EPA-450/4-75-001
January 1975
(OAQPS NO. 1.2-028)
GUIDELINES FOR AIR QUALITY
MAINTENANCE PLANNING AND ANALYSIS
VOLUME 9 :
EVALUATING INDIRECT SOURCES
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air ami Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
-------
I
I
I
I
1
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
EPA-450/4-75-001
(OAQPS NO. 1.2-028)
I
I
| GUIDELINES FOR AIR QUALITY
MAINTENANCE PLANNING AND ANALYSIS
- VOLUME 9 :
EVALUATING INDIRECT SOURCES
I
I
I
I
I
I
I
I
ENVIRONMENTAL PROTECTION AGENCY
I Off ice of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
« January 1975
-------
I
OAQPS GUIDELINES SERIES
This report Is one of the guidelines series of reports issued by the
Environmental Protection Agency, Office of Air Quality Planning and
Standards (OAQPS), to provide information on air quality maintenance fl
to state and local air pollution control agencies. Copies are avail- |
able free of charge to Federal employees, current contractors, grantees,
and nonprofit organizations, as supplies permit, from the Air Pollution «
Technical Information Center, Environmental Protection Agency, Research
Triangle Park, North Carolina 27711, or at a nominal cost from the
National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia 22161.
Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
I
I
I
Publication No. EPA-450/4-75-001 _
(OAQPS Guideline No. 1.2-028)
I
1
I
I
I
I
I
-------
I
1
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
FOREWORD
Guidelines for Air
This document is the ninth in a series comprising
Quality Maintenance Planning and Analysis. The intent of the series is
the
51.
to
provide State and local agencies with information and guidance for
preparation of Air Quality Maintenance Plans required under 40 CFR
The volumes in this series are:
Volume 1: Designation of Air Quality Maintenance Areas
Volume 2:
Volume 3:
Volume 4:
Volume 5:
Volume 6:
Volume 7:
Volume 8:
Volume 9:
Volume 10:
Volume 11:
Volume 12:
Volume 13:
Additional
Plan Preparation
Control Strategies
Land Use and Transportation Consideration
Case Studies in Plan Development
Overview of Air Quality Maintenance Area Analysis
Projecting County Emissions
Computer-Assisted Area Source Emissions Griddincj
Procedure
Evaluating Indirect Sources
Reviewing New Stationary Sources
Air Quality Monitoring and Data Analysis
Applying Atmospheric Simulation Models to Air
Quality Maintenance Areas
Allocating Projected Emissions to Sub-County Areas
volumes may be issued.
All references to 40 CFR Part 51 in this document are to the regulations
as amended through July 1974.
These guidelines are intended to provide a screening technique for
evaluating proposed indirect sources. If a more detailed analysis is
warranted or desired, it is suggested that the appendices to the guide-
lines be consulted. This document supersedes "Interim Guidelines for
the Review of the Impact of Indirect Sources on Ambient Air Quality"
(July 1974). The information in this volume is being published at this
time primarily to assist those persons having responsibility for estimat-
ing roadside carbon monoxide (CO) concentrations as the result of require-
ments imposed by environmental impact statement analysis and review and
analysis for air quality maintenance plans. Further, this document is
believed to represent a substantial improvement over the interim
guidelines.
It is anticipated that the guidance in this document will be very
similar to guidelines which will be proposed in the Federal Register
concerning the CO review suggested by Indirect Source and Parking
Management Regulations. The proposed guidelines will appear in the
Federal Register prior to the effective date of the regulations (currently
July 1, 1975).The proposal will then be subject to further change upon
receipt and evaluation of comments from the public prior to publication
in the Federal Register in final form. In the event of inconsistencies
between the guidance in this document (EPA-450/4-75-001) and that published
in the Federal Register in proposed and final form, the guidance in the
Federal Register should take precedence.
-------
1
-------
I
I
I
I
PREFACE
These indirect source technical review Guidelines have been
I
prepared in response to two regulations recently promulgated or
M proposed by the U. S. Environmental Protection Agency (EPA). First,
the guidelines may be used as one possible means for estimating the
impact of a proposed source on ambient air quality pursuant to regu-
Ilations for the "Review of Indirect Sources" (40 CFR 52.22(b)) promul-
1
gated on July 9, 1974. Although the guidelines contain some
M discussion concerning estimation of emissions of hydrocarbons
and oxides of nitrogen, the major thrust is directed toward the review
of a proposed facility's impact on ambient concentrations of carbon
j monoxide (CO). The present analytical capability for simulating the
complex interrelationships among hydrocarbons, oxides of nitrogen,
oxidants, ambient aerosols, humidity and sunlight does not permit
presentation in a general guideline document of a detailed, quantitative
technique for evaluating the impact of an individual source on ambient
concentrations of photochemical pollutants. In areas where the
validity of a photochemical dispersion model has been demonstrated,
the use of such a model to evaluate the impact of major highway
systems or large regional airports is encouraged. Frequently,
^ however, such models will not be available and it will be necessary to
l| rely on less precise approaches for protecting the public against adverse
levels of oxidants, nitrogen oxides and hydrocarbons. Although methods
I
-------
I
of analysis may be less detailed than is desirable for photochemical
pollutants, such approaches as are available may nevertheless indicate
the degree of control needed for broad-scale management of air quality. £
Regulations concerning the "Maintenance of National Ambient Air Quality
Standards" (40 CFR 51.12), proposed by EPA on June 18, 1973,3 address the
need for management of regional air resources. A series of guideline
4-16 *
documents have been published describing intergovernmental coordina-
tion, land use and transportation planning and analytical techniques
needed to support development of an effective regional air quality main-
tenance plan. Indirect source review, as presented in these guidelines, »
may be thought of as a tactic to be employed within a comprehensive air V
quality maintenance plan. These indirect source review guidelines serve
as Volume 9 of the previously referenced Air Quality Maintenance Planning
and Analysis Guidelines. In addition to the development of techniques for
evaluation of air quality maintenance plans, there are two additional
means whereby the impact of proposed facilities on regional hydrocarbon,
nitrogen oxide and oxidant problems may be estimated. The first is
2
presented in the proposed parking management regulations in which
qualitative means for assessing a proposed parking facility's impact
on vehicle miles traveled (VMT) are presented. The second means
addresses problems presented by highway systems in meeting photochemical
oxidant and nitrogen dioxide standards using existing predictive models.
The indirect source review guidelines described in this volume are
organized as follows. A screening procedure for estimating peak CO concen-
trations associated with identified traffic design and operating variables
I
V1 .__|
I
-------
I
is first presented. These estimates are then compared with the National
o
_ Ambient Air Quality Standards (NAAQS) for carbon monoxide of 40 mg/m
o
m (35 ppm) for 1-hour averaging times and 10 mg/m (9 ppm) for 8-hour
averaging times. If the results indicate there may be difficulty in
meeting the 1- or 8-hour NAAQS for CO, this is not necessarily grounds
for denial of a permit for construction of the source. The screening
technique is intended to be conservative so that situations in which a
potential problem may exist can be identified. Should such a problem
tt be indicated, the options for redesign of the facility and reapplication
of the screening procedure, or for a more complete analysis should be
offered. It is not necessary to refer to any of the appendices to the
_ guidelines unless:
1. Specified key determinants of emissions are not adequately
provided;
2. The assumptions which were made in developing the screening
procedure are clearly not applicable; or
3. There is a desire on the part of the applicant or review
agency to perform a more complete analysis.
Appendices A through G to the guidelines present more complete metho-
dologies which can be used to estimate emissions from each of seven types
of indirect source. For the most part, it should only be necessary to
refer to the single appendix which is applicable for the source category
being reviewed to estimate emissions. The exception to this is Appendix
A which may be used in estimating emissions from access roads, arterial
streets and at intersections in the vicinity of other types of indirect
sources.
I
-------
I
There are several types of indirect sources mentioned in the
I
I
indirect source review regulations (i.e., industrial and entertainment
facilities, office and government buildings and apartment and condominium
buildings) which are not specifically discussed in Appendices A-G. The
procedures for estimating traffic volume demand for each of these
resemble the one in Appendix E for parking facilities where annual I
average daily traffic is a function of the facility's size. If traffic
is more or less continuous, the method in Appendix E for estimating
emission factors, running times and queue lengths may be used. If the m
facility is an event-oriented one (e.g., entertainment facility,
industrial facility with shift work), the guidance in Appendix D (sports
complexes) may be used to estimate running times, emission factors and
emissions. Appendix H presents more detailed procedures which might
be employed in estimating the impact of the source on air quality.
Appendix I is a partial compilation of previous monitoring studies in
the vicinity of indirect sources. The purpose of Appendix I is to
provide applicants and reviewers with potential additional sources of
information.
VI11
I
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
f
I
I
I
I
I
I
I
I
I
TABLE OF CONTENTS
Page
List of Figures xi
List of Tables xii
List of Abbreviations and Symbols xiii
1.0 Introduction 1
2.0 Rationale for a Screening Procedure 2
3.0 Definitions 5
4.0 Screening Procedure for Reviewing the Impact of a Proposed
Indirect Source on Ambient Concentrations of CO 14
4.1 Impact of Traffic on Nearby 1-hr CO Concentrations 15
4.1.1 Freely Flowing Traffic 15
4.1.2 Traffic at Signalized Intersections 16
4.1.3 Traffic at Tollbooths and Unsignalized Intersections 18
4.1.4 Estimating Representative Concentrations on Sidewalks 19
4.2 Impact of Traffic on Nearby 8-hr CO Concentrations 20
4.3 Estimation of Background CO Concentrations 32
4.3.1 Seasonal Adjustment of Observed Concentrations 34
4.3.2 Interpretation and Use of Monitoring Data at Proximate
and Representative Sites 36
4.3.3 Estimating the Impact of Remote Sources within a
Proposed Parking Lot 38
4.4 The Effect of Varying Automotive Operating Factors 39
4.4.1 Fraction of Vehicles Operating from a Cold -Start 39
4.4.2 The Effect of Automotive Emission Control Programs 41
4.4.3 Consideration of Other Factors Affecting Local
Vehicle Operating Conditions 43
4.5 Special Considerations for Event-Oriented Facilities 44
4.6 Illustrative Examples of the Application of the
Screening Procedure in Indirect Source Review 45
-------
Page
4.7 Summary of the Screening Procedure 74 ||
5.0 Economic and Design Considerations 79
5.1 Data Acquisition and Application Costs 80
5.2 Time-Related Costs 80
5.3 Design Changes 81
6.0 Assumptions Used in the Screening Procedure 85 I
6.1 Meteorological Assumptions 86
6.2 Emission Assumptions 92
6.3 Traffic Assumptions 97
6.4 Assumptions Used in Evaluating Background Concentrations 103
7.0 References 104 I
Appendix A. Methods for Estimating Emissions from Highways A-i
Appendix B. Method for Estimating Ground Traffic Emissions
from Airports B-i
Appendix C. Methods for Estimating Emissions in Vicinity |
of Regional Shopping Centers C-i
Appendix D. Methods for Estimating Emissions in Vicinity I
of Sports Complexes D-i
Appendix E. Method for Estimating Emissions in Vicinity I
of Municipal Parking Lots E-i
Appendix F. Method for Estimating Emissions at Amusement
Parks F-i J
Appendix G. Method for Estimating Emissions at Recreational
Areas G-i
Appendix H. Use of Dispersion Models to Estimate Air Quality
in Vicinity of an Indirect Source H-i A
Appendix I. Compilation of Indirect Source Monitoring Studies I-i
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
LIST OF FIGURES
Figure Page
1. Key Locations in the Review of a Hypothetical Indirect Source 21
2. Volume Demand-Capacity Ratio in a Freeway or Expressway
Lane vs. CO Concentration Impact at a Perpendicular
Distance of 10 Meters 22
3. Volume Demand-Capacity Ratio in a Lane on a Major Street
vs. CO Concentration Impact at a Perpendicular Distance
of 10 Meters 23
4. Volume Demand-Capacity Ratio in a Lane Within an Indirect
Source vs. CO Concentration Impact at a Perpendicular Distance
of 10 Meters 24
5. Relative Concentration of CO vs. Perpendicular Distance from
a Traffic Lane with Freely Flowing Traffic 25
6. Maximum Impact of Traffic in an Approach Lane Upstream
from a Signalized Intersection at a Receptor Site Located
at a Perpendicular Distance of 10 Meters 26
7. Maximum Impact of Traffic in a Lane Downstream from an
Intersection at a Receptor Site Located a Perpendicular
Distance of 10 Meters Away 27
8. Relative Concentration of CO vs. Perpendicular Distance
from a Traffic Lane Near a Signalized Intersection 28
9. Impact of Traffic Upstream from a Non-Signalized
Intersection on CO Concentrations at a Receptor Site
Located a Perpendicular Distance of 10 Meters Away 29
10. Relative Concentration of CO vs. Perpendicular Distance
from a Traffic Lane Near an Unsignalized Intersection 30
11. Summary of the Indirect Source Screening Procedure 75
XI
-------
I
LIST OF TABLES
I
Table Page
1. COLD START CORRECTION FACTORS AT VARIOUS AMBIENT TEMPERATURES 40
2. CORRECTION FACTORS REFLECTING EMISSION CONTROL PROGRAMS
IN DIFFERENT AREAS 42
3. ASSUMED OPERATING SPEEDS, LEVELS OF SERVICE AND
DEMAND-CAPACITY RATIOS FOR MAJOR STREETS AND -
CORRESPONDING EMISSION FACTORS FOR FREE FLOW
CONDITIONS 99 *
4. ASSUMED OPERATING SPEEDS, LEVELS OF SERVICE AND |
DEMAND-CAPACITY RATIOS FOR URBAN EXPRESSWAYS AND
CORRESPONDING EMISSION FACTORS FOR FREE FLOW
CONDITIONS 100
5. ASSUMED OPERATING SPEEDS AND DEMAND-CAPACITY RATIOS
FOR TRAFFIC LANES WITHIN INDIRECT SOURCES AND m
CORRESPONDING EMISSION FACTORS FOR FREE FLOW CONDITIONS 101
I
1
I
I
I
I
I
I
I
I
-------
I
LIST OF ABBREVIATIONS AND SYMBOLS
I
I
I
I
I
c Traffic capacity, vehicles/hour
c.. Traffic capacity at approach (or road segment) i, lane j,
J vehicles/hour
c1 Unimpeded capacity at a signalized intersection,
vehicles/hour of green time
cf Correction factor reflecting emission control programs,
dimensionless
CPH Number of signal cycles in an hour
c(s) Speed correction factor to be applied to emission factors
Cy Cycle length or the amount of time required for a traffic
signal to complete all of its phases, sec.
I
I
I
I
I
I
D Spacing between the tailpipes of successive vehicles, m
EF Emission factor, gm/min-veh
ef Emission factor, gm/mi-veh
G The amount of time a traffic signal is green during one
signal cycle for a specified intersection approach, sec.
G/Cy Green time to signal cycle ratio, dimensionless
K Cold start correction factor, dimensionless
L Length of a queue of vehicles, m
I If Local factor, the ratio between local CO emission factor and
the national average factors, dimensionless
m Meters
m/sec Meters per second
o
mg/m Milligrams per cubic meter
mph Miles per hour
XI 1 1
-------
xiv
I
I
p Persistence factor used to account for variations in
meteorological conditions over 8 hour periods, dimensionless
ppm Parts per million, units of concentration
q.. Emission intensity for road segment (gate) i, lane j,
^ gm/sec-m ^
S Vehicle speed, mph
t Ambient temperature, °F
T. Time required to accommodate all vehicles wishing to use
1 gate i at an event-oriented indirect source, hours
v.. Traffic volume demand at road segment (approach) i, lane j,
1J veh/hr
I
V . Traffic volume wishing to use gate i at an event-oriented
1 source, vehicles
v/c Volume demand-capacity ratio, dimensionless Q
vph Vehicles per hour M
x Concentration, ppm
I
I
I
I
I
I
I
I
-------
I
m 1.0 INTRODUCTION
An indirect source is defined as a facility, building, structure
or installation which attracts or may attract mobile source activity
that results in emissions of a pollutant for which there is a national
m standard.
m A complete analysis of such a facility requires a two-tiered
examination of a source's impact. The first tier is regional in scope,
and requires a determination of consistency with applicable air quality
maintenance plans and transportation control plans. Provisions in
"Parking Management Regulations," which require proposed parking
m facilities in designated parking management areas to reduce vehicle miles
traveled (VMT) or to at least minimize increases in VMT, are intended
2
measures to achieve these goals are enumerated in the regulations.
to address regional problems posed by parking facilities. Specific
I
I
Guidelines for the review of the impact of highways and highway systems
on ambient oxidant and nitrogen dioxide concentrations are also being
prepared. In addition to identifying procedures for estimating the
regional impact of such sources, this latter set of guidelines is
intended to identify where within the institutionalized Continuing,
Comprehensive and Cooperative ("3-C") transportation planning process
such a review (required under 23 USC 109(j)) would best be placed.
The second tier of analysis is a microscale one requiring a
determination of the impact of a proposed source on ambient air quality
at sensitive locations, usually within 1/4 mile of the proposed site.
Because of the nature of the criteria pollutants emitted by motor
i
i
-------
I
vehicles, most efforts in the second tier of analysis are directed at V
reviewing the proposed source's impact on ambient carbon monoxide (CO)
concentrations. The guidelines described herein are primarily intended I
to assist indirect source review agencies, applicants and consultants
in estimating the impact of a proposed facility on air quality in its
vicinity. More explicitly, the purposes of this document are fourfold:
1. To provide means for estimating whether a proposed
indirect source may threaten the National Ambient Air Quality **
Standards (NAAQS) for CO; |
2. To provide means whereby the efficacy of good traffic
engineering practice in meeting CO standards can be evaluated;
3. To provide a simple screening procedure for review of
a source's impact on ambient CO concentrations which can be *
applied expeditiously, but which can give reasonable assurance
that sources which pass the procedure will not threaten the NAAQS
for CO; and
4. To provide assistance in estimating the gross hydrocarbon
and nitrogen oxide emissions attributable to an individual source
so that this information may be used, as needed, in other guideline
documents.
2.0 RATIONALE FOR A SCREENING PROCEDURE
Since indirect source review or parking management review
requirements may be applicable to a large number of proposed sources, I
it is highly desirable that a reviewing agency's limited resources for
assessing the impact of an indirect source on ambient CO be directed *
toward those sources most likely to threaten NAAQS. Furthermore,
where a threat to the CO standards is not likely, it is desirable to
conduct the indirect source review for CO as expeditiously as possible J
so as to minimize costs of review and delay to the applicant. For
these reasons, a conservative screening procedure is presented in
these guidelines. When no problem in meeting the standards is found
2
I
-------
I
using this procedure, it may be used as a basis for granting permission
to construct. If a potential problem is identified, the option for
doing a more complete analysis should be presented to the applicant.
Monitoring observations in the vicinity of indirect sources have
indicated that the highest concentrations of CO occur in the vicinity of
access roads, at nearby intersection approaches or near entrance/exit
"I O p"|
gates. " Therefore, the CO impact analysis for indirect sources
focuses on relationships between air quality and traffic design and
operating parameters on access roads, at nearby intersection approaches
and at exit/entrance gates. There are three key traffic determinants
1| of emission levels on portions of roadways and/or traffic lanes which
are not near intersections. These are:
1. Volume demand;
2. Volume demand to capacity ratio;
3. The type of the roadway being examined.
fl Volume demand is important, because it provides an estimate of the
source's impact on traffic demand on access roads. When there is little
I congestion, volume demand is the most important traffic indicator of
emissions. Volume demand to capacity ratio (v/c) is crucial, because
it provides an indicator of congestion. Highly congested traffic
conditions result in increased vehicle running times and lower operating
speeds (resulting in closer spacing between vehicles). The spacing
between vehicles which is required to service a given volume demand is,
in turn, a prime indicator of emission intensity generated by vehicles
using each traffic lane. Frequently, it may be difficult to project or
measure traffic volume demand for each traffic lane. If it is not
possible to obtain estimates of traffic volume demand (and therefore,
I
-------
I
volume demand-capacity ratios) by lane, estimates of through traffic
volume demand in each direction would have to suffice. Unless there
I
were indications to the contrary, through traffic in each direction
would then be apportioned equally among the through lanes in each
22 8
direction. Empirical relationships between volume to capacity ratio J0
and operating speeds, under free-flow conditions, depend on the ^
functional type of the roadway and average highway speed or the posted
speed limit, whichever is less. 8
The following traffic parameters are key determinants of emissions
at signalized intersections: 8
1. Volume demand; g.
2. Green time to signal cycle ratio; '
3. Signal cycle length; 8
4. Unimpeded intersection approach capacity.
Green time to signal cycle ratio (G/Cy) is the key determinant 8
of the capacity of an intersection approach to accommodate traffic g
volume demand. The average length of queues forming at the intersection
is directly proportional to the proportion of time that a signal cycle I
is not green, (i.e., (1-G/Cy)). Signal cycle length is also a
determinant of queuing at an intersection approach. The shorter the 8
signal cycle length, the shorter the average queue length occurring .
at the intersection approach when the light is red. However, the *
shorter the cycle length, the more frequently queuing is likely to 8
occur at an intersection approach. Thus, the impact of signal cycle
length on ambient CO concentrations at a selected receptor depends on 8
the proximity of the receptor site of interest to the intersection
4
I
I
-------
I
I
I
being reviewed. Unimpeded intersection approach capacity is the
amount of traffic which could be accommodated by the approach per
I hour of green time. This is always greater than the actual approach
capacity. Unimpeded intersection approach capacity is needed to
estimate green time to signal cycle ratios for each intersection
approach when the signal is a traffic-actuated one. Methods of
estimating unimpeded capacity and its use in the estimation of
green time to signal cycle ratios are illustrated in Appendix A.
Suffice it to say at this point that if the reviewer wants to use
m a proper G/Cy ratio in estimating the impact of traffic on ambient
CO concentrations in the vicinity of an intersection with a traffic-
actuated signal, unimpeded intersection approach capacity must be known
for each approach and the procedure outlined in Appendix A may be followed
to estimate appropriate G/Cy. The alternative is to use the more conser-
vative assumptions about G/Cy to be described in the screening procedure.
Finally, at unsignalized intersections or at tollbooths, such
as those found at exits to municipal or airport parking lots, the
two key determinants of emissions are:
1. Volume demand, and
2. Volume demand to capacity ratio.
3.0 DEFINITIONS
The following definitions apply to the identified key determinants
of emissions and in the derivation of the screening procedure for
relating traffic on roadways and at intersections to nearby ambient
CO concentrations.
5
-------
I
Volume Demandthe average number of vehicles wanting to pass a _
given point in each lane during a 1-hour or 8-hour period. This
parameter is expressed in vehicles per hour (vph) unless otherwise
stated. For an 8-hour period, volume demand is expressed in vehicles
per hour by obtaining the average hourly demand during the peak 8-hour p
period of interest. The terms volume demand and demand are used synony- H
mously throughout the indirect source review guidelines. *
Design Speed-- a speed selected for purposes of design and tt
correlation of those features of a roadway such as curvature, super-
elevation, sight distance and type of access upon which the safe operation f
of vehicles is dependent. _,
Average Highway Speedthe weighted average of the design speeds *
within a highway section, when each subsection within the section is
considered to have an individual design speed.
Posted Speed Limitmaximum lawful operating speed allowable £
for vehicles utilizing the traffic lanes of interest.
Capacitythe maximum possible number of vehicles which has a *
reasonable expectation of passing a given point in each lane during a
given time period under prevailing roadway and traffic conditions
consistent with the definition of Level of Service E. Capacity on a |
major urban street could typically vary from 550-1200 vph/lane assuming _
that intersection approach capacities provided the limiting factor on *
the street's capacity. On urban expressways and freeways capacity
may typically vary from 1300-2000 vph/lane, assuming the terrain is
reasonably level. Estimated capacities not within these ranges are Q
I
I
-------
I
not necessarily incorrect if unusual conditions regarding grade, truck
or bus use, lane width, lateral clearance and/or signalization prevail.
V Level of Servicea qualitative measure of the effect of a number
of factors including speed and travel time, traffic interruptions,
| freedom to maneuver, safety, driving comfort and convenience and operating
M costs. For traffic which is not in the immediate vicinity of inter-
sections, level of service is defined by the type of road, operating
W speed and volume-capacity ratio. At Level of Service E, volume demand
to capacity ratios often exceed 0.8 and can approach 1.0. Traffic
| flow is unstable and there can be stoppages of momentary duration.
_ The ranges of operating speeds and volume to capacity ratios corresponding
* to various designated levels of service depend on the type of the roadway
I to which the designation is being applied.
At signalized intersection approaches, levels of service are
I
I
I
I
defined by load factors. A load factor is the ratio of the total
number of green traffic signal intervals that are fully utilized
* by traffic during the peak hour to the total number of green intervals
I during that same period. The following relationships exist between
22
levels of service at intersection approaches and Load Factors.
Load Factor Level of Service Description
_ 0 A Free Flow
" £0.1 B Stable Flow
^0.3 C Stable Flow
<0.7 D Approaching Unstable Flow
<1.00 E Unstable Flow
-------
between volume-capacity ratio and vehicle operating speeds have been
22
I
Peak Hour FactorA ratio of the volume demand occurring during
the peak hour to the maximum rate of flow during a given time period
(e.g., 5 min.) within the peak hour, expanded to a full hour. I
Operating SpeedHighest speed at which a driver can travel on
a roadway under favorable weather conditions and under prevailing
traffic conditions without exceeding safe speed as determined by
average highway speed and/or posted speed limits.
Types of RoadwaysUnder conditions which are consistent with
the maximum level of service possible for the prevailing volume-
capacity ratio and vehicle operating speed, empirical relationships
developed for certain types of roadways.'"'" These roadways include:
(a) Expresswaysa divided arterial for through traffic
with full or partial control of access and generally with grade
separations at major intersections.
(b) Freewaysan expressway with full control of access.
(c) Major streetan arterial highway with intersections
at grade and direct access to abutting property, and on which |
geometric design and traffic control measures are used to
expedite the safe movement of through traffic. g
Three other types of roadways may frequently be of interest in the *
review of an indirect source. These are: I
(d) Downtown streetsthese are different from the category
of "major streets," described above, in that they carry a sub-
stantial portion of circulatory rather than through traffic; heavy g
pedestrian traffic may increase the restrictiveness of intersections
on through capacity and intersections are likely to be more closely
spaced. Because the characteristics of each intersection exert
such a dominant influence on traffic in each upstream segment of a *
downtown street, it is suggested that the analysis of an indirect
source's impact on traffic and air quality at a downtown street be
directed at appropriate signalized intersections. m
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
(e) Local streeta street primarily for access to residence,
business or other abutting property. It is suggested that such
analysis as may be required in the vicinity of such streets be
directed at the signalized or unsignalized intersections, as
appropriate.
(f) Traffic lanes within indirect sources other than highways.
Vehicle SpacingAverage tailpipe-to-tailpipe distance between
vehicles needed to accommodate a given volume demand at a given
operating speed.
Emission FactorAmount of CO emitted by a single vehicle per
unit of time.
DistanceUnless there is specific reference to the contrary,
distance refers to the perpendicular distance between a receptor and
the nearest edge of a traffic lane.
PhaseA term used at signalized intersections to denote the instruc-
tions given to traffic at each intersection approach at any specified time.
There are usually at least three phases at an intersectionred, green and
amber. At intersections where there are turn signals or where identical
phases do not occur for vehicles traveling in opposite directions (e.g.
"delayed green") the number of phases is greater than three.
Cycle LengthThe amount of time required for all phases of a traffic
signal to occur once. Cycle lengths at fixed-time signals usually vary
between 60-120 seconds. The range at traffic actuated signals is con-
* siderably larger, usually varying from 60-180 seconds.
Unimpeded CapacityThe maximum number of vehicles that could
be accommodated by a signalized intersection approach if the signal
were always green for that approach. For each traffic lane, this
parameter is expressed in vehicles per hour of green time, and is
9
-------
I
always greater than the actual intersection approach capacity per lane.
Typical values may range from 1100-1700 vehicles/lane/hr. of green time.
Green Time to Signal Cycle RatioThe fraction of the time that a
traffic light is green at a specified intersection approach.
Upstream--Traffic which has not yet passed a specified location
(e.g., an intersection) is said to be upstream from that location. M
Traffic already having passed by the location is downstream traffic.
Intersection Leg--0n a 4-way intersection (for example) each
of the roads leading to and from the intersection is called a leg to that
intersection. An intersection approach is that portion of an intersection |
leg which is upstream from the intersection. «
Operation ModesA description of the manner in which a vehicle is
being operated. Generally there are four modes of operation: accelera-
tion, deceleration, cruising and idling. Modal emissions refer to
emission factors for CO which are appropriate for each distinctive mode |
of operation. M
Cold StartIf a vehicle has not been run for a period of time
(i.e., cold soak period), when it is restarted and for a short period I
thereafter, it runs less efficiently than it does after the engine has
warmed up. This lower engine efficiency results in higher emissions |
of CO. At indirect sources where vehicles are likely to sit for »
substantial periods of time, the cold start problem may significantly
affect CO emissions in the vicinity of a source. The extent of the V
impact of cold starting vehicles depends on a number of factors
including length of the cold soak period, ambient temperature and |
engine size.
10
I
-------
I
I
I Receptor Site--A location where it is of interest to estimate
ambient CO concentrations. In general terms, analysis should center
on reasonable locations in the vicinity of that portion of the traffic
network (e.g., parking lot, access roads, intersections) where the
combined impact of the proposed source and other traffic is likely to
result in the highest traffic demand and/or most traffic congestion.
_ Definition of "reasonable" depends on the legal interpretation of the
" word "ambient." "Ambient" is interpreted as meaning that portion of
the atmosphere, external to buildings, to which the general public has
23
access. The primary standards for CO imply that reasonable sites
are required to be in locations to which the general public (note:
not necessarily any specific individual) has access. The recommended
procedure for selecting such sites is through joint review by
the reviewing agency and applicant of maps and plans of the
area and facility which are required as part of the indirect
I source or parking management application. To clarify what
_ might generally be regarded as reasonable or unreasonable receptor
sites, a few examples are cited below. It should be strongly
emphasized that these examples only suggest what is generally
expected to be the case. If the review of a specific application
J reveals that a site which may ordinarily be unreasonable is, in fact,
_ reasonable in a specific case (or vice versa) then, of course, the
specific ruling would supersede this general guidance.
a. Examples of Reasonable Receptor Sites
(1) All sidewalks where the general public has access on a
more or less continuous basis are reasonable receptor sites;
I
n
-------
I
(2) A vacant lot in which a neighboring facility is planned |
and in whose vicinity the general public (including employees if the
neighboring facility is not being built for the prime purpose of _
traffic control) would have access continuously is a reasonable
receptor site;
(3) Portions of a parking lot to which pedestrians have access
continuously are reasonable receptor sites;
(4) The vicinity of parking lot's entrances and exits is a
reasonable receptor site, providing there is an area nearby, such as a J|
public sidewalk, residences or structures (e.g. an auto service center
at a shopping center) where the general public is likely to have
continuous access;
(5) The property lines of all residences, hospitals, rest
homes, schools, playgrounds, and the entrances and air intakes to all
other buildings are reasonable receptor sites.
b. Examples of Unreasonable Receptor Sites
(1) Median strips on roadways;
(2) Locations within the right-of-way on limited access highways; _
(3) Within intersections or on crosswalks at intersections;
(4) Tunnel approaches;
(5) Within toll booths;
(6) Portions of parking lots where the general public is
not likely to have access continuously.
One further aspect of the "reasonable receptor site" problem remains
to be discussed. That is, where within a sidewalk, occupied lot,
vacant lot, etc. should the receptor site be assumed. Generally,
reasonable receptor sites would be located as follows:
(1) Occupied lotnearest edge of the subarea within the
lot where the general public has continuous access. If this cannot
be determined, use the lot's property line which is nearest to the
traffic lanes being reviewed. £
(2) Vacant lotsame as occupied lot.
(3) Sidewalkssidewalks present a problem in that the general
public is unlikely to occupy a relatively small portion of the walkway
continuously. Nevertheless, the general public does have access to the
sidewalk as a whole on a continuous basis. This suggests that it is
appropriate to consider the sidewalk as a whole as a reasonable receptor
I
-------
I
I
site. This further implies that one should estimate representative CO
concentrations prevailing at nose height over the sidewalk during the
worst 1- and 8-hour periods. The sketch shown below illustrates a
sidewalk in which the Y direction is the direction perpendicular to
curbside and the X direction is the direction parallel to the curb.
Q. SIDEWALK
M:URB
ROADWAY
I
I
I
I
I
I
I
I
Since the diminution of CO concentration with distance from the
curb is approximately linear over distances which sidewalks are generally
found from roadways (see Figures 5, 8 and 10 in Section 4.1), it should
generally be sufficient to choose the sidewalk's centerline as the
location at which to estimate CO concentrations. In order to estimate
representative concentrations at the sidewalk, it is also necessary
to average estimated concentrations along the sidewalk's centerline
(i.e., in the "X" direction). In general, this longitudinal averaging
| would be done for each block (i.e., including 2 intersections and a
« mid-block section). This cannot be a hard and fast rule, however, since
it depends on a walkway's configuration. For example, a walkway from
a facility to a parking lot may not traverse what is ordinarily thought
of as a block. The longitudinal averaging procedure is further described
in Section 4.1.4 and illustrated by Example 11 in Section 4.6.
13
-------
I
4.0 SCREENING PROCEDURE FOR REVIEWING THE IMPACT OF A PROPOSED I
INDIRECT SOURCE ON AMBIENT CONCENTRATIONS OF CO
Ambient concentrations of carbon monoxide may be regarded as the V
sum of two components:
(1) Concentrations attributable to traffic in the immediate £
vicinity of the receptor site, and
(2) Background concentrations attributable to more remote sources
of CO which may or may not be related to the operation of the proposed f|
source.
I
The screening procedure assumes, on the basis of several monitoring
_
"
18 21
studies conducted for EPA, ~ that the greatest potential threat
to ambient air quality standards for CO occurs at locations where the
first component is relatively important. Consequently, the screening
technique focuses on three such locations:
(1) The vicinity of traffic lanes accommodating freely £
flowing traffic;
(2) The vicinity of signalized intersections; "
(3) The vicinity of non-signalized intersections or tollbooths.
These locations are illustrated for a hypothetical parking lot in
Figure 1. The screening procedure is developed in the following manner. £
First, curves for estimating the impact of nearby traffic on ambient
concentrations of CO over 1-hour sampling times are presented for
each of the three types of locations depicted in Figure 1. Second,
procedures for estimating the impact of this traffic on 8-hour ambient
CO concentrations are described. Next, manners of estimating the
background component of the ambient concentration are presented.
14
-------
I
Fourth, consideration of vehicle operating factors such as fraction of
cold starts, and applicability of Federal emission standards is
discussed. Fifth, a calculative procedure appropriate for estimating
the impact of event-oriented sources is presented. Sixth, examples
using Figure 1, the various curves, and techniques developed in the
first five sections are presented to better illustrate the screening
procedure. Finally, the screening procedure is summarized.
4.1 Impact of Traffic on Nearby 1-hour CO Concentrations
4.1.1 Freely Flowing Traffic
There are four types of roadways near which the impact
of freely flowing traffic on nearby ambient CO concentrations may be of
interest. These are freeways, expressways, midblock sections of major
streets and traffic lanes within indirect sources other than highways.
Figures 2, 3 and 4 estimate the impact of traffic volume demand,
capacity and demand-capacity ratio on ambient CO concentrations averaged
over a 1-hour sampling time at a receptor located a perpendicular
distance of 10 meters from the edge of a traffic lane. Identification
of a lane's traffic capacity and demand-capacity ratio defines the
lane's traffic volume demand as well. For example, in Figure 2, if
the lane capacity is 2000 vph and the demand-capacity ratio is 0.6, the
I volume demand is 1200 vph and the resulting impact of traffic in the
lane on 1-hour CO concentrations of a receptor located a perpendicular
m distance of 10 meters away is 3.8 ppm. Figure 5 depicts the relation-
ship between the maximum impact of a traffic lane on ambient CO
concentrations and the perpendicular distance between a traffic lane
I
I
15
-------
I
and the selected receptor site. By using Figure 5 and the appropriate I
one of Figures 2-4, it is possible to estimate the maximum impact of a
roadway with any specified number of lanes having any specified width. |
This procedure is illustrated in Example 1 in Section 4.6. M
4.1.2 Traffic at Signalized Intersections
Figures 6, 7 and 8 are used in the screening procedure V
to estimate the impact of traffic at signalized intersections. Figure
6 is used to determine the maximum impact of traffic in a lane upstream |
from the signal on ambient CO concentrations at a receptor site 10 «
meters away. The impact depicted in Figure 6 arises from the traffic
cruising by the intersection approach during the green phase of the V
signal, accelerating and decelerating traffic when the light is red or
shortly after it turns to green, and idling traffic occurring during the |
red phase of the signal. It is apparent from Figure 6 that the green ^
time to signal cycle ratio (G/Cy) exerts an important influence on
nearby ambient CO levels. This ratio is a constant at fixed-time V
signals and should be readily obtainable. At traffic actuated signals
however, G/Cy depends not only on the traffic demand for the intersection {
approach to which the screening technique is being applied, but upon _
the demand at all the other approaches as we'll. A method for estimating
green time to signal cycle ratios at traffic actuated signals is
presented in Appendix A. For purposes of the screening procedure,
however, unless there is specific information to the contrary, a G/Cy g
of 0.6 should be assumed for the approach having the highest demand
on a major street. A green time to signal cycle ratio of 0.5 is probably *
I
16
I
-------
I
more appropriate for approaches on local streets or for exits leading
from indirect source parking lots. The rationale for these assumptions
is presented in Section 6.3. Note that it would be possible to simulate
the maximum impact of a left-hand turn lane with a left-hand signal by
assuming a low G/Cy ratio (e.g., 0.2) prevails for the left signal.
The demand used in such a procedure would be the number of vehicles
wanting to turn left.
In analyzing the maximum impact of a leg to an inter-
section, it is also necessary to estimate the effect of traffic on the
leg, moving in the opposite direction, which is downstream from (i.e.,
has already passed) the signal. Figure 7 is used for this purpose.
The curve which should be used on Figure 7 is determined by the vehicle
I operating speed at midblock. Table 4 in Section 6.3 provides an indicator
of how operating speed may vary with volume to capacity ratios on major
streets. If it is not feasible to determine volume-capacity ratio at
midblock, use a speed of 15 mph for city streets and indirect sources,
and 30 mph for major streets.
I Figure 8 depicts the sensitivity of the impacts estimated
-------
I
traffic on a leg of a signalized intersection having any designated
number of lanes of any width. The use of Figures 6-8 to perform such
an analysis is illustrated in Example 2 in Section 4.6. I
4,1.3 Traffic at Tollbooths and Unsignalized Intersections
Figures 9, 7 and 10 are used in the screening procedure
to estimate the impact of traffic at non-signalized intersections and
in the vicinity of tollbooths. Figure 9 identifies relationships between
volume demand, capacity and volume demand-capacity ratio and the impact 1
of traffic in a lane upstream from a non-signalized intersection or
toll booth on CO concentrations at a distance of 10 meters from the edge "
of the lane. Figure 9 compares the impacts of two operating conditions
in such a lane. At low demand-capacity ratios, congestion is minimized
and the problem posed by queues of vehicles forming at unsignalized |
exits/entrances to an indirect source or at unsignalized intersections
is minimal. Under such circumstances, the impact on CO concentrations
at nearby receptors is directly proportional to volume demand passing
the receptor. As the demand-capacity ratio increases, queue formation
is likely to exert an increasingly important impact on nearby ambient I
CO concentrations. The solid "free-flow curves" in Figure 9 depict
the range of volume demand-capacity ratios for which the volume demand
per se may exert the most important influence on nearby ambient CO
concentrations. For demand-capacity ratios exceeding the ratio at
which the appropriate free-flow curve intersects the queuing curve,
queuing at an intersection or exit/entrance may exert the maximum impact
on nearby ambient CO concentrations, and the queuing curve should be
used to estimate the impact at nearby receptors.
I
-------
1
Figure 7 is used to estimate
_ the opposite di
toll booth under
the impact of traffic in
rection which is downstream from the intersection or
review. Figure 10, when combined with Figures 9 and 7,
enables the reviewer to estimate the impact
any width at a receptor site located up to
of any number of lanes of
100 meters away. This pro-
| cedure is illustrated in Example 3 in Section 4.6.
4.1.4
Estimating Representative Concentrations on Sidewalks
The suggested screening procedure for estimating represen-
tative concentrations on sidewalks is to estimate the average concentra-
tion along the sidewalk's centerline at breathing height. Where feasible,
I average concentrations should be determined for each sidewalk on each
block which is of interest. Average concentrations along the sidewalk's
centerline can be estimated by determining
concentrations along a sidewalk's
centerline for each zone of the sidewalk using guidance in Sections 4.1.1-
4.1.3 as appropriate. For a typical block, there would be three zones
(2 intersections, 1 midblock) as shown in the sketch below.
1
1 INTERSECTION
1
1
1 ^
1
1
1
MIDBLOCK
01 02
ONE1 ZONE 2
19
INTERSECTION
03
ZONE 3
*m-, --m-f X*J ~^M_
^ -^* Ao ^
-------
(cone), (X, ) + (conc)9 (X0) + (conc)Q (XQ)
(cone) = _ ' , . __
UoncVep (X1 + X2 + X3)
I
For the case pictured in the sketch, the representative I
concentration along the sidewalk centerline would be determined using
the following expression. "
m
The size of the respective zones (i.e., X,, X^ and X,,) would be m
determined using Equations (7) and (8) in Section 6.1 to determine
the size of zones dominated by signalized and non-signalized inter-
sections respectively. The remaining portion of the block would be
assumed to be dominated by midblock traffic conditions. This pro-
cedure is illustrated with Example 11 in Section 4.6.
4.2 Impact of Traffic on Nearby 8-hour CO Concentrations
Two adjustments must be made to the procedures described
in Section 4.1 in order to adapt the screening procedure for estimating
the impact of traffic on nearby 8-hour concentrations of CO.
1. Volume demand appropriate for the peak 8^-hour use period
must be used. This demand would be obtained by estimating the mean »
hourly volume demand during the 8-hour period of interest. In all cases
the peak 8-hour volume demand would be less than the peak 1-hour volume I
demand.
2. Account must be taken of the lack of persistence of the m
unfavorable meteorological conditions which were assumed in deriving M
Figures 2-10. The following procedure is suggested for deriving a
persistence factor to account for meteorological variations occurring I
over an 8-hour sampling period.
I
20
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
o
_J
C9
CC
f) 2
= a
O)
S-
o
cc
o
CO
LU
cc
LU
n:
t-
o
Q.
>-
U.
O
LU
>
LU
CC
LU
1C
t-
CJ
o
CO
>
-------
Figure 2
VOLUME DEMAND - CAPACITY RATIO IN A FREEWAY OR EXPRESSWAY LANE VERSUS CO
CONCENTRATION IMPACT AT A PERPENDICULAR DISTANCE OF 10 METERS
35
30
T
T
T
T
T
25
20
15
C/3
<
DC
LU
o
u
10
9
8
1.5
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
VOLUME DEMAND TO CAPACITY RATIO (v/c)
22
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Figure 3
VOLUME DEMAND - CAPACITY RATIO IN A LANE ON A MAJOR STREET VERSUS CO
CONCENTRATION IMPACT AT A PERPENDICULAR DISTANCE OF 10 METERS
VOLUME DEMAND TO CAPACITY RATIO (v/c)
23
-------
Figure 4
VOLUME DEMAND - CAPACITY RATIO IN A LANE WITHIN AN INDIRECT SOURCE VERSUS CO
CONCENTRATION IMPACT AT A PERPENDICULAR DISTANCE OF 10 METERS
0.1
0.2
VOLUME DEMAND TO CAPACITY RATIO (v/c)
24
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
LU
u
=><
cj oc
UJ O
O. _l
U UJ
U. OC
OU.
o
Zu.
O u.
0
-------
Figure 6
MAXIMUM IMPACT OF TRAFFIC IN AN APPROACH LANE UPSTREAM FROM A SIGNALIZED
INTERSECTION AT A RECEPTOR SITE LOCATED AT A PERPENDICULAR DISTANCE OF 10 METERS
35
30
25
20
15
E
Q.
Q.
00
<
cc
cj
z
o
u
o
cj
cc
=>
o
o
o
CL-
IO
9
8
7
6
1.5
200 400 600 800 1000 1200
TRAFFIC DEMAND PER LANE, vph
26
1400
1600
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Figure 7
MAXIMUM IMPACT OF TRAFFIC IN A LANE DOWNSTREAM FROM AN INTERSECTION
AT A RECEPTOR SITE LOCATED A PERPENDICULAR DISTANCE OF 10 METERS AWAY
E
V)
2
o
UJ
u
2
O
u
o
u
GC
200 400
600
800 1000 1200 1400 1600
TRAFFIC DEMAND PER LANE,vph
27
-------
u.
u.
a
DC
U.
