)
(66)
66?
*Data in parentheses extrapolated from transit bus data.
F-l
-------
Table F-2
Interior Bus Noise Levels Near Driver, by Operational Mode and Bus Type
(Data from Reference 1 Unless Noted)
Bus Type
Transit
Range
Mean
School-Gas
Range
Mean
School-Diesel
Front Range
Engine Mean
Middle Range
Engine Mean
Rear Range
Engine Mean
Inter-City
Range
Mean
Interior Noise Level Near
Driver, dBA*
Acceleration
78-79
79
2
80-90
85
88-95
92
87
87
87
87
70-78
74
Deceleration and Cruise
30 mph
74
74
—
(80)
803
80
—
(75)
—
(75)
4,5 6
69 ' -75
72
55 mph
78
78
—
(84)
—
(84)
—
(79)
—
(79)
4,5
73-75 '
74
Idle
f,
60b
60
—
(66)
703
70
—
(65)
—
65
7
60
60
*Data in parentheses extrapolated from transit bus data.
F-2
-------
Table F-3
Interior Bus Noise Levels in Rear Seat, by Operational Mode and
Bus Type (Data from Reference 1 Unless Noted)
Bus Type
Transit
Range
Mean
School Gas
Range
Mean
School Diesel
Front . Range
Engine Mean
Middle Range
Engine Mean
Rear Range
Engine Mean
Inter-city
Range
Mean
Interior Noise Level in Rear dBA*
Acceleration
80-90
84
77-S42
81
(87)
(87)
(92)
70-844'5
79
Deceleration and Cruise
30 mph 55 mph
81-848
83
(80)
753
75
(75)
(80)
69-7844;5'8
S3-858
84
(81)
(76)
(76)
81-8313
82
73-7S4'5
Idle
696
69
69-7S2
74
653
65
(65)
(70)
64-728
68
*Data in parenthesis extrapolated from transit bus data.
F-3
-------
Table F-4
Derivation of Percent of Traffic Composed of
Bus and Non-Bus Vehicles, by Land Use
Billions of 1973 Vehicle Miles
Vehicle
Non-Bus
Transit
School - Gas
School - Diesel
Intercity
Total
Percent
Non-Bus
Transit
School - Gas
School - Diesel
Intercity
Total
Urban
Street
HD
223
1.20
.04
—
.01
224
99.4
.5
.1
—
—
100
LD
147
.41
.12
—
.01
147
99.6
.3
.1
—
—
100
Sub.
60.7
.13
.31
.01
—
61.1
99.3
.2
.5
—
—
100
Highway
HD
77.8
.06
—
—
.02
77.9
99.9
.1
—
—
—
100
LD
51.2
.02
—
—
.02
51.2
99.9
.04
—
—
.04
100
Rural
Sub.
