iiPA-AA-SRPB-92-01
Technical Report
Inherently Low-Emission Vehicle Program,
Estimated Emission Benefits
and Impact on High-Occupancy Vehicle Lanes
by
Lester Wyborny II
October 1992
Notice
Technical reports do not necessarily represent final EPA decisions
or positions. They are intended to present technical analyses of
issues using data which are currently available. The purpose in
the release of such reports is to facilitate the exchange of
technical developments which may form the basis for a final EPA
decision, position or regulatory action.
U.S. Environmental Protection Agency
Office of Mobile Sources
Regulation Development and Support Division
Ann Arbor, Michigan
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Table of Contents
I. Executive Summary
II. Introduction
III. Background
a. Policy Basis for ILEV Program
b. Program Provisions and Requirements
IV. ILEV Emission Reductions
a. Background
b. Base Case Vehicle Vapor Emissions
1. Emission Control Programs
2. Calculation Methodology
3. Modeling Results
c. ILEV Vapor Emissions
1. ILEV vehicles/Fuels
A. Gaseous-Fuel ILEVs
B. Alcohol-Fuel ILEVs
C. Electric ILEVs
D. Clean Conventional Fuel Technologies
2. Composite Vapor Emissions
d. ILEV Emission Benefit
1. Individual Vehicle Benefit
2. Aggregate Benefit
e. Conclusion
V. Affects of ILEV use of HOV lanes
a. Background
1. What are HOV Lanes?
2. HOV Lane Benefits
3. HOV Lane Utilization
b. Method of Analysis
c. Case-by-Case Analysis
1. Houston, Texas
2. District of Columbia
3. Seattle, Washington
4. Los Angeles, California
d. Conclusion
VI. Additional TCM Exemptions for ILEVs
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I. Executive Summary
The Clean Air Act Amendments of 1990 (the Act) require states
to implement Clean Fuel Fleet Programs in certain ozone and carbon
monoxide nonattainment areas starting in 1998. One of EPA's
responsibilities under the Act is to exempt the vehicles qualifying
for the program from certain transportation control measures (TCMs)
which will provide the fleets an incentive for their participation.
EPA has proposed regulations to meet this statutory mandate. As a
part of EPA's proposal, an important new concept in motor vehicle
emission control was introduced. With this concept, EPA would
grant expanded TCM exemptions to inherently low-emission vehicles
(ILEVs). The first of these exemptions is access to high-occupancy
vehicle (HOV or carpool) lanes.
ILEVs are clean fuel vehicles (LEVs, ULEVs, and ZEVs) with
"inherently" low evaporative emissions, such that the evaporative
emissions would remain low even if the emission control hardware
were to malfunction. ILEVs must operate solely on inherently low-
emitting fuels, which in many cases are expected to be alternative
fuels; this is in contrast with the other clean fuel vehicles
qualifying for the fleet program which are generally expected to be
low-emission vehicles (LEVs) operated on reformulated gasoline.
Thus, in proposing the ILEV concept, EPA anticipated that
significant air quality benefits would result from the use of
ILEVs.
Comments on EPA's proposed ILEV program questioned the extent
of environmental benefits that would result from the ILEV program.
Other comments also expressed concern that ILEVs could reduce the
effectiveness of HOV lanes by contributing to traffic congestion.
This report explores these two concerns in detail.
According to the detailed analysis in this report, ILEVs would
provide substantial emission reductions compared to LEVs and other
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conventional vehicles. The evaporative and refueling emissions
(vapor emissions) from ILEVs are estimated to be near zero. With
the near-elimination of vapor emissions, ILEVs are expected to emit
about one-half the volatile organic compound emissions as other
LEVs. ILEVs are also expected to emit lower exhaust emissions
based on their performance compared to today's vehicles. However,
these expected additional reductions from the use of ILEVs were not
included in this analysis because these lower exhaust emission
levels are not an absolute requirement of the program.
This report also concludes that ILEVs are expected to result
in little or no detrimental effect on traffic flow in HOV lanes.
This conclusion was derived from studying the HOV lanes in Los
Angeles, Houston, the District of Columbia, and Seattle. In almost
all cases, even widespread use of ILEVs would have marginal impact
on HOV lane flow. For Los Angeles, however, where the HOV lanes
are already heavily used, the most widespread ILEV usage currently
anticipated could impact HOV lane flow, but only in the out years
well after the year 2000. Even here, the report identifies several
ways in which Los Angeles, and any other areas with heavy HOV lane
use, could modify their HOV operations to accommodate ILEVs.