LLJ
U
V)
a;
u es
goc
S<
K-IU
DC
3
CD
" «
olX/X'NOIlVaiN3DNOO 3AI1V13U
28
<
OC
oc
<
o
DC
oc
<
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Figure 9
IMPACT OF TRAFFIC UPSTREAM FROM A NON-SIGNALIZED INTERSECTION ON CO CONCENTRATIONS
AT A RECEPTOR SITE LOCATED A PERPENDICULAR DISTANCE OF 10 METERS AWAY
VOLUME DEMAND TO CAPACITY RATIO (v/c)
29
-------
'NOIl\/HlN33N003AUViaH
30
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
(a) Select an existing indirect source or roadway
confiauration similar to ones which are likely to be proposed and which
is located in an area where wind variability is likely to be representa-
tive (e.o., an existing source located in a street canyon where channeling
may occur woulo not be suitable unless a proposed source were also to
I be located in such a site).
(b) Monitor hourly traffic at the main gate for the
selected existing source or on the existing roadway, wind speed and
direction at the site and ambient CO concentrations within 50 m of the
selected gate or roadway.
(c) For each day, note the highest measured 1-hour
CO concentration occurring with wind speeds less than 2 m/sec. Note
the traffic demand measured in both directions at the gate or on the
road during this period.
(d) For each day, note the highest 8-hour running
averane CO concentration at the existing source during hours of operation,
along with the average hourly traffic volume occurring in both directions
at the selected gate during this period. If a roadway is selected,
follow the same procedure, but limit observations to those times of day
ir which the proposed source will be operating.
(e) For each day, the persistence factor, p, can be
estimated using Equation (1).
(Max. "-hour averaae concentration)
I
I
I
I
I
VM 0)
,Max. 1-hour concentration with v/indi
speed < 2 m/sec} 1
31
-------
I
where p = 1- to 8-hour persistence factor, dimension!ess I
V, = traffic volume demand in both directions during the
hour in which hiqhest CO concentrations were observed, vph
V0 - average hourly traffic volume demand in both directions
during the 8-hour period in which the highest 8-hour
running average CO concentration is observed, vph |
(f) Choose the highest observed persistence factor M
and multiply it by the estimates obtained using Figures 2-10 to
I
estimate the maximum 8-hour impact at the selected receptor.
Using a procedure similar to the one outlined above,
a maximum persistence factor of "0.6" was observed during an EPA-
sponsored monitoring study at an indirect source. If it is
irfeasible to derive a persistence factor, or until such time as the *
appropriate data become available, a value of "0.6" may be assumed. B
Derivation and use of a meteorological persistence factor
to estimate 8-hour concentrations of CO are illustrated in Example 4 |
in Section 4.6. «
4.3 Estimation of Background CO Concentrations
Sections 4.1 and 4.2 have discussed means whereby the I
impact of traffic on nearby ambient CO concentrations can be assessed.
It is likely that the most severe threat to National Ambient Air |
Quality Standards (NAAQS) for CO will occur where this impact is
great. However, merely estimating the impact of nearby traffic
may not be sufficient to determine whether the standards are threatened. I
Even though the background concentration may frequently be very much
less than the impact of nearby traffic on ambient CO concentrations, |
the background component should be included in order to compare
estimated ambient concentrations of CO with the NAAQS. Occasionally,
32
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
when a source is to be located in a rural area and there are no
reasonable receptor sites at the downwind edge of the proposed parking
24
lot, a natural background of 1 ppm may be assumed. More often,
however, use of natural background levels may not be sufficient.
Several approaches for estimating background concentrations are
described in Appendix H. The two preferable methods for estimating
background levels would be:
(1) Note the second highest 1- and 8-hour CO concentrations
observed, during hours in which the proposed indirect source would
operate, at a continuously operated monitoring site over the past
year which is situated near the site of the proposed source or at
a similarly situated existing source and adjust these observations
to account for the effect National emission control programs will
have after the proposed source's first year of operation; or
(2) Use the results of a calibrated meso-scale diffusion
model to estimate high representative 1- and 8-hour concentrations
likely to occur during hours in which the proposed source would operate,
Unfortunately, frequently the necessary information may not be
available to take advantage of either of these two approaches.
Unless the data are already available or the modeling exercise has
already been completed, both approaches require more effort than is
appropriate for the indirect source screening procedure. Indeed,
the indirect source regulations imply that, an applicant may be
required to monitor ambient CO concentrations for no longer than
14 deys. In cases where it is not possible to use one of the two
above procedures, it may frequently be necessary for the applicant
to monitor ambient CO concentrations for e limited period. The
remaining portion of this section assumes that such is the case, and
discusses how the collected data night be interpreted and used to
estimate ambient backoround concentrations.
-------
I
4.3.1 Seasonal Adjustnierit of ObseryedJIoncejitnati ons _
Since an applicant nay only be required to monitor
ambient CO levels for at most 14 days, there is a strong likelihood
that the highest 1- and 8-hour background concentrations occurring
during a source's operating hours will not be observed. To compen- J
sate for this, the observed data should be seasonally adjusted. Two _
possible methods for adjusting observations are described below.
Other methods may be just as satisfactory or even preferable if they
are more suited to the available data. The first method described
requires the presence of a continuous nionitorinn station which has
been operating somewhere within the regional area of interest for
a year. The second method is less satisfactory, but does not require
the presence of a historical monitoring site. B
Method 1--Use of Historical Data
(1) Hote the highest 1- and 3-hour CO concentrations I
observed at the applicant's monitoring site during the times of day
in which the proposed source would be operating.
(2) Note the highest observed 1- and 8-hour concen-
trations during the source's operating hours at the historical site
most closely corresponding to the site of the applicant's monitor
during the 1& day monitoring period.
(3) Mote the hinhest observed 1- and 8-hour concen-
trations at the historical site over the past year during the source's I
operating hours.
Apply Equation (2) to estimate the seasonally
nrpntratinn .
adjusted background concentration.
34
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
/Max. observed 1-hr cone A /Max. obs. 1-hr. cone. \
@ applicant's site @ historical site duringj
I during source operating I I source operating hours I
_\hours / \in past year j_ (2)
xb /Max. observed 1-hr. cone. @ historical
site during source operating hours
1 during the 14-day period
(5) The seasonally adjusted 8-hour background concen-
tration would be obtained by substituting 8-hour concentrations for
1-hour concentrations in Equation (2).
If hourly data are not readily available at the historical site, steps
(2)-(3) and Equation (2) would have to be altered as follows:
(2a) Note the highest observed 1- and 8-hour concen-
trations at the historical site most closely corresponding to the
site of the applicant's monitor during the 14 day monitoring period.
(3a) Note the highest observed 1- and 8-hour concen-
trations at the historical site over the past year.
(4a) Apply Equation (2a) to estimate the seasonally
adjusted background concentration.
[Max. obs. 1-hr. cone. \ I Max. obs. 1-hr.
l@ applicant's site during I cone. P historical site.
_\source operating hrs. / \during past year / (2a)
xb /Max. obs. 1-hr. cone. @ historicalX
(site during 14-day period )
The use of historical data to estimate background concentrations is
illustrated further by Example 5 in Section 4.6.
35
-------
Method 2--Use of Pollution Potential
36
I
I
(1) Note highest 1- and 3-hour CO concentrations
observed at. the aoplicant's nonitoring site during the times of day
in which the proposed source would be operating.
(2) Note the x/0 value in the appropriate part of
the United States from the Figures 42-45 in AP-101 which correspond
to the tine of year ir which the monitoring is undertaken by the
applicant.
(3) Note the maximum x/Q value for the appropriate
area of the country from Figures 42-45. Use the value for the larger
city to emphasize seasonal differences.
(4) Use Equation (3) to seasonally adjust observed |
backgrouna concentrations.
I
Max. obs. 1- or 8-hr, conc.l / Maximum x/Q from!
n applicant's site during AP-101
_ \source operating hours / \ /
D (x/0 fron AP-101 during time of year]
Vin which monitoring is performed / |
Method 2 is illustrated further by Example 5 in Section 4.6. |
4.3.2 Interpretation of Monitoring Data at
Proximate and Representative Sites |
A monitoring site's location may frequently be deter- _
mined by practical constraints such as availability of electrical power
and security. The resulting location of an ambient monitoring site affects
the manner in which the screening procedure is applied. In general, there
are two types of sites, representative sites and proximate sites. A |
proximate site is one where the monitor is within 100 meters of the traffic _
lanes to which the screening procedure is being applied. As such,
I
I
I
-------
I
I
these data may already reflect a significant contribution from the
| traffic lanes being evaluated. Indiscriminate application of the
_ approaches suggested in Section 4.1 may result in the traffic lanes'
impact being counted twice. Thus, it is suggested that if the only
feasible sites are proximate ones, hourly traffic volumes on the
nearby roadway be monitored as well. It would then be possible to
"calibrate" the curves in Section 4.1 so that the estimated and
_ observed concentrations agree for the observed level of traffic.
Next, the maximum increase in traffic attributable to the new source
and/or seasonal differences in other traffic using the road should
be added to the observed traffic and the incremental iirpact should
be estimated using the "calibrated" curves. The above procedure is
_ illustrated more completely by Example 6 in Section 4.6.
The advantage of using data obtained from a proximate
site is that such data may be used to help estimate 8-hour persistence
factors as described in Section 4.2. There are several disadvantages,
I however. First, additional traffic data may be required.
_ Second, if there are several different types of critical locetions
(e. g., at midblock, at signalized intersections, at non-signalized
intersections), only the curves appropriate for the type of location
I
I
I
I
-------
I
I
near which the monitoring site is located may be "calibrated." Third,
the computations required to use proximate data in the screening pro- I
cedure are more complex. On balance it is suggested that representa-
tive sites be used to obtain air quality data whenever possible.
A representative site is one located at least 100
meters from major traffic lanes. The concentrations observed at such
sites are not likely to be dominated by traffic in the lanes being |
evaluated with the screening procedure. The use of seasonally adjusted
maximum background concentrations from representative sites is straight-
forward. The 1- and 8-hour background values thus obtained are simply
added to the impact attributable to nearby traffic. This is illustrated
in Section 4.6 with Example 7. I
4.3.3 Estimating the Impact of Remote Sources within a
Proposed Parking Lot |
When a receptor site is located within or at the _
downwind edge of a proposed parking lot, the impact of emissions which
may take place within the lot, but not in the immediate vicinity of 9
the receptor site. should be accounted for. This can be done in two
ways. First, the monitoring site selected to estimate background |
concentrations could be located in the vicinity of an existing lot _
which is similar to the one which is proposed. Background data obtained
at such a site would inherently account for parking lot emissions. If
38
I
I
I
-------
I
the first approach is not feasible, a second approach would be to add
an arbitrary increment to the background concentration to account for
I the proposed lot. Limited data suggest that increments of 5 ppm and
12 ppm would be conservative values to add to the 1- and 8-hour background
20
concentrations respectively. Estimating background concentrations in
the vicinity of proposed parking lots is illustrated in Example 7 in
Section 4.6.
| 4.4 The Effect of Varying Automotive Operating Factors
The curves depicted in Figures 2-10 are appropriate for a
national average mix of model year vehicles for calender year 1975.
This mix is composed of 88 percent automobiles and 12 percent light-duty
trucks. Twenty percent of this national mix is assumed to be operating
I from cold starts with ambient temperatures ranging from 68°F to 86°F.
If the mixture of vehicles in the area of interest has different charac-
teristics than those upon which Figures 2-10 are based, the estimates
obtained using Sections 4.1 and 4.2 must be corrected. This section
discusses correction factors needed to account for four such differences:
| fraction of cold starts, differing ambient temperatures, effect of auto-
« motive emission control programs, and the effect of local factors
altering the vehicle mix.
I 4.4.1 Fraction of Vehicles Operating from a Cold Start
Table 1 presents a series of "cold start-cold temperature
| correction factors" which should be applied if the reviewer has reason
M to believe the assumption of 20 percent cold starts is inappropriate
for the site being reviewed and/or temperatures outside the range of
I 68°-86°F are appropriate. Cold start-cold temperature correction
factors should only be applied to the estimated 1- and 8-hour impact of
39
-------
Table 1. COLD START CORRECTION FACTORS AT
VARIOUS AMBIENT TEMPERATURES*
Percent of \
Cold-Operating \ Ambient Cold Cool
Vehicles \ Temperature (?0°F) (50°F)
0
10
20
30
40
50
60
70
SO
.6 .8
1.2 1.1
1.7 1.3
2.2 1.6
2.3 1.8
3.3 2.1
3.R 2.3
5,3 2.6
4.9 2.8
90 5.4 3.1
100
59 33
*These correction factors are appropriate for cold start-cold te
emissions for vehicles which are not equipped with catalysts.
factors for catalytical ly equipped vehicle^may be estimated us
appropriate table in Supplement 5 to AP-42 and comparing the
Warm
(75°F)
.7
.9
1.0
1.1
1 .3
1.4
l.h
1 .7
1.8
1 .9
2.0
nperatm
Emissior
ing the
result
with the 55 gm/mi factor assumed in Section
40
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
nearby traffic. The estimated background concentration would already
reflect the fraction of vehicles operating from cold start. If the cold
soak period for a vehicle exceeds 4 hours and the vehicle passes in
the vicinity of the receptor point of interest within 4 minutes, emissions
from that vehicle may be appreciably greater than those from a warmed-up
vehicle. The basis for the correction factors in Table 1 are discussed
more fully in Secti'on 6.2.
4.4.2 The Effect of Automotive Emission Control Programs
Table 2 presents correction factors to reflect the
application of emission control programs. Emission control programs
are categorized in three ways: control programs applied in low altitude
areas, control programs applied in California (reflecting more stringent
emission standards for a limited time) and control programs applied in
high altitude areas.
The correction factors in Table 2 were obtained by
taking the ratio of a CO emission factor for the calender year of
interest to that for 1975 for a vehicle mix composed of 88 percent
automobiles and 12 percent light-duty trucks and rounding to the nearest
tenth. Emission factors for each calender year were estimated using
26
guidance in Chapter 3, Supplement 5 to AP-42. The national adjustment
factors in Table 2 assume a CO emission standard of 15 gm/mi applies for
1975, 1976 and 1977 model vehicles and the statutory standard of 3.4
gm/mi applies thereafter. The California factors reflect the California
interim standards through 1977.
The correction factors in Table 2 may be applied
directly to the impact of nearby traffic estimated in Sections 4.1 and
4.2. Equation (4) should be used to apply the correction factors in
Table 2 to estimated background concentrations.
41
-------
I
TABLE 2. CORRECTION FACTORS REFLECTING EMISSION
CONTROL PROGRAMS IN DIFFERENT AREAS
I
{ear
1975
1976
1977
1978
1979
1980
Low
Altitude
1.
0.
0.
0.
0.
0.
"i
u
9
8
7
5
4
Hi
Alti
1
1
1
1
1
0
gh
tude
.8
.6
.4
.2
.0
.8
Cal i form' a
1 .
0.
0.
0.
0.
0.
0
8
8
6
5
4
42
I
I
I
I
I
1
These correction factors reflect the imposition of interim
federal CO emission standards (for the low altitude and high altitude
areas) through model year 1977 and the statutory standard thereafter.
for California, the CO correction factors reflect the California
interim standards through the 1977 model year and the statutory standards
thereafter. Should amendments to the Clean Air Act proposed in March
1975 become law, correction factors for 1978 and later years may be
altered. In the event Congress amends the Clean Air Act, this table
should be altered accordingly. This may be done using Supplement 5
to AP-4226
I
I
I
I
I
I
I
-------
I
I
I
I
I
year of interest
I
(cf)
^CTJbackground
_ Example 8 in Section 4.6 illustrates the application of cold start
and emission control correction factors in the screening procedure.
I
I
I
I
I
* factors reflecting considerations other than cold start, cold temperature,
altitude and control programs (e.g., prevailing local mixes of vehicles,
driving cycles, steep grades), these should be substituted for the
g emission factors used in deriving the curves in Section 4.1. If such
_ a procedure is followed, the estimates obtained using the curves should
be multiplied by a "local factor" as determined with Equation (5).
4.4.3 Consideration of Other Factors Affecting Local
Vehicle Operating Conditions
The emission factors which were used in deriving
the curves in Figures 2, 3, 4 and 9 are based on average trip emission
factors for national average mix of vehicles (by model year) composed
of 88 percent autos and 12 percent light-duty trucks and metropolitan
27
area driving cycles as described by the 1975 Federal Test Procedure.
Figures 6 and 7 are based on observed traffic at a signalized inter-
21
section. Whenever data are available concerning local emission
(local emission factor for one year after the
-,.p _ proposed source begins operation) (5)
Tnational average trip emission factor~fo"F
one year after the proposed source begins
operation)
43
-------
jLl JL?J1§"*derations _for Events-Oriented Fjacjji ties
In defining volume demand, it is assumed that demands during
I
I
a 1-hour period are evenly spread out over the hour (i.e., peak hour
factor - 1). This assumption may not be valid for event-oriented
facilities. A prominent example of such a facility is a sports stadium.
The peak impact on CO concentrations is likely to occur shortly after I
the event's conclusion when everybody tries to leave at once. Obser-
1°
vations in the vicinity of stadiums " neve indicated periods of extreme
congestion for a fraction of an hour after the event with practically
no traffic toward the end of the hour. Accordingly, the following
procedure is suggested to determine whether key design and operating
parameters are sufficient to avoid the threat to the 1-hour CO NA.AQS
in the vicinity of event-oriented indirect sources.
(a) For Signal izgd or Non-Signalized Exits from the Parking Lot
1. Obtain estimates of the traffic volume (V, vehicles)
2. Estimate time required to accommodate all vehicles
wishing to use each qate:
I
T, , j (6)
where M'. = traffic volume wishing to use gate i, vehicles
c. = maximum capacity of gate (=(# of lanes)(average lane
capacity)), veh/hr
T. = time required to accommodate all vehicles wishing to
44
I
I
use gate i, hr
I
I
-------
I
3. Assume the volume demand is equal to the capacity
(i.e., v/c = 1) for T and is zero for the remaining portion of the
hour.
_ 4. Obtain concentration from the appropriate ones of
Figures 6-10 assuming the demand equals the capacity. Multiply the
sum of the lane contributions by "T" and add background concentrations.
( b ) For Nearby Intersections and at Midblock Sections
Unless the unused capacity of the road is very much
_ greater than that of the exit from the source, follow the same pro-
cedure outlined above using the appropriate ones of Figures 2-10,
only in step 3 assume the volume demand is equal to that generated by
traffic which is not related to the source during the remainder of
the hour. If the unused capacity of the access road greatly exceeds
the exit capacity, analyze the roadway as would be done for a non-event
source. Analysis of an event-oriented source is illustrated with
fl Example 9 in. Section 4.6.
4 . 6 Illustrative Examples of the Application of the Screening
Procedure in Indirect Source Review
The purpose of this section is to provide numerical examples
to better illustrate the screening procedure described in Sections
4.1 - 4.5. Nine examples, describing different facets of the screen-
ing procedure, are applied to the hypothetical source pictured in
Figure 1. A tenth example, synthesizing the various features of the
I
I
I
45
-------
I
screening procedure, is then presented. Finally, an eleventh example
is presented to illustrate the procedure for estimating representative 1|
concentrations along sidewalk center! ines should receptors of this
nature be of interest for the source under review. I
Example 1 _
(a) Purpose. The purpose of this example is to illustrate the
use of Figures 2-5 to estimate the impact of freely flowing traffic
on ambient 1-hour CO concentrations at nearby receptor sites.
(b) Problem. Suppose a receptor point is located a perpen-
dicular distance of 17 meters from a mid-block location of a
major street (e.g., location 1, Figure 1). Further, the receptor
is north of the street. Highest estimated traffic demand
occurring on the road during hours in which the source is operating
is estimated to be 2400 vph. This demand results from existing
traffic and the projected demand attributable to the proposed source.
During the hour of interest 60?;' of the traffic is assumed to be
traveling west. Capacity of the lanes at mid-block is estimated
as 1000 vph/lane. There are 4 lanes and each lane is assumed to I
be 4 meters wide. What is the maximum impact of the estimated
traffic on ambient 1-hour CO concentrations at the specified M
receptor point? V
( c ) Solution.
(1) Estimate the demand per lane by noting that the total
demand is 2400 vph. Since 60% of this traffic is traveling west,
the demand in lanes (1) and (2) is:
Similarly, the demand in lanes (3) and (4) is:
v = (.40) (2400) (1/2) = 480 vph/lane
I
I
46
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
(2) Estimate the demand-capacity ratio for each lane -
For lanes (1) and (2) v/c - 720/1000 = .72
For lanes (3) and (4) v/c = 480/1000 = .48
(3) Since location 1 is near a midblock location of a major street,
Figures 3 and 5 are applicable. From Figure 3, note that if each lane
were 10 m from the receptor, the following impacts would be estimated:
>.-, = 4.6 npm
X0 = 4.6 ppm
~>3 = 2.4 ppm
\. - 2.4 ppm
(4) However, the nearest lane, lane 1, is 17 meters from
the receptor. Since each lane is 4 meters wide, lane (2) is 21 meters
from the receptor; lane (3) is 25 meters and lane (4) is 29 meters
from the receptor. This information, together with the calculations
in step (3) above, is used in Figure 5 to estimate the impact of the
street on the receptor at location 1 in Figure i.
From Figure 5, note that at a 17 meter distance the
impact of a lane of traffic is 0.75 that at 10 meters. Similarly
at 21 meters, 25 meters and 29 meters, the impact is .66, .60 and
55 of the 10 meter impact respectively.
Therefore,
>1 = (.75) (4.6) = 3.5
x2 = (.66) (4.6) = 3.0
,x3 = (.60) (2.A) = 1.4
X4 = (.55) (2.A) = 1.3
Total impact of the street = 9.2 ~ 9 ppm
e 2
(a) Purpose. The purpose of this example is to illustrate
the use of Figures 6-8 to estimate the maximum impact of traffic
at a leg of a signalized intersection on ambient 1-hour CO concen-
trations at a nearby receptor point.
47
-------
I
(b) Problem. A receptor point of interest is located 20 m north m
of the east leg of the signalized intersection pictured at location |
2 in Figure 1. Traffic demand in lanes (1) and (2) is 720 vph/lane.
Traffic demand in lanes (3) and (4) is 480 vph/lane. The east leg _
of the intersection has 4 lanes and each lane is 4 meters wide. The
signal at location 2 is a traffic-actuated one. What is the maximum *
impact of the estimated traffic on ambient 1-hour CO concentrations
at the designated receptor?
(c) Solution.
(1) Since the signal is a traffic actuated one and there is I
no information given concerning demands at the intersection's other
legs, assume G/Cy for the east leg's through traffic is 0.6 as sug- _
gested in Section 4.1.2.
(2) Lanes (1) and (2) constitute the intersection approach
and hence are upstream from the intersection. Enter the abscissa in
Figure 6 at a demand of 720 vph/lane and note the intersection with the |
G/Cy =0.6 curve.
From Figure 6,
x-, = 10.4 ppm
Xp = 10.4 ppm
(3) Lanes (3) and (4) are downstream from the intersection,
so Figure 7 must be used. Since the east leg is on a major street, and j§
v/c - .48 use Table 3 to assume a cruise speed of 30 mph will be attained.
Entering the abscissa at 480 vph, note that M
X3 = 2.5 porn
X4 - 2.5 ppm
(4) The estimates in steps (2) and (3) would be appro-
priate if the distance between the receptor and each lane were 10
meters. However, lanes (1) - (4) are 20, 24, 28 and 32 meters |
respectively from the receptor site. Thus Figure 8 must be used
to adjust the estimates obtained in steps (2) and (3). The »
"upstream curve" applies for lanes (1) and (2) since they are
upstream from the intersection. The "downstream curve" applies
for lanes (3) and (4). Combining the information obtained from
steps (2) and (3) with that in Figure 8, note that: I
48
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
X] - (.59) (10.4) - 6.1
X2 = (.49) (10. a) = 5.1
X3 = (.54) (2.5) = 1.4
= (.48) (2.5) = 1.
Total impact of the intersection leg = 13.8 14 ppm
Example 3
(a) Purpose. The purpose of this example is to illustrate the
use of Figures 9, 7 and 10 to estimate the maximum impact of traffic
at a leg of a non-signalized intersection on ambient 1-hour CO con-
centrations at nearby receptor points.
(b) Prob J epi_. A receptor point is located 15 meters
from the leg of an intersection cf the major exit/entrance and a
ring road within an indirect source parring lot as shown at location
3 in Figure 1. If the capacity of the 2-lane intersection leg is
300 vph/lane and the estimated demand using the leg is 250 vph in
each direction, what is the impact of this traffic on ambient 1-hour
CO concentrations at the receptor point. Each lane is estimated to
be 3 meters wide.
( c ) Sojution.
(1) Referring to location 3 in Figure 1, traffic in lane (5)
is upstream from the intersection and traffic in lane (6) is downstream.
Therefore, Figures 9 and 10 must be used for lane (5) and Figures 7 and
10 for lane (6) .
(2) The demand-capacity ratio for lane (5) is:
-,
v/c - = .83
From Figure 9, the impact of lane (5) on a receptor 10
meters from the lane would be:
X5 = 14.5 ppm
(Note from Figure 9 that if v/c had been less than 0.38, the c = 300
voh curve would have determined lane (5)'s impact on the ambient
CO concentration at the receptor point.)
49
-------
(3) Using the 15 mph cruise curve in Figure 7, as sug-
gested in Section 4.1.2, xg = 2.6 ppm.
(4) Since the receptor is 15 meters from lane (5) and
18 meters from lane (6), Figure 10 is needed. The "upstream curve"
in Figure 10 applies for lane (5), while the "downstream curve" is
appropriate for lane (6). Combining the information in steps (2)
and (3) with that in Figure 10,
X5 = (.75) (14.5) = 10.9
X6 = (.74) (2.6) = 1.9
Total impact of the intersection leg = 12.8 ~ 13 ppm
Example 4
(a) Purpose. The purpose of this example is to illustrate the
derivation and use of meteorological persistence factors in esti-
mating the impact of nearby traffic on 8-hour ambient CO concentra-
tions at the receptor points described in Examples 1-3.
(b) Problem. Peak 8-hour traffic demand on the major street
depicted at locations 1 and 2 in Figure 1 is estimated to be 2000
vph. Traffic is assumed to be split 50-50 in each direction. Peak
traffic demand on lanes (5) and (6) within the proposed parking lot
is estimated to be 200 vph/lane for an 8-hour period. During a two
week air quality monitoring study conducted by the applicant at
a proximate site (Site A) 25 m north of lane (1), a maximum 1-hour CO
concentration of 8 ppm is observed during hours in which the source
would operate. The corresponding traffic flow observed during this
hour was 1000 vph in each direction. The maximum 8-hour concentration
observed including operating hours was 3 ppm. Eight-hour traffic
demand during this period was observed to be 1600 vph, with 800 vph
in each direction. The terrain and buildings at locations 1 and 2
are similar in size and shape. However, location 3 is considerably
more level and open. What is the impact of nearby traffic on 8-hour
ambient CO concentrations at receptor points Rl, R2 and R3 in Figure 1?
(c) Solution.
(1) Estimate the peak 8-hour traffic demand in traffic
lanes (1) - (6).
50
I
I
I
I
I
I
1
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
v] =
--- - 500 vph and v/c - 0.5
I
I
I
I
I
I
I
I
I
I
I
I
Total 1-hour impact 9 Rl =6.5 ppm
| Point R.2:
From Figure 6,
X-j = 7.4 ppm; x2 = 7-4 ppm
From Figure 7,
X, - 2.6 ppm; x# = 2.6 ppm
Adjustina these values for the appropriate receptor
distance with Fiaure 8,
51
v2 = 500 vph and v/c = 0.5
v? = 500 vph and v/c - 0.5
v4 = 500 vph and v/c = C.5
VR = 200 von and v/c = .67
v6 = 200 vph and v/c = .67
(2) Estimate 1-hour concentrations at each receptor point,
using the 8-hour demands.
Point Rl :
From the c - 1000 vph curve in Figure 3,
;vl = 2.5 ppm
y~ - 2.5 opm
y_ = 2.5 ppm
;/d = 2.5 ppm
Since lane (1) is 17 meters from Rl and lanes (2) - (4'
are 21, 25 and 29 meters away respectively, Figure 5 is used to show
:<1 = (.75) (2.5) = 1.9
>2 = (.67) (2.5) = 1.7
X3 = (.60) (2.5) = 1.5
x/, - (.b5) (2.5) = 1.4
-------
I
= (.59) (7.4) = 4.4
= (.49) (7.4) = 3.6
= (.54) (2.6) = 1.4 I
= (.49) (2.6) = 1.3
Total 1-hour impact ? R2 = 10.7 ppm
P 8 ppm \1600 vphy
Point Rl :
x - (6.5) (0.5) - 3.3 ~ 3 ppm
|
Point R3:
From Figures 9 and 10, xc = 4.6
From Figures 7 and 10, Xc = 1-3
Q ^^m
Total 1-hour impact @ R3 = 6.4 ppm
(3) Estimate 8-hour meteorological persistence factor.
Point Rl: |
Using Equation (1) at location 1, where Monitoring Site
A is located, _
3m~| ^2000 vph^ /^ |
D = .47 ~ .5
Point R2:
Since variation in traffic volume on the east leg of
the intersection is likely to be similar to that at location 1 and the |
location's aerodynamic characteristics are similar, use a persistence
factor of p = 0.5 at location 2 in Figure 1 as well. _
Point R3:
Since there have been no traffic observations at a
similar but existing source and the roughness characteristics are
different at location 3 than they are elsewhere in Figure 1, assume I
a meteorological persistence factor of 0.6 as suggested in Section 4.2.
(4) Apply meteorological persistence factors to estimated £
1-hour impacts to estimate the 3-hour impacts at the selected receptor
points. _
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Point R2:
X = (10.7) (0.5) = 5.4 - 5 ppm
Point R3:
x = (6.4) (0.6) = 3.8 - 4 ppm
Example 5
(a) Purpose. The purpose of this example is to illustrate the
manner in which background concentrations of CO observed near the pro-
posed site during a limited period can be seasonally adjusted and used
to estimate maximum background concentrations appropriate for use in
the screening procedure. The example is subdivided into three parts.
The first part assumes there is a historical monitoring site for CO
operating and that hourly data are available. Part 2 assumes that
only maximum 1- and 8-hour values are available at the historical site.
Part 3 assumes that there are no data available from a historical
station.
Part 1
(b) Problem. Monitoring Site B, at location 3 in Figure 1, is
situated at least 100 meters from any major road, and is operated for
a 14 day period. Monitoring Site C (not shown in Figure 1) is a CO
monitoring station which is maintained independently and has been
operating for a year. During the 14 day period in which Station B is
operating, the maximum 1- and 8-hour CO concentrations observed at
this site during hours in which the proposed site would operate are
4 ppm and 2 ppm respectively. At Site C the maximum 1- and 8-hour
concentrations observed during the proposed source's operating hours
are 16 opm and 4 ppm respectively. During the past year the maximum
1- and 8-hour concentrations observed at Site C during the source's
operating hours are 24 ppm and 6 ppm respectively. What background
concentrations should be assumed for the source in the screening
procedure?
(c) Solution.
(1) Estimate 1-hour background concentration with Equation
(2).
Using Equation (2),
-(4 ppm)
53
-------
I
(2) Estimate 8-hour background concentration with Equation
*
(2) in Section 4.3.1 .
= (2 ppn) (6 PPir.)
(4 ppn'
(b) Problem. Suppose only maximum 1- and 8-hour concentration |
data are readily available from the historical monitoring site. These
data indicate the following for Site C: _
Maximum 1-hour CO concentration during 14 day period is 27 ppm.
Maximum 8-hour CO concentration during 14 day period is 7 ppm.
Maximum 1-hour CO concentration during past year is 31 ppm. ff
Maximum 8-hour CO concentration during past year is 12 ppm.
(c) Solution. Use Equation (2a) in Section 4.3.1.
1-hour
Xb = (4 ppm) (Ir-SSr) = 4-6 " 5 PPm (2a)
8-hcur
Xb = (2 ppm) (^HS = 3.4~3 pom (2b)
Part 3
1-hour
/ \ /600 SBC/ITU r
= (4 ppm) (400 sec/m) 6
I
I
(b) Problem. Suppose Site C, does not exist. Assume, for illus-
trative purposes, the proposed source is located in north central .
North Carolina and the monitoring data at Site B were obtained during
the spring. *
(c) Solution. B
25 "
Note from Figure 43 in AP-101 that the upper tenth percentile
^ in central North Carolina in spring is estimated as about 400 sec/m. I
Q
Also note from Figure 45 that the worst season in terms_pf pollution _
potential in this part of the country is autumn, where x_ ~ 600 sec/m.
(2) Use Equation (3) in Section 4.3.1 to estimate 1- and
8-hour background concentrations. £
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
8-hour
PP-") ^ PP"
Example 6
(a) Purpose. The purpose of this example is to illustrate how
air quality data obtained at proximate monitoring sites (i.e. within
100 meters of the roadway being evaluated) may be used in the screening
procedure to "calibrate" the curves in Figures 2-10 and to estimate
maximum 1- and 8-hour ambient concentrations using the screening procedure.
(b) Problem. Suppose the only available air quality data available
are from monitoring Point A, the proximate monitoring site described in
Example 4. Pertinent data are as follows:
- Point A is located 25 meters from the street being examined
(Example 4) ;
- Maximum 1-hour CO concentration observed during the proposed
source's monitoring hours is 8 ppm (Example 4);
- Maximum 8-hour CO concentration observed during the proposed
source's monitoring hours is 3 ppm (Example 4);
- Maximum expected 1-hour traffic demand occurring on the
major street during operating hours after the source is built
is v, = v2 = 720 vph and v, = v, = 480 vph (Example 1);
- Maximum expected 8-hour traffic demand occurring on the
major street during operating hours after the source is
built is v, = v~ - v, = v» = 500 vph (Example 4):
- 1-hour traffic demand corresponding to the highest observed
1-hour CO concentration during source operating hours was
V1 = V2 = V3 = V4 ~ ^ VP^ (ExamPle 4);
- 8-hour traffic demand corresponding to the highest observed
8-hour CO concentration during source operating hours was
vl = V2 ~ V3 ~ V4 = 40° vph Example 4).
How can the CO data collected at proximate Site A be used to estimate
maximum 1- and 8-hour ambient CO concentrations occurring at receptor
site Rl in Figure 1?
(c) Solution.
(1) Seasonally-adjust the monitoring data.
From Part 1 of Example 5 and the maximum 1- and 8-
hour CO concentrations of 8 ppm and 3 ppm observed at Site A;
1-hour: xb = (8 ppm) (-) = 12 ppm (2)
55
-------
8-hour: xb = (3 ppm) (-») = 4.5 ppm (2)
-------
I
I
1
I
I
X2 - ^-fJ [-33] L4J
.50-, rl
< = (4-5) [^] [i] = 1.
*3 - v-.-y 175-3-j L4
| *. <'*>[;&*. i..
(3) Estimate the "calibrated" contribution of each lane at
a 10 meter distance using Figure 5.
I
1-hour
xl = (^W} = 5'6
xz = (TS^) ^ 5.6
- '2'8^ = 5.6
- 5.6
<4O'
S-hour
.60
I
I
I
I
I
I
I-q. ' .^D'
(4) Mote the incremental change in the impact of traffic
in each lane at the 10 meter distance resulting from the difference
between observed v/c's and the maximum projected v/c's.
1-hour
I For lanes (1) and (2), projected v/c = .72 while observed
v/c = .5.
= 2.2
v/c = .
For lanes (3) and (4), projected v/c = .48 while observed
Using the "calibration" version of Figure 3>
AXl = Ax2 = [4.6 - 2.5] (^f) = 4.7
= Ax4 = [2.5 - 2.5] () = 0
57
-------
8-hour
v/c = 0.4.
8-hour
X-, = 2.2 + 0.2 = 2.4
X2 = 2.2 + 0.2 - 2.4
X4 = 2.2 + 0.2 = 2.4
58
I
I
For lanes (1) - (4), projected v/c = 0.5, while observed I
Using the "calibration" version of Figure 3,
AX-, = AX, = AXo = AX? = [2.5 - 2.0] [0.5] (|4) = 0.2
I *T C. 3 £ . I
I
The "0.5" in the above equation is the meteorological
persistence factor estimated in Example 4. This should be used,
since Figure 3 is applicable for 1-hour concentrations. It was not
necessary to use the persistence factor in Steps (2) and (3) because
the derived values were based on 8-hour observations.
(5) Combine the information in Steps (3) and (4) to estimate
the projected maximum concentrations attributable to each lane at a _
10 meter distance from each lane.
1-hour
X-, = 5.6 + 4.7 = 10.3 *
X2 - 5.6 + 4.7 = 10.3 §
X3 - 5.6 + 0 = 5.6
X4 = 5.6 + 0 = 5.6
I
I
3 = 2.2 + 0.2 - 2.4
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
(6) Use Figure 5 and the information in Step (5) to esti-
mate the projected maximum 1- and 8-hour concentrations at receptor
Rl, located 17 meters from the nearest lane.
1-hour
x-, - (.75) (10.3) = 7.7
X2 = (.66) (10.3) = 6.8
X3 = (.60) (5.6) = 3.4
X4 = (.55) (5.6) - 3.1
Sum = 21.0
Therefore, the estimated peak 1-hour ambient concentra-
tion at receptor point Rl during th proposed source's operating hours
is 21 ppm.
8-hour
X] = (.75) (2.4) = 1.8
X2 = (.66) (2.4) = 1.6
X3 = (.60) (2.4) -- 1.4
x, - (.55) (2.4) = 1.3
Sum = 6.1
Therefore, the estimated peak 1-hour ambient concentra
tion at receptor site Rl including the source's operating hours is
20 ppm, and the estimated peak 8-hour ambient concentration is 6 ppm.
Example 7
(a) Purpose. The purpose of this example is to illustrate the
use of observed background concentrations at representative monitoring
sites in the screening procedure to estimate peak projected 1- and 8-
hour ambient CO concentrations at selected receptor points. The example
is divided into two parts. The first part concerns receptors which are
not located within or immediately downwind from a proposed parking lot.
The second part deals with a receptor point located within a proposed
parking lot.
59
-------
I
(b) Problem. After a joint review between the applicant and
reviewing agency, three sensitive receptor points are selected. These _
are pictured as Rl, R2 and R3 in Figure 1. After seasonally adjusting
background concentrations at representative monitoring Site B (as shown
in Example 5), the maximum background concentrations appropriate for
locations 1, 2 and 3 in Figure 1 are estimated to be 6 ppm for 1-hcur
concentrations, and 3 ppm for 8-hour concentrations. How can this |
information be used in the screening procedure to estimate maximum 1-
and 8-hour CO concentrations at receptor sites Rl, R2 and R3? JM
(c) Solution.
Parti-- Receptors Rl and R2
60
I
(1) Recall the maximum projected impacts estimated from
previous examples.
At Rl
For 1-hour, x = 9.2 ppm (Example 1) I
For 8-hour, x ~ 3.3 ppm (Example 4)
(2) Therefore, the maximum estimated ambient CO concentration
at Rl is:
For 1-hr: x = 9.2 + 6 = 15.2 ~ 15 ppm I
For 8-hr: x = 3.3 + 3 = 6.3 ~ 6 ppm _
At R2 *
(1) For 1-hour, x = 13.8 ppm (Example 2)
For 8-hour, x = 5.4 ppm (Example 4)
(2) Therefore, the maximum estimated ambient CO concentration |
at R2 is:
For 1-hr: x = 13.8 + 6 = 19.8 ~ 20 ppm I
For 8-hr: x = 5.4 + 3 = 8.4 ~ 8 ppm
Part 2--Receptor R3
(1) Recall the maximum projected impacts estimated from
previous examples. |
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
For 1-hour, x = 12.8 ppm (Example 3)
For 8-hour, x = 3.8 ppm (Example 4)
(2) Since it was not feasible to monitor background air
quality within an existing source's parking lot in this example, add
incremental impacts of 5 ppm and 2 ppm to the seasonally-adjusted
1- and 8-hour background concentrations.
For 1 hour: Xk = 6 + 5 = 11 ppm
For 8 hour: Xk = 3 + 2 = 5 ppm
(3) Therefore, the maximum estimated CO concentration at
R3 is:
For 1-hr: x = 12.8 + 11 = 23.8 - 24 ppm
For 8-hr: x = 3-8 + 5 = 8-8 ' 9 ppm
Example 8
(a) Purpose. The purpose of this example is to show how the
effect of CO emission factors differing from those assumed in Figures
2, 3, 4, 6, 7 and 9 is accounted for in the screening procedure. The
example is divided into two parts. The first part deals specifically
with the impact of national emission control programs by assuming that
the emission factors for 1975, used in deriving Figures 2-4, 6, 7 and 9
are not appropriate. The second part shows how the effect of differing
local conditions can be accounted for.
Part 1
(b) Problem. The indirect source pictured in Figure 1 is
scheduled to beoin operation in 1976. What are the estimated maximum
1- and 8-hour ambient CO concentrations which are of interest at
receptor points Rl, R2 and R3?
(c) Solution.
(1) Since the source begins operation in 1976 and the time
of interest is 1 year after the source begins operation (i.e., it is
assumed that the source will not be entirely operational immediately),
the critical time is 1977.
(2) From the second column in Table 2 in Section 4.4.2,
the appropriate correction factor reflecting the status of emission
control programs in 1977 is 0.8.
61
-------
(3) Tabulate the information in Example 7 as shown below:
1
1 Sampling; Component
Point Time , Impact of Nearby Traffic
Rl 1-
8-
i
R2 : i-
! 3-
R3 1-
8-
j
hr. , 9.2
hr. 3.3
l
hr. 13.8
hr. j 5.4
hr. 12.8
hr. 3.8
Background
6
3
6
3
11
5
Estimated
Max. Cone.
15.2
6.3
19.8
8.4
23.8
8.8
(4) Since ambient CO concentrations are almost entirely
attributable to automotive emissions, both the background and nearby
components can be multiplied by 0.8.
Therefore, in 1977
At Rl
For 1-hr
For 8-hr
At R2
x = (15.2) (.8) = 12.2
x = (6.3) (.8) = 5.0
x = (19.8) (.8) = 15.8
x - (8.4) (.8) = 6.7
12 ppm
5 ppm
16 ppm
7 ppm
x = (23.8) (.8) = 19.0 ~ 19 ppm
x - (8.8) (.8) = 7.0 ~ 7 ppm
For 1-hr:
For 8-hr:
At R3
For 1-hr1
For 8-hr:
Part 2
(b) Problem. Suppose the peak demand at the source described in
Part 1 occurs during a time of year when the ambient temperature may
be 20°F. Suppose further it is assumed that the vehicles traveling
on the major street (e.g., at locations 1 and 2 in Figure 1) are all
sufficiently warmed up so that the percent of cold starts is zero.
What are the maximum 1- and 8-hour ambient CO concentrations at
receptors Rl, R2 and R3 during hours in which the proposed source
will operate?
62
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
(c) Solution.
(1) Refer to the table presented in Part 1. Note that the
background concentrations are based on observed air quality data.
Thus, the background component is unaffected by assumptions concerning
percentage of cold starts and altitude. Therefore, the background
component is only affected by the effect of emission controls, while
the impact of nearby traffic is affected by local emission peculiar-
ities in addition to control programs.
(2) Note from Table 1 in Section 4.4.1, the cold start-cold
temperature correction factor to be applied to the impact of nearby
traffic at receptors Rl and R2 is 0.6, and the cold temperature correc-
tion factor at receptor R3 is 1.7.
(3) Therefore, in 1977, with the assumptions which have been
made about the percentage of cold starts and cold ambient temperatures,
At Rl
For 1-hr: x = (9.2) (.8) (.6) + (6) (.8) = 9.2 ~ 9 ppm
For 8-hr: x = (3.3) (.8) (.6) + (3) (.8) = 4.0 - 4 ppm
At R2
For 1-hr: x = (13.8) (.8) (.6) + (6) (.3) = 11.4 ~ 11 ppm
For 8-hr: x = (5.4) (.8) (.6) + (6) (.8) = 7.4 ~ 7 ppm
At R3
For 1-hr: x = (12.8) (.8) (1.7) + (11) (.8) = 26.2 - 26 ppm
For 8-hr: x = (3.8) (.8) (1.7) + (5) (.8) = 9.2 ~ _9
Note: No correction factor for percentage cold starts is
used at location 3 (i.e., 20 percent of the vehicles are assumed to
ooerate from cold starts).
63
-------
I
Example 9
(a) Purpose. The purpose of this example is to illustrate the
application of the screening procedure to estimate the maximum ambient
1-hour CO concentration likely in the vicinity of a proposed event-
oriented indirect source. B
(b) Problem. Suppose the source pictured in Figure 1 is to be
a sports stadium operating in 1976. Seasonally-adjusted 1-hour back- |
ground concentrations are assumed to be 6 ppm at receptors Rl and R2,
using one of the approaches described in Example 5. The following «
estimates are made regarding the traffic volume generated by the source: I
Lane (1): V ] = 220 vehicles
Lane (2): v' = 220 vehicles
I
Lane (3), lane (4): V 3 = V 4 = 0 vehicles
Lane (5) V 5 = 200 vehicles
Lane (6) V g = 0 vehicles I
Assume 50 percent of the vehicles are operating under cold start
conditions by the time location 3 is reached and 0 percent are operating
under cold start conditions at locations 1 and 2. Assume existing demand
on lanes (1) - (4) is 500 vph/lane. Assume the ambient temperature
during the period of peak demand is about 50°F.