21.2
.01
—
—
—
21.2
100
—
—
—
—
100
Main
Road
461
—
.86
.03
1.11
463
99.6
—
.2
—
.2
100
Local
Road
137
—
.93
.03
—
138
99.3
—
.7
—
—
100
F-4
-------
Table F-5
Percent of Trucks of Model Year Remaining in Calendar Year
10
Prior to 1978
1978-1979*
1980-2000**
Calendar Year
1979
86
14
0
1981
57
29
14
1983
35
21
44
1985
22
14
64
1987
14
7
79
1990
7
3
90
1995
3
00
97
2000
0
0
100
*Estimated from data for 1982-1984 in Reference
**Remainder of percent.
10
Table F-6
Percent of Autos and Motorcycles of
Model Year Remaining in Calendar Year
10
Model Year
Prior to 1979
1979-2000
Calendar Year
1979
91
9
1981
71
29
1983
49
51
1985
26
74
1987
2
98
1990
0
100
1995
0
100
2000
0
100
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TABLE F-39
Bus Type
Inter-City
Transit
School
Contributions of Different Types of Buses
to the Reduction of Hearing Loss and
Speech Interference Impacts
Impact Reduction %
Speech Interference
1
63
36
Hearing Loss
(Operator)
1
24
75
Hearing Loss
(Passengers)
1
63
36
F-38
-------
FIGURE F-l
TOTHL NIGHTTIME POPULRTION
EXPOSED VS SOUND EXPOSURE LEVEL INSIDE
HOMES PRODUCED BY BUS PRSSBYS IN 1979
0
Q
EXTERIOR
REGULATION
SCHEDULES
m
8
35-40
40-45 45-50 5Q-55 55-50 50-55
SOUND EXPOSURE LEVEL (SELJ ,DB
i
2,3
4,5
6,7
8,9
10,11
12,13
14
15
65-70
F-39
-------
FIGURE F-2
TOTflL NIGHTTIME P0PULRTIQN
EXPOSED VS SOUND EXPOSURE LEVEL INSIDE
HOMES PRODUCED BY BUS PRSSBYS IN 1981
o
o
EXTERIOR
REGULATION
SCHEDULES
m
-K
Y
1
2,3
4,5
6,7
8,9
10,11
12,13
14
15
35-40
40-45 45-50 50-55 55-60 60-55
SOUND EXPOSURE LEVEL (SEL).DB
65-70
F-40
-------
FIGURE F-3
TQTflL NIGHTTIME PGPULRTIQN
EXPOSED VS SOUND EXPQSURE LEVEL INSIDE
H8MES PRODUCED BY BUS PRSSBYS IN 1983
CD
O
EXTERIOR
REGULATION
SCHEDULES
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SOUND EXPQSURE LEVEL (SEL3 .DB
1
2,3
4,5
6,7
8,9
10,11
12,13
14
21 15
55-70
F-41
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TGTRL NIGHTTIME PGPULRTIGN
EXPOSED VS SOUND EXPOSURE LEVEL INSIDE
HOMES PRODUCED BY BUS PRSSBYS IN 1985
a
a
a
a_
IN
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14
15
35-4D
40-45 45-5D 5D-55 55-BD 60-65
SQUND EXPOSURE LEVEL. (SEU.DB
65-70
F-42
-------
FIGURE F-5
T0TRL NIGHTTIME P0PULRTIQN
EXPOSED VS SOUND EXPOSURE LEVEL INSIDE
HOMES PRODUCED BY BUS PRSSBYS IN
O
0
O
EXTERIOR
REGULATION
SCHEDULES
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H
*
Y
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SOUND EXPOSURE LEVEL fSELJ.DB
1
2,3
4,5
6,7
8,9
10, 11
12,13
14
15
65-70
F-43
-------
FIGURE F-6
TQTflL NIGHTTIME PQPULRTION
EXPOSED VS SOUND EXPOSURE LEVEL INSIDE
HOMES PRODUCED BY BUS PRS5BYS IN 1990
EXTERIOR
REGULATION
SCHEDULES
CD
8
*
Y
T
Z
31
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SQUND EXPOSURE LEVEL (SEL).DB
1
2,3
4,5
6,7
8,9
10,11
12,13
14
15
65-70
F-44
-------
FIGURE F-7
TQTRL NIGHTTIME POPULRTION
EXPOSED VS SOUND EXPOSURE LEVEL INSIDE
HOMES PRODUCED BY BUS PRSSBYS IN 1995
o
o
EXTERIOR
REGULATION
SCHEDULES
m
Y
35-40
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SOUND EXPOSURE LEVEL (SEL).DB
1
2,3
4,5
6,7
8,9
10, 11
12, 13
14
15
55-7D
F-45
-------
FIGURE F-8
TOTRL NIGHTTIME POPULRTION
EXPOSED VS SOUND EXPOSURE LEVEL INSIDE
HOMES PRODUCED BY BUS PRSSBYS IN 2000
o
o
EXTERIOR
REGULATION
SCHEDULES
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Y
IT
Z
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QUND EXPOSURE LEVEL (SEL),DB
1
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4,5
6,7
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12, 13
14
15
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F-46
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APPENDIX F
REFERENCES
1. Booz/Allen Applied Research, "An Assessment of the Technology for Bus
Noise Abatement," draft final report submitted to U.S. Environmental
Protection Agency, Office of Noise Abatement and Control, June 22, 1976.