(c) Solution.
I
At Rl
(1) Estimate impact without source. Note that without the
source, v/c - 0.5 for lanes (1) - (4). Thus from Figure 3, the impac
of each of these lanes on a receptor 10 meters from each is 2.5 ppm.
(2) Estimate unused capacity. Since existing volume is
500 vph in each lane, and the capacity in each lane is 1000 vph, |
unused capacity is 500 vph/lane.
(3) Estimate the time required for vehicles exiting from
the source and using lanes (1) and (2) to be accommodated. Use
Equation (6).
I
For each lane; T = - = 0.44 hours (6)
(4) Therefore for lanes (1) and (2) assume v/c = 1 for 0.44
hour and v/c = 0.5 for 0.56 hour. For lanes (3) and (4), v/c = 0.5 |
for the entire hour.
Thus, using Figure 3 for a 10 meter distance, I
I
64
-------
I
I
I X-, = (6.2) (.75) = 4.7
I
I
I
I
I
For lanes (1) - (2) x = (2.5) (.56) + (10.9) (.44) = 6.2 ppm
(5) Using Figure 5 to estimate the impact at Rl,
xl
X2 = (6.2) (.66) = 4.1
X3 = (2.5) (.60) = 1.5
X4 = (2.5) (.55) = 1.4
I
I
I
I
I
1
I
I
_ (2) Therefore, unused capacity at the approach (i.e. lanes
(1) and (2)) is 500 vph/lane.
oon
(3) Therefore, T = (^j-) = 0.44 hours (6)
I Note that if the intersection approach capacity were
less than 1000 vph/lane, the proportion of the hour (T) in which demand
equals or exceeds capacity would be greater.
Total impact of nearby traffic at Rl = 11.7 ppm
(6) Apply cold start-cold temperature correction factor.
From Table 1, K = 0.8
Therefore,
Total impact @ Rl = (0.8) (11.7) = 9.4
(7) Add background concentration and apply correction factor
to reflect the status of emission control programs in 1976 to estimate
maximum 1-hour ambient CO concentration expected at the receptor.
xh = 6 ppm, and the appropriate correction factor is 0.9
(from Table 2).
Therefore, at Rl:
x = (9.4 + 6) (0.9) = 13.9 ~ 14 ppm
At R2
(1) Assume, for simplicity, that the intersection approach
capacity is identical to mid-block capacity 1000 vph/lane.
65
-------
X2 = 10-7
X, = 2.7
- .7
Using Figure 8 to estimate the impact at R2,
Total impact @ R2 = (14.4) (.8) = 11.5
(7) Thus the maximum 1-hour CO concentration at receptor
R2 in 1976 is estimated as:
X = (11.5 + 6) (0.9) - 15.8 ~ 16 ppm
At R3
is 300 vph.
(2) This step is not necessary at location 3, because all
of the traffic in lane (5) is assumed to be generated by the proposed
source.
66
I
(4) For lanes (1) and (2) assume v = 1000 vph for 0.44 hr. I
and is 500 vph for 0.56 hr. Assume v = 500 vph the entire hour for "
lanes (3) and (4).
(5) Using Figure 6 to estimate the impact of lanes (1)
and (2) at a 10 meter distance, and Figure 7 to estimate the impact
of lanes (3) and (4) at a 10 m distance,
X] = (.44) (15) + (.56) (7 A) = 1C. 7 *
X4 - . I
X-, = (10.7) (.58) = 6.2 *
X2 = (10.7) (.50) - 5.4 |
x3 = (2.7) (.54) = 1.5
xd = (2.7) (.48) = 1.3 I
Total impact of nearby traffic at P.2 = 14.4 ppm
(6) Applying the apprpriate cold start correction factor,
I
I
(1) From Example 3, note that the capacity cf lane (5)
3) T = () = 0.67 hours (6)
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
(4) For lane (5), v/c = 1 for .67 hour and is 0 for the
remainder of the hour. For lane (6), v = 0 for the entire hour.
(5) Using Figures 9 and 10 to estimate the impact of traffic
in lane (5) at receptor R3,
X5 = (34) (.67) (.74) = 16.9
(6) Note from Table 1, Section 4.4.1 that the cold start
correction factor, K for 50% cold starts is 2.1.
Thus, xc = (2.1) (16.9) - 35.5
J
(7) Combining the approaches illustrated in Example 5 with the
knowledge that traffic at location 3 is only present for .67 of an hour,
xb = 6 + (5) (.67) = 9.3
Thus, x = (35.5 + 9.3) (0.9) = 40.3 ~ 40 ppm
Example 10
(a) Purpose. The purpose of this example is to synthesize the
points illustrated in the previous nine examples so that the estimation
techniques which have been described may be presented in the order in
which they may frequently be applied in the screening procedure.
(b) Problem. Figure 1 depicts a non-event source scheduled to
begin operation in 1976. The source is in a low altitude area outside
of California. It is of interest to estimate maximum 1- and 8-hour
ambient CO concentrations at points Rl, R2 and R3 during hours in which
the source will operate. The table on the following page tabulates
pertinent information needed to apply the screening approach. This
table consolidates information presented in the problem statements
of Examples 1, 3, 4, 5 and 8.
(c) Solution.
(1) Estimate seasonally-adjusted background concentrations
using the information in columns (2) - (7).
TJ6) ^-^^
For 8-hr: x (2) (6) , nnm
b8 [4T~~ ^EHL
(See Example 5 for details.)
(2) Estimate 1-hr impact of nearby traffic at points Rl,
R2 and R3 using information in columns (8), (9), (10) and (12).
67
-------
(D
^
T3
CD
O
O
S-
D-
0)
QJ
S-
u
oo
CU
_c
+J
it-
CD
o
03
O
Q-
Q.
TD
0)
4J
ttf
*J
cfl
Q
~ K 'a
cj\ flj 14-1 4J
H OJ O C
x-' >-, M
c
-~v 01
00 -H &
rH 42 g
^ E <1»
< H
cn
4_>
.--> -a V4
f- ,H to
«H &-S O 4J
*- U C/3
T3
0) ~,
> Q)
^ V-< t-i E
^ QJ £ 3 J3
TH [/) | T t ft
' J5 CO O >
0 >
T3
O -N
. > CU
""i M H E J3
H QJ j= p a,
^^ ' CO 1 rH >
J2 rH 0
0 >
T3 n)
£ a)
3 > G^
sj- -H 0) t- O
rH x ai x: c
s-' nl XJ 1 O
SI o co u
TJ ClJ
e a)
^ D > (2J
c^ e w
iH -H 0) V-< CJ
^ X CO rC C
ca ,£; i o
S 0 -H U
>1
4J
oj cj .C
T-H 03 D
^ &. >
cfl
CJ
a Ai
d) rt
u a)
'-s a P. T3
r~\ QJ C
rH -m 1-* rt JH
^^ O J^ E p
VJ 1 0 P
P-i 00 Q
-T3 ^i
QJ rt
-u a) -a
o &- c -c
/~N a) rt p
o -o H e >
1 0 JS CU
^-- l-i 1 C
P- T-H
,£
- QJ W
c^ C ^
J 3:
0
H 1 C
14-1 OJ M C
,--4-1 C -H -r-
GO rt cfl to 4-
H ^ Q C
(51 r-^
rt v-i
. o rt
-^ co -H S a
i=:o o
. 4-1 QJ JJ
^ « M 4-J «
\D rt >H -H f;
^~^ y4 p^ c/: c
CH> ^H v-
. C] g j:
---, en o &
IT) .O «H P- K
o
-"v ^; j-t cu K
v^- tU Ul 4-1 X
V- ' QJ -H H
c^ pn m --
Tj
QJ QJ
> -t-l
, i-i -H S-
m QJ c/; E 4:
^^ w P-
,n 4-j o. a
O nj
if]
^-> ^ O 1.
CM ra C J^
^-^ QJ O
d, U r-
(1)
Tvpe of
Background
Monitoring
4J
i
H
X
0
VJ
a-
Proximate
1
1
i
D.
a
i.
H
J
j
H
1
8
EX
CX
OJ
4J
H
tn
e
a
a,
QJ
4-1
H
LO
-C
CO
Vj
1
rH
(Ti
rH
T3
iH
O
O
o
o
o
-------
I
At Rl from Figures 3 and 5,
X-, = (.75) (4.6) = 3.5
| X2 = (.66) (4.6) = 3.0
X3 = (.60) (2.4) = 1.4
I X4 = (.55) (2.4) = 1.3
IY = 9 2 DDm
1nr. '-'
(See Example 1 for details)
I At R2 from Figures 6, 7 and 8
X-, = (.58) (10.4) = 6.0
I X2 = (.49) (10.4) = 5.1
X3 = (-53) (2.5) = 1.3
X4 = (-48) (2.5) = 1.2
xl-hr. = ' ' ppm
(See Example 2 for details)
I At R3 from Figures 9, 7 and 10
X5 = (-75) (14.5) = 10.9
X6 - (.74) (2.6) = 1.9
| xl-hr. = 12-8 PPm
(See Example 3 for details)
(3) Estimate 8-hour meteorological persistence factor using
information in columns (13) - (16).
_ _ r3-, ,2000^ = Q>5 for points R] an(j R2> (1)
_ Note that information in columns (13) - (16) may fre-
quently not be available. In such cases, a persistence factor of 0.6
~ may be assumed. A persistence factor of 0.6 is assumed for point R3.
(See Example 4 for details)
I
I
69
-------
I
(4) Estimate 8-hr impact of nearby traffic at point Rl,
R2 and R3 using information in columns (8), (9), (11) and (12),
and Figures 3, 5, 6, 7, 8, 9, and 10.
At Rl : x-, = (-75) (2.5) = 1.9 I
X2 = (.66) (2.5) = 1.7
X3 = (.60) (2.5) - 1.5 I
X4 = (.55) (2.5) = 1.4 -
Xl.hr- = 6.5
XQ hr = t-5' (6-5) = 3.3j3pm I
o - r 11 .
At R2: x-, = (-58) (7.4) = 4.3
X2 = (.49) (7.4) = 3.6 I
X3 = (.53) (2.6) = 1.4 |
X4 = (.48) (2.6) = 1.2 "
Xg_hr_ = (10.5) (.5) = 5.3 ppm
At R3: x5 = (.75) (6.1) = 4.6 |
X6 = (.74) (2.1) = 1.6 -
xl-hr. = 6<2
Xs_hr = (6.2) (0.6) = 3.7 ppm
(See Example 4 for details)
(5) Estimate the maximum 1-hour and 8-hour ambient CO I
concentrations occurring at point Rl, R2 and R3 taking into consideration
cold temperature-cold start and emission control correction factors. Mote
that a correction factor for 1977 is used since this is the first year
after the source starts operation.
Using the information in columns (1),(17), (18) and (19), the I
maximum 1- and 8-hour ambient concentrations at Rl, R2 and R3 are
estimated as follows:
70
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
At R1:
X]_hr = (9.2) (.8) (.6) + (6) (.8) - 9.2 ~ 9 ppm
X8_hr = (3.3) (.8) (.6) + (3) (.8) = 4.0 ~ 4 ppm
At R2:
X]_hr - (13.6) (.8) (.6) + (6) (.8) = 11.3 ~ 11 ppm
x8-hr = (5'3) (>8) ('6) + (3) ('8) = 4'9 ~ 5 PPm
At R3:
X-,_hr = (12-8) (.8) (1.7) + (11) (.8) = 26.2 - 26 ppm
x8-hr = (3'7) ('8) (1'7) + (5) (>8) = 9'° ~
(See Examples 7 and 8 for details.)
Example 11
(a) Purpose. The purpose of this example is to illustrate how the
screening procedure can be extended to estimate a representative CO
concentration along a sidewalk centerline.
(b) Problem. Suppose it is of interest to estimate the worst
representative CO concentration at breathing height along a sidewalk's
centerline which is 5 meters from curbside. The sidewalk is adjacent
to a 2-lane road over a block which is 300 meters long (see sketch on
the following page). The intersection at one end of the block (inter-
section 1) is signalized with G/Cy = 0.6 and a cycle length of 120
seconds. The other intersection (intersection 2) is non-signalized,
with a STOP sign serving as the means of traffic control. Assume each
lane is 5 m wide. The following traffic data are given:
V7 = 1000 vph
vg = 400 vph
Non-signalized intersection capacity = 500 vph.
Assume midblock capacity is controlled by the intersection
capacities so that
c7 ~ 1200 vph
Cg ~ 500 vph
What is the representative impact of the adjacent roadway on CO concen-
trations along the sidewalk centerline?
71
-------
ROADWAY
CURB
fc «
R4 R5 5m
o ^
INTERSECTION
1
ZONE
«V| ^^
^~s
MIDBLOCK
ZONE
^ X? 1
inn m
(
R6
r*\
f~-
W
INTERSECTION
2
ZONE
"c X3 ^»-
(c) Solution.
(1) Divide block into three zones.
Zone 1 = signalized intersection zone.
Zone 2 - midblock zone.
Zone 3 = unsignalized intersection zone.
(2) Use Equation (7), Section 6.1 to estimate size of zone 1.
X] =
= 107 meters
(7)
(3) Use Equation (8), Section 6.1 to estimate size of zone 3.
,2
(400'
[500
3 [500 (500 - 400)
8 = 26 meters
(8)
Estimate midblock zone size.
X2 = 300 - 107 - 26 = 167 meters
(Note that as congestion becomes greater, the block
becomes increasingly dominated by the intersection zones.)
72
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
(5) Estimate maximum concentrations in each zone.
(a) For R4:
X7 = 15 ppm (From Figure 6)
X8 = (2.5) (1.22) - 3.1 ppm (From 25 mph curve
Figures 7 and 8)
Therefore,
= 18.1 ppm
(b) For R5_:
X7 = 9.4 ppm (From Figure 3)
xg = (2.5) (1.22) = 3.1 ppm (From Figures 3 and 5)
Therefore, XDC = 12.5 ppm
(c) For R6_:
X7 - 2.5 ppm (From Figure 7)
X8 - (12.5)0.22) = 15.3 ppm (From Figures 9 and 10)
Therefore,
= 17.8 ppm
(6) Estimate weighted average of zonal concentrations.
(18.1)007) + (12.5)(167) + (17.8)(26)
xRep 300
xRep
15 ppm
The analysis can be extended to estimate 8-hour concentra-
tions. The procedure would be to reidentify the zones estimated in
steps (l)-(4) above using the hourly average traffic demands for the
8-hour period of interest. Next, procedures outlined in Section 4.2
and illustrated in Example 4 may be used to estimate the maximum CO
impacts in each zone. Finally, the weighted average of the zonal
impacts is estimated as in step (6) above.
73
-------
I
4.7 Summary of the Screening Procedure
Figure 11 is a flow chart illustrating the screening pro-
cedure for the review of the impact of a proposed indirect source on I
ambient carbon monoxide concentrations. The screening technique
proceeds as follows:
1. Obtain and review information received from the applicant I
concerning projected 1- and 8-hour traffic demands and capacities at
locations in the vicinity of identified key receptor points. |
2. Assuming there is no continuously operating representa-
tive CO monitoring site in the vicinity of the proposed source, obtain
background concentration data from the applicant.
3. Seasonally adjust background data as described in Section
4.3.1 and in Example 5, Section 4.6. If the background monitoring site |
is within 100 meters of a major existing road being evaluated, proceed in M
"calibrating" the curves in Figures 2-10 and estimating 1-hour and (for
non-event sources) 8-hour ambient CO concentrations as described in Section I
4.3.2 and in Example 6 in Section 4.6. Preferably, however, the
background data should be obtained at a representative site at least |
100 meters from any major existing road. If this is the case, proceed
as described in the remaining steps.
4. Estimate the impact of nearby traffic lanes on 1-hour I
CO concentrations at selected receptor points. Estimates are made
using Figures 2-10 as described in Section 4.1 and in Examples 1-3 |
in Section 4.6. If the source is an event-oriented one, such as a
74
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Q)
J-
3
a
ai
o
o
s_
QJ
GJ
S-
O
ai
co W
rd S-
O
oo QJ
<->
' 00 QJ
-a
OJ
o
ai
-5-1.
O oo rcj
S- "O V
ro
co
X QJ .
rO CZj 4J
I- T3
o I _j JT
-
-------
-Q
n
x
o
o
S-
M-
-------
I
I
I
I
I
I
I
I
I
I
I
X
o
.Q
o
S- o3
O
1- to
+->
CO S-
S- ro
O +->
4-> 00
O
rO T3
U- .
O
O
S-
S- "
O co CO
o ) 3
. +-> Q
Q. rC E
Q_ S_ ro
ct O) X
-
*-~^
rC
,
'
X
o
_a
£
O
s_
O- LU
o e
*-> CD C
1 -^
CO
-4-* "T3
oS C C
- « Q) (O
ro < "t^
ro -Q *3-
i (/)£
+-> -r-
ai c 4->
CO O r
Z3CJ.cC
1
"^
1
T (
w I
O)
+-*
o
as o
r" i
a>
l/> "O
£
*-> 1C
ro
C7>
CO «
E
LU
4^>
*^-^ ^^^* 13
cy
i- CO
^:
i c:
CO
o<3 CO
ro
I
CO i
+J
+J c i
c '-
a.
03
+-> o
co at
LU a:
O)
3
c
o
u
a>
s_
3
T3
a>
o
o
i_
D.
O.
CL
ro
03
cz
-o
at
co
c >>
O -(J
o
ro
«=i: c
01
ai co
r- (U
> "O
ra
-->
GJ
U 03
o o
to c_3
77
-------
I
sports stadium, revise the analysis as described in Section 4.5 and
as shown in Example 9 in Section 4.6. m
I
5. If the source is not an event-oriented one, derive
an 8-hour meteorological persistence factor. Use this factor with
the projected 8-hour traffic demands, and apply Figures 2-10 to
estimate the impact of nearby traffic on ambient 8-hour CO concen- |
trations at the selected receptor points. This procedure is described _
in Example 5 in Section 4.6. *
6. Apply cold temperature-cold start and altitude correction
factors (obtained from Tables 1 and 2) to the estimated impacts of nearby
traffic, as needed. Apply a correction factor reflecting the status I
of emission control programs (as appropriate) to both the estimated _
impact of nearby traffic and the seasonally-adjusted observed background
concentration. This procedure is described in Section 4.4 and in
Example 8 in Section 4.6.
7. Add the estimated impact of nearby traffic to the I
estimated background concentration to obtain estimated 1- and 8-hour
ambient CO concentrations at all receptor points of interest. This
procedure is described in Section 4.4 and in Examples 7, 9 and 10
in Section 4.6.
8. If the conservative screening procedure indicates the
National Ambient Air Quality Standards will be met at all selected
receptor points, it may be assumed that the proposed source will not
pose a threat to the ambient CO standards. If the NAAQS is exceeded
at one or more of the selected receptor points, the applicability of
i
i
-------
I
I
the assumptions used in deriving the screening procedure should be
reviewed. These assumptions are described in Section 6.0. Depending
_ on the outcome of this review,
(1) The source could be redesigned in some manner and
the screening procedure could be reapplied, or
(2) A detailed modeling analysis, using meteorological,
m emission and traffic assumptions specifically applicable for the
source under consideration, could be initiated.
5.0 ECONOMIC AND DESIGN CONSIDERATIONS
There are three types of costs associated with indirect source
review. These are:
(1) Cost of data acquisition and application preparation;
(2) Time-related costs, and
H (3) Cost of design changes necessitated by indirect source
review.
Information concerning each of these costs has been compiled in a
I
I
I
I
OQ
regulations which has been prepared for EPA. It is strongly
report on the economic and land use impact of the indirect source
I
I
recommended that indirect source reviewing agencies become familiar
with the contents of this report and the insight it provides concerning
basic concepts and principles governing the real estate development
industry.
79
-------
I
5.1 Data Acquisition and Application Costs
The following estimates are provided so that reviewer and
applicant alike may have an indication of the scope of effort
envisioned for various levels of analysis.
Effort Approximate Cost
1. Obtaining traffic data not already available, I
filling out the application form and applying
the screening procedure described in Section
4.0 without air quality monitoring data. $3000. V
2. Obtaining and reducing 14 days of air quality
monitoring data collected at one site. $6000.
3. Performing a complete modeling analysis
including the costs of monitoring meteoro- _
logical, air quality and traffic data at
several locations, and computer costs
required to use observed data in an atmos-
pheric dispersion model.28 $35,000-$50,000. I
5.2 Time-Related Costs
These costs accrue from the delay and uncertainty which may
be introduced by regulatory programs or other factors such as bad
weather, labor problems or shortages of key construction materials.
Time-related costs can, in some cases, greatly exceed even the costs
of a complete modeling analysis. For example, in six case studies
90
examined in the previously cited report, estimated time-related
costs associated with an assumed three month delay in construction
for large projects (i.e., $25-125 million) exceeded the cost of a
complete modeling analysis by an order of magnitude. Of particular
importance is the developer's own capital ("front-end money") which
I
must be invested before a loan can be secured from a savings and
80
I
I
-------
I
loan institution. The ease with which such a loan can be obtained
(so that the developer's money can be reinvested) depends upon,
among other things, amount and length of uncertainty associated with
indirect source review. Degree of uncertainty is particularly
crucial during times when credit is "tight." Time-related costs
are further aggravated by inflation, high interest rates once a
loan is secured and shortages in building materials resulting in
less flexibility in delivery dates. It should be readily apparent,
from the brief preceding discussion, why it is essential to minimize
delays occasioned by the processing of indirect source review appli-
F cations. To minimize such delays, indirect source reviewing agencies
should make every effort to develop close working relationships with
other agencies (e.g., State and local highway departments) which may
become involved in the review procedure.
5.3 Design Changes
The costs associated with changes in design necessitated
by analysis of a proposed source's impact on ambient air quality
depends on: (1) the degree of the problem identified in the analysis,
and (2) the measures selected to eliminate the unacceptable impact
I on air quality. Obviously, the first consideration is highly variable,
i resulting in costs ranging from zero all the way up to prohibitive
levels which would make the project infeasible. Essentially, design
I changes involve measures reducing or redistributing traffic demand
during critical periods, or measures increasing the capacity of the
proposed facility or surrounding road network to accommodate traffic.
I
I
-------
Alterations in traffic demand and/or capacity could be effected
threat to CO standards.
5.3.1 Traffic Demand Determinants
82
I
by changing certain operating procedures (e.g., providing for
traffic supervision during peak use periods, altering direction of
flow, etc.) or design features at the source or in its vicinity.
There are a number of ways in which design and/or operating changes m
could be made. The following is a list and description of some
important determinants of traffic demand and capacity which might
be altered in order to improve traffic flow and thereby reduce the I
I
Existing and future through traffic demand on roadways m
adjacent to or within an indirect source are determined by two factors:
(a) The existing future area wide arterial and/or
expressway system, and
(b) The potential for activity growth in the vicinity I
of the site.
Traffic demand generated directly by the source itself is dependent
upon the following design and operational parameters:
(a) Size and nature of attractions (e. g., tenant mix
for shopping centers, type of activities offered at recreational areas, |
etc.); m
(b) Operation of the source (e. g., opening times,
special event days, time and scheduling of special activities such
as sales or sporting events, employee working schedules);
I
1
I
-------
I
M (c) Split of transportation modes (e. g., bus, rail,
pedestrian, automobile, etc.).
I The traffic distribution to the source and using any single nearby
roadway is determined by:
| (a) Geographical location of the source with respect
» to trade area population and area road network;
(b) Predominating levels of service on the roadways
I comprising the road net;
(c) Number and design of entrances serving the source.
5.3.2 Traffic Capacity Determinants
« Traffic capacity at entrance/exit gates and at
* at-grade intersections may be altered by changing one or several of
the following factors:
(a) Intersection Geometries
(1 ) Turning radii .
A (2) Number of lanes.
(3) Lane widths.
fl (4) Presence of turning lanes.
(5) Storage distances for turning lanes.
(6) Presence of parked vehicles.
m (7) Lateral clearance.
(3) Grade.
(9) One-way or two-way streets.
I
I
I
-------
84
I
(b) Traffic Controls
(1) Type of control (e.g., traffic signal,
stop sign, yield sign, policeman, etc.).
(2) Operation cf controls. These considerations I
include signal phasing, green tine to signal cycle ratio, signal cycle
length, signal actuation progression (i.e., how well successive signals
are coordinated) and presence of right- and/or left-turn signals. a
(c) Nature of Traffic Demand
(1) Number of trucks.
(2) Number of buses .
(3) Number of turning vehicles (left and right)
vs. number of through vehicles. m
(4) Surging effects (peak hour factors, land
factors) and their impact on congestion on successive road segments.
(d) Environmental Factors
(1) Population in area (i.e., is area urban,
rural , etc?) . m,
(2) Location (central business district, fringe
area, outlying business district, residential, rural).
( e ) Entrance/Exit Gate Controls
(1) Manual vs. automated issuance of parking |
tickets (with or without parking gate controls). M
(2) Manual vs. full or semi-automated collection
of parking fees at exit gates. M
I
-------
I
I
(3) Self-service vs. attendant method of parking
ft operation.
(f) ^ehj^cle^Moyerent/ClrcuTatjon Inside Indirect Sources
(1) Type of narking facility (i.e., short term,
long tern, nix of both, etc.).
(2) Internal functional efficiency of parking
facility (i.e., circulation pattern, one- vs. two-way movement, parking
stall sizes and layout, directional and informational signing, pre- vs.
exit-cashiering, etc.).
ft 6.C ASSUMPTIONS USED IN THE SCREENING PROCEDURE
In order to develop the reasonably simple methodology relating
ft traffic demand, capacity and demand-capacity ratios to CO concentrations,
. it has been necessary to sacrifice flexibility in evaluating a source's
impact by making a number of assumptions. These assumptions are enumer-
ated in this section. Since it is necessary that the screening procedure
provides reasonable assurance that the NAAQS are protected, most of the
I assumptions are conservative ones. In cases where it is relatively easy
_ to adapt the procedure presented in Section 4.0 to different assumptions,
ft this is so indicated. Where different assumptions may not be so readily
ft incorporated in the screening procedure, it may be necessary to refer to
Appendix H and the appropriate one(s) of Appendices A-G to estimate the
impact of a proposed source on ambient air duality.
I
ft 85
I
-------
I
I
6.1 Meteorological Assumptions
A. Wind speed--A steady wind speed of 1 m/sec was assumed fl
in deriving Figures 2-10. Estimates of 1-hour CO concentrations can
be adapted for different wind speeds by dividing the concentration I
obtained with the figures by the wind speed. For example, if a
1-hour concentration of 10 ppm were estimated and the wind speed were
2 m/sec, the 1-hour concentration estimate would be revised to 5 ppm.
The adaptation of the screening procedure to account for wind speeds
exceeding 2 m/sec can only be extended to 8-hour concentrations if a
persistence factor is derived specifically for observations occurring
near the proposed source site. These observations must reflect
variations between observed 1- and 8-hour CO concentrations which occur
when the wind speed during the hour in which the peak 1-hour concen-
tration is observed corresponds closely to that assumed in the metho-
dology. Since persistence is not independent of wind speed, the
arbitrary value of "0.6" cannot be used unless verified directly by
observation for higher 1-hour average wind speeds near the site.
B. Wind directionA wind direction making an angle of 10°
with the roadway was assumed in deriving the free-flow curves in
Figures 2, 3, 4, 7 and 9. For a long line source of pollution, this wind
angle is believed to be among those resulting in highest concentrations
at nearby receptors. The curves in Figure 6 and the queuing curve
in Figure 9 are the result of a series of analyses of concentrations
occurring with different wind angles. This approach was necessi- V
tated, because the impact of queues at intersections occurs over a
86
I
-------
1
relatively short distance and is best represented by a finite line
source. Therefore, "edge effects," resulting in the dilution of
emissions in the finite line source with relatively clean air, can play
an important role in determining CO concentrations at receptors located
^ near a roadway. The importance of edge effects depends on the length
of the queue and the downwind travel distance between the roadway and
the receptor point. The downwind travel distance, in turn, depends on
the wind angle and perpendicular distance between the roadway and
receptor point. For a given perpendicular distance, the smaller the
wind angle, the greater the travel distance. This concept is sketched
below for receptor points located a perpendicular distance of 20 m
from the road, wind angles of 10° and 90° and a queue length of "L."
ff CASE (A) 0 = 10°
10°
I^~~~T~^~~~"~*^-
\ * L ^
\ '
I< f
' <
20m ~~~~2 |p-
1C] *10 / "~~ """"-- C\
u 4 ^J
Rb 7 Ra
Iy (MAX. IMPACT
DOWNWIND TRAVEL OCCURS HERE)
DISTANCE IS 11 5m
1
1
CASE (B) 0 = 90°
J
90° 1
* I »
i >
] 1
; /^|-^ DOWNWIND TRAVEL
' /90°JL DISTANCE IS 20m
Rb Ra
(MAX. IMPACT
OCCURS HERE)
1
-------
L =
v
c(c-v)
(8)
downwind travel distances. For greater downwind travel distances,
the edge effects become so great that the impact of the queue is negligible
88
I
I
An adaptation of the "Red Time Formula" was used in estimating the
average queue length resulting during the red phase at signalized |
21
intersections. _
i/(i_ R/rv'in ft
Lv \ i / ~*.y / / °7 \ ^B
= * [ I j
CPH "
where L = queue length, meters;
v = traffic demand, vph;
G/Cy = green time to signal cycle ratio, dimensionless; |
D = spacing between successive vehicle tailpipes in the **
queue, assumed to be 8 m/veh;
CPH = number of signal cycles per hour.
An adaptation of a formula from classical queuing theory was used
29
for non-signalized intersections. W
|
I
where c = capacity, vph, and the other symbols are as defined
for Equation (7).
Equations (7) and (8) indicate that for low demand-capacity ratios
and demands, the average queue length (L) is short. Under such
circumstances, edge effects become important even with very short
I
1
I
-------
I
Thus, there is a trade-off between the (a) high concentrations
resulting with small wind angles but having relatively great edae
effects, and (b) low concentrations accompanying large wind angles
| but having relatively minor edge effects. In order to provide a
£ conservative evaluation of the impact of queues (represented as finite
line sources), a wind angle of 90° was assumed for queue lengths of
V 25 meters or less, and a series of wind angles decreasinc from 20°
to 10° were assumed for increasing queue lengths greater than 25
jf meters.
C. Atmospheric Stability--Pasqui11-Gifford Stability-
Class 0 is assumed in the line source model (HIMAY) used to
derive the curves in Figures 2-10. « value of 1.5 meters is
used for the initial vertical plume speed parameter (r ) in HIHAY.
Assumption of the Class D Pasquill-Gifford stability class as a
v/orst case was made because the indirect source-parking management
review programs are likely to focus on urbanized areas. Increased
atmospheric turbulence, attributable to a greater degree of surface
roughness and increased convective turbulence in such areas, are
likely to make plurne spread predictions based on Pasquill-Gifford
stability classifications (which are based on observations in open
country) overly conservative. A dispersion study conducted in
St. Louis" indicated that for downwind distances ranging from
about 1000-10,000 meters, observed plume spread occurring at night
I
I
I
I
II
I
I
-------
I
with meteorological conditions indicative of Class E and F stability
in rural areas corresponded approximately with that estimated using
Pasquill-Gifford Stability Class D stability. The previously
31
referenced study' indicated a tendency for the Pasquill-Gifford
plume spread curves to become increasingly conservative as
downwind travel distances decreased. Therefore, in general, an m
assumption of Pasquill-Gifford Stability Class D is believed to be m
conservative for most areas in which indirect source review will
occur. It should be emphasized, however, that after appropriate
data are reviewed for a proposed site by a trained meteorologist,
more or less stable conditions than Pasquill-Gifford Class D may |
be appropriate.
The value of a =1.5 meters, used in the EPA
street with trees or either side have indicated greater vertical
D!lime spread immediately downwind from a highway which may be
generated by vehicular motion (at the expressway) or by surface
roughness (at the residential street). This implies in some cases,
larger a values may be appropriate in the immediate vicinity of
90
1
HI HAY model, is representative of the lower range of values observed
30
from a limited data base. v Subsequent studies conducted in the
3' 1
vicinity of an expressway " and in the vicinity of a residential p
^
I
roadways than are currently used in the HIWAY Gaussian line source _
model. On the other hand, however, the a value used in HIWAY *
does have an empirical basis, and the model was able to simulate fl|
I
I
-------
I
I
I
1
I
I
I
I
_
1
I
I
I
I
CO concentrations observed in the vicinity of a suburban intersection
*""" T
quite well/ The data which have been reported to date are not
believed sufficient to warrant revising the assumption about
o7 in the HIWAY model. On the basis of the limited data available
at the present time, however, there are indications that the assump-
tion of a =1.5 meters is conservative.
n. Persistence of Constant. Meteorological Condi_tjo£rs_--
The relationships between traffic and nearby CO concentrations depicted
in Figures 2-10 are based on the assumption that the unfavorable
meteoroloqical conditions described above will persist for at least
an hour during periods in which the source will be utilized at peak
levels. The persistence factor which should be used in estimating
8-hour concentrations is an acknowledgment that such conditions are
not likely to persist for 8 hours. The figure ''0.6," which is
suggested for use if it is infeasible to derive a persistence
factor reflecting local meteorological variability, is an empirical
20
factor based on a limited data base. The value was derived by
noting the ratio of 8-hour to 1-hour maximum concentrations at a
receptor in the vicinity of the major entrance/exit qate to a
regional shopping center on days in which the hourly average wind
speed accompanying the maximum observed 1-hour concentration was
less than 2 m/sec. Next, the corresponding traffic volume flow
rates (in veh/hr) were recorded for the selected 8-hour and 1-hour
91
-------
S-. = vehicle operating speeds at gate (road segment) i,
lane j , mph
(EF). . = speed-dependent CO emission factor for vehicles
' J
92
I
periods and factored out. After account was taken of differences V
in traffic demand, the resulting ratio between the 8- and 1-hour
maximum CO concentrations at the exit gate was assumed to be |
attributable to meteorological changes over the 8-hour period. _
The largest observed ratio was about "0.6." *
6.2 Emission Assumptions
A. Free-flow Line Source Emission IntensityEquation (9)
was used to estimate emission intensity for an infinitely long line £
source of freely flowing traffic (used in deriving the "free-flow"
curves in Figures 2-4 and 9).
where q.. = line source emission intensity at exit gate (road m
segment) i, lane j, gm/sec-m
v.. = traffic volume demand at gate (road segment) i, V
lane j , vph
I
operating at S . ^ in lane j at gate (road segment) i, V
gm/min-veh
(1.036 x 10~") = conversion factor from 4-2 r- to gm/sec-m
mi n-m i
B. Line Source Emission Intensity Arising from Queues »
------ - _ ------ |
1 . S i g n a 11 zed I n t e r j> e c ti p r^ Ap proa c h e s . The metho-
dology used at these locations is similar to that used in Reference 21.
1
I
-------
I
_ Emissions arising from queues are regarded as the sum of three components:
" a component attributable to cruising vehicles, a component resulting from
I accelerating and decelerating vehicles, and a component resulting from
idling vehicles. The first component is assumed to occur over an infi-
J[ nitely long line source. The second and third components are manifested
over a finite line source whose length is estimated using Equation (7).
* Equation (9) is used to estimate the emission intensity which would result
if all vehicles comprising the traffic demand were cruising past the inter-
section at a given intersection approach speed. Appropriate intersection
|| approach speeds were estimated using empirical relationships between mid-
_ block volume-capacity ratios and vehicle operating speeds on major
22
streets. Midblock capacity was assumed to be (2000)(G/Cy)(# of Lanes).
The second and third components are regarded as "excess emissions"
occurring over the finite queue length as a result of acceleration/
£ deceleration and idling. The intensity of the acceleration/deceleration
_ component is:
m q..
(EFTij
5Q
^ where q. . = line source emission intensity gm/sec-in;
D = spacing between successive vehicle tailpipes,
assumed to be Sm/veh;
(EF). . = average emission factor for an accelerating and
I'J
decelerating vehicle over the estimated queue
« length, gm/min-veh;
G/Cy = green time to signal cycle ratio, dimensionless:
IcrT = conversion factor from min~ to sec~ .
ou
1
93
-------
I
The intensity cf the idling component is:
(0.5) (EF)^ (1 - G/Cy) |
qij = ~~COD ^]1'
v/here (EF).^ = the CO emission factor for idling vehicles,
' -> ^B
Qp'/min-veh
C/Cy = green tine to signal cycle ratio, dirrensionless
D = spacinq between successive vehicle tailpipes, m
assumed to be Grp/veh
0.5 = constant denoting that the average vehicle ir «
the queue is only there for 1/2 the signal's
red phase, dimensionless. IV
'- ^'on-Signalized Intersection Approach. The queuing
curve in Figure 9 was obtained by assuming that, on the average over |
the entire period of interest, the average queue length rray be estimated .
using Fouaticn (8). The intensity of this finite line source is:
(EF)iJ *
qij = "^ 02) f
where (EF)^ = sveraqe trip emission factor for vehicle speeds |
about 0 rr.ph: gn/min-veh. ^
The other terms are as defined in Equation (11).
Note that (EF).. in Equation (12) is not the sane as the idle emission V
1J "
factor used in Equation (11). The emission factor in Equation (12) is
rrcre appropriate for stop-and-start traffic likely to be found ir, very |
congested locations or unstreen' fron a toll booth or1 "STOP" sign.
94
I
I
I
-------
I
C. Emission Factor AssumptionsThe CO emission factors
assumed in deriving Figures 2-4, 9 and 10 were obtained by using the
emission factor information for a national average mix of vehicles
(by model year) derived from Supplement Number 5 to AP-42 for the
n C
calender year 1975 and speed correction factors from the same reference.
It is assumed that 20 percent of these vehicles are operating from a
cold start and approximately 88 percent of the vehicle mileage is
^ attributable to light-duty vehicles and 12 percent is the result of
light-duty trucks. Emission factors in the correct units (gm/min-veh)
0 were obtained using Equation (13).
I
rr - (ef) (c(s)) (vehicle speed) (13)
-' ~ 60
where ef = composite emission factor for calendar year 1975,
qm/mi-veh
c(s) = sneed correction factor from Supplement Number 5
I to AP-42, dimension!ess
vehicle speed - miles/hour
EF = emission factor, gn/rnin-veh
1/60 = conversion factor from hr~ to min"
The emission factors obtained using Equation (13) appear
in Tables 3-5 in Section 6.3. Emission factors (gm/min-veh) for
vehicle speeds less than 5 mph were estimated by extrapolating a
curve plotting EF vs. vehicle speed. The emission factor corres-
por.dinq to an average trip speed of 0 mph using this procedure was
20 gm/min-veh. This factor was assuned ir deriving the queuing curve
V in Figure 9.
I
I
95
-------
96
I
I
The emission factors used in derivino Figures 6 and 7
wore estimated using the Automobile Exhaust Emission Modal Analysis A
34
Model. ' Combinations of vehicle operating modes used in the model
1
were similar to observed traffic in the vicinity of a signalized
21
intersection. Since the Automobile Exhaust Emission Modal Analysis
Model assumes that there are no vehicles operating from a cold start, ft
a correction factor was applied to the estimates obtained with the ^
model to reflect an assumption of 20 percent cold starts. This was done
so that all the curves in Section 4.1 reflect consistent assumptions ft
about the percentage of cold starts. The ambient temperature was
assumed, to range from 68°F-86°F in deriving the curves in Section 4.1. |
Correction factors for cold starts and cold temperatures, «
appearing in Table 1, were obtained using procedures outlined in
26 «
Supplement Number 5 to AP-42. These procedures are, in turn, based
Or oc ^^
on published data' '" reflecting the impact of differing ambient
temperatures on emissions from cold and warmed-up vehicles using the f
27
1975 Federal Test Procedure. A cold soak period of 4 hours is ^
suggested as a guide to ascertain whether cold operation of vehicles *
oc i^^
is significant. Data concerning this question are not extensive at
"D "7 O O ^^^
present. Other data' ' indicate that increased CO emissions attributable
to cold starting vehicles in cold temperatures essentially all occur J
within the first 4 minutes of operation. ^
The correction factors for national emission control *
programs and altitude were obtained by first estimating CO emission ft
I
I
-------
I
factors for a typical nationwide mix (by model year) of vehicles for
a mix in Denver and for a mix in California for each of the indicated
calendar years. These factors were obtained by following the procedures
OC
recommended in Supplement Number 5 to AP-42. The emission factors
thus obtained were divided by the factor 55 gm/mi-veh, considered
appropriate for a national average mix of vehicles in 1975 (composed
of 88 percent light-duty vehicles and 12 percent light-duty trucks)
to obtain the correction factors in Table 2.
m 6.3 Traffic Assumptions
In estimating the emissions from free-flowing traffic, it is
V necessary to assume values for representative vehicle operating speeds.
Relationships between volume-capacity ratios and operating speeds on
various types of roadways with specified average highway speeds can be
22
m estimated from the Highway Research Board's 1965 Highway Capacity Manual
providing it is assumed that traffic on the roadway is being accommodated
at the maximum level of service consistent with the indicated v/c ratio.
This procedure was followed in derivina Fiqure 2 for freeways and
I"
expressways and Fiqure 3 for major streets. Actual observations of
speed-volume relationships for a qiven road under review would, of
course, be preferable. For the free-flow curves, it was assumed that
demand-capacity ratios were identical with volu_m_e-capacity ratios.
This assumption implies that, 'aider free-flow conditions, traffic i_s_
moving at the maximum level of service consistent with the specified
volume-capacity ratio. Thus, it is possible to estimate operating
I
I
I
97
-------
It is not possible to relate operating speeds to volume-
capacity ratios for traffic lanes within indirect sources with the given
20
state of the art. It has been noted at a regional shopping center that
I
I
speed on a roadway given the demand-capacity ratio. The combinations
of operating speeds and demand-capacity ratios used for arterial streets |
and expressways, along with the corresponding levels of service and CO
emission factors, appear in Tables 3 and 4.
vehicle speeds average from 11-15 mph with little congestion. These ^
average speeds included time spent stopping at signalized exit/entrance
gates. Since it was reasonably consistent with observations, a speed
of 15 mph was assumed in deriving the free-flow curves in Figure 4.
The resulting CO emission factor used in deriving the free-flow curves J
in Figure 4 is presented in Table 5. _
In deriving and using Figures 6-8 to estimate the impact
of traffic at signalized intersections, assumptions concerning the
green time to signal cycle ratio, signal cycle length and approach
speeds have been made. If detailed information concerning the green I
time to signal cycle ratio and the degree of signal progression between
successive signals is not known but it is known that the approach is
on a major street, a G/Cy = 0.6 is suggested for use. The rationale for
this is that the indirect source review will focus on times and locations
where projected traffic demand is greatest. A traffic-actuated signal
apportions green time according to traffic demand; so it is reasonable
to assume that more green time will be available to the intersection »
98
I
-------
I
I
_
I
I
I
I
I
I
I
I
I
I
I
I
Table 3. ASSUMED OPERATING SPEEDS, LEVELS OF SERVICE AND DEMAND-CAPACITY
RATIOS FOR "1AJOR STREETS AND CORRESPONDING EMISSION
FACTORS FOR FREE FLOW CONDITIONS
Assumed Demand- Level CO emission
operating capacity of factor,
speed(mph) ratio Service qm/min-veh Description
30
25
20
15
15
<_ 0.60
0.70
0.80
C. 90
1.00
A
B
C
D
E
17.2
17.6
18.1
18.6
18.6
Completely free flow
Stable flow (slight delay)
Stable flow (acceptable delay)
Approaching unstable flow
(tolerable delay)
Unstable flow (congestion,
intolerable delay)
99
-------
Table 4. ASSUMED OPERATING SPEEDS, LEVELS OF SERVICE AND DEMAND-CAPACITY
RATIOS FOR URBAN EXPRESSWAYS* AND CORRESPONDING EMISSION
FACTORS FOR FREE FLOW CONDITIONS
Assumed Demand-
operating capacity
speed (MPH) ratio
57 0.1
55 0.2
53 0.3
50 0.4
47 0.5
45 0.6
42 0.7
40 0.8
37 0.9
30 1.0
*
Average highway speed
Level CO Emission
of factor
Service gm/min-veh
A 16.0
A 16.0
A 16.1
A 16.2
B 16.3
C 16.3
C 16.4
C 16.5
D 16.6
E 17.2
assumed to be 60 mph
100
Description
Completely free flow
Completely free flow
Completely free flow
Completely free flow
Stable flow (upper
speed range)
Stable flow
Stable flow
Stable flow
Approaching unstable flow
Unstable flow
1
1
1
I
I
1
1
1
1
1
1
1
1
1
1
1
-------
I
I Table 5. ASSUMED OPERATING SPEEDS AND DEMAND-CAPACITY RATIOS FOR
- TRAFFIC LANES WITHIN INDIRECT SOURCES AND
" CORRESPONDING EMISSION FACTORS FOR
fl
FREE FLOW CONDITIONS
Assumed Demand- CO Emission
operating capacity factor,
speed (mph) ratio gm/min-veh
15 0-1.0 18.6
I
I
I
I
I
I
I
I
I
I
I
101
-------
I
leg having the heaviest demand. For a major street, it is unlikely
that the intersecting road will have as great a demand as the approach J|
being reviewed. In addition, any kind of coordinated signal progression «
among signals with fixed cycles would exert the same impact on queue
lengths and emissions as an increased G/Cy (i.e., fewer vehicles would V
arrive during the red phase). A more conservative G/Cy ratio of 0.5
is suggested for an approach on a local street or at an exit to an |
indirect source. In such cases it is possible that the traffic demand _
on the intersecting road (which could be a major street) may be as *
great as that on the local street or exit lanes, even during hours W
of peak demand on the smaller streets, and well -coordinated signal
progression may be less likely. p
For most demands, a signal cycle length of 120 seconds was _
used in deriving the curves in Figure 6. This number represents a
value at the upper range of signal cycle lengths found at fixed-time
signals, and about in the middle of the range commonly found at traffic-
39
actuated signals on arterial roads. " Near the highest volume theo-
retically possible for a signalized intersection (estimated by multi-
plying a nominal lane capacity of 2000 vph by the green time to signal
cycle ratio), a cycle length of 180 seconds was assumed. This value is
representative of the upper range of cycle lengths for traffic-actuated
signals. Longer-than-average cycle lengths were used, because they are
22
most likely to occur with higher traffic demands. In addition, the
impact of queuing appears to be greater with longer cycle lengths.
A third assumption concerning approach speed is needed if
it is not feasible to determine volume-capacity ratio at midblock. The
suggestion to use 30 mph for major streets is based on speed limitations
102
tt
I
-------
I
which may frequently prevail on such streets and the wide range of v/c
ratio for which this speed is assumed in Table 3. The suggestion to
assume a cruising speed of 15 mph for traffic lanes within indirect sources
20
is made on the basis of observations made within a major shopping center.
I 6.4 Assumptions Used in Evaluating Background Concentrations
Background concentrations of CO are the result of:
P (1) General urban background levels of CO, and
_. (2) Increases in general urban background levels due to
* vehicular activity in and around the indirect source but not in the
V immediate vicinity of the receptor.
The value of "5 ppm" suggested in Section 4.3.3 for adding
to the maximum observed 1-hour CO concentration at the site of a
proposed source was obtained by comparing observed 1-hour CO values
at monitoring sites near the upwind edge of a regional shopping center's
^H 9fl
ft parking lot with those near the downwind e.dge of the lot. The com-
parisons were confined to periods in which the wind speed was less than
p 2 m/sec and to stations which were located within the parking lot but
not in the vicinity of entrance/exit gates. The value "5 ppm" is
* representative of the larger differences observed between upwind and
downwind sites, and is assumed to represent the impact of emissions
within the parking lot. The "2 ppm" value to be added to the observed
8-hour maximum concentration was obtained by multiplying the "5 ppm"
1-hour value by a meteorological persistence factor of 0.6 and by a
ratio of peak 8-hour traffic demand to peak 1-hour traffic demand of
0.67. The basis for the "0.6" persistence factor has been described
in Section 6.1. The "0.67" value is based on a report prepared for
I4Q
EPA on traffic characteristics in and around regional shopping centers.
103
-------
I
7.0 REFERENCES
(1) 40 CFR 52; "Approval and Promulgation of Implementation Plans:
Review of Indirect Sources"; Federal Register; (July 9, 1974), p. 25292.
(2) 40 CFR 52; "Approval and Promulgation of Implementation Plans:
Proposed Amendments to Parking Management Regulations"; Federal
Register; (August 22, 1974); p. 30440.
(3) 40 CFR 51; "Preparation, Adoption, and Submittal of Implementation 0
Plans: Maintenance of National Ambient Air Quality Standards";
Federal Register; (June 18, 1973), p. 15834.
(4) U.S. EPA, Office of Air and Waste Management, Office of Air Quality V
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 1: Designation of Air Quality Maintenance Areas" |
EPA-450/4-74-001, (September 1974); Air Pollution Technical Information _
Center, Research Triangle Park, N. C. 27711. *
(5) U.S. EPA, Office of Air and Waste Management, Office of Air
Quality Planning and Standards; "Guidelines for Air Quality Maintenance
Planning and Analysis, Volume 2: Plan Preparation"; EPA-450/4-74-002; J
(July 1974); Air Pollution Technical Information Center, Research _
Triangle Park, N. C. 27711.
(6) U.S. EPA, Office of Air and Waste Management, Office of Air V
Quality Planning and Standards; "Guidelines for Air Quality Maintenance
Planning and Analysis, Volume 3: Control Strategies"; EPA-450/4-003; |
(July 1974); Air Pollution Technical Information Center, Research ^
Triangle Park, N.C. 27711. "
I
104
I
I
-------
I
(7) U.S. EPA, Office of Air and Waste Management, Office of Air Quality
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 4: Land Use and Transportation Considerations";
EPA-450/4-74-004; (August 1974); Air Pollution Technical Information
Center, Research Triangle Park, N. C. 27711.
(8) U.S. EPA, Office of Air and Waste Management, Office of Air Quality
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
£ and Analysis, Volume 5: Case Studies in Plan Development";
m EPA-450/4-74-006; (In preparation); Air Pollution Technical Information
Center, Research Triangle Park, N. C. 27711.
(9) U.S. EPA, Office of Air and Waste Management, Office of Air Quality
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 6: Overview of Air Quality Maintenance Area
Analysis"; EPA-450/4-74-007; (September 1974); Air Pollution Technical
Information Center, Research Triangle Park, N. C. 27711.
(10) U.S. EPA, Office of Air and Waste Management, Office of Air Quality
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 7: Projecting County Emissions"; EPA-450/4-74-008;
(September 1974); Air Pollution Technical Information Center, Research
Triangle Park, N. C. 27711. .
m (11) U.S. EPA, Office of Air and Waste Management, Office of Air Quality
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 8: Computer-Assisted Area Source Emissions
Gridding Procedure"; EPA-450/4-74-009; (September 1974); Air Pollution
m Technical Information Center, Research Triangle Park, N. C. 27711.
105
I
-------
I
(12) U.S. EPA, Office of Air and Waste Management, Office of Air Quality §
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 9: Evaluating Indirect Sources"; EPA-450/4-75-Q01;
(January 1975); Air Pollution Technical Information Center, Research
Triangle Park, N. C. 27711.
(13) U.S. EPA, Office of Air and Waste Management, Office of Air Quality I
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 10: Reviewing New Stationary Sources";
EPA-450/4-74-011; (September 1974); Air Pollution Technical Information
Center, Research Triangle Park, N. C. 27711.
(14) U.S. EPA, Office of Air and Waste Management, Office of Air Quality I
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 11: Air Quality Monitoring and Data Analysis";
EPA-450/4-74-012; (September 1974); Air Pollution Technical Information
Center, Research Triangle Park, N. C. 27711.
(15) U.S. EPA, Office of Air and Waste Management, Office of Air Quality I
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 12: Applying Atmospheric Simulation Models
to Air Quality Maintenance Areas"; EPA-450/4-74-013; (September 1974). mm
Air Pollution Technical Information Center, Research Triangle Park,
N. C. 27711. f
(16) U.S. EPA, Office of Air and Waste Management, Office of Air
Quality Planning and Standards, Volume 13: Allocating Projected Emissions |
to Sub-county Areas"; EPA-450/4-74-014; (In preparation); mm
Air Pollution Technical Information Center, Research Triangle Park,
N. C. 27711.
106
I
-------
I
(17) "Assessment of Photochemical Oxidant and Nitrogen Dioxide
Ambient Concentrations from 3-C Plans"; Volume 1 - Guidance Manual
(January 1975); Volume 2 - Technical Backup Document (April 1975);
Under preparation for U.S. EPA, OAQPS, Strategies and Air Standards
Division, Research Triangle Park, N.C. 27711.
» (18) U.S. EPA, Quality Assurance and Environmental Monitoring Laboratory,
"Carbon Monoxide Measurements in Vicinity of Shopping Centers";
I EPA-450/3-74-048; (April 1973): Air Pollution Technical Information
Center, Research Triangle Park, N. C. 27711.
(19) Bach, W. D., B. W. Crissman, C. E. Decker, J. W. linear, P. P.
Rasberry and J. B. Tommerdahl; "Carbon Monoxide Measurements in the
Vicinity of Sports Stadiums"; EPA-450/3-74-049; (July 1973); U.S. EPA,
fl Air Pollution Technical Information Center, Research Triangle Park,
N. C. 27711.
(20) Patterson, R. M., R. M. Bradway, G. A. Gordon, R. G. Orner,
_ R. W. Cass and F.A. Record; "Validation Study of an Approach
* for Evaluating the Impact of a Shopping Center on Ambient Carbon Monoxide
Concentrations"; EPA-450/3-74-059; (August 1974); U.S. EPA, Air Pollution
Technical Information Center, Research Triangle Park, iM. C. 27711.
(21) Patterson, R. M. and F. A. Record; "Monitoring and Analysis of
_ Carbon Monoxide and Traffic Characteristics at Oakbrook"; EPA-450/3-74-058;
(November 1974); U.S. EPA, Air Pollution Technical Information Center,
Research Triangle Park, H. C. 27711.
(22) Highway Research Board; "Highway Capacity Manual 1965"; Special
§ Report 87; NAS-NRC; Washington, D.C. (1965).
107
I
-------
I
(23) 40 CFR 50.1 (e); "National Primary and Secondary Air Quality E
Standards: Definitions"; Federal Register 36; (November 25, 1971);
p. 22384. |
(24) U.S. DHEW; Public Health Service, National Air Pollution .
Control Administration; "Air Quality Criteria for Carbon Monoxide";
NAPCA Publication Number AP-62; (March 1970): Washington, D. C.
(25) U.S. EPA Office of Air Programs; "Mixing Heights, Wind
Speeds and Potential for Urban Air Pollution Throughout the Contiguous £
United States"; Office of Air Programs Publication Number AP-101; _
(January 1972); Air Pollution Technical Information Center, Research
Triangle Park, [I. C. 27711.
(26) U.S. EPA, "Compilation of Air Pollutant Emission Factors";
Publication Number AP-42; Supplement #5 to the Second Edition; |
(In Press.); Air Pollution Technical Information Center, Research
Triangle Park, N. C. 27711.
(27) 40 CFR 85; "1975 Federal Test Procedure," Federal Register 36,
No. 128; (July 2, 1971).
(28) U.S. EPA, Office of Planning and Evaluation; "Report on the |
Economic and Land Use Impact of Regulations to Review New Indirect
Sources of Air Pollution Prior to Construction"; To be available
through the National Technical Information Service, Springfield,
Virginia, 22161.
(29) Hillier, F. S. and G. J. Lieberman; Introduction to Operations |
Research; Holden-Day, Inc.; San Francisco, California (1967), Chapter
10.
108
I
I
I
-------
I
(30) Zimmerman, J. R. and R. S. Thompson; "User's Guide for
« HIWAY: A Highway Air Pollution Model"; Environmental Monitoring
" Series EPA-650/4-008; National Environmental Research Center, U.S.
EPA, Research Triangle Park, N.C. 27711; (In preparation).
(31) McElroy, J.L. and F. Pooler, Jr.; "St. Louis Dispersion
Q Study Volume II--Analysis"; NAPCA Publication Number AP-53;
(December 1968); U.S. EPA, Air Pollution Technical Information
* Center, Research Triangle Park, N. C. 27711.
(32) Clarke, J. F. and K. F. Zeller; "Tracer Study of Dispersion
from a Highway"; Paper presented at the Symposium of Atmospheric
J[ Diffusion and Air Pollution; American Meteorological Society;
_ (September 9-13, 1974); Santa Barbara, California.
* (33) Smith, J. H., W. B. Johnson, F. L. Ludwig, R. E. Inman, L. A. Cavanagh
and L. Sal as; Air Quality Impact Study for Proposed Highway Widening Near
Ojai ; Part 1-A; Chapter V, "Microscale Tracer Experiment"; Report prepared
for State of California Dept. of Transportation and the Federal Highway
Administration, SRI Project 2852, Contract J-7290; (July 1974).
(34) Kunselman, P., H. T. McAdams, C. J. Domke and M. Williams;
"Automobile Exhaust Emission Modal Analysis Model"; EPA-460/3-74-005;
(January 1974); National Technical Information Service; Springfield,
I Virginia 22161.
(35) Williams, M. E., J. T. White, L. A. Platte and C. J. Domke;
"Automobile Exhaust Emission SurveillanceAnalysis of the FY 72 Program";
EPA-460/2-74-001 ; (February 1974); National Technical Information Service;
Springfield, Virginia 22161.
I
109
-------
I
I
(36) Ashby, H. A., R. C. Stahman, B. H. Eccleston and R. W. Hum;
"Vehicle EmissionsSummer to Winter"; Paper Number 741053 Presented *
at the SAE Automobile Engineering Meeting, Toronto, Canada; II
(October 21-25, 1974); Society of Automotive Engineers, Inc.;
400 Commonwealth Drive, Warrendale, Pa. 15096. J
(37) Miles, D. L. and M. F. Homfeld; "The Effect of Ambient Temperature _
on Exhaust Emissions of Cars with Experimental Emission Controls"; *
Paper Number 741052 Presented at the SAE Automobile Engineering Meeting,
Toronto, Canada; (October 21-25, 1974); Society of Automotive Engineers,
Inc.; 400 Commonwealth Drive, Warrendale, Pa. 15096. B
(38) Grinberg, L. and L. Morgan; "Effect of Temperature on Exhaust _
Emissions"; Paper Number 740527 Presented at the SAE Combined Commercial
Vehicles and Fuels and Lubricants meetings; Chicago, Illinois; (June 17-21,
1974); Society of Automotive Engineers, Inc.; Two Pennsylvania Plaza,
New York, New York 10001. £
(39) Johnson, B. C.; Barton-Aschman Associates, Inc.; Chicago,
Illinois 60626. Personal communication.
(40) Thayer, S. D. and K. Axetell, Jr.; "Vehicle Behavior in and
Around Complex Sources and Related Complex Source Characteristics
Volume IShopping Centers"; EPA-450/3-74-003-a; National Technical
Information Service, Springfield, Virginia 22161.
I
I
no
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
APPENDIX A. METHODS FOR ESTIMATING EMISSIONS FROM HIGHWAYS
This appendix is intended to provide guidance concerning a
more detailed analysis of proposed indirect sources should
this be necessary or desirable pursuant to 40 CFR 52.22(b).
The materials contained herein are offered as suggestions.
Alternate analytical approaches for evaluating the impact
of a proposed source may be used if it can be demonstrated
that they are more applicable to the source under review.
U. S. Environmental Protection Aaency
Office of Air Quality Planning and Standards
Research Triangle Park, N. C. 27711
January 1975
A-i
-------
-------
I
I
I
I
I
APPENDIX A.
METHODS FOR ESTIMATING EMISSIONS FROM HIGHWAYS
The purpose of this Appendix is to assist air pollution control
agencies or developers in estimating CO, HC, and NO emissions resulting
from the use of a new or improved highway. In accordance with Federal
regulations on indirect sources, the estimated emissions may then be used
as a basis for determining whether construction and operation of one or
| more sections of the highway is consistent with the applicable SIP require-
_ ments (macro-analysis). In addition, the estimated emissions may be used
to assess the impact of the highway and its access roads on ambient CO
tt concentrations in the immediate vicinity of the right-of-way (micro-analysis)
It should be acknowledged from the outset that there is a wealth of
information concerning the operation, design and environmental impact of
highways which has been published by the Federal Highway Administration
* and professional journals in the field of traffic engineering. Some of these
B references are documented in the section on supplemental references. It
should also be pointed out that there are a great many potential environ-
| mental impacts other than air quality attendant with the construction or
_ improvement of a highway. These are discussed in some detail in EPA's
~ "Guidelines for Review of Environmental Impact Statements, Volume 1, Highway
o
W Projects." The analysis herein has the more limited objectives of relating
key highway design and operating variables to emissions. Estimated
emissions may then, ultimately, be related to air quality using procedures
similar to those outlined in Appendix H.
A-l
-------
I
This appendix presents Procedures for estimating emissions for macro- _
and micro-analyses of a hiahway's impact on air duality in sections AI and
All. These summaries are then followed by discussions of how the information
needed to implement the procedures might best be obtained.
"Macro-analysis" addresses the impact of the source on emissions over
2
areas which are usually thought of as at least 1 km . "Micro-analysis"
4. Obtain HC and NO emission factors (ef) for the appropriate year
X
I
I
pertains to estimating CO emissions so that the distribution of CO concen-
trations in the immediate vicinity of the roadway nay be estimated. Such an
analysis is primarily of interest in determinina peak CO concentrations to
which people are likely to be exposed.
AI. Procedure for Fstimating Emissions from Highways for Macro Analysis
1. Obtain the design and operating parameters indicated in Table ^1 m
from the applicant. Consider each direction separately, and divide the
highway into segments as determined by access roads or changes in design.
2. Determine whether Eq. (AA) or (A5) is appropriate to estimate I
emissions. If Eq. (A5) is acceptable proceed as indicated below. If Fc.
°> I
(A4) must be used, follow the procedures in Supplement Number 5 to AP-42"
to estimate emission factors for light and heavy-duty vehicles separately.
Correct for cold start percentages differing from 20C= and for ambient
4
temperatures, differing from those used in the Federal Test Procedure,
using factors presented in Section 4.4 of the screening procedure or
3 I
techniques presented in Supplement Number 5 to AP-^2.
3. Obtain segment lengths (d,) from plans.
I
I
from Table A3.
5. Obtain traffic volume demand (v.) for each road segment durino
A-2
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
usina Fo. (A7). Obtain averane fraffic volume demand for each road
seonent, usir.a Fo. C*-9] .
f . If rnass transit has not been considered, replace the volume
Demands obtained in Eos. ("7) or (A9) vn'th those obtained vn'th Fas.
(f-°) or C\9a).
7. I-F the caoacitv r,f each, road secn'ent (c.} is rot orcy'd^, :-'se
Fq. (A10) arc Tables A5 and ^F, to estimate (c,. ^ . Thpn use Fi auras AZ',
i
/\?% AU or ^5 to estirrate the averane cperatir.n sr,eeH in each son^ent
oiven the averaae h.ichwav soeed and v./c..
°. Mse the oneratincj speeri to estimate the sceec correction factor
(c(s).) obtained usinc Table 3.1.2-ba in ^uonlepent Number 5 to AP-^2."
9. Calculate the total HC and '.'0 , emissions ^ron the ^io'^wey
A
usino Equations C\5) or (AA).
lr. Co'TioarP1 the emissions estimated usinr1 steos 1-3 uith the erissions
Vv'hich would occur if the hiahway were not built, in order to estimate the
net ir'oact of" the hinhway on total en-issions.
AIT. Procedure for F. sti>ating Cr'is sions *gr Micro Analysis of a
1. Estimate traffic den:and for each "ane i in ^oad seonent i usiric
Fqs. (A12) cr (Al'i). If necessary, adjust the der'and for the impact o^
irass transit usina Fns. (A1O or (A15). Apportion derand aronr lanes
based on local conditions, rakinq sure that Fa. ("2; is satisfied.
':. If the analysis dees not concern an at-nra'Je intersection,
estimate capacity of the road secrr>ent usinn Fa. (Alri) anr the lane capacities
usino Fa. (A16). Check that Fq. (A3) is satisfied. I£ not, adjust the
lane capacities so that Fq. (A3) is satisfied.
3. Oeterrine volume to capacity ratios (v.,./c.,. ) for «-v.cu lane.
A- 3
-------
I
f. piiven the type of road and the average hiqhway speed, use the
appropriate one of Fiaures A2-A5 to estimate operatinq speeds (S..) for
each lane.
5. Use Figure A6 to estimate the speed-corrected emission factor
(FF).. for each lane. For years other than 1975, adjust this emission I
factor usina Equation (M7). Correct for cold start and ambient temperatures
usino Section ^.4 in the screeninn orocedure or Supplement Number 5 to AP-42.
If local emission factor data are available, multiply the factor thus obtained
by an appropriate local correction factor.
6. Use Equation (All) to estimate the line source emission intensity
(q) for each lane of traffic.
7. For at-orade sionalized intersections, use information concerning |
signal cycle lennths and green time to signal cycle ratio to estimate queue
lennths with Fq. (A18). Consider emissions over the nueue to be the sum of
emissions resultina from freely flowing traffic and excess emissions. Else- I
where emissions are attributable to freely flowing traffic. Calculate excess
emissions using Eq. (A19). Alternatively, use the information in Tables |
A°.-A12 directly tc estimate appropriate emissions and queue length. «
ft. For non-siqnal ized intersections, estimate average queue
length usinc Fq. (/^20). Use Eq. (A21) to estimate the emission intensity
over the queue at the intersection approach. Estimate the distance over
which vehicles may accelerate and decelerate using Fq. (A22). The |
emission intensity over this distance is estimated usinq Eq. (A23). ^
Use FQ. (All) to estimate emission intensity elsewhere.
£. 111. Identification of Key design and Operating Variables
^ny methodology annearina in a set of Federal guidelines must
necessarily be oeneral in scone. Therefore, these guidelines should |
I
-------
I
I serve the Purpose of identifying highway design and operating variables
to which emissions are most sensitive. Determination of the values of
key design, and operating variables is heavily dependent on local
conditions. Therefore, it is necessary that these parameters be assessed
on a case-by-case basis by personnel familiar with traffic engineering
I concepts. Once values for the key variables are estimated, they can be
related to emissions using the methodology described herein.
Table Al presents key variables which ideally should be supplied by the
developer or appropriate highway department for the analysis to proceed. Road
segments may be conveniently defined as the portions of roads between adjacent
exits/entrances. In analyzing the impact of a highway on air quality, it is
desirable to divide the highway into seoments, because the traffic volume
demand and the nature of the traffic (i.e. number of trucks, etc.) are likely
to chanae from segment to segment. Such chanaes, in addition to imposing
varying demands on the capacities needed to avoid congestion (arid the
resulting higher emissions), may actually affect the capacity itself. For
example, if one segment has more truck traffic than another, its capacity
will he less, all other factors beina equal. Traffic capacity per lane per
road segment is ? key (lesion parameter, because it provides a means for
determining when traffic volume demands will result in congestion thereby
causino high emissions. Design speed is primarily of importance in
determining speeds (and therefore emission factors) undpr various volume
I
I
I
I
demand-to-capacity ratios. Vehicle speed and volume ^emand-to-capacity retics
determine the level of service occurring en a road. pinht-of~way is of
Level of service is the degree of operational freedor available
on the highway.
-------
Table Al . KTY PIGI-'HAY OFSIH!; AMD OPERATING VARIAPLFS
FPP FSTIMATING VEHICULAR Ef''Ir,S
V_a riable
Traffic Capacity per lane per
Road Seqment (including
mercie lanes).
Remarks
A road segment is ordinarily that portion
of a highway between adiacent entrance/ey'ts.
Capacity is consistent with Level of ^ervice F
Desinn Speed
This variable \vculd ordinarily be the
posted speed limit,
Rinht-of-Wav and Median width
Number of Lanes per Road Segment
Access Roa^ Capacity per Lane Consistent with Level of Service F
Number of Lanes per Access
Road (For key access roads)
and number of merge lanes
A key access road wou^d ordinarily be one
in which traffic volume demand approaches
access road capacity.
Annual Average Daily Traffic
(AADT) for each seament
Even more desirable would he the AADT per
lane per segment if the demand is exnected
to be substantially different for different
lanes in a seament.
Seasonal, Meekly and Diurnal
Use Patterns
Estimated Peak 1-hour, 8-hour
Traffic Volume Demand per
Road Segment
Vehicle Mixes Utilizing
Segments
For example, age mixes and proportions of
light, medium and heavy-duty vehicles.
A-6
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Table Al (continued)
Variable
Plans or Blueprints of the
Highway, its Route and Access
Roads
Remarks
Needed to identify road sepments for each
direction.
Average Highway Speed
Weighted average of design
speeds within a highway segment
Green time to Signal
Cycle Ratio
Used in estimating capacity at
intersections
Cycle Length
The sum of time a traffic signal soends
in each phase of the signal cycle.
Useful in estimating gueue lengths
upstream from intersections
Location of the road segment
evaluated
Central business district, fringe
areas, outlying business district,
residential, rural areas
A-7
-------
I
interest in selecting sensitive receptor sites. Ordinarily, such a M
site would not occur within the right-of-way. Number of lanes per road
segment is important to know in applying a line source diffusion model to I
estimate CO concentrations in the vicinity of the highway. In addition,
number of lanes per segment is one of several determinants of the segment's |
capacity and would be needed to estimate capacity if estimates of this «
parameter were not directly available. Number of lanes and capacities
for access roads are imoortant, because the oeak impact of a major high- |
way may occur at sensitive receptors in the vicinity of on- or off-ramps.
The three operational parameters (AADT, use rate patterns and peak demands) |
are important for two reasons: .
1. As an estimate of the sheer numbers of vehicles using road segments. *
2. As an indicator (along with capacity) of whether congestion is V
likely.
The vehicle mix utilizing each segment is a determinant of the appro- |
priate emission factor per segment as well as the segment's capacity. _
AIV. Scope of Analysis and Basic Concepts
Table A2 summarizes the types of analyses reguired for highway fl
projects of various sizes.
Table A2. TYPES OF ANALYSES REQUIRED FOR HIGHWAY PROJECTS |
I
Macro and Micro Only Micro Analysis in
Analysis Required SMSA's Required M
Construction of
a new Highway Anticipated AADT* >_ 50,000 Anticipated AADT >_ 20,000
Modification of I
an existing Anticipated Increase in Anticipated Increase
Highway AADT >_ 25,000 in AADT >_ 10,000
*Annual Average Daily Traffic, vehicles/day |
A-8 |
-------
I
Figure Al is a schematic drawing of one segment of one direction of
an 8-lane highway. In Figure Al, the v's represent volume demand
m (vph). The first numerical subscript refers to the road segment, while
the second numerical subscript refers to the lane within the segment. The
first lane is defined as the outside lane. The letter subscripts are
interpreted as follows: "x" stands for exiting traffic; "e" stands for
entering traffic, and "t" stands for through traffic. The "d's" in Figure
Al represent the length of a given road segment. For any road segment, the
traffic volume demand is given by Eq. (Al).
v = v. T , +v. -v. (Al)
i ,t i-l,t i,e i ,x ^ '
Thus for road segment 1 in Figure Al,
- vlt = vot+vle - vlx (Ala)
* Also, for any road segment, the traffic volume demand is the sum
B of the demands in all the lanes.
m
v.. = £ v. .
'it "V-, vijt (A2)
or, as applied to Figure Al,
vlt = vllt + V12t + V13t + 14t (A2a)
m The traffic volume demand can be determined for a segment if a
direct estimate is provided by the developer or if estimates for all
preceding exit and entrance demands are known and an estimate of the
traffic volume demand entering the area of interest (i.e. v .) is
provided. It would be most convenient if the traffic volume demands were
I A-9
I
I
-------
U UJ
111 >
oc <
CD
_c
CD
CD
E
CD
CO
c
CD
E
CD
i_
O)
CD
y
(-<
CD
E
o>
^:
CJ
CO
A-10
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
approximately the sane for each lane, i'nfortunately, this frequently
may not he the case. For example in Figure Al, if lane 4 were desianated
as a mass transit (bus) lane and lane 1 were used primarily by exit and
entrance traffic, there mioht be an appreciable difference in traffic
volume demand among lanes. Hiven the information which is usually
available however, it may only he possible to identify traffic flow by
direction. Information about the amount of traffic enterina and
exitino (or turninq on arterial roads) may be used as a basis for more
refined apportionments in each direction if such information is available.
Making reference once again to Fioure Al, with similar notation, the
following definitions and relationships apply with respect to capacity.
I
"
"c-." is the capacity of lane j in segment i.
°it ~~=] CiJt (A3)
or for Fiqure Al ,
clt = cllt + C12t +C13t +C14t
8 Capacity is determined by a number of factors, many of which can only
be determined upon examination of plans including information about
g such considerations as volume demands and capacities on succeedina road
seoments, demands and capacities on access roads, and presence of
turning or exit/entrance lanes. In addition to determinants of capacity
which can only be determined upon study of detailed plans, there are
several determinants whose effects can be gauged on a more general
P basis. These include such operating and design parameters as lane
width, lateral clearance, percentage of trucks utilizing the hiahway,
desiqn speed and grade.
A-ll
-------
I
AV. Estimating Emissions for Macro Analysis
With the basic concepts, definitions and relationships presented
in Figure Al and Equations (AT) - (A3) in rnind, the procedure described
below may be used to derive emissions from the proposed new or improved
highway. Emissions may be estimated using Equation (A4). I
. )(ef) (c(s)). (N.) (A4) I
I
." ldv V
1=0 1=0
where
(ef), . = emission factor from light-duty vehicles (including 88" auto-
mobiles and 12% light-duty trucks), operating at an average
speed of 19.6 mph during the calendar year of interest,
gm/mi-veh.
c(s)., = speed correction factor to emission factors applicable to I
road segment i for light-duty vehicles (use information
Number 5 to AP-42 ). Assume the relationships for model
compiled in Tables 3.1.2-6a and 3.1.2-6b in Supplement
I
year 1972 hold for later models as well.
v- = volume demand for light-duty vehicles, vph.
d- = length of segment i, mi.
(ef),jnu = emission factor from heavy-duty vehicles (trucks, buses)
nUV
gm/veh-mi.
c(s)., = speed correction factor for heavy-duty vehicles. Unless
information is available to the contrary, use the same
speed correction factors as for light-duty vehicles.
N- = volume demand for heavy-duty vehicles, vph.
n = number of road segments in the area of interest.
Q =\ejriission rate from all road segments, qm/hr.
A-12
-------
I
I
I
I
If the projected vehicle nix for the highway appears to be dominated
by light-duty vehicles, Eq. (A4) can be simplified as expressed in
Equation (A5).
In
0=z (d )(ef)(c(s}) (Vl) (A5)
i=o i
where
ef = average emission factor for the calendar year of interest,
gm/mi-veh.
c(s), = speed correction factor.
v. = volume demand (all vehicles on road segment i), vph.
If the mix of model years is typical, Tables A3 may be used to estimate
emission factors (ef) for various calendar years. If the projected traffic
* mix for a hiohway indicates that this simplified procedure is net appro-
o
priate, Supplement Number 5 to AP-42 should be consulted. The resulting
emission factors would then be used in Equation (A4). For illustrative
purposes, the subsequent analysis assumes that the simplifying assumptions
are reasonable and that Equation (A5) may be used.
Eq. (A5) could be simplified still further provided the operatinq
fl conditions and mix of traffic which would utilize the new or modified
highway are not sianificantly different from that usino the existing
P configuration of roads. Instead, "equivalent vehicle miles traveled
_ (EVMT)" may be estimated using Eq. (A6) and compared with the EVMT
which is estimated for the case in which the highway is not built.
EVMT =l (d.) (c(s).)(v.) (Af)
i=o
A-13
-------
Table A3. COMPOSITE EMISSION FACTORS BY CALENDAR YEAR ASSUMING
88 PERCENT LDV TRAVEL AND 12 PERCENT LOT TRAVEL (NO HDV)
I oji__AHJJ_yrV_. 'ion-California
PoTJutrtnt,
Cj lender -Year
1975
1976
1977
1978
1979
1980
Calendar-Year
1975
1976
1977
1 978
1979
1980
CO
55.0
48.2
42.0
35.8
29.9
24.1
High Altitude
Pollutant
CO
97.2
86.4
77.3
6C.9
56.0
45.6
HC1
5.3
4.8
4.3
3.8
3.2
2.8
, Non-Cali
, gn/ini
HC1
7.1
6.5
5.8
5.2
4.5
3.8
HC!
2.3
2.3
2.2
2.1
2.1
1.8
fornia
3.0
2.8
2.7
2.6
2.4
2.3
NOX
4.0
4.0
3.8
3.4
3.0
2.6
3.0
3.2
3.2
3.0
2.7
2.4
California
Calendar-Year
1975
1976
1977
1978
1979
1930
*
Pollutant
co.
53.9
44.9
41 .4
33.8
28.5
23.3
, cim/mi
HC1
5.2
4.7
4.2
3.6
3.1
2.7
1 _ .. .1 _ J, L .-
HC2
2.2
2.1
2.1
2.1
2.1
1.8
._.._i. j, i i r\
3.8
3.6
3.4
3.1
2.6
2.4
Reflects interim emission standards through the 1977 model year and
statutory standards thereafter. If amendments to the Clean Air Act proposed
in March 1975 hecore law, Appendix D in Suoplenient 5 to AP-42 should be used
to derive new factors for 1978 and later years.
Excludes evaporative and crnnkcase hydrocarbons. Speed correction
factors apply.
o
Evaporative and crankcase hydrocarbons. Speed correction factors
do not apply. /\_]
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
A. Length of Road Segments (d.)
This parameter would be determined directly from the plans
provided by the developer. Each direction would be considered
separately in dividing the road into segments.
I B- Emission Factors (ef)
I
Emission factors for the appropriate year should be obtained
3
from Table A3 or from AP-42. These factors are appropriate for
"average" trip speeds, and reflect the combination of acceleration,
deceleration and constant-speed traveling used in the 1975 Federal
14
Test Procedure. If information were available about the likely pro-
portions of time to be spent in different operational modes (e.g.
acceleration, deceleration, constant speed), a more satisfactory
procedure would be to combine emission factors for each mode in accordance
with each mode's relative importance to obtain average trip emission
factors.
C. Traffic Volume Demand (v.)
The traffic volume demand estimate which should be used in
Eqs. (A5) or (A4) depends upon the applicable standard for the
pollutant of concern. In any case however, projected traffic volume
demand should reflect diverted and induced traffic as well as possible.
Diverted traffic is the result of trips which are diverted from other
' road(s) to the new or modified highway. For example, the presence of
the highway might make it much more convenient to utilize shopping
center A rather than shopping center B which is located in a different
area. The result is an increase in traffic along the route caused by
A-15
I
-------
I
people formerly using different routes to arrive at shoppinq center
B. Induced traffic is caused by attractions building up along the route
of the highway and nenerating trips. The amounts of diverted and induced
traffic depends entirely on local conditions, so that only qualitative
suggestions for their determination can be provided here. The economic- m
demographic determinants of traffic demand enumerated in Section 5.0
in "Guidelines for the Review of the Impact of Indirect Sources on
Ambient Air duality" should be checked for relevance. Land use and
other maps plotting census information may orovide additional insight
in estimating diverted and induced demand.
1. H£
Total non-methane hydrocarbons are primarily of
interest, because they appear to be precursors of oxidants. Therefore,
in estimating hydrocarbon emissions from highways, one is indirectly
assessing the effect of a highway's presence on oxidant concentrations.
The standard for hydrocarbons is for 3 hours which must be met between
the hours of 6 A.M. - 9 A.M. in areas where there is difficulty in
meeting the oxidant standard. Hence, one period in which the traffic
volume Hemand nay be of interest is the peak one occurring during
6-9 A.M. at times of the year in which photochemical oxidant formation
has been observed as a oroblem. The traffic demand during such periods
may be determined as follows for use in Equation (A5).
I
A-16 I
I
I
-------
I
(a) Start with the estimated annual average daily
traffic (AADT), veh/day.
(b) Multiply AADT by the peak seasonal adjustment
j factor during which oxidants are a problem to qet peak seasonal average
daily traffic. Peak seasonal adjustment factors depend on the area of
the country in which the road is located and whether the highway is
urban or rural. Estimates of seasonal variations in traffic should also
| be required from the applicant.
(c) Multiply peak seasonal average daily traffic
by a factor denoting the use of the highway during 6-9 A.M. on the
I
I
I
busiest day of the week. If this information is not available from
56
the developer, it has been estimated ' that for urban highways, the
Friday morning 6-9 A.M. period is likely to be busiest. The fraction
which traffic utilizing the highway during this period constitutes of
the average daily traffic during the season of peak daily use has been
estimated as shown in Table A4.
Table A4. PEAK USE FACTORS
Type of Road Peak 6-9 A.M. Use Daily Traffic in Peaj< Season
Urban freeways .22
Suburban freeways .20
Urban arterials .20
Rural arterials .17
A-17
-------
I
Summarizing steps (a) - (c), the traffic volume demand during
6-9 A.M. may be estimated using Eq. (A7).
(AADT). ; Seasonal Adjustment;! (6-9 A.M. traffic) i
NDemand Factor /I (daily traffic during peak season}-^ «
Vl ' 3 (A7) " I
where «
(AADT). = annual average daily traffic estimated for road segment
i, veh/day I
1/3 = conversion factor from (3-hr) to (1-hr)
I
v. = vph
If mass transit use is not already implicitly accounted for in the
estimates of v- should be adjusted as shown in Eq. (A8).
v - FO
vi - Eq> - TTJJiVo) 3
where
segments.
I
T = the number of mass transit passengers during the peak
6-9 A.M. period
P = the fraction of passengers who would normally use a
private auto were the mass transit facilities not available J
(avo) = the average number of passengers per auto
B. = the number of mass transit buses using road segment i *
during the peak 6-9 A.M. period.
2. N02
Since the standard for NCL is an annual one, AADT
may be used directly to estimate mean traffic volume demand for road
I
I
-------
I
I
|(AADT)i
vi =-lT~ (A9)
flj where 1/24 - conversion factor from veh/day to vph
Similarly, if mass transit is not accounted for in the estimate of
v., use Eq. (A9a) to obtain an adjusted traffic volume demand.
B
Vi = Fq' (A9) - -(24)(avo) + 24" (A9a)
where
T = average number of mass transit passengers during a day
P = fraction of passengers normally using a private auto
B. = average daily number of mass transit buses using road
segment i, veh/day
(avo) = average number of passengers per auto
Equations (A9) and (A9a) may also be used to estimate average annual
daily HC emissions if this is to be used as a criterion for whether
or not a proposed highway or highway system is acceptable.
D. Speed Correction Factors (c (s),)
The speed correction factor used in Eq. (A5) is determined by
the average operating speed on road segment i. This speed, in turn,
is a function of the highway design speed and the ratio between the volume
I demand and the capacity for segment i (v./c. ratio). Thus, to determine
_ the appropriate speed correction factor and speed, it is first necessary
to estimate the capacity of road segment i (c.). As indicated earlier,
under some circumstances capacity can be largely determined by the design
of succeeding road segments or exit/entrance ramps. If these designs are
inadequate, they may have a predominant effect on the capacities of pre-
_ ceding segments. However, since the general traffic engineering practice
appears to be to design a highway to accommodate the traffic demand at
A-19
-------
I
the 30th highest hour maintaining a level of service of "D" or better I
at the segment with the lowest capacity, the possibility of back-
ups from successive segments occurring during the peak 6-9 A.M. |
period or during the average day can be ignored. If the information is M
not available directly from the developer, capacity of segment i can be
estimated using Tables A5 and A6 and Equation (AID). I
c. = 2000 M. W. T. (A10)
I III ^^H
where |
M. = number of lanes (one direction) segment i
W.j = adjustment for lane width and lateral clearance,
obtained from Table A5 I
T. = truck-bus adjustment factor (which includes an adjustment
for grade) obtained from Table A6. |
If capacity is likely to alter appreciably from lane to lane, a separate «
analysis would have to be done for each lane. Once capacity for segment
i is known, v./c. ratio can be determined.
The relationship between volume-capacity ratio and operating speed
for freely flowing traffic depends on the type of roadway beinq considered |
and the average highway speed or posted speed limit. Figures A2-A5 depict
these relationships for expressways, multi-lane rural highways, two-lane
rural highways, and urban and suburban arterial streets. Relationships
shown in Figures A2-A5 are empirical ones based on observations over
several years in a number of locations. However, if a specific relation- |
ship between volume-capacity ratio and operating speed has been developed
I
A separate analysis should be conducted for each direction.
I
A-20
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Table AS. co;':M:;rn crim or LANF. IIIDTH A::J RESTRICTED LATERAL
CLE/ RANGE
DISTANCE I
IRAfflC I AN!
TO Olr.lKl'C
(n)
N CAPACITY
AND E XI' RES'
IDGE
I ION
;:.;. SERVICE v. :.u;:;.s OF uiviDLO
>'.,Y.YS -HTM UNINTERRUPTED FLON
AHJUS1MINT IACIOR," 1C, IC'T. LANE WIDTH AND LATIKAL
0!'S1
ON
12-1T
LAM-S
TCTION ON ON'r SIDI OF
--DHilCIION ROADSVAV
1I-FT
1 ANI5
10-n 9-rr
LANli LA.SLS
ORST RUCTION'S ON IX)
; , .. L . . ,' \ l ^
CI I. \KANCF
TM SIDLS OF
ONl-niitlCTION KOAWVAY
12-fT 11-FT 10
LAM5 LANLS LA
-FT 9-tT
Nf.S LANLS
(a) 4-LANL DIMDID FKUWAY, ONE DikrcnoN OF TRAVEL
6
4
2
0
1.00
0.99
0.97
0.90
0.97
0.96
0.94
0 87
0.91 0 SI
0.90 0 80
0 88 0 79
0.82 0.73
1.00 0.97 0.
0.98 0.95 0
0.94 0.91 0.
0.81 0.79 0
91 0.81
c'9 0.79
86 0.76
74 0.66
(!>} 6- AND 8-l.AM DIVHMD I'lurv.'AY, O-;i. DmrrnoN OF TRAML
6
4
2
0
1.00
0.99
0.97
0.94
0.96
0.95
0 93
0.91
0 89 0 78
0 88 0 77
0.87 0 76
0.85 0.74
.TO 0.96 0.
0 98 0.94 0.
0 96 0.92 0
0 91 0.87 0.
89 0.78
87 0.77
85 0.75
81 0.70
Some adjustments for capacity nnd .nil levels of service.
Fable A6. AVERAGE GENERALIZED ADJUSTMENT FACTORS FOR TRUCKS
FREEWAYS AND EXPRESSWAYS, OVER EXTENDED btCTION LENGTHS2
PERCENTAGE OF
TRUCKS, PT
on
FACTOR, T, FOR ALL LEVELS OF SFRVICE
TRUCKS, PT
1
2
3
4
5
6
7
8
9
10
12
14
16
18
20
LEVEL TERRAIN
0.99
0.98
0.97
0.96
0.95
0.94
0.93
0.93
0.92
0.91
0.89
0.88
0.86
0.85
0.83
ROLLING TEKRA1N
0.97
0.94
0.92
0.89
0.87
0.85
0.83
0.81
0.79
0.77
0.74
0.70
0.6S
0.65
0.63
MOUNTAINOUS TERRAIN
0.93
0.88
0.83
0.78
0.74
0.70
0.67
0.6-1
0.61
0.59
0.54
0.51
0.47
0.44
0.42
A-21
-------
I
for a road under review, it should be used instead. Use of Figures
A2 - A5 to obtain vehicle operating speed is illustrated by this
short example. A 6-lane urban freeway with a design speed of 60 mph is
proposed. The volume to capacity ratio for segment i is 0.6. What is
the operating speed? Since an urban expressway is of interest, Fiqure
A2 is used to obtain an average operating speed of about 45 mph.
Therefore, the speed correction factor for the pollutant of interest I
which corresponds to a speed of 45 mph would be derived from Table 3.1.2-6a
3 I
in Supplement Number 5 to AP-42.
For HC's; c(s). = 0.59 (Mote that this factor applies to exhaust I
pmi<:<:irmc nf huHv^nrarhnnc nnlu ^ H
emissions of hydrocarbons only.)
For NO ; c(s). =1.20
x i
The upper curves should always be used in Figs. A2 - A5 to estimate
operating speed unless v./c. > 1. In this case service level F (forced I
i i ^*
flow stop and start traffic) should be assumed and speed cannot be
determined. Occurrence of level F in the macro analysis would mean *
a traffic jam lasting at least 3 hours is likely to occur. This should
be grounds for redesign of the highway.
AVI. Estimating Emissions for Micro Analysis |
Micro analysis of roadways is needed to determine the impact _
of traffic on nearby 1-hour and 8-hour ambient concentrations of CO.
For such a purpose, two considerations are necessary. First the levels
of concentration at sensitive receptors attributable to freely flowing
traffic on the most heavily used road segment of an expressway or at |
mid-block locations on major streets may be of interest. Second, _
concentrations occurring in the vicinity of signalized or unsignalized
at-grade intersections may be critical.
A-22
I
-------
APPROX.J
0
NO.OF
BASIC
1.0 PHF
INDEPENDENT
LEVEL
OF
SERVICE .
RANGES H
JES
4
6
8
. «i r. E V/U C9IIU C rfr
« E . »
C -£-,- D -H E
-c )< ' D »!« 1 E
A « B »- ^ C j «"l-
4 c-^«-D±TL -
' A -» B * ; c~~ciir6~T
D ^|- E »
-E- L-=T^C
$ D-|L E »
1.00
0.91
0.83
0.77
0,91
0.83
0.77
1.00
0.91
0,33
0.77
i i vj *Ji _ i \ e , il\_ilULi\-'iiv>llllu/O I^/^^LVVL^V^II v I \j i u 1.1 ^y '-J I I v_l i^r f^i l^ I U I II I VJ J f-* V-. W VJ .
freeways and expressways, under uninterrupted flow conditions.
. on
A-23
-------
HIGHWAY CAPACITY
T 70
A
B
60
C x 50
Q.
LU
D £ 40
APPROX.
20
10
-B-
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
V/C RATIO
D-
BASIC
INDEPENDENT
LEVEL _*.