2. U.S. Environmental Protection Agency Noise Enforcement Facility, "Lima
School Bus Test Report," Sandusky, Ohio, June, 1976.
3. Wilbur Smith and Associates, "Transportation and Parking for Tomorrow's
Cities," New Haven, Conn., 1966.
4. U.S. Environment Protection Agency, "Noise Levels of New MCI Buses,"
Advance Report, July 23, 1976.
5. U.S. Environmental Protection Agency, "Noise Levels of New Eagle
Buses, November 16, 1976.
6. U.S. Environmental Protection Agency, "Passenger Noise Environments
of Enclosed Transportation Systems," Report Number 550/9-75-025,
June 1975.
7. Russ Kevala, Booz-Allen Applied Research, Personal Communication,
September 23, 1976.
8. Booz/Allen Applied Research, memo to Wyle Research, March 12, 1976.
9. U.S. Department of Transportation, Federal Highway Administration,
Highway Statistics, Washington, D.C., Government Printing Office,
1975.
10. U.S. Environmental Protection Agency, "Background Document for
Medium and Heavy Truck Noise Emission Regulations." EPA Report
550/9-76-008, March 1976.
11. R. E. Burke, S. A. Bush, and J. W. Thompson, "Noise Emission
Standards for Buses - A Draft Environmental Impact Statement,"
Wyle Research Report WR 76-21, submitted by Wyle Laboratories
under EPA Contract No. 68-01-3512, prepared for the Office of
Noise Abatement and Control, October 19, 1976.
12. House Noise — Reduction Measurements for Use in Studies of
Aircraft Noise, SAE Report AIR 1081, October 1971.
13. Warnix, J. L. and Sharp, B. H., "Cost-Effectiveness Study of Major
Sources of Noise. Vol. IV - Buses," Wyle Research Report WR 73-10,
April 1974.
F-71
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APPENDIX G
MODEL NOISE ORDINANCE
A. ELEMENTS OF A MODEL ORDINANCE
In view of the previous lack of state and local interest in
regulating the noise emissions of buses, it is useful to note their
possible future interest in enforcing a model ordinance to be developed
by EPA specifically for buses. In general, the response is positive
depending, of course, on the recommended noise standards, i.e., provided
they are not less restrictive than those presently in force. However,
the question often raised is that there may be difficulties in the adop-
tion of a model ordinance by local governmnents when the enforcement will
be directed towards the procurement of additional facilities or equipment
of a city agency; namely, the local transit authority. It is to be ex-
pected that the adoption will be resisted if the enforcement interferes
significantly with the operation of the fleet. This means that the test
procedure must be as simple as possible, and yet consistent with good
acoustical practice. Basically, there are three methods available,
namely:
° SAE J366b Test—involving a full throttle acceleration
past a microphone to measure near maximum noise level.
o Stationary Test—involving a rapid acceleration to
governed engine speed in neutral gear, followed by a
rapid deceleration.
G-l
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o Pass-By Test—involving a measurement of the noise level
in a highway situation as the bus passes by operating
under normal conditions.
In addition to the tests involving noise measurements, an effec-
tive method of enforcement can involve a careful vehicle maintenance
checking procedure. A statement of the advantages and disadvantages of
the four possible methods of enforcement are given in Table G-l.