OF
SERVICE
RANGES
Figure A3. Relationships between v/c ratio and operating speed, in one direction of travel, on
multilane rural highways, under uninterrupted flow conditions.
A-24
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
1
1
1
-in
i i"
-|- 60
i i
1
- 50
i c!
-j-B 40
D co
1 1
APPROX.
1
1
I
r|
oc
LU
Q.
o
20
10
n
.«. i«^^^»i»^__-
^
^x
IOC
m
% WlTu
^90%^
«**!*
^-20%_
%^^0
^^^
U7° "^^==^11
_____ ( -
tcONTROLLING 0<1 °
^
S"
*+
^r
Vj\£^^"^
""
.2 0
3 0
_ LEVEL
4 0
5 0
6 0
7 0
8 0
^*^
^
»
.9 1.0
V/C RATIO
I OF
SERVICE
RANGES
1 Figure A4. Relationships between v/c ratio and operating speed, overall for both directions of
travel, on two-lane rural highways with average highway speed of 50 mph, under uninterrupted
flow
1
1
1
1
1
conditions.
A-25
-------
1
1
1
1
60
£ 50
a"
UJ
UJ
5; 40
i
A ^
DC
h- in
i =1
t <
DC
P LLJ
^t-o 20
D uj
j > 10
F <
I ,
LEVEL
OF
SERVICE
Figure A5. Ty
of travel, on ur
HIGHWAY CAPACITY _
_ 1
1
CURVE 1 - UNINTERRUPTED FLOW OR GOOD PROGRESSION
35MPHSPEEnillWIT
CURVE II -PERFECT PROGRESSION- ""^v
30 MPH SPEED " -^^ ^
^ ' 9
^^-^ 1
I 1 .. | L-^-f --"<
i 1- r i
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
V/C RATIO | | i i I
An R >J« P L n >J« F r
^ *- Q - t ^ L> p 1^ LI ' 1 * L |
1 1 1 1
pical relationships between v/c ratio and average overall travel speed, in one direction
ban and suburban arterial streets.
1
1
1
1
A-26
1
-------
I
I
I
A. Concentrations Attributable to Freely Flowing Traffic
A line source dispersion model may be used to estimate
concentrations in the vicinity of a roadway accommodating such traffic.
Since line source models are capable of distinguishing conditions among
traffic lanes and variations among lanes may alter predictions, it
would be preferable to do a lane-by-lane analysis for emissions. In
doing so, the relationships expressed in Equations (A2) and (A3) should
be recalled.
I
I
The basic equation for obtaining line source emission rates by
lane is:
q.. = (1.036 x 10~5) (EF).. (v../S..) (All)
IJ J * J ' (.J
where
segment i, gm/sec-m
(EF).. = speed corrected emission factor, am/min-veh
for vehicles in lane j of segment i
I
I
1
I
m
Vit Yi vijt (A2)
Cit cijt (A3)
q.. = line source emission rate in lane j for road
v.. = traffic volume demand in lane j, segment i, vph
S.. = vehicle operating speed in lane j segment i, mi/hr.
' J
(1.036 x 10" ) = conversion factor from ^~p to
A-27
-------
I
1. Traffic Volume Demand Per Lane (v^) I
The total traffic volume demand of road segment i
can be estimated for 1 and 8-hour periods by beqinnina with (AADT) . I
and rrulti plying by peak seasonal adjustment factors. Since CO is the _
pollutant of concern, whether or not photochemical reactions are
prevalent need no longer be a factor in choosina the maximum seasonal V
adjustment factor. The peak seasonal average daily traffic rate would
then be multiplied by the peak weekly 1-hour (8 hour) adjustment factor. g
Thus, ..
v. = (AADT). /Seasonal Adjustment^/Fraction Peak 1-hr Demand is \
1
. -
ioemand Factor A of Peak Seasonal Daily Demand/ (/no\
or
(AADT). [Seasonal Adjustment) (Fraction Peak 8-hr Demand is j
1 \Demand Factor Mof Peak Seasonal Daily Demand/
8 " (A13)
where v. - traffic volume demand for road segment i, vph. |
If the information concerning diurnal and weekly variations in traffic «
patterns is insufficient to use Eqs. (C12) or (A13), information
5
contained in a report prepared for EPA may be used to derive EQS.
(A12a) and (A13a).
v. = (.094) /Seasonal Adjustment] (AADT).
1 VDemand Factor ' (A12a)
(.50) /Seasonal Adjustment] (AADT). I
v. = \Demand Factor /
1 8(A13a)
If seasonal changes are not known, it is suggested that the factors
presented in Table A7 be used in Equations (A12a) or (A13a).
5-28 _
I
-------
I
I
I
I
I
I
1
I
I
I
I
I
I
I
I
I
I
I
Table A7. SEASONAL ADJUSTMENT DEMAND FACTOR
'\U3cation
AADT \.
< 20,000
20,000 - 50,000
> 50,000
Urban
1-hr.
1.70
1.38
1.06
8-hr.
1.40
1.30
1.20
Rural
1-hr.
1.70
*
*
8-hr.
1.68
1.68
1.40
*Assume each lane accommodates 2000 vehicles per hour and v. = (number
of lanes) (2000).
If the v- calculated with Equations (A12) and (A13) did not take account
of mass transit, the volume demand would have to be adjusted using
Equations (A14) and (A15).
vi=
v-Eq. (A13) -
(A14)
B,
(A15)
where P = fraction of passengers normally using a private auto where
mass transit is not available
favo) = averaae number of passengers per auto
B. = number of mass transit buses using road segment i during the
selected 1- or 8-hour period
T = number of passengers utilizing buses during the selected 1-
or 8-hour period
v. would then be apportioned among the lanes in segment i in accord-
ance with such locally determined considerations as presence of bus
lanes and volume demand at nearby exits and entrances. Care should be
taken that Eq. (A2) is satisfied in apportioning traffic demand for
segment i lanes.
A -29
-------
24
22
20
18
I
0>
of
o
14
co
co
10
T
T
10 15 20 25 30 35
VEHICLE SPEED, mph
40
45
50
55
60
Figure A6. Composite emission factors for carbon monoxide for calendar year 1975.
A-30
I
I
I
I
I
I
f
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
2 . Operating Speed Per Lane ( S . . )
Operating speed nay be estimated by v. ./c-- ratio
and the average highway speed. It can usually be assumed that the
could be estimated using Eq. (A16).
average highway speed is the same for all lanes. The c.. for each lane
c... = 2,000 W... T... (A16)
The values of c.. calculated with Eq. (A16) should be checked with
U
Eq. (A3) to make sure c. is not exceeded. If the capacity of the
I segment is less than the sum of the lane capacities, the capacity of
the lane adjacent to a lateral obstruction should be reduced. Once
v-./c. . is known for each lane, S.. may be estimated using the appro-
priate one of Figures A2 - A5.
3. Speed Adjusted Emission Factor (EF). -
Figure A6 plots CO emission factors as a function
of operating speed for a vehicle mix of light-duty vehicles (composed of
88% cars and 12% light trucks) during 1975. Once the operating speed has
I been determined, (EF).. may be obtained from Figure A6. If some year
J
other than 1975 is of interest, the appropriate CO emission factor may
be estimated using Eq. (A17).
where
(EF) is the emission factor for the year of interest;
(EF)75 ^s t'1e ^975 emission factor obtained from Figure A6;
* (ef) is the value of the CO emission factor found in Tables A3
for the year of interest.
A-31
I
-------
"55" is the CO emission factor for an average trip with a 1975
mix of vehicles. It should be noted that the emission factor in Fig-
national average mix of model years is inappropriate, local emission
factors, reflecting a more appropriate mix can be derived by following
3 ~
procedures outlined in Supplement 5 of AP-42. If the assumption of
I
I
ure A6 corresponding to 0 mph is indicative of stop-and-start traffic _
rather than idling. The emission factors obtained using Figure A6 and
Eq. (A17) are appropriate for a national average mix of light-duty fl
vehicles in which 20 percent of the vehicles are operating from cold
starts and driving cycles are similar to that used in the 1975 Federal |
4
Test Procedure. Ambient temperatures are assumed to range from 68-86°F. _
Such assumptions may not be appropriate for an individual location. If a '
20 percent cold starts or of ambient temperatures of 68-86°F is _
inappropriate, derived emission factors can be corrected using Equation
(3.1.2-2) and Tables 3.1.2-7 or 3.1.2-8 in Supplement 5 to AP-42.3 This
procedure was followed in deriving the correction factors for CO emission
in Section 4.4.1 of the Indirect Source Guidelines. If the driving cycle |
(i.e., the mix of vehicle operating modes) at a location is not well _
4
represented by that used in the 1975 Federal Test Procedure, the EPA m
Automobile Exhaust Emission Modal Analysis Model, may be used to
estimate emissions resulting from any sequence of operating modes.
This procedure was followed for signalized intersections in deriving
the curves for signalized intersections in Section 4.1.
I
A-32
1
-------
I
B. Concentrations in the Vicinity of At-Grade Intersection
Equations (A12) and (A13) may be of use in estimating
traffic volume demand at intersections. However, estimating resulting
emissions at an approach or at approaches to intersections is more
complicated than it is fcr freely flowing traffic. Two major types of
intersection approaches are of interest: signalized and non-signalized.
A signalized intersection is distinctive in that queuing may occur at
m discrete time intervals (i.e., during the red phase of the signal) and
traffic may be freely flowing much of the rest of the time. A non-
I
signalized intersection approach (e.g., one having a STOP sign), however,
is likely to experience queuing at irregular intervals.
One approach which has been suggested fcr estimating
emissions at signalized intersections is to consider emissions at each
intersection approach to be the sum of two components. The first com-
ponent consists of emissions which would occur if there were no impedence
A to traffic flow caused by the light. These emissions are estimated
using Equation (All). The second component is that attributable "excess
emissions" occurring at each approach to an intersection ever a finite
distance defined by the average queue length accumulating during the red
phase of the signal. Excess emissions occur for three reasons:
(1) As a result of higher emission factors attributable
to accelerating vehicles;
(2) As a result of vehicles staying in the approach
longer (i.e., when idling during the red phase) than is the case under
free-flow conditions; and
I A-33
I
-------
I
(3) As a result of closer spacing between idling
vehicles than would occur with freely flowing traffic.
The first step in estimating "excess emissions" is to II
estimate the average queue length accumulating during the red phase of
the signal, equation (A18) provides a means for doing this. |
1
i J
L.. = i (A18)
J CPH
where
L. . = average queue length of vehicles accumulating at approach i, fl
^ lane j during the red phase of a traffic signal, m |
v.. - traffic volume demand at intersection approach i, lane j, vph .
(G/C ). = green time to signal cycle ratio at approach i, dimensionless *
D =
vehicles, m
CPH = number of signal cycles per hour, hr~
D = spacing (tailpipe-to-tailpipe) between consecutive queuing ft
Calculation of queue length using Equation (A18) is
straightforward at an intersection where the traffic signal is a fixed-
time one. However, the use of Equation (A18) is more complicated for a
traffic actuated signal. This is because the G/C ratio and signal I
cycle length vary depending upon the traffic demand and the distribution
of demand among the approaches to the intersection. Detailed discussions
8 12 13
having traffic actuated signals are available in several references. ' '
on how to estimate G/C ratios for the approaches to intersections
I
I
The following discussion briefly outlines the procedure which can be
used for relatively simple signalized intersections. The discussion is
followed by a short numerical example.
A-34 §
I
-------
I
(1) Estimate the capacity (consistent with Level of
Service E) for each intersection approach as if the intersection did
not exist. This can be done using Equation (AID) and Tables A5 and A6
as appropriate.
(2) Estimate volume demand-capacity ratios (v/c)' for
each approach, using the capacities estimated in Step (1).
(3) Note the intersection leg having the highest (v/c)1
ratio for each phase of the traffic signal.
i
(4) Add the highest (v/c) 's for each phase of the
signal. Add "0.1" to the total to account for the time that the signal
is amber. The sum is the (v/c)' for the intersection.
(5) If the (v/c)' determined in the previous step is
less than "1," the intersection is able to accommodate traffic at the
specified Level of Service (i.e., Level of Service E) or better.
(6) Apportion the difference between "1" and the
intersection's (v/c)' (estimated in Step 4) among each phase at the
intersection in proportion to the maximum (v/c)' estimated for that
phase to determine how the excess G/C is apportioned among phases.
(7) Add the results of Steps (3) and (6). The sum
* is the computed G/C for each approach to an intersection having a
traffic actuated signal.
This seven-step procedure is illustrated for the intersection sketched
on the following page.
A-35
I
I
-------
Example. For four 1-lane approaches to an intersection having a two-
phase cycle, what is the G/C for each approach given the volume demands
shown in the sketch? Assume the unimpeded capacity is 2000 vph/lane.
N Leg (1)
VA = 1100 vph
/D = 500 vph'V-
Leg (4)
Phase I: Green light
for approaches L) and b,
Leg (2)
. ) VB = 400 vph
Leg (3)
= 700 vph
Phase II: Green
light for approaches
A and C.
(1) cft = CB = cc - CD = 2000 vph
(2) (v/c)'A = 1100/2000 = 0.55
(v/c)' = 400/2000 = 0.20
D
(v/c)'c = 700/2000 = 0.35
(v/c)'D = 500/2000 = 0.25
(3) For Phase I, the highest (v/c)' is (v/c)'D = 0.25
For Phase II, the highest (v/c)' is (v/c)'A = 0.55
(4) Therefore, (v/c)' for the intersection is 0.25 +
0.55 + 0.1 = 0.90. The l!0.1" is used to account
for the time during which the signal is amber.
(5-6) For Phase I, excess G/C = ( ^ 55)(1-.90) = .03
For Phase II, excess G/C = ( £1 55)(1-.90) = .07
(7) Therefore, for approaches A and C,
(G/C )TT = 0.55 + .07 = 0.62 and
y ii
for approaches B and D,
(G/C )j = 0.25 + .03 = 0.28
A-36
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
1
1
1
I
1
1
1
1
I
1
I
1
After the
(A18) can
green time to signal cycle ratio has been estimated, Equation
be
used to estimate queue lengths occurring at each approach
to the intersection. The excess emission intensity to be
the queue
Equation
qij
applied for
length L,. in lane j at approach i may be estimated using
' j
(A19).
(EF).. 1-G/C 0.5(EF)'.. (1-G/C .
\ ij/ y i + TJ y i
60D 60D
(A19)
~~ J
where q..
= 1
ine source emission intensity to be applied over a queue
length, L.., in lane j at intersection approach i, gm/sec-m;
' J
(EF)
i J
1
60
D
= average emission factor for acceleration and decelerating
vehicles over the estimated queue length, gm/min-veh;
-1 -1
= conversion factor from min to sec ;
= spacing between successive vehicle tailpipes i
n the queue,
assumed to be 8 m/veh;
0.5
= constant denoting that the average vehicle in
only there for 1/2 of the signal's red phase,
the queue is
dimensionless;
(EF)'.. = emission factor for idling vehicles in the queue, gm/min-veh;
G/C
y
intensity
= green time to signal cycle ratio at approach i
, dimensionless
Tables A8 - A12 depict queue lengths, excess emission
over the queue length and emission intensity resulting from
freely flowing vehicles at approach speeds of 15, 20, 25,
respectively.
30 and 35 mph
For lanes which are downstream from intersections,
ordinarily the emission intensity associated with freely flowing traffic
1
1
should suffice. The emission intensity values in Tables A8 - A12 are
appropriate for a 1975 national average mix of light-duty
A-37
vehicles, 20%
-------
M
f>
r!
M
II L/l
X
L~ :r
-j
o
M
CO
M
H
II L/l
_J
>- u.
X
O I
_J
c?
s
n
II I/I
_J
>- Lv
to 3"
J
c-
HT
W-l
k-l
it O
_J
>- U.
X
_J
t- .
01
'1 Ll
X
LT 3
j
1 1 l<1
j
C.
X
cj n_
K
_J
I
r-'
r i
r-1
II VI
> U-
X
o -x.
V-
1-1
o
(St UI ^
£3 0 Q
ci o a
roN a
-as
in H co
N m f-
oop
a o o
ca oo co
a o o
a o a
a a a
CO LO tf
rH fg
Ul rH Ul
t-g in f*-
Q CJ O
a a o
r~ in o
Cj CJ .-4
C. L C
f1- M Cj
LJ 'H rg
i i'J r-i
I 1 iH LO
r-J ' 1 f
C-. O O
r- & M
0' 'H f>
LJ O C,
' » r- cj
r--, 0 CJ
1-1 rH LO
CM in r*
tj » r'
c ci o
O C. C
IP ff> u,
f U ID
O U O
r- - ) o
*
Ul rH
C. CJ
o a
\TI r-
0 C
r-i r
rH r-g
1.1
M r i
a LJ
M r-
l* L.'
CJ
H
CJ
a
c.
'V,
in r- D
o a o
N CT *">
a ro r-
M K) JT
N r-
H rH
O D
a rst
a u
H H
a o
o a
CO LO
csi
in
H
a
CO
rH
C
C
5
rH tH rH
ill
So a
a o
"as
in H LO
*si in f*
§o a
0 0
CO CO CO
in LO h-
cj o a
a o o
r*«a
a r-4 CM
in H LO
f\i in h-
88B
o o a
csi j r-
5 Si'
(vj u"> r-
a cj o
r-- j- a
n rH r j
0 r-l ,H
a c: u
-0 ,5 M
f~ L ' r-)
I I -H u>
C 1 LI r*-
LJ CJ U
LJ CJ J
*
u) -j- r-
r-l . 4 rH
C, CJ C.
*
I ' * I.
r j i > i
o r, j
c; c, t ,
LO f i ft
KI in 11
i-3 ~ .J
en co h-
fl- ci d
f i a- r
c. c?.
C, L.
ID >r>
H -H
O LJ
3- m
CO LJ
f-J 1.1
^-r^
0
i
s
H
a
3
LO
CO
a
o
r-
(M
Q
H
a
c
o
CT
U")
Q
C
(N
O
^
r-
CJ
o
a
CD
0!
a a a a
CJ o o a
c e BE
ro » * in
3S3
CO 01 O1
OO CO CO
O CJ O
O O 0
M O P*.
M * if
m a) r-1
h- fsi
^
UT UI
a a
o o
rH fO
rH lO
n
o
o
T«
a>
03
HH^S
O D
o 5
11
H
u> H
^* m
§8
OQ co
in ui
8§
K^ f^«
HI (S(
8O
CJ
h- on
o a
o o
TO U)
r i~>
LA rH
fxi in
0 CJ
tTl rH
CJ iH
a a
rg j
r i 3-
rJ U)
U' J
LO fO
in * to M «*
M M ^ m tO p*
ID r-i r- (si r*-
O t-l r-t M r-4
o o o a a
CO O rH) t-4 r-4
r a M
a- in LO co en
co H r- f^
h- o rg in
o 3 o o
uj i*" r* r*-
01 en c*^ cr*
a a a a
D o a o
r^> rH m r
u) r 'O o
h- CJ (M
O O LJ
rH rH tH
0 0 U
f^- tf r ^
nj m .-t
1
h- cj
o .-*
U LJ
C. r-
C- 0
CO t_j
Cj
U1
a
O'
LO co cj r 3- i 3
ml TH uj r-t r- (sir-fo
fsi*nh-cDCsiinP-o
aparHr-*fHrH(SJ
ocjucjcicjacj
Mi^LOtjptnuiLnLo
S D G C E Cj O D
i
3jH r*l r^ KI ^ jt* in
**' wi & in u) p* co
in »H co H r> c\j r-
(si in t*- a (si ui r-
00 CO if U~i ID LO LO
o CD a o Q o o
a o a o Q a o
cj a a ^ a a a
m (vi co * a LO M
*-< ^) a* u> 03 en H
rH
in rH U rH K CJ
fsi 1.1 r- o (si M
8Q P rH "4 rH
o Q cj LJ cj
r- Q H rg <\j ra
^ ff1 en ci en o^
o c o a a a
o o a o a o
M h- c. M r- o
rH rg j- tf> vj ro
rj a- a ro cj rj
rH rH
UI rH 10 rH t^
a o u c o
cj o a o Q
r - M c ,- ' i
J L i iO C, M
Hi rH LO rH
C"i L) r-- LJ
J LO >_J -H
O -J _j ^
L.T ro 3" 3"
r i r j r-i r j
u u cr- L-
"^ .T tffi TX>
ro \O C7i rj
i . r t t a
CJ LJ
- C" C
fsj zr
- ! J J
K^:
0 0
CT, CJ
LTJ V'
J Ui
^ r^ r^ rH
in rH U> H r
csj m r- a N
O CJ Q iH r-4
o o 3 a a
CO O) rH (M CM
m LO r*- r- r
a Q o p o
o o o 5 o
r* n a r* to
rH f" IT( (*" O1
TJ m r- C (M
8CJ CJ rH r-l
Q a a cj
r r- cc co o)
r~ CT co ai CD
j c. a cj cj
o c o c o
en 0. ^ uj 3-
* ^? rt S d
f j i-i r- Q -J
a cj c: cj o
1"- ' 3- -T -3"
0 0 C tJ U.
CJ .H r-t rH rH
O O U CJ O
.-' ' J "1 3 0
'4 1 J T" J- I'"1
L. . -H UJ r- J
1 1 i ) !*
J t, _J Ij
r < ( j r-i r
r- 1 -H -< . 4
0 , _
- * Csi C
' 10
r j i~~ r-
C. r ' C
i - v t"
r n r-'
T-* r-
-r i r
u") V»^l
C-' L^
n i_o
cn "i
' -J T L J ci ) _J
(SI
rH
CJ
LO
m
e
^
N
in
H
CJ
rg
f
CJ
a
CJ
rH
tH
(M
L .
H
a
CO
c,
,.
rn
t j
f- D
a o
LO U)
U*| Ul
f- O"
en o^
r-
rH
r;
CSI
o
r
u
r- '
rH
M^
c: j o cj cj c; L c.
A-38
I
I
I
I
1
1
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Table A8 (continued). EFFECT ON SOURCE STRENGTH OF SIGNAL CYCLE LENGTH, TRAFFIC DEMAND, GREEN TIME, AND APPROACH SPEED -- APPROACH SPEED 15 mph
D
O
r
r
5
in
r-j
o
o
LI
CJ
fo
( i
f J
B
t-
r^
c.
a-
o
in
c
c,
L,
)
':]
'
f\
o
cc
t_
c
3
'
^
a a o a a o a
a c a o p o o
o o c> c; 5 o c-
* r- rH r- <\] h-
m r- o fsj m r-
a O H »H tH ^t
n o o a D a
f~* CO XI T> 31 CO
o a u o o a
o a o a o o
r- o ro r-. a M
r ' 3- ui LO co en
^- 10 co o cj a-
t-J rH «-(
rH u. *-4 r-- r-j
ui r- cj M in
C O M -H *H
o o o a o
J- 1.1 L . LO U)
u) CC CO < .. CO
C) Q CJ O Q
O O O C, D
c- r-> CD rj r-
0 in f) r ; ^
1,1 co H ^ r--
. * tD '-1 r-
*-i r- L_ c j
c c: .-H -H
C3 0 Ci rj
L a c- L.,
u. D c., a
. ^ t~~ '> o
r* c, --r C
L r- o
-j a '-.
* *
r- r- r-
f* c_ r~
I/I I) LJ
tiS ( j r
in r-
0 c*
o a
L j
-)
rH
j- i.j f c rJ 3" i j
< ^ H -1
i U C O cj ( , C
o a
CJ CI
o a
00
ss
tfl H
s§
» tn
o a
o a
a a
s ?
in H
(M in
h- CJ
h- CO
O CJ
C D
0 U
(N J-
ro o
r j n
c c
o a
at cr
o a
o o
U 'J
a t_;
IT) *H
C) CJ
8
O
a
0
lO
r-
u
01
cr>
O
CJ
D
U)
p
Q
L. ,
c.
C_i
r-4
r-
a
L,
0
J
3«H H H (N
a a o a
gg§i§
aot^oo
t-t H
SRHP
a o a &
u> r- r* r-
u a a o
a a a a
a a a o
LQ Q -3" GO
01 rj
M
§
i
ro
1/1
if» H iO
sag
CO
o
o
c-
u>
rw
u>
N
8
r-
r-
o
o
U)
ro
in
c:
o
(p
.,.
?
s
rj
c
1 1
L 1
Q
C,
CO
rj
LO
C_i
-T
31
C
fj
I ,
U)
a
a
n
3
UI
8
3
a
a
H
-
C
Q
r~-
CJ
c.
m
O
O
c.
r-~
01
r-t
IT
r
c-
ij
L/l
G
CM
-r
c,
-j
I
a
3
|
H
r-
cj
o
§
^
a u>
GO a
u>
8
a>
a
o
^
ia
a
d
H
a
OJ
a
o
IM
H
C H
o a
a
ro
ro
a
a
c
Q
u.
r
c,
O'
r j
r-
n.
UJ
C
a
i j
Ol
r- N
M 10
T-4 !-«
o a
i-4 fH
CO CO
a a
o a
a) ro
^ ^
(N)
r-*
O
c-
D
*N
r j
1 '-1
a r~-
C -J
rj rj
a3
||
»(M
5H
r-
o
in
to
o
o
r~-
cO
J- U3
> H iH
a c
i J rj
A-39
-------
Table A9. EFFECT ON SOURCE STRENGTH OF SIGNAL CYCLE LENGTH, TRAFFIC DEMAND, GREEN TIME, AND APPROACH SPEED -- APPROACH SPEED: 20 raph
r-i H
-i a
M a
M H
II H u>
_j a
v u. a
01 a
Z CO
a
M Ol
I" ^
Pi §
"* rH
II Li CO
-1 O
> u. o
N,
-4 H
M -n
_j a
M O
H rH
11 LO c_,
V U. C,
V,
_J --*
CD
-J U
1 rH
t 1 L i ( J
-J T-^
> L r.
c;
t' x t:
LO
J 4
J
k C
< £J
r-
'if 3-
J »
X
. i j. r
_J rH
r- (T'
L 1 . »
>- H" LJ
C )
X
t
2 -«
-J C\l
O
L^ -J
CJ LJ
r- 10 in » csi H o
CJ C3 0 0 rH H -H
o a a a o a o
en r* LD -3* f>d H in
* ul u> r-t aft en o ro rs.
O Lfl H LD t«4 £ fsj
r- LQ in * eg »H
ro in r* en H 10
SO O a H rH
a o a o o
ro u> 03 o * r-
r- H) CT» rH rH rH
O Q O H rH H
o a o a a o
o o cj o a a
iD * «N C3 CO U>
rH J tf Ul
p-- LO ui ^ r^j
ro tfi r-- en H
SSSBS
co * f> rj in
O 'H rH rH »H
c> c, a a a
f C, f- ro a
^H (M
C- C.
c c
rH rH
r- o,
r- LO
r*
t
r-
3- 10 <-j u rj a- LO
o .TI c ' a o o c
i-i LI> u i.j ui LO i a
cnr-u)in*fM^o
§gg§§3g3
gliliiis
HM^*^r.« tf> » N fH
ro \f\ r>* OT «Hl W
0000800
*H ro u> in 01 H f3
a) r* co on on o Q
0 O a O Q rH rH
o o a o o o d
r*- ro a f r»i o ?
o H csj rg ro a- *
rH CM ro * in 10 r^-
H M in r*- tn rH
88S88S
r-4 00 rH IP OT £3
CO (P rH H rH fvl
CJ O rH rH H »H
a o o a o o
*
j- en rj u) »H ui
^H hi m r- en
C1 c a o D
0 0 0 0 O
rH f J rH Ul IO
CJ. oj hi ro r*>
o CJ a o a
o u 1^1 -H o
r- 11 hi rH fO
r< "1 Ul r- o>
O CJ u C,
u -) a cj
c c o c
ro t- c, fi
i ^ a
ir LJ o
r-' tH rH
r a c_
*
ri -T-' r
C. L.
' i O
Li- CO
'-J CJ
3- en
f i 1.1
f J & LO >o «i>
a a
P
m
ro u3
H CSJ
88
H 00
co - in
rH hT
.-'HJ ri
0 O
Q O
O I-H
O 0
^ j-
f J ^p
rH ro
(J 0
LJ LJ
C U
r - r
CD ro
c c"
n r-
u c_
' > C,
f , (
^O
10 , 4
' i r-
i j ^r
^ r"*'
Q O O rH rH i-t
a o a o a o
giiggg
Srf> ff M N -r-l
ro a- m uj r-
u> m ^ CM H
to f*- IT * ri
10 r- on rn
88§E!
in -jo 01 o
cj a LJ 4
O O CJ 0
f, M en f-
ro rH fO LJ
Ul r- ai C
UJ I,' ;r
O C- O
o c c
fM ri fg
O C O
r- o .H
v*j °0 ri
CJ i^,
O LJ
*
cj CM
3- -3-
C- (^
o ^
c
f-
tf
rH
*
0
>0 ft U < ' T W
T^ r ( »-*
C, L C ' L_ --
on T^ tfl
IH ro iq
§P Q
a a
gig
3SW
U) a- N H D
r- ^J (O
-H ro jj-
* in LO u»
00 00 CO 00
a a o o
a a o a
o a o o
* D LO (VI
o r- 10 in * M
H M iri r- -l
o a a
r> t- a
n » *
H ro in
o a a
000
M rH 1-4
U* U fc-
1- M D
l-J LO CL
« i r- u>
. 1 f) L.T
,_j Q O
*
< r j a-
i-j h Ki
rH r 4 . -t
c, c c_;
» r L
Q >_) C/
w C, C
rH 'j L
(*n i O
r cr f^j
*o f - r-
C LO
r-~ hi
1 4 ID
J CO
C M -f -,
. 1 1
Q a o
rH rH rH
a o c
M r- o
Ul U) *
D C1
a o
CO 00
,T
DO
t O
h- C,
U L
O LO
' ' r
i *
a) *n » (si
IT! f- 01 rH
SB^S
r-
i
-
LO
i
pii
d?
Cl Cl rH
0 O O
OO LT> O rH
r- r- co oo
J o o o
o o o o
a
u>
to
u>
u>
CJ
a
r~
s
o
CJ
c
r-i
, ,
S
-,
L^
r- ro a
;f ro (\j
r- Ol rH
rH
ui ^f r^
r-
»H ' (
CJ U
r CD
I ! U)
^
. ! iH
j ^- a
rH O
ro in
H rH
0 0
U> L0
SS
^ on
OO CTt
rH
ro
rH
O
rH
OO
O
U
r
rH
T -. j
* 'i
A-40
I
I
I
I
1
I
I
I
I
1
1
1
I
I
I
I
I
I
-------
I
I
I
t
I
I
1
I
I
I
I
I
I
I
I
I
I
I
I
cn
rH
O
O
O
C)
C
(M
if
rH
m
8
rH
U>
CJ
ro
t\j
CT1
rH
8
C
j.
.-o
CJ
11
H
O
CJ
r- .
a-
LJ
LJ
-H
cr
f
rH
G
if
C!
9\
'0
in
r j
LJ
lO
r- u) wi *
ro m P- c~>
o o a c.
o o a o
cn u>
* in
o a
C' O
* p-
CO fM
r- LO
Q a
a a
IM tn
r- r-
CJ C3
a a
r- a
r-i 3-
3- U>
h- LD
CJ Q
o a
* a
u a
o o
cn M
.n 1 1
o o
L- LJ
rH rH
o a
4 --
,H J
f-* C
^3
C- U
-J L-
CM t J
O IT-
in o->
-'J C\
- 1
r- uj
C- C-
O r-<
& a
-4 rH
r-
ro
C.
c,
o
r«
rH
C 0
'H i-H
co cn
m m
Cl D
o c.
rH
t.3 H
in p~
m j"
o o
0 0
U.i LO
f^- r-
O O
ro r»
m LO
03 O
rH
in tf
P~ 0'
C3 CJ
0 0
(NJ rH
rH ro
rH rH
a a
S3
p CP
CJ C-
K m
w OT
CO 0^
H *(
a a
»> r-
i~- r~
a a
a a
a M
«o cn
H rH
(M
a
O
a
r-4
D
c
co
r4
yi cn cn
a a cj
a CJ o
0 CM
n r«j
^ :r
r- fr\
C U
c, o
o o
r< rH
a o
i g i
3- r-
rH »-<
LJ
lO
fj
r--
0
* 3
a a
1.0 tJ
rH 1 (
^
CJ
,-! rf
Q C
LJ 1 0
O
to
cn
o
0
0
o
s
s
§
LO
a
o
a
5
rH
C3
U
CD
Q
O
C
(M
CT1
O
rH
C
rH
a
CJ
CJ
cr
cn
rH
, J
on
rH
rH
a)
j-
C,
1 1
rH
3
a
*
a)
cn
H
C-,
Cj
r i
i-i
-H
a
03
O
r* co tn
gg§
o o a
CJ CO tf
f*l 3* uj
M i/i r-
88§
r- r- r-
ago
o 3 a
a a a
aj rg (D
3- r- i GO
ID (SJ p*
o * r-
r< rH «-J
',3 in 3-
ij> f"- cn
a a c:
c a o
ro M Ki
C_ O CJ
rH rH r-H
O LJ CJ
.-, ^ ,
-H rH fj
U" i. '
L > h-
CJ LJ
LJ U
cr TI
-H H
rH rH
C C-
LJ 1 1
J rH
-H ( I
C,
r-
o
CO
H
H
o cj a
l J 0 t- .
JH) »-4 H
o a Q
u) in in
in in in
888
it^^;
8 a- N
CM d»
art
So
» r-
88
a f»
a -0
to co
rH fH
a
CO
CJ
O
n
H
d C' C_
A-41
-------
IN TIME, AND APPROACH SPEED -- APPROACH SPEED: 25 mph
Table A10. EFFECT ON SOURCE STRENGTH OF SIGNAL CYCLE LENGTH, TRAFFIC DEMAND, GRE
M
1/1
(H
CD
t
M
U fl
^
C.)
N*
0 DC
t-
z
J
c*
H
LA
H
^
) -4
11 f>
_J
>- U-
C1
X
CO X
r
z
J
C1
M
u
-J
1- 1
LO
r 4
11 Li
_J
> U
CJ
X
(J T
^
J.
(
1--4
t1
_l
h 4
I ! L-n
-J
>- U.
o
X
> E
-J
t l
I i
-J
J-
t- -
_l
>- U
u
X,
t'> J-
h
J
I U
J
>- IJ-
L'
V
< i .1
_ J
_J
r t
_)
>- kt
LJ
X
C> X
. J,
O
o
(-
.J
C J
a- en iv>
H *N a-
CJ 0 O
a a a
? in «i
8§S
U1S3
3R3
88S
H in to
LO f- co
U O CJ
u a a
j a a
co LD a*
rH N
iT 0*1 to
t-H CNJ if
ago
o o a
ri 1/1 r
a rj .3-
c O o
ro p- r_j
r-' LO d
.H INJ J-
JT cn ro
» rj *r
vJ 'J CJ
Ll 0 0
r u a
< j m u>
r-» 1-1 rH
C.. LJ O
0 CJ C,
s^-j
3 cn f>
. t M j-
i_ C, U
c^ c, c,
M Ui ,H
3- 1 C
r I ft ^
k . L- I-
r- ("i « j
o f~ VD
r. M if,
j- m
<-4 rj
0 C_
(." IJ
3- f*-
i ' o
tH < -4
J O
ro f-~
. 4 OJ
1 J 3"
( J 3- iJ
LO 10 lO
r-
in
o
a
2
§
«
r^
in
8
fsj
a
rH
O
0
(SJ
rO
r-
in
8
ro
ft
r-*
o
r-
fNJ
a-
r-
Ul
C-
r_j
r-
U J
O
ro
r i
r-
LI
c,
j
r
rH
c»
LJ
3-
vj
t>
U
.
H l\i (M
3H r-t
o a
a o a
Q CO U)
3- if in
rj u>
r- co
§8
r-* f-
^ a-
rH rH
0 CJ
f" CJ
to ^
1 1 o
J
r-
CJ
13
3"
LJ
0
r-
!>
o r j j- j
: H rH rH rH
i J 1 J L_' C-.1
LO LJ tJ Ul
a/
H
S
^
e
r-
3
a
^
LJ
U
CJ
r-
O
i-H
»
t~*
3
TJ
CO
a
D
rg
*
1-1
a-
H
CJ
o
&
r-4
0
cn
t-
i-l
3-
r-H
c.
LJ
fl
r j
r-4
C,
to
3-
C1
C
f- >
3-
a
r
3-
rH
c
c
3-
LJ
iH
U
3
CO
f-i
"
1.0
cn fo t*>
N a- to
C' C.) D
L CJ CJ
Sen eo
iO U)
B8g
cr H m
r^ tSj IM
m to r*
(Si 3- tn
sss
UT co a
r- aj o
a a H
u u u
ro a r-»
rH CM rg
<\i ro 3-
O
UJ 1 > r 4
Ul K> rH
f- i/j r-
ci r*> r-
r , a- t*
O Ll U
L, _) CJ
a 10 03
rH ( rH
U l^ CJ
r- o M
r I 3- bi
c" ro
r i O
{ L-
LO r~
< rH
cn ^
3- r-
tr
t j
c,
c:
f
c*
.H
U
cn
i j
T <0 <0
uj OT n
N U5 O *n
N. 5 a »H
SO H r-<
a o o
K 5 o5 CTI
gglB
StN to t~-
(M U)
r- co
ss
cn IN
(NJ rO
O 0
t-i f-1
--» bT
r co
(SJ
r~-
c.
0
m
a-
tH)
0
"T|
otf
CO
u rj 3- UJ
.-t -H rH rH
cj c r^ c-
iU (O >.O ')
& en ro
r4 04 a;
§0 O
a o
r- N u>
in r- eo
o o o
O Ci O
H a cn co * ao
a*t iJ> IA uj [- r-
?BBBBB
m5fi
5R3
SO O
O O
-i Ul eo
u> r*- co
8 a o
a Q
M r- a
fO U) U
»H rg 3-
a- cn ro
r-* tN *
888
CJ U 0
CO Q . 1
O O U
eo u) K)
r- ui -o
rH r i T
a- cn n
r4 *N a/
O p Q
CJ CJ C,'
(M rg rH
CD rj ^'
rH H »-H
CJ Q C3
» i a- r-
TJ 3" O
rj a- o
a- cn r ,
Hrjjr
L_. LJ LJ
LJ O rj
h CJ t
f- a- ui
rH rH -H
tJ L, L,
t- ' > U
u ' 'i L-
M 1*1 ft,
3 m *i
i-t (St f
a LJ o
C- U C)
Kl rH O.
« ^i1 I
r4 , < r
CJ U "
rH rj ro
rH C ' 1"
r*, lo m
a- cn
rH f J
C U
I CJ
3- CJ
1.1, rO
H ,H
o a
LO rH
m H
to r-
IN y U
LJ LJ i_)
LJ c a
in ar M
ro a- in
l>- M LO
m r- eo
888
a* cn rg
cn cn C3
CJ D fH
o o o
to r^ a
ro u> o
i.) io eo
r- rg DO
U) h- CO
888
1.1 Cn rH
i-H . 1 fj
o Q a
rH tn r-
.4 tt> U)
r-
Oi
^r j
4 -H
f ' '-J
afcnfir^-rJUjQir)
HtNia-^^-COOrH
8C- O O O LJ r-4 rH
CJ C3 O a CJ CJ D
HcacnoHa-ajr^
a'lrtinujr-r-r-r-
80 u o o o p o
n r- n a c o o
HrMKifl-LnLQf-co
* m ro r- N u) a
H rg a- in N- co o
§O O Q O Q rH
a a o a a o
r-1 ifi U) O M in LL)
us r*- a,
80 o o a u
B o o ci o
(M m i ) cn f j M
OQ Ul LJ O M rH
O CJ rH rH rH rH
Q CJ C U 0 0
1-1 r- c, f r- c
H r, 3- "> 'Q co
oj J- 'O ''J Cj fg
r-1 r'
3- n ro f rj
rH I J ST Ul f-
o cj c. a a
C, LJ c; a c
rg cn 1/1 co *TI
c5 rH ri 1 4 r^
o a LJ a cj
r-- M c r- ro
LO ri rj J to
r j t, ! ro L ^ ,
- -4 >«
Jr CT! M 1
U (_i -J U
wj I'j l_J ij
f'l M J- J"
C I 1 C
CJ LJ CJ L-
r i & \. >
4
a- G^ ro
i r ' .r
Cj r, c,
Cj C, C,
fo u O
if ui lu
rH -H 'H
LJ U
M r- c,
r 3- t l
f-T) r- r 1
3- 1
1 fM
C CL
LJ LJ
to to
u. t-
4 . 4 4 < -1
C"1 CJ CJ L C "3 L L C
J i J J J ( J , J ' J - J
a- er>
H og
CJ 0
o o
sa
88
rH rg
a- cn
H rg
LJ- o
CJ O
r-4 in
10 r-
n a
LJ CJ
r-» to
m r-
rH M
a- r
M r
c 9
o Q
rj L,
OJ 0^
0 O
u c.
tn o
3- n
f-J 3-
4- ,n
< H t J
C. CJ
' J C
r i L>
C_ -H
r-< rH
C^ U
H i I
. 4 f J
J- O"1
J l
J J
r ' r--
r*i r-
~£
' C.
, c
f r<
^- »'
f-rt r
-r «
j- CTi
.H r^j
r C
L L
r H - *
n UJ
Ci Ol
r i- '
f > -T
-r ^r
m r-
* vn
o o
0,0
cn a-
in to
p o
r. a
K) Jf
to r-
a- in
0 O
o a
(M LO
CO 03
C3 CJ
o a
o r-
Lfl 3-
in r-
ro r-
a- D
ss
( J 3"
LJ a
rH rH
o c-
r > j
f^ T)
fo r-
C- L
0 C.
C' r-1
rj r
rH rH
O C
-1 3-
f 1 3-
1 (
L_i LJ
U ' '
1 J
^t
d-
r^
Q
ro
^r J"
(M LD
r- co
o xn
o o
r- o
to f
8?
LO r-
rg LD
r- co
ScS
>o n
CO co
O LJ
o a
ro o
M r i
tT r-4
r-j Li1
CJ C
C. LJ
i r
lJ L
J) C.
3- t 1
3- '-1
CJ -T
r
C,
0
to
t j
CJ
^4
"^ r H
-.- J-
u m
0 -4
rH) r-4
0 0
«H (M
r- »>.
0 0
C CF'
CD cn
a
o
rH
CJ
LJ
Ol
(J
LD
r»
n
ro
rH
j- )
< 1 i
~r 3-
A-42
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
y ci M r- rvj CQ a 10
rH CM a- in r- m a H
o
l/l
s:
o
CJ
o
OCJOOOOHH
aooaoaoo
> o a o a a i
t U) U)
ao
c a o o c o
c; o p P o i
D Q £ B O (
!gg
CM
a-
rH
9
8
r-4
U
U
M
CN
3
8
CM
01
C-
Q
a-
10
C J
3-
C
O
r.
0
cj
0
t ,
1 ,
»
l_
f ,
f J
l_
r -
(M
-
y
T- 1
[
C,
c
a-
:;
o
0
^
M
C
c_
CO
L/>
r^
J
01
J
* f-
CO M
(SI #
jT] fo
O 0
a a
* Of
a a
a a
r- a
(M Sf
*T 10
r-1 er
8§
* CO
m m
H CO
c*i ro
i 4 ;t
c_ c,
^ a
r i cj
a a
* « r-
H UO
1- O
^r
CJ 0
t_ c_
r- O"
j *
5 u
^m
0 O
01 3
Cj
L,
C-
^
U3
4
'.J
co
s*
m
CO
if}
In
a
o
fsj
00
a
M
m
CO
in
8
CJ
H
O)
M
r-t
^
U")
O
^
H
0
U
r 4
j-
tH
h
L f
LJ
a-
M
CJ
t-
,"
i"-
^
rH M CD «0
r-« tO (T Kl
p» CO ffl "
H
M CO O
r- «j 5
8SS
-a- in UT
CO CO CO
o a a
a a a
r- a t-t
SCO CTl
N a-
rH »M H
(N IO
f- CO
83
L O
rH r-t
tM f^-
1 1 t3
3- r-
rH r-t
pg
1^-
o
C,
0)
H
a
o
r~
r*
-H
O
LD
H
»
r-1
8
H
CO
O
O
O
if
a-
H
g
K
«O
O
o
c
C>J
M
y.
rH
O
O
fvi
a
u
o
J-
a a
CO CM LO
OT K> h-
CJ » m
888
rj in h-
01 01 01
o a a
a o o
a o a
J 10 TJ
U 01 (M
rH
'i f*i r-i
get a
a c-
ci rg ^-T
rl rH H
a a a
cj a 'j
C I O O
CO ( J U)
rH rH
m ri r-
ri * u1
Q U U
'3 u a
r- cn a
r i rg K)
H rH rH
ci c; o
t
C) C_ O
tO ^- "J
o~i ^ cn
T* -H
c> r
c . j-
C.) I-.
c c.
JJ- U-
3- ^r
CJ O
LJ iJ
r cr
t-t U
t < rH
r>j
Cj
C-
T-4
CJ
i H
O
O
^
a a a o
a u> N w
CO 5> r-i CSI
rH rH
N a> a
r- 3 3
a n H
O O t)
a rH rH
CO CO CO
o a Q
a a a
a Q a
a * co
^ rH rH
f J U)
P- CO
88
a.
cn CP
a u
a a
o o
C3 *N
U) 01
r-t rH
r~i
r-
a
^
r-H
O
J
a
a
rj
CO CO
G»
SB
S8
fH H
ui !-
a o
o a
t- n
03 M
fM 1.1
5S!
gs
rsj cj
co cn
o o
o a
CO r-4
Ul .H
M r-
a- cn
'H f^
c- a
a a
rH CG
Cj CJ
O CJ
* n
7 03
j O
M U)
H H
(N 10
88
3- a-
01 01
O (=1
a a
f» M
r- f*i
N r~»
r- Tt
r j
r
C
Cj
u
o
J
<^J
rj
(N
*
*
(M
H
8
rH
O
CO
r-
o
o
r.
LD
00
rH
CJ
3
H
cJ a c_ o o ^ _J j
rj i\j r^ f 4 rj r t ' J r J
A-43
-------
-C
CL
E
O
ro
Q
SPEED -- APPROACH SPE
Table All. EFFECT ON SOURCE STRENGTH OF SIGNAL CYCLE LENGTH, TRAFFIC DEMAND, GREEN TIME, AUD APPROACH
M
f/l
ri
CO
M
II 01
v^
O
X
c- ^
r-
z
_l
C"
n
L/I
_J
r H
r--
M
II 1/1
>d
tj
X
0 X
r-
r:
_j
o
h
L i
_J
rH
O
II LI
-J
>- U-
U
X
CO I
r
z
J
(-
1 4
LI
-J
\-*
11 (.1
_J
> U.
CJ
\
J -
z
-J
Cl
r-'
U)
.J
\- '
3"
_J
> I
Ci
X
LJ n
J
_]
t-
K-l
H LI
~J
> U
t_
X
<. ' 3"
_J
! i
1 1
-J
rH
f J
n
n n
>- u.
o
X
O X
r-
J
r-j
I 1
(J
T
CMroinu>oQOiHro
HcMrojinf-cOot
o CJ o o ci o P u
ac'oocjaao
HHOcncocor-ro
3>mu>Lor-aoo"to
a c' a a cj co o TH
O Cl CJ C1 O C1 Cl C
inpLOfHLQNr-rM
H H CM CM ro ro *
CM rO in LD CO p .H
rH CM ro 3- in N CO
o o o D a a p
a n o o a a o
IM LO a J t) ro co
03 r- o*> o «-( CM (M
a a a .H IH H H
a O a a u o a
a a o a a u a
CO ifl 3* M CJ 00 LO
rH fM M 3- 3- UI
(\) rO in LO 00 C,
M CM ro j- LO N
gggggg
* i rH C3 UI f-J Cn
OQ Q CM ro 3 3-
C_ O O O Q 0
r- M cj r K> cj
0 rH U (M ro 3-
.H f J ro 31 ui uj
ri M n LO °i
H IM .-o 3- 1.1
C, C C) C CJ
a o Ci CL D
ro u> o CD LO
CJ ri in D u>
rH >H H rH tH
Cj O CJ CJ O
' i r~- o r-) r
f i L. a ro i.
rH fJ 3" tO LJ
CJ r^ tn i.)
M n »o 3-
L. a o o
C <~J <.J -J
3- fM H -H
f j in r- co
rH rH ,H .H
t, L, CJ t.
c. o c, c
I *
-4 r j u
r i r ir>
'- iJ CJ
C 0 C
3- r- ri
3- F*- in
rH 1 r-»
J v-l LJ
(-')_;
o r ui
t » ro L
r i r,
- 1 J
C- U
u -J
L> C"
LD ""*"!
- 4 rJ
f1 r-
r-* ' J
[-4 3"
r. 3- -o o o M * >o
n> lo u LO L.O LO o ui
(M rO in LD
H u>
gigg
H CM KI *
co o H m
in r* oo en
ci o ci a
a o a o
CO LQ Ol CM
r* co ep en
go p o
C CJ D
to i>. ad en
r--»t-teoin(M(PU)
M (M M 10 * tf UI
(M ro m us
H CM ro 3-
CD O O D
a o o O
(M U3 a INJ
ua f en a
a u a H
LJ a o a
f- »o o r~-
Cl iH (M CM
fH [J Kl 3-
CJ M Lfl LO
r-1 CM M »
O Q Q O
o Q O o
ro ^ co ft
eu u fH c j
O Cj C t
rj 3- h- en
3- (t) rj ui
*H f J 3- Ul
CH "O LO Ul
fH C4 M 31
C C_ C- C-
O O O C
r-i t.a CTI r-
U t- fO 3^
rH rH «H *H
a o L a
O ' 1 Kl .-1
f*- u ri ^
rl f > IT f
ri r u> LJ
LJ Cj tj U
UJ -J L"J J
3- L. CJ CO
rj o UT -j
rH -H r< .H
f C CJ C,
r-^ h C r-
r < 1 -T LI
C -J Ji'
r , r- i, >
r-< ( f-
u ._ o
C, C, C
3- rn C_
3- i. > ai
rH rH . J
O L- U,
at c*i r^
^ c .3
ft * r
rj '-T
r 1 1 J
C, C
C. L-
Lt- ">
ir a,-
^ rH
O L.'
a- en
00 ' J
C . i 1
JO Ol")
cp P H
m (^ eo
a P p
a a a
f*- N LO
Q rH H
H H ^t
L3 O 0
ro a r-*
ro * a-
in io r-
SE
88
.H LO
to ro
o a
^ M
-H 'O
r- co
CO
ui
CJ
a
j-
L>
H
CJ
-fl
ro
a>
-H rH H <-H
ro CO cX) ro
N n
H CM
O O
a o
33
88
^J 3-
O Q
r- r- j
ra 1 1
rj r
rH f ,
a cj
a cj
«
3" f 1
3" W
rH
O L.
*H r
h > L
f-1 ro
iH J
o c
u u
UI M
LD tn
H rH
a a
l^J rH
10 rH
ro r-
J O
Ifl LO CO G rH !>O
ro a- in r*. co to F- OQ
80 o o a
o 5 c 5
o u) a * co
en OT o o a
a a r-t H »H
a a a a o
a ro r^ o M
P ro LO a ro
cf- in LO en 01
in tc oo ci
ro 3- to f-
S9 P a
a o a
H r- ^^ CD
tH rH TJ CM
c a a a
*o rH ci r-
fO T-4 1> )0
in r- no a
^*
U" LJ 05
ro 3- L/)
U CJ C
0 C.' (_
c i m ,.i
f-i f ,r
rH rl rH
o a cj
r- "1 rH
o u ^
rH
to LD
ri j-
LJ CJ
vj a
fM O
Ui LJ
C Tj
C- t-
* *
n L ,
r-
c-
C
r.
r
C-
' i
^
p
rH ^H rH rH
o a cj o , u
cj ro in
H 'M rO
a a a
a o a
5!rf3
ggg
K ro a
SSP!
CM ro tn
H CM ro
Q a a
p p a
N us m
co r*- oo
POO
o o o
3 o a
a> CM oo
M ro fif
CM ro in
r-4 fM (1
O Q C3
cj a o
f-> O to
CO C U
C> C 0
M r- o
-H rj 3-
->) 3- 'J
rj ro in
-H rj n
e cj c,
uj 0 C
ro o"> h-
C, >H TN!
* «H M
U O CJ
r- ro u.
L f> O
ri L.) en
4 r i b
O Cj cJ
vJ -J LJ
3- ((
j C-i J
». C, I
I
3- r- L.I
.-r ir o
< . -t 4
' f - i
r-- 3 P
r ,H
r FT
i rg
L. C
. L,
3" i )
I 1 f-
C L-
r-~ r-i
' i LI
J C"
I j J 0
j ' J - J
U> CO p H tO
d- tn h- co en
p a a a o
o a p a p
SSftPi
§g?eg
r» ro o r- r^
fM ro or * in
3- ui LO r- co
U) co p H
3- u1) F- co
BO O C)
a o o
a ui TI r\i
0"> CT* 0"> O
o a o .-4
o a o o
o a o a
3- a LO D
UI 00 01 fH
fH
LO 00 Cj
a1 m r
o a o
o a o
rj r r^
r-1 ^ (NJ
CL o a
M r- c.
LO L.O m
^ J i J
rH i~<
LO CO
31 if)
a c
O C-
ro co
tH tH
U O
r- (-->
ID r->
C M
"< r^
u
3-
3
IO
ui
--*
I
c,
-o
0 J ( J 3" 1
iH rH rH , H
g (-j f-i r i i
(Si fO UT(
»-t M ro
o p p
o p B
333
Bgg
* 01 ro
fM * r-
r4 rM ro
PM r*i L/>
r-* CM n
BCJ O
0 0
rj u) M
u) rv co
U O a
oca
r ro O
co r- LO
fH ro to
rj ro ui
CO P
* t/1 h-
o a P
Q P O
in as t-4
a» LO r*
o a p
en a a
tTt fM 3>
* ID r-
LO 00 CJ
3/ m r-
Qua
n o o
r- H J"
oo a> OT
a o Q
u a a
f- ro Q
^ ro M
r- crv r4
H
LO CO C
3- u-> r-
CJ U Q
o o 3
Q- f J W
0 rH -t
O CJ C,
L.I 3- ^,
01 rj ir
t_0 nl
3- i i
C C-
c~ c
m r
tg M
rH rH
Q CJ
3- i
3- i-"
r-4 f t
t )
3-
-J
n
-T
L
4 1
3-3-3-
H ro
oa
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
CVJ fO
H (NJ
U C3
CJ CJ
I.? CJ
c r
r a-
3^
r\l ro
rH fM
r> a
CJ O
CJ 0
^ r-
r>j 3-
1 J M
rH PJ
' 1 -T
uj Ci
C. C.
c c;
rr r
.."j u'
rj n
H rj
c: c.
r- fi
c_ a
, J H
; , ::*
c
r f >
i i ^
C r
a- o
ro j
g§
S3
u o
r M
r- er
f U)
in u)
ro *
CJ CJ
a a
O co
a C3
a a
a M
lO CD
in <.->
a f j
a a
a m
t- LJ
C C'
M n,
! 1 rO
J 4
I 1 i, J
M 'f
C C-.
C tJ
f J f f
C. CJ
r- j
i i r
f , I-
c >-
Li J
uJ 1 -
i . f-
.-< -1
r
L
f ,
r-
u
c
co a
a u
o o
in ao
U> U)
C CJ
c t-
rH r>
Z£
an p
O C3
O D
co H
ao cn
O O
a a
r- a
U) CO
o TJ
rH rH
CO C
is* r-
Bi_)
c
a. M
Cj rH
rH rH
L- Q.
i j r-
i -J J
c
r:
-
LJ
,
"^
rH rO
CO 01
a o
u a
H ro
f- r*
c a
C C)
UJ «3
en H
rH
rH
C?
a
tn
a
o
ro
H
(M
H
C
D
H
O
C
C
H
O
a
U3
C1
O
13
04
ro
u
f-
00
a
a
c
Jo
H
c]
^
LJ
C
r
O
o
. -1
i 1
,4
C
J-
< i
1 J
U
u
M ro *
O O O
0 D 0
in in 3
BBS
COO
W CO &
f) 3- U>
o o a
a o o
f*l aj f«J
r- r«- eo
o u a
o u a
Q a o
S££
r") in CJ
f r
ss
a P
O Q
u> oi
in m
fOH
fO H
tn r>>
m u>
8§
UJ O
h- 00
U Q
o a
o r-»
a u)
eo a
rH
ro st
gs
u) a
^ o
O rH
0 0
r- -H -H
LJ a
r , D
f"O PN.
-v K
^H rH
L) UJ
cj a
n ro
-H H
o o
C ">
*
) H
rH fSI
I"
t,
CD
O
CT,
rH
eo o
in r*
o o
H *
go
El
-------
-c:
E
LU
a.
CO
5
1
a.
OL
<
1
LU
UJ
a.
00
CJ
§
cc
0.
Q
?
jg
h~
UJ
a:
cT
UJ
a
CJ
u.
j
UJ
i
Ul
-J
CJ
CJ
1
U.
o
c.CE STRENGTH
0
CO
r-
o
UJ
LU
LL)
CM
0)
-Q
fO
f
M
ri
M
II 1/1
C X
H
_J
e
M
(/J
H
H
II 1/1
CD X
z
O
h-1
L/t
ri
M
(( t/1
V U.
U 3
2
J
t/l
M
1 1 L/>
>- Li_
X
CJ X
-J
o
_J
II LI
-J
>- i.
(.'! X
t--
_j
ii f
O -E
13
L-1
/ 1 (.T
-J
> U.
O
X
O X
-J
o
r-
CJ
LO
oacn m
a o o c
a o o a
H H a a
D D O O
i" r- a i*i
" S 3 S
asss
gaga
a a a
(si u> H m
UJ h- ffl o
o u o H
a o a o
o a a o
°Q to tf tSI
>H rj ro
O t Oi 01
H Pi rj ro
88SS
r-i CM H co
oo O 1-4 ro
o o a a
f- ro a r-
O -H CJJ <\J
H ig ii j
M rj CM ro
C- O O O
C3 D O O
=r r*- H rj
o o o o
n <- U ^
»-* f 4 J L."i
O Q CJ LJ
(_) Q CJ D
*
d- ro & u>
r j u-i r- co
,-4 ,H H a
I.T 10
a
o
^
j
t~
1.0
" ^ 2 ^
C CJ O O
LJ (0 J 'J
0091
o a o
a o o
OOP
H M r"
-art
O Q cn
M tSf N
a a a
o a o
N U3 H
§a D
o o
r- ro -3
OHM
r-4 rV M
r5 Kj (M
ro rj d
CO U H
O O a
CM * Is-
j- oo r-J
H (M J-
SO cn
rj rj
a a o
cj o a
O C J J
a c. c.
(1 ^ r 1
r- m r-i
a (^ 01
M M f\l
a rj LJ
L3 .J ~U
j- . ^ 'O
r t 1.1 ..J
r^ ^* , 4
r c c.
C [ .* )
U ' '
O r. J
c c_ c,
in ^ ui
3 r <-"
r . < > r-
f ' cJ- t-
C_ i_
< f J
U C
L_ L
CU J^
rH i *
U C.
CT ri
r-j , 1
C O C
O 0 nj
,p r--
ro * in
r- in f
rj ro «
000
01 H M
iO -4 ui
11 r*- co
ro *
Cj CJ
^ 01
LO I.'
c a
-t ^
^-4 CO
f- CQ
f*l
r-
r-l
C.
^ r-1 -( ,-+
,OO (O '0 -O
0 o H t- M (fl ro
LO r- 01 in a ca H
a a o o H rH H
a a a o u a a
ro r. a ro r-» a ro
ro to D ro LO a ro
r-d rw cr t>"> to co m
c c. 01 c~i 01 o^
88S8gg
CO O l-H (Nj Cj M
D O C O C. O
« u, K, ^ a, r-
tH ro ui r** -0 o
r-« (sj rj ro ^r
o c; c c o
0 O 0 O O
^ LO LO ^ M
O fM ro if L ,
O O O O C,
J if r- TI rs
c j d- u> co ^
f J d" UJ CO - H
CT O 01 (71
r-t r-J ( J ro
0 U LJ (j
O O U J
3- UT IJJ lO
1NJ iT Ul LJ
D O O C.
h ro c r
ID 'I L_ (
C-' L L-
^ n f-
a t-
C L.
C O
LD O)
cj a
LO -H
L 1 .-H
M r-
"a"l-"',^^-J; :°
.j c a J -J c Jo
30
a o
a a
H H
4* ifi
d o
a 5
3 t-t
N
11
C3 O
o a
C3 O
U) (V
yfi
88
to a
C3 a
nV
--i rj
CJ C
M ri
d rj
cj r j
Q 0
r- f i
10 fO
(j in
CO L-
U CJ
Cj J
i j ^t
O C^
f -i -T
f - CJ
< > ( 1
C' CJ
^ c.
I ' t-
I'-l l~~
r j
> i i j
1. L
< --<
L L-,
-r ii j
' J *
J j
- 1 . <
m cncnmcn a>
a o Q o a o
a o o o a o
§§§§§§
N fy fO * * m
ro tf in uo ^*- oo
N ro ^ ui LC
Q O Q O O
a o o a a
h- ro oo ro t^
03 01 01 a a
o a a TH H
a o o D a
a a a o a
a> j- O uj f\i
CT IO QJ £P « (
fsj 10 * trt
888S
01 w r-j r-
o H CM r .
c o a c-
a f ) r- a
vo -o a cj
CJ D O
c c u
CJ u~* ^f
r-1 ^ J
cj a u
O r r i
O U f'l
r J r
LJ O
-) 'J
ui in
t- CJ
o.> >0
CT f 1
c-
c
(-.'
C-
r
r
" " ^ M M H
LJ U C) L I , L,
J J J i1 1 ! ! <\l
, H r< r' < ' t ' J
ao cifficnoi
O O C3 C O Q
a a o o o cj
C) CD D Q D CJ
CJ 0 C C C' C
ri (Sj ro * to f"*-
go (p 01 01 01
fsj CNJ ro j* LO
ssssss
fM LO sf o in cn
tO ^ aO <7l ffl 01
O Q O Q Q O
CJ Q C3 D O L3
r M o r- ro o
fO h- 1,0 ^ ro f^i
CJ C. c- cn cn cn
r-4 1 J r I 'O -31 LIT
gLJ CJ LJ CJ O
a a a cu c
f i cn u, n r» t-<
or> cn o »H --* c -
0 C 0 C- L, C
n o> r- LD cr r,
t 3- r TI . J r
r: d ci 71 rt
. ^ fj TJ ro ,-r
o e o cj a
cj c; c. a a
3 Ul f-, Kl 'O
L rH f I ' 1 f 1
(.J CJ LJ C_, CT
. H J t ) T D
.^ T f 1 J '
f . t CM r
_! iJ (J _)
^t- c > r- ^
i i r- ,_, r
». L i.
\ ' ^
i (
^ r-
',"> U)
t 4 <
* " * " " *
-------
1
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
o
o
rH
C
D
(NJ
r4
3
a
a
CNJ
0
a
m
t-H
r-j
c?
a
c
aj
CL
O
^
OD
a
c,
c,
LJ
,-t
o
J J
o
-d-
r t
j
a
c.
M
c
c
L
cn
<
a cn cn
N CM ft
a D a
a o a
H 0 -*
cj o a
C) C' O
st- r- cn
a en CA
(\J fVJ t*l
o o a
a o a
LU CM N.
CJ CJ (J
a a a
r- c:>^
r i * ui
c . cn cn
rJ CM M
888
U3 t*l T*
o *-i r-4
CJ CJ O
0*1 K) r f >
b i r 1 Oi
,.-4 ,-4 ,-(
c, c. c;
j i j r-
L-, '
( r
c* a
L
( 1
C
ft
er
-T ,o m
i CJ i -1
cn cn
d- in
gg
5P!
Sg
f-t fn
H in
r- oo
cn cn
.* in
o o
D O
H in
at cn
a a
a a
r* a
D N
.* in
88
ro r-
<-* lO
o a
rt (SI
gg
gg
o a
38
as
gg
0 O
o a
a a
a- <»
rg a-
88
CJ O
o a
a o
M U)
a a
^* r j
a a
0 0
U T*
CJ 0
O Cj
CJ O
L. O
u o
fill
;u c,
C L^
0- c'
O CJ
C, (_
Cj rj
J ^j
a a
U' f
c c
U' C1
c_ a
u r^
rH .H
a c
r: Cj
-T ro
-t
f, »
o o
O T)
cn cn
IN m
D D
o a
SN
L0
gg
o a
CO *
y L0
CM M
g§
o in
00 CO
O Q
O O
O Q
f-J U)
r- cn
cn cn cn cn
a a a a
a a a a
gggsj
o a o o
O LQ (SJ CO
<» m H N
H H
* m u)
gg§
01 og in
co 01 cn
O Q O
a a o
a * ao
(\l * LD
^H ^ H
8888
H ID
C. C
iH H
0 a
c u
n cj
cn ff»
(M '-O
CL, O
a c
C ( C 1
H »H
a a
U CJ
u -j
r t uJ
u u
-J CJ
J -T
r. CJ
i j
c_
cn
Ll
CJ
i "i ' J
LJ C
1 'O
a CN
iH «-!
o a
O Cj
uj n
L
r.
c
u
CJ
t i
r j .-r L i
C, (' C t
>0 ) H) .J
i
H
5
9
g
a)
a
a
r.
fM
C.
8
K)
CO
0
o
U)
u)
O
a
r i
a
.,
*
CJ
u
u
TJ
u
u)
CL,
cn
M
C '
C
L.
LJ
i-H
(-.
U
C
O 0
a a
M
KK
as
9 o
f*1
c, c
a"1 tn
^- L i
*
if 10
^ o_
LJ
t~,
u
&
rH tH
Cn CP
f"> £T
88
-* r-t
a c
rj o-
f-j r-
if T
a o
fi rg
C) CJ
1 ' J
f- r-j
H T4
M
Q
a
o
CJ
CJ
. 1
TTcV
ig r i
g
i
H
51
J1
00
§
a
a
to
Cn
8
CO
r-t
C
"1
f J
f-l
r-l
H
a a
M
r-4 H
cn
8
a
a
^
CO
fH
--T 0
'-( H
b?T
j j
A-47
-------
of which are assumed to be operating from a cold start in ambient
information is obtained.
A-48
I
temperatures ranging from 68°-86°F. For different years, vehicle mixes,
percentages of cold starts, procedures similar to those described in
Section 4.4 should be followed to derive correction factors which can be
^^
1
applied to the emission intensities appearing in Tables A8 - A12.
For ambient temperature ranges outside of the range for which Tables
A8 - A12 apply, Section 4.4 or Supplement Number 5 to AP-42 should be
used to derive correction factors as needed. Referring to Tables I
A8 - A12, the column labeled SCL is the signal cycle length in
seconds. TD is the traffic demand in hundreds of vehicles per hour
(i.e., TD = 2 is equivalent to 200 vph). QLNTH is the average queue
length forming during the red phase, in meters. FLSI is the "finite
line source intensity" attributable to idling, accelerating and decel-
erating vehicles (gm/sec-m) and is applied only over the queue length.
ILSI is the infinite line source emission intensity attributed to cruising M
vehicles, gm/sec-m. The ILSI is applied over the queue length as well as
upstream and downstream from the queue. To illustrate the use of
Tables A8 - A12, the emission intensities and queue lengths appro-
priate for the intersection legs sketched on page A36 will be obtained.
Assume, for illustrative purposes, that the approach speed for each m
of the intersection approaches is 25 mph and the signal cycle length
is 100 seconds. Note that for approaches A and C, G/C = 0.62, and
for approaches B and D, G/C = 0.28. Since the approach speeds are all
assumed to be 25 mph, Table A10 applies. From Table A10, the following
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
1
I
I
I
I
CM
cr
CM
0
rx o
u
>> '
o cr
CT>
CTl
-^ o
O 0
i .
v.
to'
to
co
oo
o
o
CM
O
1
0
o
o
co
oo
o
0
CO
co
0
o
0
o
^j-
i^
un
0
O
^.
en
O
O
CO
00
IT)
""i
li
>j
0
"^.
03
OO
*
11
>}
C__?
^-^.
O5
CM
1
>}
O
CI3
CM
o-
CM tO OO I~-
Pv. CO 'd' LO
O O O O
O O O O
,_
o~
(D i O tO
i CM i i
r r r r
O O CD O
r s.
E
!*
C3-1 [^ OO i
CO tO OO i
co O in r-,
CT> cr> oo
C\J
cr
CM CM >=i-
o o o
O O O
r- i CO
Cr
to to to
r r r
O O O
-
£
i »
CM CM 00
CM CM OO
to to o-i
en CTI oo
CM CM -=j-
o o o
CM
o
O O O
o o m
CO OO OO
i
cr
0 00
JC
cu -»->
3 en
CU £='
3 O) E
, , [-^
i tD
r-^ r^»> cD
* ^
jCT
CL
>
^^-^
O
i- T3
M- C
t»- (O
tO E
i- CU
10
o o o o o o o
o o o o o o o
O OJ «^J- ^O CO ^± ^£>
r r
c
o
£
en
cu
cu
O)
cr
o>
-C
S-
cu
o
cu
+J
1
JD
r-
r~
X
CU
^ X
E
1
O
cu
to
^^
E
en
>>
Ul
CU
+J
t
i
j-
O
r-
to
to
CU
to
to
CU
(J
X
cu
II
, _
c~y
CU
S-
cu
-C
S
4->
to
CU
Ol
-
tj
o
cu
c
fC
cu
^:
4-^
C
'*~
(J
t^
ti-
ro
£;
cu
en c:
c ro
to
- cu
3 -C
t ^_J
u
c:
O -i-
4->
CU
CU i.
cu
f~l ^c~
fO 5
*-> >1
3 S-
JD CU
il CU
4_) "O
fd cu
^1"'
-l-> J3
to -C
c: x
cu cu
4_)
C "
c: i
O O
r- CU
(/) CO
CO ^-N.
*' E
E en
CU-
II
CM
o-
^
_j_j
en
c:
OJ
r«
CU
CU
cr
cu
^_,
S-
QJ
O
-o
cu
.,
e~t
i
JC
X
cu
^ ,
E
1
o
cu
CO
*s^
E
CD
^
i
to
c:
o>
c:
-r~
c-
0
CO
in
'i
cu
1
ro
O
.[-.5
II
C\J
o-
^_
I
O'
<_) -C
cu o
S- 0
cu
i-
0_
Q.
o
A-49
-------
1
The information obtained from Table AID may be interpolated to estimate
queue lengths and emission intensities for each Ten of the intersection fl
shown below.
LEG(1) *
APPROACH
1
LEG (4)
q = 0029
1
APPROACH
0
O7
r-
^_
c
M
C
(0
0)
ll"
0)
a
o
-t-
o
ll"
a-
i i
1
q=.0036+.0168=.0204
^f ftn in ^u
^ ou m ^"*^
09
r*.
o
0
ll'
a-
r
]
£
c»
a
\
j
i
i
o
in
0
o
ll"
O"
-
~
II
o
o
o
in
o
o
ll'
=r -
o
in
n'
a-
APPR
1
1
1
q=.0165+.0029=.0194
I nmo
L
^ 04 ni ^ 1
E
s
i
OACH
C
LEG (2) 1
1
1
LEGO)
1
A-50
1
-------
I
Frequently, it should be sufficient to use the traffic
parameters in Tables A.8 - A12 most, closely corresponding to those which
are observed. Thus, in the above example,
For Approach A, G/C = .6, V = 1200 vph, L - 106.7 IP, the
emission intensity over the finite queue = Q, + Qp = .0207 gm/sec-m, and
I
the emission intensity elsewhere in the lane (Q0) = .0086 gm/sec-m.
For Approach B, G/C = .3, V = 400 vph, L = 62.2 m, the
I emission intensity over the finite queue = Q, + 0- = .0161 + 0029 =
.0190 gm/sec-m, and the emission intensity elsewhere in the lane (O^) =
For Approach C, G/C = .6, V = 800 vph, L = 71.1 m, the
.C029 qm/sec-ni.
I
emission intensity over the finite queue = Q, + Q~ - .0116 + .0057 =
.0174 gm/sec-m, and the emission intensity elsewhere in the lane (Q-) =
.0057 gm/sec-m.
1 For Approach D, G/C = .3, V = 600 vph, L = 93.3 m,
emission intensity over the finite queue = Q, + Go = .0168 + .0043 =
.0211 qm/sec-m, and the emission intensity elsewhere in the lane (Qp) =
.0043 gm/sec-m.
The foregoing discussion of estimating emissions at signalized
B intersections has ignored the impact of good signal progression by assum-
ing that vehicles are equally likely to arrive at an intersection during
red and green phases. Good signal progression, however, could result in
a greater proportion of vehicles arriving during the green phase than
would otherwise occur. In such a case, the excess emissions due to
idling and acceleration/deceleration would be less, and would occur over a
A-51
I
-------
I
shorter queue length. To illustrate the impact such signal progression
would have, suppose the traffic signals upstream from approaches A-D
in the previous example were coordinated in such a way that 80 percent jl
of the traffic arriving at the intersection does so when the light is
green. Considering only Approach A, this means that 20 percent of the Q
1200 vph arrive during the red and amber phases rather than the 40 _
percent which would occur if traffic arrived uniformly and G/C were *
0.6. Hence, from Equation (A18) the queue length L would be A
L = V-^V^uuMuy = 53 m (A18) g
where the "0.2" is substituted for (1-G/C ). In other words, this is
equivalent to setting G/C equal to 0.8 with uncoordinated signals. I
Therefore, one can account for good signal progression in estimating the
infinite and finite line source emission intensities by using the information
for G/C = 0.8 in Table A10. Thus, the emission intensity over the 53 meter
I
queue would become Q, + Q? - .0078 + .0086 = 0164 gm/sec-m and the emission
intensity elsewhere would be .0086 gm/sec-m.
The procedure for estimating emissions at non-signalized inter-
sections differs from that at signalized intersections, because queuing may m
occur continuously. Further, traffic is more likely characterized by
stopping and starting motions as traffic moves up position by position in
the queue. The average length of a queue accumulating during an entire
hour (i.e., not just during the red phase of a traffic signal) nay be
9
obtained from queueing theory using Equation (A20). m
c.. (c.. -v.., J (A20)
I
A-52
-------
I
I
I
I
where L.. = everage queue length in lane j at approach i, m;
v.. = traffic volume demand in lane j, approach i, vph;
c.. = approach capacity for lane j at approach i, vph;
D = spacing assumed between vehicle tailpipes, m/veh.
I Emission intensity over the queue length is given by Equation (A21).
I
qi:j = (EFJ.../60D (A21)
where (EF).. = emission factor for stop-and-start traffic having an average
speed approaching 0 mph, gm/min-veh
D = spacing between the tailpipes of vehicles in the queue,
in/veh
1/60 = conversion from min~ to sec"
q.. = emission intensity in lane j at approach i, gm/sec-n.
' J
The impact of accelerating and decelerating vehicles would occur over
a distance immediately downstream and upstream from the queue respec-
tively. This existence may be estimated using Equation (A22).
^.. .... l(Fina1 Velocity)2 - (Initial Velocity)^
Distance =
where Distance is in meters.
The velocity terms are in m/sec.
12
The acceleration term is in m/sec .
Emission intensity over the distance obtained with Equation (A22)
9 may be approximated using Equation (A23).
I
(A22)
q... = (1.036 x 10"5) WJ.. V.../S... (A23)
where
(EF") . = the average emission factor for a vehicle accelerating
(decelerating) between initial and final velocities
designated in Equation (A22), gm/min-veh
A-53
-------
v. = traffic volume demand, vph
S.. = approach speed x 1/2, mi/hr
A-54
I
I
The value of TEFL- could be obtained by using the Automobile Exhaust V
10
Emission Modal Analysis Model. If it is not feasible to use the
modal model, average trip speed emission factors similar to those used
in Equation (All) would have to suffice. This would result in under- ^
estimating emission intensity just downstream from the intersection
approach. Equation (All) may be used to estimate emission intensity
at all other locations on the roadway.
I
I
I
I
I
1
I
I
I
I
I
I
-------
I
REFERENCES
(1) 40 CFR 52; "Approval and Promulgation of Implementation Plans--
Q Review of Indirect Sources"; Federal Register; (July 9, 1974);
_ p. 25292.
* (2) U.S. EPA; Office of Federal Activities; Guidelines for Review
flf of Environmental Impact Statements, Volume 1, Highway Projects;
(September 1973).
0 (3) U.S. EPA; "Compilation of Air Pollutant Emission Factors"
m Publication No. AP-42 (Second Edition) U.S. EPA, OAWP, OAQPS,
* Research Triangle Park, N.C. 27711 (Supplement No. 5, In Press).
(4) 40CFR 85; "1975 Federal Test Procedure"; Federal Register; 36_;
No. 128; (July 2, 1971).
(5) Thayer, S. C. and J. D. Cook; "Vehicle Behavior in and Around
_ Complex Sources and Related Complex Source Characteristics: Volume 6-
" Major Highways"; FPA-450/3-74-003-f ; National Technical Information
Service, Springfield, Va. 22161. (November 1973.)
(6) Tittemore, L. H., M. R. Birdsall, D. M. Hill and R. H. Hammond,
"An Analysis of Urban Area Travel by Time of Day," Report Mo.
FH-11-7519, U.S. DOT, FHA, Office of Planning, Wash., D. C. (1972).
(7) Mr. Robert Probst, Federal Highway Administration, Personal
Communication.
(8) Highway Research Board. "Highway Capacity Manual 1965"; Special
| Report 87; NAS-NRC; Washington, D. C.; (1965).
I
I
I
A-55
-------
I
(9) Hillier, F. S. and G. J. Lieberman; Introduction to Operations _
Research; Hoi den-Day, Inc., San Francisco, Ca.; Ch. 10; (1967).
(10) Kunselman, P., H. T. McAdams, C. J. Domke and M. Williams;
Automobile Exhaust Emission Modal Analysis Model; EPA-46Q/3-74-005;
January 1974); National Technical Information Service, Springfield, Jj
Va. 22161.
(11) Patterson, R. M. and F. A. Record; "Monitoring and Analysis of
Traffic Characteristics at Oakbrook"; EPA-450/3-74-058; (Nov. 1974);
National Technical Information Service, Springfield, Va. 22161.
(12) Leisch, J. E.; "Capacity Analysis Techniques for Design of I
Signalized Intersections"; Public Roads 34, Nos. 9, 10 (Aug. &
Oct. 1967).
(13) Traffic Institute, Northwestern University; "Capacity Analysis
Procedures for Signalized Intersections" Publication No. 3900.
(14) Ashby, H. S., R. C. Stahman, B. H. Eccleston, R. W. Hum; J
"Vehicle Emissions-Summer to Winter"; Paper No. 741053 Presented at
the Society of Automatic Engineers Automobile Engineering Meeting;
Toronto, Canada; (October 21-25, 1974); Society of Automotive
Engineers, Inc., 400 Commonwealth Drive, Warrendale, Pa. 15096.
(15) Williams, M. E., J. T. White, L. A. Platte and C. J. Domke; I
"Automobile Fxhaust Emission Surveillance -- Analysis of the FY72
Program"; EPA 460/2-74-001; (February 1974); National Technical
Information Service, Springfield, Va. 22161.
A-56
I
I
I
-------
I
_
I
SUPPLEMENTAL REFERENCES
(1 ) Traffic Information Requirements for Estimates of Highway Impact
I on Air Quality. Air Quality Manual Vol. Ill, FHWA-RD-72-35. Prepared
for Federal Highway Administration, Office of Research, Washington, D.C,
I (2) Lynch, Kevin, 1962. Site Planning. The M.I.T. Press,
mt Massachusetts Institute of Technology, Cambridge, Massachusette.
(3) Benioff, Barry and Ahmad Moghaddas. February 1970, "Stopped
Vehicle Spacing on Freeways," Traffic Engineering.
(4) Automobile Exhaust Emission Surveillance. May 1973. Prepared
| for Environmental Protection Agency by Calspan Corporation.
_ PB-220-755.
(5) U. S. Department of Commerce, Bureau of Public Roads, Highway
I Statistics, GPO, Washington, D. C.
(6) May, D. A., "Traffic Characteristics and Phenomena on High
| Density Controlled Access Facilities." Traffic Engineering, 31:
- No. 6, 11-19, 56 (March 1961).
(7) Keefer, L. E., "The Relation Between Speed and Volume on Urban
V Streets," Quality of Urban Traffic Service Committee Report, HRB,
37th Ann. Meeting (1958) (unpubl.).
(8) Webb, G. M. and K. Moskowitz, "California Freeway Capacity
Study--1956." Proc. HRB, 36: 587-642 (1957).
(9) Edit, L. C., R. S. Foote, R. Herman, and R. Rothery, "Analysis
V of Single-Lane Traffic Flow." Traffic Engineering, 33: No. 4, 21-27
(January 1963).
I
A-57
-------
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
APPENDIX B. METHOD FOR ESTIMATING GROUND TRAFFIC
EMISSIONS FROM AIRPORTS
This appendix is intended to provide guidance concerning a
more detailed analysis of proposed indirect sources should
this be necessary or desirable pursuant to 40 CFR 52.22(b),
The materials contained herein are offered as suggestions.
Alternate analytical approaches for evaluating the impact
of a proposed source may be used if it can be demonstrated
that they are more applicable to the source under review.
U. S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, N. C. 27711
January 1975
-------
-------
I
APPENDIX B.
METHOD FOR ESTIMATING GROUND TRAFFIC EMISSIONS FROM AIRPORTS
The purpose of this Appendix is to provide a means -For estimating
I emissions from ground traffic at airports which handle primarily commercial
M carrier-tyoe operations. It has been estimated that within the next 10
years, 112 new airports of this nature are likely to built. Consequently,
I the development of major new airports to handle commercial carriers is a
relatively rare event, and it is likely that a detailed environmental
impact statement would be reauired to accompany the development of each
_ such airport. Aroonne National Laboratory, under contract to the Fnviron-
* mental Protection Agency, is preparing a methodology for assessina the
many impacts arising from development of a new or larger airport. The
air pollution impact is discussed in detail in /"PTD 1470. The accomoany-
ina analysis is intended to provide sugoestions for fulfilling the more
_ limited ooal of estimating emissions of pollutants -from nround traffic
* which can ultimately be used to assess the impact of the airport on air
tt Quality. The methodology for estimating emissions from ground traffic at
airports is summarized in Section PI. The remainino sections provide
suggestions for implementing the methodolcny in Section FI.
_ BI. Summary of the Methodolory for Estimating Fmissions Associated
with Airports
A. Macro-Analysis
1. Obtain the parameters indicated as essential from Table Dl.
I
I
I
B-l
-------
I
2 I
2. Use AP-42 to obtain emissions from relevant stationary sources. |
3. Use Table B2 to estimate appropriate emission factors for light- M
duty vehicles in 1975. Use Equations (B3) - (E5) for emission factors for
other years. Correct for cold starts-cold temperatures and altitude using I
c B
guidance in Section 4.4 of the screening procedure or Supplement 5 to AP-42.
4. Estimate traffic demands. |
a. If trip data are available from the developer, use «
Equations (B7) - (B12). *
b. If trip data are not available but population data are,
use Equations (B13), (B13a), (B14), (B17) - (B19) to estimate ADT and then
use Equations (B7) - (E12). J
c. If neither trip nor population data are available, use _
aircraft operation data. Use Table B4, (B17) - (B22), (B13), (B13a) and
(B14) to estimate ADT. Then use Equations (B7) - (B12) to estimate traffic
demands of interest.
5. Estimate running times.
a. Running time within the airport. Use Equation (B24) to _
estimate a typical running time after using Equations (B24), (B25) and *
(B27) - (B31) (for non-signalized intersections) or (B32) (for signalized
intersections) to determine running times for vehicles going through each
entrance/exit gate and base running time. Estimate average running time
with Equation (B33).
b. Impact of the airport on emissions within 3 miles of the
airport. I
Estimate typical vehicle speed and travel distance based on
design information on planned and existing access roads and the I
B-2
I
-------
I
distribution of volume demand over each road segment. Follow the pro-
_ cedure outlined in the macro-analysis section of Appendix A.
6. Estimate emissions using Equation (Bl) plus emissions from
stationary sources.
B. Micro -Ana lysis
Refer to the micro-analysis section in Appendix A to estimate
the impact of freely flowing and/or queuing traffic on nearby CO
concentrations. The procedure is as follows:
1. Estimate traffic demand for each lane j in road segment i
using Equations (A12) or (A13). If necessary, adjust the demand for the
impact of mass transit using Equations (A14) or (A15). Apportion demand
among lanes, making sure that Equation (A2) is satisfied.
2. If the analysis does not concern an at-grade intersection,
estimate capacity of the road segment using Equation (AID) and the lane
capacities using Equation (A16). Check that Equation (A3) is satisfied.
If not, adjust the lane capacities so that Equation (A3) is satisfied.
3. Determine volume to capacity ratios (v-./c--) for each lane.
^H ' J ' J
Given the type of road and the average highway speed, use the appropriate
one of Figures A2-A5 to estimate vehicle operating speeds in each lane.
4. Use Figure A6 to estimate the speed corrected 1975 emission
factor for each lane. For years other than 1975, adjust this factor with
Equation (A17). Use guidance in Section 4.4 of the screening procedure or
I
Supplement 5 to AP-42 to correct for cold starts and ambient temperatures,
as needed.
5. Use Equation (All) to estimate the line source emission
intensity of freely flowing traffic.
I B-3
-------
I
6. For at-grade signalized intersections, use information
concerning signal cycle lengths and green time to signal cycle ratios
to estimate queue lengths with Equation (A18). Consider emissions to |
be the sum of those from freely flowing traffic and excess emissions
occurring over the queue length. Estimate emissions from freely flowing
traffic using Equation (All), and excess emissions using Equation (A19).
Alternatively, use the information in Tables A8-A12 directly to estimate
appropriate emissions and queue lengths. I
7. For non-signalized intersections, estimate the average _
queue length using Equation (A20). Use Equation (A21) to estimate the
emission intensity over the queue at the intersection approach. Estimate
the distance over which vehicles may accelerate and decelerate using
Equation (A22). The emission intensity over this distance is obtained I
using Equation (A23). Use Equation (All) to estimate emission intensity
elsewhere.
BII. Key Operating and Design Variables
In a report prepared for EPA , one of three sets of airport utiliza-
tion parameters is considered to be an essential prerequisite for estimating I
emissions from ground traffic associated with airport activities. The
preferable set would be trip data. If these data are not available, then
data concerning airport population or aircraft operations would have to
serve as the starting point for deriving trip data and ultimately emission
data. In any case, certain airport design information should be required
from developers. This design information should include a schematic
B-4
I
I
-------
I
I
layout of the airport with approximate dimensions indicated, the number of
public parking spaces available, number of parkinp lot oates, nate capaci-
ties, terminal curb frontaar and frontage road capacity. Table BI sumna-
rizes needed parameters which should be supplied. Referrino to Table HI,
parameters in oroup ID as well as a complete set of group IA or B or C
parameters are essential. It would be desirable to have the information
I specified in group II "useful" parameters for the individual airport
planned. However, if this information is not available, estimates can
| be obtained from the data Gathered for EPA for 13 major airports. If the
j planned airports would not cater primarily to commercial carrier operations,
certain of the ''useful parameters" in Table PI would become essential
I
I
I
I
-
I
since the approximations in this appendix are based on observations at
airports servicing primarily commercial carrier operations.
A. Emissions from Stationary Sources
1. Hacro-Analj/'sis
For the 'area-wide analysis" required in the Federal reaula-
4 .
tions it is only necessary to estimate total emissions arising from airport
related activities. In this type of analysis, one need not be overly
concerned with the spatial distribution of emissions. Since CO, photo-
chemical oxidants and T!0 are of most concern, emissions of CO, total
A
hydrocarbons and P!0 are of nrime interest. The only two types of stationary
/\
I sources, associated with airports, which may be significant, are combustion
sources and refuse incinerators. Estimates should be made of the tons
(coal or refuse), gallons (oil) or cubic feet (gas) of material likely to
B-5
-------
I
be consumed in a year. This estimate can be made using degree-day data
and the anticipated size of facilities. Annual emissions of CO, HC
emission factors presented in tables in Chapters 1 and 2 of AP-42.2
and NO from these sources may then be estimated using the appropriate I
I
I
Since stationary source emissions associated with the airport are likely
to be small compared with those from mobile sources, daily emissions from
combustion sources could be estimated by dividing the annual amount of
fuel consumed by days in the heating season. Daily refuse consumption I
would simply be the annual figure divided by days in the year. Similarly,
unless better information is available, uniform emission rates throughout |
the day would probably suffice. «
2. Micro-Analysis
A more detailed look at stationary sources of CO may be required
in the micro-analysis for peak CO concentrations. Procedures for estimating
maximum ground-level concentrations resulting from elevated point sources of |
emissions are presented in Volume 10 to the Guidelines for Air Quality
5
Maintenance Planning and Analysis .
Bill. Emissions from Mobile Sources
P-6
I
I
A. Macro-Analysis
The major impact of the airport on air ouality will arise from
mobile sources. Equation (Bl) is used to estimate the emissions from
mobile sources.
I
I
I
I
I
-------
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Table Bl . COMMERCIAL AIRPORT PARAMETERS
ANALYSIS
I. Essential Parameters
Parameters
A. Trip Data
--ADT
B. Passenger/Employee/Visitor
--Average Daily Airport
Population
--Estimated Fraction of
Passengers on Through
Flights or Transferring
Planes
NEEDED FOR AIR QUALITY IMPACT
Remarks
Average daily trip generation
rate, where a "trip" is a one-
way trip to or from the airport.
A round trip would be 2 "trips."
Parameters
Includes passengers, visitors
employees.
This parameter could vary
markedly depending on airport
location.
-- Fraction of Passengers
Accommodated by Mass Transit
-- Number of Buses
C. Aircraft Operations
--Annual Number of LTD
Cycles
--Estimated Passenger
Seats per LTD Cycle
--Number of Airport
Employees
F'-7
One LTD cycle is one landing
plus one takeoff.
This depends on the mix of
commercial aircraft classes.
This parameter is needed because
there is no clear-cut relation-
ship between employees and
aircraft operations discernible.