In enforcing the model ordinance for newly manufactured buses,
it is not necessarily essential to test every bus in a fleet. A sample
of identical buses is all that is required to identify a common factor
that results in an increase in noise with time—a poor muffler design,
for example. All other factors causing degradation can be identified
by correct vehicle maintenance at regular intervals. With this simpli-
fication, the optimum enforcement procedure can be stated as follows:
o A stationary test on a sample of diesel-powered buses
(mainly transit buses).
o A unmodified SAE 366b test for gasoline-powered buses
(mainly school buses).
o A comprehensive procedure for bus maintenance (this will
also be to the prevention of noise degradation of the older
buses in the fleet).
With this background, it is possible to develop a simple,
proposed model ordinance for buses.
G-2
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Procedure
1. Controlled SAE Test
Table G-l
Bus Noise Enforcement- Methodology
Advantages
o Suitable for application
to all bus types
• Fairly repeatable
• Well documented
Disadvantages
• Large amount of space
required
• Time consuming
2. Stationary Test
• Simple
• Quick
• Only limited space
required
Difficult for application
to ungoverned engines
(school buses)
3. Uncontrolled Pass-By
Simple
Expedient
Not as accurate as
other methods
Requires driver cooperation
4. Vehicle Maintenance
Check
• Expedient
• Strong possibility of
adoption by local agencies
Does not provide
quantitative results
G-3
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B. PROPOSED MODEL ORDINANCE
Applicability
The provisions of the model ordinance shall apply to any motor
vehicle having a Gross Vehicle Weight Rating (GVWR) in excess of 10,000
Ibs. designed for the transportation of 10 or more people, other than
the driver, that is manufactured after the year .
Standards For Buses Equipped With An Engine Governor
No person shall operate a motor vehicle as defined above that
is powered by an engine with an engine speed governor which generates a
noise level in excess of dBA when measured with fast response with
the vehicle stationary at a distance of 50 feet from the vehicle center-
line, on a line perpendicular to the exhaust outlet, when the engine
is accelerated in neutral gear from idle with wide-open throttle to the
governed engine speed.
Standards For Buses Not Equipped With An Engine Governor
No person shall operate a motor vehicle as defined above that
is not equipped with an engine speed governor which generates a noise
level in excess of dBA when measured according to the test procedures
defined by the EPA Procedure for Measurement of the Noise Emissions of
New Buses (modified SAE J366b).
Vehicle Maintenance Procedure (Recommended Practice Rather Than
Part Of An Ordinance)
Regular vehicle maintenance for all buses shall include inspec-
tion and necessary repair of the following equipment in addition to normal
running maintenance:
G-4
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1. Exhaust Systems
o Mufflers and connecting pipes should be in normal
working order, be free of visible corrosion and
external carbon deposits.
o Flexible joints should be free of carbon deposits and
should not exude smoke, fumes, etc.
o Exhaust manifold bolts and gaskets should be checked
for tightness and replaced where necessary.
2. Body Work
o All access doors and panels should be checked for
proper closure and weatherstripping.
o Where applicable, "under-belly" pans should be in place
and correctly fitted.
G-5
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GENERAL REFERENCES
APPENDIX G
1. U.S. Environmental Protection Agency, "Noise Source Regulation
in State and Local Noise Ordinances," Report No. 550/9-75-020,
February 1975.
2. Society of Automotive Engineers, "Exterior Sound Level for Heavy
Trucks and Buses," SAE Standard J366b.
3. "Interstate Motor Carrier Noise Emission Standards," Federal
Register, Vol. 38, No. 144, July 27, 1973.
4. "Interstate Motor Carrier Noise Emission Standards—Final
Regulations on Compliance," Federal Register, Vol. 40, No. 178,
September 12, 1975.
5. "Existing Noise Regulations Applicable to Buses," Draft Final
Report submitted by Wyle Laboratories under EPA Contract No.
68-01-3516, prepared for the Office of Noise Abatement and
Control, June 24, 1976.
G-6
* U.S. GOVERNMENT PRINTING OFFICE : 1977 0-729-826/1472
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