-------
Table Bl (Continued)
D. Design Parameters
--Number of Public Parking Spaces
--Number of Gates
--Gate Capacities
--Gate Traffic Control Characteristics
--Number of Employee Parking Spaces
--Terminal Curb Frontage
--Terminal Frontage Road Capacity
--Plans and/or Blueprints
Remarks
I
I
I
I
For example, green time to signal
cycle ratios and signal cycle
lengths |
To provide a schematic
picture of access roads,
traffic lanes, and the
dimensions of the com-
plex.
11. Useful Parameters
--Peak Daily Airport Population
--Peak and Average Daily Passenger
Population
--Peak and Average Daily Visitor
Population
--Vehicles/Airport Population
--Peak and Average Daily
Employee Population
--Peak and Average Daily
Vehicle Population
--Percent Peak 1-hr, and 8-hr.
Vehicle Trips of Peak Daily Trips
--Percent Peak 1-hr, and 8-hr. Employee
Trips of Peak Daily Trips
--Percent Peak 1-hr, and 8-hr. Passenger
and Visitor Trips of Peak Daily Trips
--Percent Vehicle Trips from 6-9 A.M.
of Peak Daily Vehicles Trips
--Peak Daily, Hourly and 8-hr. LTO's
LTO's from 6-9 A.M. on Peak Day
Typical Percent of Aircraft
Seating Capacity Filled
c-e
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Table Bl (Continued)
II. Useful Parameters (Continued) Remarks
Vehicles/Ho
--Peak Daily Trip Rate
--Peak Hourly Trip Rate
Peak 8-hr. Trip Rate
--Peak Trip Rate (6-9 A.M.)
Peak Trip Rate (6 P.M.-6 A.M.)
--Yearly Trip Rate
--Base Running Time at Airport Typical running time by a
vehicle with no congestion.
--Average Speed on Airport Outside of the airport but with-
Access Roads in three miles of the boundary.
B-9
-------
0,, =
(EF)(V)(RT)
216,000
Airport
K-l
(dk) (ef) (C(S)k) (Vk)
(Bl)
Q,. = emissions from mobile sources gm/sec
EF = emission factor gm/veh-min
V = traffic demand, vph
RT = typical vehicle running time, sec
M = total number of road segments within area of interest
d. = length of road segment k, mi
ef = emission factor for appropriate year and pollutant, gm/veh-mi
(obtained from Table A3, Appendix A or if the assumptions in
Table A3 are inappropriate, from Supplement 5 to AP-42 )
(C(S),) = speed correction factor (from Supplement 5 to AP-42 )
(V. ) = traffic demand on road segment k resulting from airport
traffic plus other traffic, vph
jQQQ- = conversion factor from *i , to gm/sec
1
3600
= conversion factor from hr~ to sec"
The first term in Equation (Bl) estimates emissions within the bounds of
the airport, while the second term covers emissions outside of the airport
but within a 3-mile radius of the property line.
B-10
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I 1. Calculation of Emission Factors (EF)
Since the designated area of interest with regard to estima-
' ting airport-related emissions is anywhere within 3 miles of the airport,
a variety of emission factors may be needed to account for different
operation speeds. For example, speeds near 0 mph may be assumed in the
parking lots while somewhat higher speeds would be expected to occur on
access roads. In Table B2, the emission factors were obtained using
Table A3, speed correction factors derived from Tables 3.1.2-6a and
3.1.2-6b in Supplement 5 to AP-42 and Equation (B2).
- EF = (cf)(ef)(Speed)/60 (B2)
where EF = emission factor, gm/min-veh
cf = the speed correction factor
ef = the emission factor in gm/mi-veh and
"Speed" = the assumed vehicle operating speed, mph.
If the projected mix of vehicles utilizing the airport has an important share
of heavy-duty vehicles (e.g., buses), or is unusual in some other respect,
Supplement 5 to AP-42 should be used to derive a more appropriate factor.
The resulting value would be substituted for "EF" in Equation (B2) and for
the "Table A3 value" in Equations (B3) - (B5). This procedure assumes the
I variation of heavy-duty emission factors with speed is similar to that for
light-duty vehicles. The preceding discussion has assumed that 20% of the
I vehicles are operating from cold starts and that the area is relatively near
sea level. Further the effect of ambient temperature (T) on emissions may
introduce an additional correction factor. This is of particular importance
I for CO, and the discussion in Section 4.4 concerning CO correction factors
should be referred to. The effect of ambient temperature on HC and NO
|X
emissions can probably be ignored. The data concerning NO emissions vs.
/\
-------
Table B2. AVERAGE EMISSION FACTORS FOR HIGHWAY VEHICLES*
\
Pollutant
CO
Speed
\(mph)
0
20.0
5 10
19.5 19.0
20
18.0
30
17.2
40
16.5
45
16.4
HC's
(exhaust + crankcase
and evaporation)+
NOX
(as N02)
2.24 2.47 2.80 2.99 3.22 3.38
.36
.69 1.33 2.16 3.09 3.60
*Numbers are in gm/min-veh for a 1975 national average mix by model year of
light-duty vehicles (88% cars, 12?^ light trucks).
+Non-exhaust HC emissions do not vary with vehicle speed.
If some year other than 1975 is of interest, emission factors for that
year may be obtained as shown in Equations (B3) - (E5).
/Table A3 Value \
For CO: EF =
If or Year of Interest/
55
/Table B2 Value for\ (B3)
\Speed of Interest /
For HC's: EF =
/Table A3 Value \
\for Year of Interest/
7.7
/Table B2 Value for
\Speed of Interest
(B4)
For NO : EF =
X
/Table A3 Value
yfor Yearof Interest/
4.0
/Table B2 Value for\ (B5)
\Speed of Interest )
P-12
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
ambient temperatures are ambiguous, while HC (as a precursor of oxidants)
_ is chiefly of interest at relatively high ambient temperatures. If ambient
temperatures exceeding 100°F were common, it may be necessary to introduce
a correction factor for HC emissions. Supplement 5 to AP-42 contains a
more complete discussion of how HC emissions vary with temperature. It
I should also be pointed out that if it is determined that extra emissions
_ attributable to cold starts and cold temperatures only occur for a relatively
* short time (e.g., 4 minutes), higher emission factors should be used only
until a typical vehicle becomes warm.
2. Calculation of Traffic Demand (V)
There are three basic approaches which can be taken to
_ estimate ground traffic demand generated by the airport's presence.
a. Trip Data
First, and most preferable, one can work directly with
expected trip generation rates provided by the developer. This type of
information could take 2 forms. Ideally, the trip generation estimates
would correspond to the periods of interest specified by applicable air
quality standards. On the Federal level, this would mean:
(1) For carbon monoxide:
The peak hourly trip generation rate;
the peak 8-hour trip generation rate.
(2) For hydrocarbons and photochemical oxidants:
Peak trip generation rate from 6 A.M. to 9 A.M.;
peak daily trip generation rate.
(3) For NO :
X
I
I Annual average daily trip generation rate.
I
B-13
-------
I
I
Estimates of this sort may be difficult to obtain,
however. Annual averaoe daily trio Generation estimates may be all I
that are possible. If this is the case, data comniled ^or EPA3 for
R-14
I
I
a sample of airports would he used to infer trip neneration rates for
appropriate periods. Equations (B7) - (B12) provide means for estimation
trip generation rates for various periods of time. Equations (B7) - (B12)
were derived usino Tables 12 and 16 in reference 3, information about the I
relative numbers of nassenoers, visitors and employees on neak and
average days and the assumption that employees and visitors' trips are
two-way.
Peak Daily Trip Pate, POT = .05^ /ynj (B7)
Peak Hourly Trin Rate = .07° POT = .11? APT (BR) I
Peak P-f'our Trip Rate = ."PI POT = .003 APT (B9)
Peak Trip Rate = .o/<0 PDT = .050 />ni (BIO) I
(6-9 A.:1.)
Peak Trin Pate = .0?q RDT = .n?r. ^rrr (Bill I
(£ P.M. - * -V.)
Yearly Trir -ate - .043 APT (Bl?) I
The annronriate units for the le^t-hand sides of Eauations (R7) - (PI?)
are in vehicles per hour (vnh). ACT in Equations (P7) - (Dl9) is the
annual average dailv trip rate, trips/day.
k Airport Population nata
In some instances, a dpveloner ma.*/ only have airport
population estimates rather than direct estimates ahout trip neneration
rates. Airport populations are divided into 3 distinct catennries:
I
I
-------
I
nassenners, visitors and employees. Obviously, if there is
information available about peak an^ tvnical numbers "'"or ^ach cateoorv,
this should be useH. Otherwise, the information in Tablo P3, vhich has
beon compiled from a sannle of 1" naior airoorts, '-'ill havp to suffice
I for estimating neak and tvnical numbers of nessonnprs, visitors and
employees present.
I
Table B3. ESTIMATES OF PEAK AND TYPICAL NUMBERS
I OF PASSENGERS, VISITORS AND EMPLOYEES
I -
Fraction of a Typical Day's Airport Population
Passengers Visitors Employees
Typical Day .45 .33 .22
Peak Day .60 .52 .23
Estimation of traffic volume from population data proceeds
as follows. First, the number of passengers, visitors and employees on
peak and typical days are computed by multiplying a typical day's airport
population by the appropriate factors in Table B3. The second step is to
estimate the number of vehicles used by nassenoers, visitors and employees.
For passenpers, this number is nreat.lv dependent on the- fraction of nassen-
qers simply transferrinn planes or on a throuoh-flioht. These oassengers
I do not generate any oround traffic at all. This fraction varies nreatly
P-15
I
-------
I
depending on the location of the airport. It is essential that the
developer provide an estimate of the fraction of throuqh or transferring
passengers in order for the control anency to successfully relate airnort I
population to vehicle population. Once the faction of transferrinci
and through passenqers is known, Equation (R13) may be used to estimate |
the number of vehicles used by passengers and visitors. «
(Veh) = .75 (total passenoprs ner day) H-T) (B13) I
pv g
where (Veh) is the number of vehicles used ner day bv |
P passenqers and visitors:
T is the fraction of through and transferring nassenqers:
The parameter (Ven) can be adjusted to reflect increased
use of mass transit by aonlyino Equation (P13a).
I
I
where b = fraction of nassenners usino pass transit
P = number of buses running durino nerio--1 of interest
I
I
Next, average daily traffic (AnT) can be estimated from the information
present in Table B3, Equations (P13) and (Bid). In estimatino ART, .it I
I
P-16 _
I
(Veh)DV = .75 [(total nassenoers) (1-b)] (1-T) + F (P13a)
(Veh)E = .82 (rumher of Employees Present ner Hav
is necessary to apportion O'eh) amono nassenoers who nark their
-------
I
I
vehicles and those who are dronoed off or nicked un by visitors. From
Table P<3, the total nunber of nasseneers orininatino or terninatinq
their flinhts at the airnort on an averane dav is:
F - .45 (Total Avr. POD.) (1-T) (P15)
I total number of visitors is:
I V - .33 (Total Ave. Ron.) (Rlf.)
Thus, the fraction of vehicles driver by visitors of the total nunber
of vehicles driver, by passengers and visitors is:
I
I
I
v ".33 + ."5
and the fraction driven bv nassenrers is-
F = -ij ^'-! ; fPTQl
.33 + .*F (1-T) l ' ''
r,
If the assmpticr is n'ade that vehicles driven hv visitors anH ennloyees
n>ake 2 trips per day (one corinn, one ooina) anc^ vehicles Driver bv
passenoers nake 1 trip/day, then the averane cailv traffic is niven by
Equation (HI0).
P-17
I
I
-------
APT = 2Fv(Veh)Dv + Fp(Veh)DV + ?(Veh)E (B19)
Daily LTO Cycles = ^.nual LTO r^rcTes (B20)
airport. Table BA presents different classes of aircraft and the mean
of mixes observed at & lame airnorts .
I
I
The results of Ecuation (HI 9) can now be used in Fcuations (R7) - (R12) I
to estimate traffic volumes for annronriate oeriods of interest.
c . Aircraft Operation Pata
The third and least nreferable approach for estimating
traffic volume is to use aircraft operation data to estimate nround
traffic demand generated by nassenoers and visitors tonether with
employee data. As v/ith the other two approaches, if the develoner is
able to nrovice reliable estimates o£ the various 'useful parameters" in
Table Bl , these should be used directly rather than derived usinn infor-
mation based on EPA's limited sample of airnorts. Startinn v/ith the
annual number of LT^ cycles (1 Landinn + 1 Takeoff Operation), the
averane daily number of LT^ cycles would simnlv be:
I
I
The other ream'red parameter, passenrer seats ner LTO cycle, can be
estimated by anticinat.inn the 'mix11 of aircraft likely to be usino the
I
I
I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Table B4. AIRCRAFT CLASSES AND THEIR OBSERVED
UTILIZATION AT FOUR LARGE AIRPORTS
1.
2.
3.
4.
5.
6.
7.
Aircraft
SST
Jumbo Jet
Long-Range Jet
Medium- Range Jet
Turbo-Prop
Business Jet
Piston Engine Utility
Seating
Capacity
136
490
129
116
61
10
1
% of LTO's
at Airport (1969)
38%
49%
13%
In the absence of no re specific data ^ron the developer,
Table B'1 is used to estinate a tynical runner of passeraer seats ner
aircraft of about 115. This is equivalent to ?30 nassenner seats per
LT^ cycle. To estinate the number of nassenners ner LTO cycle, data
provided by the developer on -Fraction of seatino canacitv utilization
v;nuld be useful. If this information is unavailable, information
3
compiled for FPA indicates that in 197H approximately 47'' of seats
were filled. Hence, one should use Equation (B,?l) or (!??) to esti>ato
the number of passenners per [J^ cycle.
n-19
-------
I
Passenqer Fraction of I
P/LTC) , = Seats Per Seating (B21)
cycie LTO Cycle Utilized
I
where P/LTO cvc-]e "is the number of passengers per LTD cycle.
Using data compiled for FPA , Equation (B21) becoires
I
P/LTO = (230)(.47) = 108 (B22)
I
Combining the results of Equations (B13), (B14), (B17), (B18), (B19) _
and (B20), one pets: "
I
ADT = .75 (Daily LTO Cycles) (P/LTO Cycles) (1-T)[F + 2F ]
p V (B?3)
+ 1.64 (Number of Employees) '
I
Once the average daily traffic volume is obtained from Equation (B23),
Eouations (B7) - (B12) can be used to estimate traffic demand for
the appropriate period of interest. I
3. Calculation of Punning Time(RT)
Total running time is the sum of running time associated |
with two types of traffic. The first is the amount of time a vehicle's
engine runs within the boundaries of the airport. The second is the
amount of time it takes a vehicle to reach a distance of greater than I
^^»
|
3 miles ( the distance cited in the Federal regulations from the
airport bounds).
B-20 |
I
-------
pT
RT =
I
Running time within the airport bounds is the sum of the
"base runninn time" plus any additional tine required to enter or leave
I a parking lot caused by conoestion.
I
I
Referrinq to Equation (R2^)» "BR.T" is the base runninq
time required for a vehicle to arrive, enter, move to a parkinq space,
park, unpark, move to an exit lane, exit and depart from an airport
parking lot. The base runninq time can be estimated by studyina the
physical configuration of the proposed airport and its parkinq lots.
An example of the procedure v.'hich mi'qht be follov/ed in cstimatirq base
m runninq time from the airport's physical configuration and applicable
traffic regulations is illustrated in Equations (p?Fa) - (P25h).
Distance between entrance and nearest
Base Approach Tine , ^ L (R?5a)
n, r^^,, T,- Number of entrance lanes at, nain nate
Rase Entrance Time =
|
I
(Main entrance rate capacity, veh/sec
Base Mov-ent In Tin,e - 1 5 &^
Base Parking Time = 5-10 sec
Base Unparking Time = 5-10 sec (D25e
B-21
I
-------
I
I
i o r^ r*^n (**i IOT ^*o *~A ^ "i ^ f^ v n r ^ ^^^
_ ._._ _"*_,_"_ . ._ '^/ ^ , .'_*_.. m^. f Q t) C -p j
'sneed linit in 1pt) '"""
I
*ase fxit Tire = ^
(am exit rate canacit'',
lanes at na-jp rate)
|
"'istancp hetvepp riaip pxit -pd ^earpst
Pase >naptups Ti access
r
(D25f) +
^ ip rnuatTOP Cn?/1^ -is thp nean extra mrninn
sneed lirit, P/SPC ''" ''''
I
I
I
scent in f-.xit or entrance oueues. ler each nor-s"1 nnanze^ oxit/ertrapce '"
oate, i, runninc tisne snept in a ruoue is estimate'"' usinn ?,r rpnation
TO m
fror nueuinn theorv
, * §
^: } =: __ _ ; v./c_. ^ _PD ,P07/
I
(PT0)1. = runninri tire snort in pupun at natc- i, rpc
v. = enterinn or pyitirn traffic volure "enand
at natp i , veh/hr.
c- =
. . .
traffic volume denand durinn the tire neried cf irtpr^st is apportionpd
anona nates. Tf this ?stiratp ^'s unavailablp fron ^pvoloners, r>uations
_____________
*A separate analvsis is r.ppded ^or enteripn and
I
I
I
-------
I
I
m (P28) or (B29) should be used to estimate the traffic volume demand at
gate i.
Iv [-Capacity of acc£ss road i ->
vi ~ v Lz (Capacity of all access roads)J
" Or, if there are 2 or rrore pates exiting onto the same access road
(or if access road capacity is unknown),
vi = V r\- (B29)
all i1
I
It should be noted from Aquation (P30) that as v. approaches c.,
(RT ). becomes very large. The following suggestions are therefore
made.
(RTQ). = 3GOO(20/Ci), .95 < v./c. <_ 1 (B30)
v./c. > 1 (B31)
I
I r (v.-c.
(RTQ). = 3600 20/Ci + -f2-
Ecuation (B31) assumes the length of the line e.t
exit/entrance is small at the beginning of the time period of interest.
If this assumption were not valid, Eouation (B31) should be altered as
shown in Equation (B31a).
I
P-23
I
-------
I
I
(RT ). * We. * (averare 0"eug length )_ . u_/c >, (B3)a) «
l
Excess runninn time spent enterinq or exitinq from a narkino lot Kith
sionalized exit/entrances ray be estimated usinq Fauation (B32).
vc
v/here
(P.T ). = excess runninn tine snent exitinn or enterinn at
exit/entrance i, sec j J
Cv = siqnel cycle length, sec _
c' - uninneded capacity at ? sionalized intersection *
apnroach, vph B
o = amount of oreer. tire per sional c.vcle ^or the
intersection annroach O-P interest, sec £
G/C^ ~ opppr, ti>e to sinnal cycle ratio, dir^nsionless
v = traffic derand at the intersection approach of
interest, vnh. M
11 "
Equation (P32) is adanted fron concents exnrossed hv "pvell cen-
cerninc tipps spent by vehicles at approaches to r,inpalizrd intersections. I
The averaoe runninr tine s^ent in nneues in Fquation fP°M is ^irmly
1
R-?4
I
I
-------
I
1
I
I
I
1
1
I
I
I
I
I
1
I
1
I
I
I
all.
vhere I = the total number of exit and entrance rates.
^'- Micro-Analysis
If it is of interest, to estimate neak TO concentrations in the
vicinity of exits/entrances to narMno lots, in the vjcim'tv o* Access
roads or at nearbv intersection snnrr.ac^r?, it is essential that emission
estimates from traffic ir traffic lanes Treated near by the receptor of
interest be estimated. Tvo situations are nf oeneral interest: the case
where traffic flows freely by the recentnr; and the case where ououes
form in the vicinity of the receotor. At traffic lanes within or adjacent
to the airport parkino lot, the impact of freely flowiro and/or oueuinq
vehicles on C^ concentrations in the vicinity of the lanes should be added
to CO concentration estimates obtained usinn an area source me^el relation
the source's size and emission dersitv to Cn concentrations, and aeneral
background levels. More details concernina this orocedure are nresented
in Appendix K. The first terr in Fouation (PI) may be Hivided by th°
area of the narkinn lot to obtain an estimate of emission density, as
shown in Couation (P34).
n = imivKfli. (B3M
^16,000 A l J
B-25
-------
I
where 0 = emission density, gm/sec-m m
A = parking lot area, m
All other terms are as defined for Equation (Bl).
The discussion in Appendix A concerning micrcscale impact
analysis may be used to estimate the impact of freely flowing or queuing
traffic on nearby CO concentrations. Equation (All) is used to estimate
emissions from freely flowing traffic. If traffic in the vicinity of a
signalized intersection is of interest, excess emissions over a finite I
queue (obtained using Eauations (A18) and (A19)) are added to emissions m
estimated for an infinite line source of freely flowing traffic with
Equation (All). Emissions at a non-signalized intersection may be
approximated with Equations (A20) - (A23) and with Eouation (All).
C. Emissions Outside the Airport but within a Three-Mile Radius
of the Airport Boundary m
Since there is a need to estimate the aggregate impact of
airport-related emissions in the vicinity of the airport, a methodology
is suggested for doing so. Emissions covered by the methodology relate
only to those generated by vehicular traffic going to and from the |
airport. Other emissions, such as those oenerated by stationary sources m
like motels and service industries, are not considered in this treatment.
Specific treatment of the impact of such facilities or of traffic related
to them which is not directly dependent on the airport is not possible
result of the dependence of subsequent development on existing land use M
B-26
I
-------
I
patterns in the airport's vicinity, future land use plans and the
availability of appropriate services located elsewhere.
In estimating vehicular emissions outside the airport boundaries,
the traffic volume assumed should be the same as that estimated within
the airport for the period of interest. This traffic volume should then
be apportioned among roads comprising the road network within 3 miles
M of the airport. Traffic volume not related to the airport but using
network should be estimated using the methodology described in the
fl macro-analysis section of Appendix A. The traffic volume to and from the
airport during periods of interest should be superimposed upon these
u estimates to obtain total traffic volume demand on each road segment,
* (V,). The resulting volume demand should then be used, in conjunction
with the segment's capacity (C.) to estimate average operating speeds
and speed adjusted emission factors for each road segment, as described
in Appendix A. The resulting emissions obtained from Equation (81)
1
should be compared with those which would result without the presence
of the airport in order to assess the net impact of the airport on
CO, HC and NO emissions.
A
I
1
I
I
I
E-27
I
I
-------
I
REFERENCES
(1) Norco, J.E., R.R. Cirillo, I.E. Baldwin and J.W. Gudenas; "An Air |
Pollution Impact Methodology for Airports and Attendant Land Use--Phase I";
APTD 1470 (January 1973).
(2) Compilation of Air Pollutant Emission Factors, EPA Publication
No. AP-42 (Second Edition), (April 1973).
(3) Thayer, S.D.; "Vehicle Behavior in and Around Complex Sources and |
Related Complex Source Characteristics: Volume I--Airports"; EPA-450/3- m
74-OQ3-b;(August 1973); National Technical Information Service, Springfield, "
Virginia 22161. V
(4) 40CFR52; "Approval and Promulgation of Implementation Plans: Review
of Indirect Sources"; Federal Register; (July 9, 1974); P.25292. |
(5) U.S. EPA, Office of Air and Waste Management, Office of Air Quality
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 10: Reviewing New Stationary Sources"; EPA-450/4-74-011; jf
(September 1974); Air Pollution Technical Information Center, Research
Triangle Park, N.C. 27711. |
(6) U.S. EPA; "Compilation of Air Pollutant Emission Factors";
Publication Number AP-42; Supplement 5 to the Second Edition; (In Press
1975); Air Pollution Technical Information Center, Research Triangle A
Park, ;i. C. 27711.
(7) Williams, M.E., J.T. White, L.A. Platte and C.J. Domke; "Automobile f
Exhaust Emission SurveillanceAnalysis of the FY 72 Program"; EPA-460/2-
74-00]; (February 1974); National Technical Information Service; Springfield,
Virginia 22161.
B-28
I
I
-------
I
I
(8) 40CFR85: "1975 Federal Test Procedure"; Federal Register 36 No. 128;
(July 2, 1971).
(9) Ashby, H.A., R.C. Stahman, B.H. Eccleston, R.W. Hum; "Vehicle
EmissionsSummer to Winter"; Paper No. 741053, presented at the Society
of Automotive Engineers Automobile Engineering Meeting, Toronto, Canada
(October 21-25, 1974); Society of Automotive Engineers, Inc.; 400
Commonwealth Drive, Warrendale, Pa. 15096.
(10) Hillier, F.S. and G.J. Lieberman; Introduction to Operations Research;
Holden-Day, Inc.; (1967); Ch. 10.
m (11) Newell, G.F.; "Approximate Methods for Queues with Application to the
Fixed Cycle Traffic Light"; S. I. A. M. Review; 7 No. 2;(1965).
I
I
1
I
1
I
I
fi
I
I
B-29
-------
I
I
I
i
3
I
I
-------
I
I
1
I
1
I
I
I
I
I
I
I
1
t
I
t
I
I
APPENDIX C. METHODS FOR ESTIMATING EMISSIONS IN VICINITY
OF REGIONAL SHOPPING CENTERS
This appendix is intended to nrovide ruidance concerning a rore
detailed analysis of proposed indirect sources should this he
necessary or desirable pursuant to 40 (TR F2.22(h). The pateria^s
contained herein are offered as suoqestions.Alternate analytical
approaches for evaluatinp the impact of a proposed source nay be
used if it can he demonstrated that they are rore applicable to the
source under review.
I'. S. Fnvironmental Protection Poency
Office of /*ir duality Plannina end Standards
Research Triangle Park, f'orth Carolina 27711
January 197E
C-i
-------
I
I
I
I
I
I
I
1
1
I
I
I
I
I
I
I
I
t
-------
I
I
I
I
APPENDIX C.
METHODS FOR ESTIMATING EMISSIONS IN VICINITY
OF REGIONAL SHOPPING CENTERS
The purpose of this Appendix is to provide a means for assisting
I"
air pollution control agencies, applicants and consultants to estimate
CO emissions in the immediate vicinity of a regional shopping center.
A regional shopping center is thought of as one having more than 300,000
square feet of gross leasible floor space and characterized by at least
one or two major department stores. The major difference between
d regional and community or neighborhood shopping centers, other than
M size, is tenant mix. Generally, the tenant mix at the smaller shopping
centers results in shorter visits and, therefore, smaller accumulations
V of vehicles within the parking lots. If it is possible to obtain an
estimate of average daily trip generation rates and diurnal and
| seasonal usage patterns for a proposed community or neighborhood
M shopping center, the methodology described in Appendix C could be
applied to these smaller centers as well. If it is necessary to
f estimate HC and NO emissions at the shopping center, emission factors
x
should be obtained for these pollutants as described in Appendix B.
I
I
I
-------
I
If such a macro-analysis is performed, it is essential that any
reduction in vehicle miles traveled, arising from the use of the large
regional center at the expense of a number of smaller centers, be m
accounted for. This consideration is particularly crucial for shopping m
centers, which are among the most competitive of the indirect sources
considered in the Federal Regulations.
Section CI of this Appendix summarizes one means which could be
used to estimate total CO emissions arising from the operation cf a
regional shopping center. A methodology for estimating CO emissions ur
in the vicinity of locations likely to experience peak CO concentrations
(e.g. exit/entrance gates, traffic lanes at nearby intersections) is V
also presented. The remaining portions of the Appendix discuss how
the procedures described in Section CI might best be implemented. flj
CI. Procedure for Estimating Emissions in the Vicinity of Regional «
Shopping Centers
1. Obtain design and operating parameters indicated as essential
in Table CI. If possible obtain estimates for the other parameters
which are indicated as important in Table CI. |
2. Estimate appropriate emission factors using modal emission _
model applicable for shopping centers. If this is not possible, use *
Figure CI and, if necessary, Equation (C4). Correct for cold start-cold M
temperature emissions using Section 4.4 in the screening procedure or
Supplement 5 to AP-42. If the vehicle mix is substantially different |
from that assumed in deriving Figure CI , review Supplement 5 to AP-42
and derive appropriate average trip emission factors. *
I
C-2
1
-------
I
3. Estimate volume demand at the shopping center using (a) the
developer's estimates; or (b) Eqs. (C5a) and (C5b); or (c) Eqs. (C6a),
I (C6b), (C6c) and (C6d).
K 4. if it is necessary, adjust traffic volume demand to consider
increased use of mass transit, using Eqs. (C6e) and (C6f).
|| 5. Estimate Base Running Time using expressions similar to
(C7a) - (C7g).
6. (a) If the lot is unsupervised and the accumulation of
vehicles in the parking lot exceeds 80 percent of the parking capacity,
use Table C3 to estimate a correction factor depicting the increase
in running time attributable to the difficulty in finding and maneuvering
into a parking space.
(b) If the lot is supervised, use an expression similar to
, (C8) to estimate the increase in running time when the lot is completely
utilized.
n 7. Use Eqs. (CIO) and (Cll) or (C12) and (C13) to estimate entering
and exiting traffic demands at each entering and exit gate.
£ 8. Use Eqs. (C9) or (C14) or (C15) to estimate running time spent
in queues at each exit and entrance gate not having a traffic signal.
For signalized exits or entrances use Eq. (C16) to estimate delays
spent in exit or entrance queues. Then use Eq. (C17) to estimate
average running time spent in queues for all entrance and exit gates.
9. Use Eq. (C18) to estimate running time associated with a
typical one-way trip at an unsupervised parking lot. If the lot is
w supervised, use Eq. (C19) instead.
I
I
c-:
-------
I
10. Use Eq. (Cl) to estimate total emissions at and in the vicinity
of the shopping center which are attributable to the shopping center.
Use Eq. (C2) to estimate emission density at the shopping center. Jj
11. If point sources of CO are significant, use guidance in Vol-
ume 10 of "Guidelines for Air Quality Maintenance Planning and Analysis"
discussing stationary sources. Add these emissions to those estimated B
for mobile sources.
12. Refer to the micro-analysis section in Appendix A to estimate £
the impact of freely flowing and/or queuing traffic on nearby CO con- .
centrations. The procedure is as follows:
a. Estimate traffic demand for each lane j in road segment i 1|
using Eqs. (A12) or (A13). If necessary, adjust the demand for the
impact of mass transit using Eqs. (A14) or (A15). Apportion demand p
among lanes, making sure that Eq. (A2) is satisfied.
b. If the analysis does not concern an at-grade intersection,
estimate capacity of road segment using Eq. (A10) and the lane capacities IV
using Eq. (A16). Check that Eq. (A3) is satisfied. If not, adjust the
lane capacities so that Eq. (A3) is satisfied. £
c. Determine volume to capacity ratios (v../c..) for each
I J I J ^^|
lane. Given the type of road and the average highway speed, use the
appropriate one of Figs. A2 - A5 to estimate vehicle operating speeds
in each lane.
d. Use Fig. A6 to estimate the speed corrected 1975 emission M
factor for each lane. For years other than 1975, adjust this factor
I
I
I
-------
I
with Equation (A17). Use Section 4.4 of the screening procedure or Supple-
ment 5 to AP-42 to correct for cold starts and ambient temperatures, as
needed.
m e. Use Eq. (All) to estimate the line source emission intensity
of freely flowing traffic.
f. For at-grade signalized intersections, use information
concerning signal cycle lengths and green time to signal cycle ratios
to estimate queue lengths with Eq. (A18). Consider emissions over the
« queue length to be the sum of those from freely flowing traffic and excess
emissions. Elsewhere, emissions are attributable to freely flowing
traffic. Estimate emissions from freely flowing traffic using Eq. (All),
and excess emissions using Eq. (A19). Alternatively, use the information
W in Tables A8-A12 directly to estimate appropriate emissions and queue
j» lengths.
g. For nonsignalized intersections, estimate the average
IB queue length using Eq. (A20). Use Eq. (A21) to estimate the emission
intensity over the queue at the intersection approach. Estimate the
| distance over which vehicles may accelerate and decelerate using
*m Eq. (A22). The emission intensity over this distance is obtained
using Eq. (A23). Use Eq. (All) to estimate emission intensity elsewhere.
I CII. Identification of Key Design and Operating Variables
Table Cl identifies key design and operating parameters which
| should be supplied by developers of shopping centers. Also listed in
Table Cl are a number of optional parameters which should be obtained
' if possible.
I Physical configuration of the shopping center provides an indi-
cation of size, arrangement of vehicles within the center and a means
C-5
-------
I
for estimating the amount of running time required for a vehicle to B
enter the parking lot, move to a parking space, park, unpark, move to
an exit and exit. Number and capacity of exit/entrance gates are crucial J|
parameters since highest CO concentrations are likely to occur in the _
vicinity of the gates. If the volume demand at a gate begins to approach
the gate's capacity, extensive queuing is likely. The result is likely 9
to be a large increase in vehicle running times leading in turn, to
greater emissions. Configuration and lane capacities of access roads jj
are important, because they may influence the demand at exit/entrance _.
gates and provide a determinant of gate capacity. In addition, access
road capacity, and the approach capacity at nearby intersections on 1|
access roads are prime considerations in determining whether CO levels
will be high at the intersection as the result of extra traffic generated £
by the shopping center. Gross leasible floor space and tenant mix pro- ^
vide an indication of average trip duration and the number of parking
spaces needed to accommodate demand and avoid congestion. Average
daily trip generation rate, demand on access roads, peak demands,
seasonal and diurnal demand patterns and distribution of traffic among |
gates determine the volume of traffic utilizing the source and passing
key locations during any time of interest. When this information is
combined with capacity information, the amount of congestion can be
estimated by volume demand-capacity ratios. Average vehicle occupancy
and mass transit usage are important in relating number of customers p
to number of vehicles at the center.
C-6
I
I
1
-------
I
I
I
I
1
1
I
I
I
I
f
I
I
I
I
I
I
Table Cl . KEY DESIGN AND OPERATING PARAMETERS FOR
REGIONAL SHOPPING CENTERS
I. Essential Parameters
Parameters
Remarks
A. Design Parameters
Plans or Blueprints of
the Shopping Center and
Surroundings
Number and Capacity of Exit/
Entrance Gates
Access Road Configurations and
Capacities (by lane preferably)
Nearby Intersection Approach
Capacities
Gross Leasible Floor Space and
Tenant Mix
B. Operating Parameters
Seasonal and Diurnal Trip
Generation Rate Patterns and
Use Patterns on Access Roads
Angle of Parking
Average Daily Trip Generation
Rate
Traffic Volurre Demand on
Access Roads
Average Visitor Vehicle
Occupancy
Should include such features as
traffic lane locations, number of
lanes at gates, design of gate
approaches and design intersection
approaches on access roads.
Affects time needed to park arid
unpark vehicle.
Number of one-way trips per day. A
trip to and from a shopping center
represents two trips by this definition
and thus counts each vehicle twice.
Denand is the sum of traffic which is
independent of the shopping center
and shopping center traffic which has
been properly apportioned among the
roads on the surrounding road net.
C-7
-------
Table Cl . KEY DESIGN
AND OPERATING PARAMETERS FOR
1
1
REGIONAL SHOPPING CENTERS (Cont'd)
I. Essential Parameters
Parameters
Fraction of Visitors Using
Mass Transit
Number of Buses Arriving and
Departing from the Center
During Peak Daily 1- and 8-
Hour Use Periods
Green Time to Signal Cycle
Ratio to Each Approach at
Nearby Intersections
Number of Traffic Signal
Cycles per Hour at Each
Intersection
II. Additional
A. Design Parameters
Number of Available Parking
Spaces to Visitors
B. Operating Parameters
Peak 1-Hour and 8-Hour
Trip Generation Rates
Highest 1-and 8-Hour Trip
Generation Rates Occurring
During Periods when Non-shopping
Center Traffic is Greatest
Distribution of Traffic
Among Gates
Distribution of Operation Modes
Remarks
Needed to estimate approach capacities
and queue lengths at approaches during
the red phase of a signal.
Needed to estimate queue lengths at
intersection approaches during
the red phase of a signal.
Useful Parameters
Includes information about numbers of
left- and right-hand turns.
Useful in obtaining good estimates
1
m
1
1
1
Vft
t
I
I
t
(i.e., acceleration, deceleration, for emission factors.
etc.) for a Typical Vehicle
Visiting a Shopping Center
c
-8
1
-------
I
fl CIII. Estimating Emissions in the Vicinity of a Regional Shopping Center
Two types of analyses are desirable in estimating emissions in the
j§ vicinity of a regional shopping center: (1) Total emission rate attri-
_. butable to vehicles and stationary sources should be estimated; (2)
* emissions in the vicinity of the most congested exits/entrances, and
I emissions in the vicinity of nearby intersections should be estimated.
A. Total Emission Rate. Total emission rate is of importance
£ for two reasons:
_ (1) To provide a means (together with possible reduction
of visits to competing shopping centers or stores) for relating the
construction of the shopping center with emission density limitations
which may be imposed by land use or air quality maintenance plans, and
£ (2) To provide a means for estimating the emission density
^ at the shopping center and its resulting impact on background (or
* representative) concentrations of CO.
f Volume 10 of the "Guidelines for Air Ouality Maintenance Planning
1
and Analysis" should be consulted if stationary sources of CO will be
P significant at the proposed shopping center. Equation (Cl) may be used
^ to estimate total emission rate from vehicles visiting a shopping center.
n - (FF)(V)(RT) ,m
_ gtot 216,000 ^LU
If-Q. . is divided by the area of the shopping center and its
surroundinq parking lot, the center's emission density may be estimated.
I
I
I
- (EF)(V)(RT)
~ 216,OOOA
C-2
-------
where
2
Q = emission density, gm/sec-m
I
I
0, ₯ = total emission rate, gm/sec
L (j i~> ^^w
EF - emission factor, gm/min-veh _
V = Traffic volume demand, veh/hr
RT = Typical vehicle running time for ! trip during the period
interest, sec 1
A = Area occupied by the shopping center and its parking lot, m'" y.
"1/216,000" is a conversion factor from ?.'" ^ to gm/sec.
1. Estima tiP,CJ_ Em ssio_n_Factors (EF)
Probably the most accurate estimates of CO emission factors
at shopping centers could be obtained if typical driving cycles (i.e., £
amounts of time and sequence of acceleration, deceleration, steady speed m
modes of travel) were known for shopping centers. A typical driving
cycle could then be simulated using the EPA Automobile Exhaust Emission ff
2
Modal Analysis Model to obtain average trip emission factors for
shopping centers. This approach has been followed in characterizing ft
emissions at signalized intersections in Appendix A. Unfortunately, ~
there is not yet sufficient data available to use this technique else-
where within a shopping center. In the meantime, use of the average trip W
3
emission factors contained in Supplement 5 to AP-42 may have to suffice.
Figure Cl was obtained using the 1975 Federal Test Procedure emission |
factor for CO presented in Table A3 in Appendix A for a 1975 mix of ^
light-duty vehicles (88% cars, 12% light trucks) at sea level and *
f\
Tables 3.1.2-6a and b in Supplement 5, AP-42 to obtain appropriate speed K
C-10 fl
t
-------
I
V
correction factors (C(S)). Note that the emission factor at 0 mph
represents a factor for stopping-and-starting traffic, rather than
idling.
If the mix of vehicles at the shopping center were not
predominantly composed of light-duty vehicles and/or the national average
mix of model years assumed in deriving Figure Cl were not appropriate,
_ Figure Cl could not be used and it would be necessary to refer to
3
Supplement 5 to AP-42 to derive emission factors for the appropriate
W mix of vehicles utilizing the shopping center. The curve in Figure Cl
is also based on the assumption that 20 percent of the vehicles are
M operating from cold starts under ambient temperatures ranging from
68°F-86°F at a location near sea level. If the assumptions concerning
percentage of cold starts and ambient temperature used in deriving an
emission factor are not appropriate, correction factors can be obtained
using Equation (3.1.2-2) and Tables 3.1.2-7 or 3.1.2-8 in Supplement 5
3
to AP-42. This procedure was followed in deriving the correction
I
factors for CO emissions appearing in Section 4.4.1 of the screening
procedure.
Ife It should be pointed out that if it is determined that
extra emissions attributable to cold starts and cold temperatures only
I occur for a relatively short time (e.g., 4 minutes), higher emission
factors should be used only until a typical vehicle becomes warm.
I
I
-------
24
22
20
18
16
cc
o
14
Z
O
to 17
GO **
10
T
T
10 15 20 25 30 35 40 45
VEHICLE SPEED, mph
50 55
60
Figure C1. Composite emission factors for carbon monoxide for calendar year 1975.
C-12
I
I
1
1
I
I
I
1
I
I
I
I
I
I
1
I
I
I
-------
I
Equation (C4) should be used to estimate CO emission factors
for vehicle mixes during years other than 1975.
FF = [calculated 1975] /ef\
th [Emission Factod \55/ (C4)
I
I
where
ef = CO emission factor obtained from Table A3 in Appendix A3
for the year of interest, gm/mi-veh
I
_ "55" = CO emission factor for 1975 obtained from Table A3,
M gm/mi-veh
2. Estimation of Traffic Volume Demand (V)
There are three ways in which this parameter may be estimated.
» These are listed in descending order of preference.
a. Use peak 1-hour and 8-hour trip generation rates
(vehicles per hour) provided by the developer as the result of a bonafide
study of the locale. Alternatively, if traffic on the surrounding road
net is the prime consideration, periods in which the sum of shopping
m center traffic and other traffic is greatest would be of most interest.
In locations where there is substantial traffic not related to the
shopping center, the highest demand on the surrounding roads (attribut-
able in part to the shopping center) may not occur when demand generated
I by the shopping center is greatest. It has been suggested that for such
m cases peak hourly traffic demands appropriate for 1- and 8-hour periods
on the day having the tenth highest daily demand be used. Such a
procedure would avoid holidays and Saturdays in December when unrelated
traffic may be light.
I
C-13
-------
1
b. Use expected average daily trip generation rate provided
by developer together with seasonal and diurnal usage patterns applicable
for similar existing shopping centers in the area to estimate peak 1-
and 8-hour traffic volume demand. This procedure is illustrated in
Equations (C5a) and (C5b).
(1 ) For 1-hour:
Peak Hour Demand at Existing \
V - (ADT) / Peak Seasona1 Demand! Nearby Similar Facilities
( M Adjustment Factor 1 Peak Seasonal Daily Demand©
' ' Existing Nearby Similar Facilities
where \ /
\
ADT = Average daily trip generation rate, vehicles/day
V = Traffic volume demand, vph
(2) For 8 hours:
Peak 8-hr. Demand at Existing
(ADT) Pea'< Seasonal Demand\ Nearby Similar Facilities
Adjustment Factor Peak Seasonal Daily Demand at
' Existing Nearby Similar Facilities
V " 8
3. If data from nearby existing facilities are unavailable,
estimate peak 1-hour and 8-hour traffic volume demand from data com-
piled for EPA from a limited sample of regional shopping centers.
a. Weekday Peak Hour Volume: V = .16 ADT
This is assumed to occur from 8-9 p.m. within 12
o
shopping days of Christmas.
b. Weekday Peak 8-hour Volume: V - .12 ADT
1
(C5a)
*
1
jm*
I
I
(C6a) -
I
1
(C6b)
j^h.
This is assumed to occur from 1-9 p.m. within 12 shopping |
o
days of Christmas.
C-14
1
1
-------
I
I
I
I
I
I
ft
I
I
I
I
I
I
c.
Saturday Peak Hour Volume: V = .24 ACT (C6c)
This is assumed to occur from 3-4 p.m. the Saturday
O
before Christmas.
d. Saturday Peak 8-hour Volume: V = .16 ADT (C6d)
This is assumed to occur from 10 a.PI. to 6 p.m. the
Saturday before Christmas. "V" in Equations (C6a) - (C6d) is in vph.
Table C2 is presented to provide an indication of ranges of
Average Daily Trip Generation Rates likely to be estimated for various
sizes of regional shopping centers.
If it were of interest to note the impact of increasing the
use of mass transit at the shopping center above the usage already
inherently included in the developer's estimate of Average Daily Trip
Generation Rates, it would be necessary to adjust the estimated volume
demand. The adjusted volume demand could be estimated as shown in
Eq. (C6e) for one hour periods.
where
V = traffic volume demand adjusted for increased use of
mass transit, veh/hr.
T = number of mass transit passengers during the 1-hour
period of interest
* P - fraction of passengers who would ordinarily use a private
auto were the mass transit facilities not available
avo - average number of passengers per auto
B - increase in number of buses during the hour due to
increased use of mass transit, veh/hr.
C-15
-------
Table C2. TRIP GENERATION DATA FROM THE COG* REPORT, AND SUGGESTED
VALUES FOR USE, AS A FUNCTION OF REGIONAL SHOPPING CENTER SIZE
Center Size
1000's sq. ft.
300-399
400-499
400-599
700-900
1,000-1,500
Total
Number
of
Centers
11
3
10
4
2
30
II
From
Median
40
30
40
36
28
Average
(per
the COG
Mean
40
34
38
36
28
Day" Tri
1000 sq
Report
Range
16-62
38-42
18-58
18-52
26-30
p Generati
. ft. per
on Rates
day)
Suggested
Median
40
40
40
36
30
Mean
40
38
38
36
30
for Use
Range
20-60
20-60
20-60
20-50
20-30
*Washington Metropolitan Council of Governments
C-16
I
I
1
I
I
I
I
I
I
i
i
i
i
i
i
i
i
i
-------
I
_ Equation (C6f) would apply for 8-hour periods.
t
I
I
V' = V ' ISTT^bT
M where
T = number of passengers utilizing mass transit during
H 8-hour period -of interest
R = increase in number of buses during 8-hour period,
" veh/8-hour
W 3. Calculation of Running Time (RT)
The running time (RT) for a typical vehicle is the sum of the
time it takes to approach, enter, move in, park, unpark, move out, exit
and depart from the source's parking lot during periods with little
9 congestion, plus any extra time resulting from congestion of the facility
during peak usage periods. The time required during periods of little
congestion is referred to as the base running time (BRT) and ideally
I should be provided by the developer. If this estimate is not available,
it should be obtained by studying the facility's physical configuration.
w An example of the procedure used in determining BRT is depicted by the
following expressions:
(Distance between Entrance and Nearest
| Base Approach Time IpS^/H^.^)^' "' '"^
Base Entrance Time "
- "- (Main Entrance Gate" Capacity"," veFTsec"
(Distance from Center of Lot to Main
| Base Movement-ln Time ^^^uretMcy^ffic Lanes, m) (C7c)
(Speed Limit in Let, m/sec)
Base Stop, Base Start Time ~5-10 sec each depended on angle of (C7d)
parking and lane width
C-17
-------
I
(Distance from Center of Lot to Main H
Ra,-p MnvPfTiPnt-nut TimP -Exit Measured Along Traffic Lanes, m) (C7e)
Base Movement-uut lime (Speed Limit in Lot, m/sec) -
1 (C7f)
Base Exit Time ~(Main exit gate capacfty, veh/sec)
(Distance between Main Exit and Nearest
Base Departure Time -Intersection on the Access Road, m) (C7g)
h (posted speed limit, m/sec)
Typical Base Running Times observed at a limited number of
shopping centers in the Washington, D. C. area indicated a Base Running I
Time of about 270 sees. In a study conducted for EPA at a regional
9
shopping center Pase Running Times (running time in and running time
out) averaging about 220 sees, were observed.
As a rule, the components of running time most affected by
congestion are the movement-in, exit and entrance modes. In the case
of unsupervised parking (e.g. shopping centers), increases in movement-
in time results from cars searching for the few remaining parking spaces.
Table C3 presents a series of correction factors which should be applied
to shopping centers and parking lots of various sizes when the accumu-
lation of vehicles in the lots begins to approach or exceed the parking
lot capacity. Table C3 is based on information contained in reference 8.
Accumulation of vehicles in the lot should be estimated from diurnal
9
use patterns. Limited data which are available indicate that running £
time begins to increase appreciably when the lot is more than 80 percent
occupied. It is, therefore, suggested that Table C3 be applied during II
C-10 I
I
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Table C3. GUIDELINES FOR ASSESSING THE IMPACT OF PARKING
CAPACITY EXCEEDENCE ON BASE RUNNING TIME
(1)
Gross
Leasible
Fl. Space
103 Ft2
300 - 399
400 - 499
(2)
Parking
Spaces Per
1000 ft. of
Gr. L. Fl. Sp.
< 4
>_ 4, < 6
1 6, _< 8
> 8
< 4
>_ 4, < 6
I 6> f 8
500 - 599 < 4
> 4, < 6
> 6, < 3
> 8
(3)
Ave. Daily Arrivals*
Per 1000 Ft2 of Floor
Space Per Day which
Correction Factor is
Needed
16 arrivals/1000 Ft2-
day
23
25
Correction Factor
not needed
16
23
25
Correction Factor
not needed
16
23
25
Correction Factor
not needed
(4)
Correction Factor
(CF) Needed to
Compute Overall
Traffic Density
of = (V * .20 PC**,
V
,V + .10 PC
v V
,V + .05 PC
V
1
V + .20 PC,
V '
,V + .10 PCN
( V )
fV + .05 P^
1 V >
i
f\l + .20 P^
1 V >
,V + .10 PC,
{ V '
/V + .05 PCs
C-19
-------
Table C3. GUIDELINES FOR ASSESSING THE IMPACT OF PARKING
CAPACITY EXCEEDENCE ON BASE RUNNING TIME (Cont'd)
(1)
Gross
Leasible
Fl . Space
103 Ft2
600 - 899
> 900
(2)
Parking
Spaces Per
1000 ft. of
Gr. L. Fl. Sp.
< 4
> 4, < 6
L 6 > < 8
> 8
< 4
>_ 4, < 6
> 8
(3)
Ave. Daily Arrivals*
Per 1000 Ft2 of Floor
Space Per Day which
Correction Factor is
Needed
14
20
21
Correction Factor
not needed
n
13
13
Correction Factor
not needed
(4)
Correction Factor
(CF) Needed to
Compute Overall
Traffic Density
,V + .20 PC
1 V
,V + .10 PC
1 V
,V + .05 PC
( V
1
,V + .20 PC
( V
/V + .10 PC
,V + .10 PC
( V
1
)
-)
)
* Daily arrivals = (1/2) (Average Daily Trip Generation Rate)
** PC = parking lot capacity -- the number of parking spaces
in the shopping center lot
V = number of vehicles to be accommodated during the hour
of interest
C-20
I
I
I
I
I
1
I
I
I
I
I
I
I
-------
I
periods in which the accumulation of vehicles in the parking lots
exceeds 80 percent of the lot's parking capacity and there is no super-
vision of parking. If parking is supervised, additional running time
spent in the movement-in mode would occur only if the accumulation of
9 vehicles in the lot exceeded the parking capacity. Extra time would
then be required to move to an auxiliary lot. This additional running
time, AV.J, would be estimated using an expression similar to expression
1 (C8).
1
I
I
tist. from Center of Main IDist. between Main Lot
ot to Main Lot Exit / \Exit & Aux. Lot Entrance/
"MI (Posted Main Lot Speed Limit) (Posted Speed Limit)
|[Dist. between Aux. Lot)
\Entrance and Center / ( C8 )
(Posted Speed Limit)
_ where
Distances are measured along traffic lanes in meters
fl Posted speed limits are in m/sec
= increase in movement-in, time resulting from exceedence
m of the main parking lot's capacity, sec
Increased running times occur in the exit or entrance modes
when volume demand approaches gate capacity. When this happens queues
form at the exit (entrance) thereby increasing running times. The
increase in running time for each lane of traffic at a gate, i, having
no traffic signal may be estimated from queuing theory using Equation
(C9).10
v.
(- ), Vi/ < .95 (C9)
ci -vi ci -
C-21
-------
I
where RT = time spent in queue, sec
I
c. = entrance or exit capacity of gate i (obtained from
developer) veh/hr*
v. = traffic volume demand entering or leaving at gate i,
1 veh/hr ~~
The parameter "v.." is obtained by apportioning entering and leaving traffic £
among gates and lanes. Ideally the apportionment of entering and exiting «
traffic should be provided by the developer, and should reflect the
orientation of the shopping center with respect to the population center. V
However, if the apportionment is not provided, it may be estimated in one
of the following ways: |
(a) According to access road capacities.
r _ i-c-i (capacity of access road to gate i) (CIO)
i L J (capacity of all access roads)
where
E. = traffic entering gate i during the 1- or 8-hour
period of interest, veh/hr
total entering traffic duri
period of interest, veh/hr
_ r-w-i (capacity of access road to gate i) (Cll) ft
i ~ L J (capacity of all access roads)
E = total entering traffic during the 1- or 8-hour
where
X. = traffic exiting rate from gate i during the 1- or J|
8-hour period of interest, veh/hr
X = total exiting traffic rate during the 1- or 8-hour
period of interest, veh/hr
I
*NOTE: The demand and capacity terms in Eqs. (C9), (C14) and (C15)
pertain to the demand and capacity upstream from a constriction (e.g.,
an intersection or toll booth). For example, if traffic were entering
a lot by making a left turn from an access road, the volume of traffic
turning left and the capacity of the access road to accommodate this
traffic at Level of Service E should be used in the equations.
C-22
I
-------
I
I
(b) If access road capacities are unknown, or if more
I than one gate empties onto the same access road, traffic can be
apportioned according to gate capacities.
F - fEl (Entrance capacity of Gate i) (C12)
i ~ L J (Entrance capacity of all Gates)
,_ . y = ry-i (Exit capacity of Gate i) (C13)
ana A.. LAJ (Exl-t capacity of all Gates)
To estimate time spent in exit queues, v. is set equal to X. and
Equation (C9) is used. A similar procedure may be followed for entrance
queues if E. is apportioned directionally on the access road, and the
I entering traffic volume from each direction is set equal to v.. For
entering traffic, the excess running time spent entering would be the
mean value of the excess running time spent entering entrance i from
the various directions on the access road. If the entering or exiting
traffic at a gate is estimated to be greater than 95 percent of the gate's
exiting or entering capacity, the excess running time spent in queues
should be approximated using Equation (C14).
RTn. = 3600 \^\ .95 < v./c. £ 1 (C14)
I
If v./c. > 1,
RT . = 3600
20
c.
,
V./C.J > 1 (C15)
M- ^i
V Excess running time spent entering or exiting from a parking lot with
signalized exit/entrances may be estimated using Equation (C16).
I
C-23
I
-------
q'i
(C,)(c')(l - G/C )2 1800 vC 2 /ricx
y y + y (^ i°j
2 (c1 - v) c'G(c'G - vC )
J i
where (RT ). = excess running time spent entering or exiting
q at entrance/exit i, sec
C = signal cycle length, sec
c1 = unimpeded capacity at a signalized intersection
approach, vph
G = amount of green time per signal cycle for the inter-
section approach of interest, sec
G/C = green time to signal cycle ratio, dimensionless
y
v = traffic demand at the intersection approach of
'
interest, vph
1
1
I
w
1
u^b.
Equation (CIS) is adapted from concepts expressed by Newell con- |
cerning delay times spent by vehicles at approaches to signalized
intersections.
Throughout the shopping center, average excess running
1
time spent in entering and exiting queues is given by Equation (C17).
1
Z RT . H
RTq - all.
I
where I = total
qi (C17)
number of exit and entrance gates
Equation (CIS) should be used to estimate running time
for a typical vehicle-trip during the 1- or 8-hour period of interest
if the parking
nT Dr\
Kl = -jr
is not supervised.
r ~i r i
^ + \(rf UPRT entering traffic j + py (ciB]
L~ «J L.^0 Uu 1 Ui clTT I C 1 C]
1
I
1
cF = 1 if lot is less than 80% full
C-24
I
-------
I
If parking is supervised, Equation (C19) should be
used instead.
|RT _ BRT Pentering traffic! ^ (C19)
K1 " "T"+ AMI Ltotal traffic J R1q
where
AMI = 0 if lot is not full
It is necessary to divide the Base Running Time by "2" in Equations
» (C18) and (C19) since each trip is a one-way trip. Thus, in determ-
ining average daily trip generation rate, each vehicle is counted
twice. Since the Base Running Time refers to the total time required
I to enter and leave a shopping center, it should be divided by "2."
B. Estimating Peak Impacts Within or Near the Parking Lot
or on Access Roads Removed from the Lot.
Peak concentrations of CO are likely to occur in the
vicinity of exit/entrances to the lot, near access roads or at nearby
I intersections. Traffic at such locations may be characterized as line
sources of pollution. Two situations are of interest: the case where
traffic flows freely by the receptor; and the case where queues form in
the vicinity of the receptor. At traffic lanes within or adjacent to
the parking lot, the impact of freely flowing and/or queuing vehicles
on CO concentrations in the vicinity of the lanes should be added to
estimates obtained using an area source model relating the source's
m upwind dimension and emission density to CO concentrations and general
background levels. More details concerning this procedure are pre-
sented in Appendix H. Equation (C2) is used to estimate the appro-
priate emission density.
I
I
C-25
-------
I
(C2)
The discussion in Appendix A concerning microscale impact
analysis may be used to estimate the impact of freely flowing and/or
queuing traffic on nearby CO concentrations. Equation (All) is used
to estimate the impact of freely flowing traffic. If traffic at a
signalized intersection is of interest, excess emissions over a finite
queue (obtained using Equations (A18) and (A19)) are added to emissions
estimated for a line source of freely flowing traffic with Equation fl
(All). Emissions near a nonsignalized intersection may be approximated m
with Equations (A20) - (A23) and with Equation (All).
CIV. Qualitative Guidelines 1
In addition to the quantitative evaluation procedures developed
above, the review of shopping centers as complex emission sources should
also include the following considerations which are not presently
reducible to quantitative terms:
1. Main entrance/exitways should preferably be on a highly visible
local secondary street that feeds into the nearest arterial, so that the
transition from highway driving to parking lot driving and vice versa m
is not too abrupt. m
2. Any left turn movement across traffic flow that is used by a
significant number of the shopping center patrons is a potentially
large congestion point and emission problem.
3. At centers with multiple entrance/exits, the vehicles will
generally tend to distribute themselves among the available gates to M
minimize their running times. However, if unbalanced gate use does
C-26
I
-------
I
_ occur, it may be reduced by stationing personnel in the parking area
* to divert outgoing traffic from the overburdened exit or by the use
of traffic information signs.
4. Personnel (including police) may also be effectively used to
g speed traffic flow during periods of highest congestion.
^ 5. Prior provision for overflow parking in a temporary or remote
lot may be an appropriate requirement for centers with anticipated
flj marginal parking capacities.
6. The design of curbed entrances and exit "streets" within the
parking lot (but separate from the parking areas) may reduce the inter-
m ference of exit queues with in-lot movement and move congestion points
away from the gates to a more desirable (or controllable) location in
the lot.
I
I
I
I
I
I
I
- C-27
I
-------
I
REFERENCES
(1) U.S. EPA, Office of Air and Waste Management, Office of Air Quality 9
Planning and Standards; "Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 10: Reviewing New Stationary Sources"; EPA-450/
4-74-011 (Sept. 1974); Air Pollution Technical Information Center, Research I
Triangle Park, N. C. 27711.
(2) Kunselman, P., H. T. McAdams, C. J. Domke and M. Williams;
"Automobile Exhaust Emission Modal Analysis Model"; EPA-460/3-74-005
(January 1974); National Technical Information Service, Springfield,
Va. 22161. |
(3) Compilation of Air Pollutant Emission Factors, EPA Publication
No. AP-42 (Supplement 5 to the Second Edition); (In Press).
(4) 40 CFR 85; "1975 Federal Test Procedure"; Federal Register 36,
No. 128 (July 2, 1971).
(5) Williams, M. E., J. T. White, L. A. Platte and C. J. Domke; I
"Automobile Exhaust Emission Surveillance -- Analysis of the FY 72
Program"; EPA-460/2-74-001 (February 1974); National Technical I
Information Service; Springfield, Va. 22161.
(6) Ashby, H. A., R. C. Stahman, B. H. Eccleston and R. W. Hum;
"Vehicle Emissions - Summer to Winter"; Paper No. 741053 presented I
at the Society of Automotive Engineers Automobile Engineering Meeting;
Toronto, Canada (October 21-25, 1974); Society of Automotive Engineers, I
Inc., 400 Commonwealth Drive, Warrendale, Pa. 15096.
(7) Clear, D. R. and M. G. Dolan; Barton-Aschman Assoc., Washington,
D. C.; personal communication.
C-28 I
I
-------
I
* (8) Thayer, S. C. and K. Axetell; "Vehicle Behavior in and Around
Complex Sources and Related Complex Source Characteristics: Volume I -
Shopping Centers"; EPA-450/3-74-003a (August 1973); National Technical
£ Information Service, Springfield, Va. 22161.
(9) Patterson, R. M., R. M. Broadway, G. A. Gordon, R. G. Orner,
" R. W. Cass and F. A. Record; "Validation Study of an Approach for Eval-
uating the Impact of a Shopping Center on Ambient Carbon Monoxide
Concentrations"; EPA-450/3-74-Q59; U.S. EPA, Air Pollution Technical
£ Information Center, Research Triangle Park, N. C. 27711.
_ (10) Hillier, F. S. and Lieberman, G. J.; Introduction to Operations
Research; Holden-Day, Inc., San Francisco, California (1967); Chapter 10.
(11) Newell, G. F.; "Approximate Methods for Queues with Application
to the Fixed Cycle Traffic Light"; S. I. A. M. Review; 7_ No. 2
| (1965).
I
I
I
I
I
I
C-29
I
-------
I
Additional Data Sources
Books and Reports
Baker, Geoffrey, and Bruno Funaro. Shopping Centers - Design and Operation.
Reinhold Publishing Corporation, Progressive Architecture Library.
New York City.
Baker, Geoffrey, and Bruno Funaro. Parking. Reinhold Publishing Corp-
oration, Progressive Architecture Library. New York City.
Barton-Aschman Associates, Inc., "Traffic Planning for Shopping Centers" |
School of Design and Construction, ICSC University of Shopping Centers;
Chicago, Illinois (February 1973). «
Lynch, Keven. Site Planning. The M.I.T. Press, Massachusetts Institute
of Technology, Cambridge, Massachusetts.
Gruen, Victor, and Larry Smith. Shopping Towns U.S.A. - the Planning of
Shopping Centers. Reinhold Publishing Corporation, Progressive
Architecture Library. New York City.
Institute of Traffic Engineers Technical Committee 5-DD Draft Report,
"Shopping Center Access," (1974).
Metropolitan Washington Council of Governments, National Capital Region
Transportation Planning Board. Traffic Characteristics of Shopping
Centers - A Review of Existing Data. Technical Report No. 3, July
1970.
Urban Land Institute. Planning Requirements for Shopping Centers - A
Survey. Technical Bulletin 53. Research sponsored by the Research p
Foundation of the International Council of Shopping Centers.
Automotive Environmental Systems, Inc. A Study of Emissions from Light I
Duty Vehicles in Six Cities. EPA Document No. APTD-1497. March 1973. *
Maryland Bureau of Air Quality Control. Method for Estimating Light Duty V
Vehicle Emission on a Sub-Regional Basis. Report BAQC-TM 73-107.
April 1973.
U. S. Environmental Protection Agency. Compilation of Air Pollutant |
Emission Factors (Second Edition). EPA Publication No. AP-42.
April 1973. -
Architectural Record. Building Types Study 432: Shopping Malls in *
Suburbia. Vol. 151, No. 3. March 1972.
Zoning Ordinances for Various Communities. m
Washingtonian Magazine. Supermalls! August 1973, pp. 58-63.
C-30
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
APPENDIX D. METHODS FOR ESTIMATING EMISSIONS IN VICINITY
OF SPORTS COMPLEXES
This appendix is intended to provide guidance concerning a
more detailed analysis of proposed indirect sources should
this be necessary or desirable pursuant to 40 CFR 52.22(b).
The materials contained herein are offered as suggestions.
Alternate analytical approaches for evaluating the impact
of a proposed source may be used if it can be demonstrated
that they are more applicable to the source under review.
U. S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, N. C. 27711
January 1975
D-i
-------
I
I
I
I
I
I
-------
I
I
APPENDIX D.
§ METHODS FOR ESTIMATING EMISSIONS IN VICINITY
. OF SPORTS COMPLEXES
The purpose of this Appendix is to provide a means for assisting
air pollution control agencies or developers in estimating vehicular
£ emissions associated with the operation of a sports complex. If
_ stationary sources are of significance, Volume 10 of the "Guidelines
for Air Quality Maintenance Planning and Analysis' should be referred
to. Emissions estimated using the guidance in this appendix may then
be used to estimate the impact of the complex on nearby ambient CO
| concentrations. The methodology proposed in Appendix D is based
2
largely on information contained in a report prepared for EPA under
contract concerning vehicle behavior in and around sports stadiums,
and upon observations made during a monitoring study of traffic and
ambient CO concentrations conducted for EPA in the vicinity of major
league baseball stadiums. The general approach of the proposed metho-
dology is to require prospective developers to submit certain essential
information. A second body of information is designated as optional.
It would be preferable to have a complete set of optional information
supplied by the developer as well. If this is not possible, however,
I data compiled for EPA for a limited sample of sports stadiums can be
substituted. The methodology for estimating emissions is necessarily
I
I
-------
I
general. Therefore, the developer should be encouraged to perform |
a detailed analysis of the impact of the proposed facility using
data and methods which are specifically suited for the case under
review. If it is necessary to estimate HC and NO emissions at
the sports complex, emission factors should be obtained for these
pollutants as described in Appendix B. Since it is very unlikely I
that the sports complex (functioning as a sports complex) will
attract traffic from 6-9 A.M., the impact of the complex on NO
/\
emissions may be of greatest interest. There is, of course, the
possibility that the stadium lots could be used for commuter lots
(e.g., Shea Stadium in Mew York City) during periods in which HC I
emissions are of interest. In such cases however, the traffic may
lose its "event-oriented" attributes associated with large sporting »
or entertainment events, and the methodology presented in Appendix
E on parking lots would be more appropriate.
Section DI of this Appendix summarizes the methodology for I
estimating total CO emissions resulting from the operation of the
complex, emissions which occur in traffic lanes, in the vicinity of m
congested exit or entrance gates and at nearby intersection approaches.
The remaining portions of the Appendix discuss how the methodology
presented in Section DI might be implemented.
DI. Procedure for Estimating Emissions Resulting from the Operation
of a Sports Complex I
D-2
I
I
I
-------
I
1. Obtain estimates for the key design and operating parameters
indicated in Table Dl .
| 2. Consider automobiles and buses separately. Estimate appro-
priate emission factors from modal operation patterns at sports com-
plexes. If this is not possible, use Fig. Dl (and Equation (D4) if
I necessary) to estimate automobile emission factors. Apply appropriate
correction factors for altitude, temperature and percentage of cold starts
I using Section 4.4 of the Screening Procedure or Supplement 5 to AP-42.
m Use Supplement 5 (Sections 3.1.4.3 and 3.1.5) to estimate appropriate
emission factors for diesel and gasoline-powered buses (in gm/veh-mi).
I Convert to appropriate units (gm/min-veh) using Fig. Dl and Eq. (D5).
3. If volume (i.e., not volume demand) of automobiles using parking
| lots is not provided, estimate it using Eq. (D6). If volume of buses
« using parking lots is not provided, assume it is the same as the number
of parking spaces allotted for buses.
I 4. It is assumed that essentially all traffic arrives at the
complex within an hour of the scheduled start and leaves within an hour
| after the event's conclusion. Therefore, divide the auto and bus traffic
volumes by one hour to obtain auto and bus traffic volume demand in vph.
5. It is assumed that maximum emissions occur in the hour following
fl| an event's conclusion. Thus, running time is the amount of time it takes
to unpark, move out, exit and depart from the facility. Estimate unpark
| and movement-out time using the source's physical configuration and
_ operating procedures. If stall parking is used (e.g. with buses), estimate
unparking and movement-out time with Table D2. Traffic demand in the
I
I
D-3
-------
I
remaining running time calculations is assumed to occur entirely within I
the parking lot emptying time. If traffic distribution through the exit
gates is about uniform, use Eq. (D7a) or (D8) - (D8b) to estimate running |
time spent in exit queues upstream from unsignalized intersections. For _
signalized intersections use Eq. (D7a) or (D9). If traffic is not evenly *
distributed, use Eq. (DID) or Eqs. (Dll) or (D12) to estimate running
time in queues at each gate and then use Eq. (D13) to obtain average
running time spent in queues. J
6. Combine stadium bus and auto traffic with unrelated traffic _
and apportion the total among access roads. Use demand-capacity ratios *
vs. speed relationships depicted in Appendix A to estimate operating
speeds on road segments. Departure running time is estimated using
Eq. (D15). |
7. Obtain total running time required for leaving, using Eq. (DIG) _
and combine this with estimates for volume demand and emission factors
in Eqs. (Dl) and (D2) to estimate total peak 1-hour emission rate and
emission density. This emission density applies for the amount of time
required for traffic to dissipate. The remainder of the time the I
emission density is zero.
8. If the impact of entering traffic at the beginning of an event
is of interest, volume demand and emission factors are obtained as
before. Running time is the sum of the time spent in the arrival,
entering and movement-in and parking modes. Assume arriving vehicles I
are, unlike departing vehicles, evenly spread out over the hour. Using
this assumption, use Eq. (D15) to estimate arrival mode running time. B
D-4 I
I
-------
I
Equations (D8), (D9), or (Dll), (D12), or (D21) should be used in
estimating entrance mode running times. Use Eq. (D22) to estimate
£ movement-in and parking times. Total entrance running time is given
_ by Eq. (D23). Use the total entrance running time along with volume
demands for autos and buses and emission factors to estimate total emission
rate and emission density with Eqs. (Dl) and (D2).
9. Refer to the Micro Analysis section in Appendix A to estimate
I the impact of freely flowing and/or queuing traffic on nearby CO con-
centrations. The procedure is as follows:
a. Estimate traffic demand for each lane j in road segment i
using Eqs. (A12) or (A13). If necessary, adjust the demand for the
impact of mass transit using Eqs. (A14) or (A15). Apportion demand
I among lanes, making sure that Eq. (A2) is satisfied.
b. If the analysis does not concern an at-grade intersection,
' estimate capacity of the road segment using Eq. (A10) and the lane
capacities using Eq. (A16). Check that Eq. (A3) is satisfied. If not,
adjust the lane capacities so that Eq. (A3) is satisfied.
Ic. Determine volume to capacity ratios (v. ./c-.) for each
I J * J
lane. Given the type of road and the average highway speed, use the
appropriate one of Figs. A2 - A5 to estimate vehicle operating speeds
in each lane.
d. Use Fig. A6 to estimate the speed corrected 1975 emission
factor for each lane. For years other than 1975, adjust this factor
with Equation (A17). Correct for cold starts and ambient temperatures
as needed, using Section 4.4 of the Screening Procedure or Supplement 5
to AP-42.
D-5
I
-------
I
I
e. Use Eq. (All) to estimate the line source emission
intensity of freely flowing traffic.
f. For at-grade signalized intersections, use information
concerning signal cycle lengths and green time to signal cycle ratios Q
to estimate queue lengths with Eq. (A18). Consider emissions over the _
queue length to be the sum of those from freely flowing traffic and
excess emissions. Emissions elsewhere are attributable to freely
flowing traffic. Estimate emissions from freely flowing traffic using
Eq. (All), and excess emissions using Eq. (A19). Alternatively, use |
the information in Tables A8-A12 directly to estimate appropriate
emissions and queue lengths.
g. For non-signalized intersections, estimate the average
queue length using Eq. (A20). Use Eq. (A21) to estimate the emission
intensity over the queue at the intersection approach. Estimate the I
distance over which vehicles may accelerate and decelerate using
Eq. (A22). The emission intensity over this distance is obtained
using Eq. (A23). Use Eq. (All) to estimate emission intensity elsewhere.
DII. Identification of Key Design and Operating Variables
Table Dl presents the essential and desirable parameters which I
the developer should supply the control agency so that emissions
associated with the operation of the sports complex may be estimated.
I
I
D-6
I
-------
1
I
Table Dl . SPORTS COMPLEX PARAMETERS NEEDED FOR ESTIMATING EMISSIONS
-
I. Essential Parameters
Parameters
Seating capacity
1 Average attendance
Available parking spaces
1
1
Number and capacity of parking
lot gates
_ Surrounding street con-
figurations, capacity and speed
* limits (within 2 km of stadium)
Estimated traffic volume on nearby
streets not related to
stadium activities
Number of parking spaces
allotted for buses
1
1
1
Remarks
Assumed to be equivalent to peak
attendance
Possible sources of information for this
parameter include market surveys con-
ducted for new teams or previous
experience of established teams moving
to new areas
This parameter should be broken up
into 3 subtotals :
a. Spaces available in off-street
stadium operated parking lots
b. Spaces in other off-street public
and private parking lots
c. On-street spaces available within
3/4 km and within 1 km of the stadium
property
This information should be contained on a
set of plans or blueprints provided by
the developer which present a schematic
picture of access roads, complex dimensions
and configuration
ii ii n M
This information should be solicited
from local and State Highway Depts .
Should be available from parking lot
design
-------
Table Dl (continued). SPORTS COMPLEX PARAMETERS NEEDED FOR
ESTIMATING EMISSIONS
I. Essential
Parameters
Stadium emptying time
Plans or blueprints of the
stadium, parking lots and
surrounding access roads
Green time to signal
cycle ratio for each
intersection
Number of signal cycles
per hour at each intersection
II. Desirable
Percent of spectators arriving
by automobile
Average vehicle occupancy
Number of buses
Estimated order of preference
for parking facilities
Vehicle spacing in queues
Distribution of operation modes
(i.e. acceleration, deceleration,
etc.) for a typical vehicle
visiting a sports complex
Parameters
Remarks
Time after end of an event by which
all spectators have reached their
parking spaces
Needed to prorate demand among gates
and access roads and as an indicator
of the complex's size
Needed to estimate traffic capacity
at each intersection approach and to
estimate queue lengths resulting at
each approach
Needed to estimate queue lengths at
intersection approaches.
Parameters
Obtain estimate from local transit
authority or bus companies
This is the developers' estimate of
the order in which the 3 types of
parking facilities are utilized by
spectators
Tail pipe-to-tail pipe distance
Useful in obtaining estimates for
emission factors
D-8
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
-------
I
Dili. Estimation of Emissions in the Vicinity of Sports Complexes
Since the usage of sports complexes occurs at discrete times as
dictated by the sporting event, traffic is characterized by very heavy
demand over relatively short periods and little demand the rest of the
time. Consequently, the capacity of nearby (e.g., within 2 km of the
I stadium property) roads and intersections may be exceeded. Thus, the
possibility exists that the worst impact of the sports stadium on CO
I concentrations may occur relatively far away from the stadium. This
possibility means that two separate analyses may be needed:
1. An analysis in the immediate vicinity of the stadium, taking
I account of emissions within the parking lot and queues at the most
congested sections of the parking lot.
2. An analysis of nearby access roads and intersection approaches
to determine points at which traffic volume demand approaches or exceeds
road capacity.
I A. Emissions in the Immediate Vicinity of the Stadium
(i.e. Parking Lots)
1. Total Emission Rate and Emission Density
These variables are of interest for two reasons:
(a) to provide a means for relating construction of
the sports complex with emission limitations which may be imposed by
land use or air quality maintenance plans;
8 (b) to provide a means for estimating the emission
m density at the sports complex and the resulting impact on background
(or representative) concentrations of CO.
I
I
D-9
-------
Equations (Dl) and (D2) may be used to estimate total emission rate
and emission density for the stadium and its surrounding parking lots.
Q'
Q
autos
buses
Q = E(EF)(V)(RT)] autos + [(EF)(V)(RT)] buses (D2)
216,OOOA
RT = average running time, sec
A = contiguous area of the stadium and its surrounding
2
I
I
where Q1 = emission rate, gm/sec
p
Q = emission density, gm/sec-nr
EF = emission factor, gm/min-veh I
V = traffic volume demand, veh/hr.
I
parking lots, nf
1/216,000 = conversion factor from jffi^hr to 9m/sec I
The separate terms in Eqs. (Dl) and (D2) for buses are probably needed
since there is often a large number of buses at events, and frequently
these may be separated into segments of the lots reserved for buses. I
If traffic generated by the source takes less than an hour to dissipate
from the source after an event's conclusion, Equations (Dl) and (D2) |
would only apply for that portion of the hour. The rest of the time,
the emissions would be zero. *
I
D-10
I
I
-------
I
I
B. Determination of Emission Factors(EF)
0 (1) Automobiles
Probably the most accurate estimates for emission
* factors at a sports complex would be obtained if typical driving
cycles (i.e. amounts of time and sequences spent in acceleration,
deceleration and steady speed modes of travel) were known for sports
p complexes. A typical driving cycle could then be simulated using the
4
EPA Automobile Exhaust Emission Modal Analysis Model to obtain average
trip emission factors which are explicit for sports complexes. This
approach has been followed in characterizing emissions at signalized
intersections in Appendix A. Unfortunately, there is not yet sufficient
| data concerning vehicle operating characteristics at sports stadiums to
implement this technique elsewhere within a sports complex. Thus, infor-
nation appearing in Supplement 5 to AP-42 which reflects emission factors
obtained using the 1975 Federal Test Procedure (FTP) will have to suffice.
Figure Dl was obtained using the 1975 FTP emission factors for CO for
Jj a national average mix of light-duty vehicles for calendar year 1975 and
_ speed correction factors obtained from Tables 3.1.2-6a and b in Supple-
" ment 5. The mix upon which Figure Dl is based is composed of 88 percent
cars and 12 percent light-duty trucks. The curve in Figure Dl is also
based on the assumption that 20 percent of the vehicle emissions occur
from vehicles operating from cold starts with ambient temperatures
ranging from 68°F - 86°F at a location near sea level. If the assumption
concerning altitude, percentage of cold starts and ambient temperature
D-ll
I
-------
24
22
20
18
16
oc
o
o 14
co 12
co ''
10
T
T
10 15 20 25 30 35 40 45
VEHICLE SPEED, mph
50 55
60
Figure D1. Composite emission factors for carbon monoxide for calendar year 1975.
D-12
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
used in deriving an emission factor are not appropriate, correction
factors may be derived using guidance presented in Section 4.4 of the
screening procedure or Supplement 5 to AP-42. It should be pointed out
that if it is determined that extra emissions attributable to cold starts
and cold temperatures only occur for a relatively short time (e.g.,
I 4 minutes), higher emission factors should be used only until a typical
vehicle becomes warm. The emission factors obtained for 1975 with
Figure Dl can be adjusted for other years by using Equation (D4).
EF (Corrected Value from Fig. Dl) (ef) /D4\
3 3
I where ef = the emission factor for the year of interest obtained
from Table A3, Appendix A, gm/mi-veh
I "55" = the emission factor in Table 3.1.1-1 which is applicable
for 1975, gm/mi-veh
(2) Buses
In the absence of modal emission data for buses
5
at sports complexes, Sections 3.1.4.3 and 3.1.5 in Supplement 5 to AP-42
may be used to provide emission factors (in gm/mi) for heavy-duty gasoline
and diesel-powered vehicles respectively. There is no differentiation
with respect to model year for diesel emissions. It should suffice for
the purpose of this analysis to assume average emission factors suitable
for the 1970-73 model years. Once the appropriate emission factors for
I gasoline and diesel-powered buses are estimated from AP-42, a bus emission
factor suitable for use in Eqs. (Dl) and (D2) can be calculated using
Equation (D5).
I D-13
I
-------
I
(Fig. Dl Value) (#Gas. Buses)(ef)n + (#Diesel Buses)(ef). I
FF = _ - _ , _ , _ 9 _ d.J (D5)
tr (Total # of Buses )(ef) { '
where (ef) is the estimated emission factor for heavy duty gasoline
powered vehicles as determined from Section 3.1.4.3 in |
Supplement 5 to AP-42, gm/mi-veh
and (ef). is the estimated emission factor for heavy duty diesel
powered vehicles as determined from Section 3.1.5 in I
Supplement 5 to AP-42, gm/mi-veh
(ef) is the emission factor for light duty vehicles (gm/mi-veh), |
5
estimated from Table A3 or from Supplement 5 to AP-42. _
It is assumed in Equation (D5) that the variation of heavy duty vehicle *
CO emission factors with speed is similar to those for light duty vehicles.
C. Determination of Traffic Volume Demand (V)
(1) Automobiles |
Total volume of automobiles utilizing parking
facilities in the vicinity of the stadium may be estimated using Eq. (D6). *
where V = number of autos using parking facilities, vehicles
A = attendance. For peak use periods this can be considered
equal to seating capacity
P = percent of spectators arriving by auto
avo = average vehicle occupancy for automobiles |
D-14 I
I
y = (D6)
avo v '
-------
I
The attendance term (A) should be estimated from the
stadium seating capacity. This parameter should be required from the
I developer. The percent of spectators arriving by auto (P) and the
_ average vehicle occupancy terms (avo) in Eq. (D6) should, ideally, be
provided by the developer on the basis of the local situation and
practices. If this is not possible however, most commonly accepted
design values are that 88% of the spectators come by car with an
p average vehicle occupancy of 3.5 persons/auto for football and 2.5
persons/auto for baseball. ^ For events other than football and
baseball games and for facilities other than outdoor stadiums, the
developer should be required to provide documented estimates of the
percent of spectators arriving by automobile and the average vehicle
J| occupancy.
Automobile traffic volume, as determined by Eq. (D6),
is the sum of vehicles parked in the stadium lots, on nearby streets
and in privately operated lots. Parking capacities for each type of
facility within 1 km of the stadium site should be obtained from the
developer in order to estimate localized high levels of CO. In addition,
an order of parking preference should be indicated. Unless otherwise
indicated, the order of preference should be: stadium lots, on-street
p
parking and privately owned parking lots. Under such an order of
preference, it should be assumed that the stadium lots fill up first,
followed by the on-street parking spaces and finally by privately-
operated lots, until the total traffic accommodated is equal to V.
For purposes of assessing peak impacts on CO concentrations at exits or
I 0-15
I
-------
I
entrances or within parking lots, only analyses of off-street parking I
facilities are needed. On-street parking will be assessed in evaluating
the impact of the sports facility's operation on nearby access roads |
and at intersections.
To convert traffic volume to traffic volume demand
for use in Eqs. (Dl) or (D2) it is assumed that essentially all traffic
will arrive or depart from the lots within an hour's time. Thus, even
if traffic persists for less than an hour at a somewhat higher flow
rate, the net effect will be the same in terms of emissions, providing _
the actual lot emptying and filling times are used in computing typical
automobile running times.
(2) Buses
Estimates for the number of buses (B) expected at an J
event should be obtained from the developer or promoter. If this estimate
cannot be obtained directly, it could be made from the number of parking
spaces allotted for buses. It seems reasonable to assume that the most
heavily attended events would be the ones at which the number of buses
would approach the parking capacity for buses. Once the number of buses I
is determined, the same rationale as was applied for autos should be
used to obtain the bus volume demand (veh/hr) for use in Eqs. (Dl)
and (D2).
D. Determination of Running Times (RT)
In the procedure described below for estimating running I
time, it is assumed that automobiles and buses park in separate lots or
sections of lots, and do not use the same exit/entrance gates. Conse-
quently, separate analyses are performed for automobiles and buses. If
D-16
I
-------
I
these assumptions were not true, the average running times for autos
and buses would be the same, and the total vehicular volume using
I off-street parking (i.e. V + B) should be used in the methodologies
described below for estimating running times spent in the exit and
entrance modes. In any case, it is probably advisable to consider
total vehicular volume in estimating running times in the arrival
and departure modes on access roads.
(1) Automobiles
Since it is assumed the peak 1-hour impact of a
sports complex occurs shortly after an event's conclusion, the running
time which should be used in Equations (Dl) and (D2) is the time it
takes an automobile to unpark, move out to an exit queue, exit and
lots running times in the unpark and movement-out modes (RT) should
depart. Unless there is evidence to the contrary, for conventional
I
I
be assumed as being the distance measured along traffic lanes from the
center of the lot to the main exit divided by a vehicle speed charac-
*
teristies of level of service E. Running times in the unpark and
I movement-out modes may be substantially longer for lots with "stall
parking" (i.e. where each vehicle does not have free access to an exit
| lane). Table D2 expresses typical waiting times before vehicles parked
2
« in such a manner can gain free access to exit lanes. Waiting times
are not synonymous with running times, however, since some people may
I wait in their cars with the engine off.
and 6.75 m/sec (15 mph) for major streets.
D-17
*This speed is approximately 2.25 m/sec (5 mph) for downtown streets
I
I
-------
Table D2. RUNNING TIMES FOR EXIT FROM PARKING STALLS
(1)
Ave. cars/stall
2
3
4
5
6
7
(2)
Ave
4
8
10
12
14
15
. waiting time, sec
.98
.28
.74
.60
.10
.3
(S
(S
(S
(S
(S
(S
.E
.E
.E
.E
.E
.E
.T.) +
.T.)
T.)
.T.)
T.)
.T.)
(3)
. Assumed
4
8
10
12
14
15
(RT) running time, sec
.98
.28
.74
.60
.10
.3
(S
(S
(S
(S
(S
(S
.E
.E
.E
.E
.E
.E
.T.)
.T.)
.T.)
T.)
T.)
-T.)
(F)
(F)
(F)
(F)
(F)
(F)
+S.E.T. = stadium emptying time, a design figure provided by the
developer for the number of minutes after the end of an event
it takes all spectators to reach their vehicles.
In Column (3) Table D2, "F" is the fraction of waitinp time spent
with the enaine runninp.
Averaqe runninp time in the exit mode can be estimated usinn
Eouation (D7a).
(auto traffic in lot) -S.E.T.
(# of auto exit lanes) Uve. capacity per lane)
D-18
(D7)
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-------
I
I
I
I
or
(auto traffic in lot) i -S.E.T.
(# of auto exit lanes) (ave. capacity per lane)
where TTT = average running time spent in exit mode, sec
"60" = conversion factor from min. to sec.
| "1/2" = factor to obtain average running time in exit mode
ave. capacity per lane = vehicles/min.
S.E.T. = stadium emptying time, min.
The first term within the square brackets in EQ. (D7a) represents the
parking lot emptying time (P.L.E.T.). As the Stadium Fmptying Time
J approaches the Parking Lot Emptying Time, Fq. (D7a) becomes unsatis-
_ factory. If IT is estimated to be less than 30 sec. using EC. (D7a)
(as might happen for sparsely-attended events), PLET-SET < 1 min. and
it is assumed that the condition of random arrivals at the exit queues
is met. In such cases, average running time snent in exit aueues at
non-signalized intersections may be estimated using Eo. (D8) - (D8b).
(D8)
or
FT0 = 1200/C, .95 < v/c <_ 1 (D8a)
I
I
0-19
I
-------
or
RT = 1200/C + 3600 [££) , v/c > 1 (D8b)
M \^C / ~~
v
(l^)(cr)(l-E792
2(F - 7)
1800 7TT 2
c"1 £(c"' (
>-vrj
where ET = average excess running time spent in queues, sec
I
I
where c = total exit capacity = (# of exit lanes) (ave. exit lane capacity), I
veh/mi n.
v = traffic volume demand (not the same as V), veh/min. |
"60" = conversion factor from min. to sec in Eq. (D8). In Eq. (D8b), _
"3600" is the number of seconds in the period in which demand
exceeds capacity.
If Equation (D7a) cannot be used and the exits have traffic signals,
excess running time spent in queues upstream from signalized intersections |
should be estimated. For such cases, Equation (D9) may be used instead _
of Equation (D8).11
I
(D9)
I
I
r = average signal cycle length at each exit, sec
I
c1 = mean unimpeded capacity for each of the exits, vph m
£" = mean amount of green time per signal cycle for each exit gate
S7T = mean green time to signal cycle ratio at each exit
7 = mean traffic demand at each exit, vph.
I
D-20
I
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
In deriving Equations (D7a), (D8) and (D9), it was assumed
that traffic is approximately evenly distributed among exit gates.
Frequently this assumption may be invalid. It would be necessary to
apportion traffic among the exit gates and apply Equations (DIG),
(Dll) or (D12) as appropriate for each exit gate i.
RT - in (auto traffic at Gate i)
qi " jj# of auto exit lanes at i)
(ave. lane capacity;
"1-S.E.T.
II
(D10)
or
«<
, v./c. <_ .95
or
RT . = 1200/c., .95 < v./c. < 1
RT . + 1200/ci + 3600
:.- > 1
where
c.
v.
gate capacity at i, veh/min.
traffic demand through gate i, veh/min.
(Cy)(c')(l-G/Cy)
1800 v C
2(c'-v)
c'G(c'G-vCy)
D-21
(Dll)
(Dlla)
(Dllb)
(D12)
-------
'TOT
= 60
V + B + V
(P.L.E.T.)
(D14)
where VTQT = total demand from all stadium traffic, veh/hr
D-22
I
where the terms are as defined for Equation (D9), except that they I
are explicit for exit (approach) i. Average running time spent in
queues would then be: m
s RT
Q ^H
RTq = a1\1 (D13)
I
Running time in the departure mode ((RT)n) can be estimated
I
by apportioning total stadium traffic onto the network of access roads
and determining the resulting demand to capacity ratios on the road
segments between the sports complexes and the nearest intersections.
Traffic which is unrelated to the stadium should be included in the I
estimate of traffic volume demand on these road segments.
The total stadium traffic volume is the sum of off-street and |
on-street parking. This total stadium volume is converted to volume
demand (for the purpose of estimating running time only) by using
Equation (D14).
I
I
V = autos using off street parking, veh |
B = buses present, veh _
V = autos using on-street parking, veh
"60" = conversion factor from min" to hr"
P.L.E.T. = parking lot emptying time, min.
I
I
-------
I
"^TOl" 1S t'ien aPPort1'onecl among access roads and added to the
non-stadium traffic on each road segment to obtain an estimate of the
I traffic volume demand for that road segment. This segment's total
demand is divided by its capacity in the appropriate direction to
obtain a demand-capacity ratio. Operating speed can then be estimated
using the appropriate one of Figures A2-A5 in Appendix A. If the demand-
capacity ratio exceeds "1", assume an operating speed of 5 mph (2.25
m/sec). The average amount of running time spent in the departure
mode is thus:
I
I " TspeeS^
(RT)D = *H-| (D15)
mm where (RT)D = sec
d. = distance along road segment i to the nearest intersection, m
I (speed). = average operating speed on road segment i, m/sec
I = total number of road segments immediately adjacent to
| sports complex
mm Total running time for use in estimating the 1-hr, impact of a sports
complex is given in Eq. (D16).
I
I
D-23
I
I
|