Finally, this report identifies two important reasons for
granting expanded TCM exemptions to ILEVs. First, the positive
environmental impact of any increase in ILEV usage could be
substantial while as demonstrated by this analysis of HOV lane
traffic flow, the impact on the effectiveness of HOV lanes is
expected to be insignificant. Thus, expanded TCM exemptions
offered to ILEVs would appear to be beneficial. Second, some
fleets cannot take advantage of the HOV exemption incentive either
because they do not operate during rush hour, or because HOV lanes
may not be available where they do business. Granting additional
incentives beyond HOV lane exemptions could encourage the purchase
of ILEVs. Such additional incentives could also help fleets
overcome obstacles to the purchase of alternative-fueled ILEVs,
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such as the initial capital cost for fueling points.
Overall, this report concludes that widespread and rapid
introduction of ILEVs would generally offer significant air quality
benefits to society wherever they are used, and that the prudent
use of TCM exemptions and incentives could encourage these
purchases without significant impact on the effectiveness of the
other programs.
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List of Abbreviations
CFFV Clean Fuel Fleet Vehicle
CNG Compressed Natural Gas
CO Carbon Monoxide (pollutant)
EPA Environmental Protection Agency
E100 Neat Ethanol Fuel
GVWR Gross Vehicle Weight Rating
HDGV Heavy Duty Gasoline Vehicle
HOV High Occupancy Vehicle
ILEV Inherently Low-Emission Vehicle
LEV Low-Emission Vehicle
LDV Light-Duty Vehicle
LDT1 Light-Duty Truck
LDT2 Light-Duty Truck (6000 - 8500 Ibs. GVWR
LNG Liquid Natural Gas
LPG Liquid Petroleum Gas
Ml00 Neat Methanol Fuel
NMHC Nonmethane Hydrocarbon
NOx Oxide of Nitrogen (pollutant)
SIP State Implementation Plan
TCM Transportation Control Measure
ULEV Ultra Low-Emission Vehicle
ZEV Zero Emission Vehicle
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II. Introduction
The Clean Air Act (the Act) requires states comprising certain
areas exceeding the National Ambient Air Quality Standards for
ozone and carbon monoxide to implement clean fuel vehicle fleet
programs. These fleet programs are to begin in 1998 and will
require fleets to purchase clean fuel vehicles which emit less
exhaust emissions than conventional vehicles. To further define
the fleet program for the states, the Act requires EPA to
promulgate specific regulations. Among the regulations which must
be promulgated, is the exemption of clean fuel fleet vehicles
(CFFVs) from transportation control measures (TCMs), encouraging
purchase of these vehicles.
EPA proposed a two-tiered approach to TCM exemptions. All
CFFVs would be exempt from temporal (time-related) TCMs instituted
in whole or in part for air quality reasons, while a cleaner group
of CFFVs, termed ILEVs, would receive expanded TCM exemptions. EPA
proposed to exempt ILEVs owned by eligible fleets from high
occupancy vehicle (HOV) lane restrictions and to pursue additional
select exemptions by regulation in the future.
In terms of an overview, Section III discusses the policy
basis for the ILEV program and describes the requirements and
provisions of the program. The report then analyzes the projected
vapor emissions of ILEVs and presents a comparison of those
emissions with base case vehicles expected to be purchased as
CFFVs. Section V of the report then presents a study of the impact
of the ILEV HOV lane restriction exemption. And finally,. Section
VI concludes with a discussion of several additional incentives
which could further encourage the use of ILEVs.
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III. Background
a. Policy Basis for ILEV Program
The Clean Air Act directed EPA to develop regulations which
provide CFFVs exemptions from "time of day, day of week, and
similar transportation control measures." The language of the
statute was problematic because it did not explicitly state which
of the TCMs should be included in the exemptions. In discussions
with EPA, fleet owners indicated a strong preference for a broad
interpretation of the provisions because they viewed these
exemptions as a direct recompense and incentive for their
participation in the fleet program. Some fleet owners listed TCMs
for which they wanted to receive exemptions, while others requested
specific exemptions from only certain TCMs. The TCMs exemptions
they requested ranged from temporal TCMs (i.e., time of day, day of
week), to such nontemporal TCMs such as traffic flow measures,
urban vehicle management, road pricing and trip reduction
ordinances.
EPA and several of the states suggested that a more limited
interpretation was appropriate since most CFFVs will have exhaust
emission levels similar to vehicles being developed for public sale
as part of the California Low Emission Vehicle program. Concern
was expressed that broad exemptions may tend to undermine the
environmental effectiveness of current and future TCMs and may lead
to an adverse public reaction from those who purchase the
California vehicles in California, and potentially in other states
as well, but would not get such exemptions.
As a balance between these two views EPA developed (and will
soon finalize) a two-tiered approach to implementing the TCM
exemption provisions. The first tier provides CFFVs exemptions
from temporal-based TCMs instituted wholly or partly for air
quality reasons. This provides CFFVs with the TCM exemptions
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explicitly stated in the Act without allowing exemptions for non-
air quality related TCMs or those not temporally based.
The second tier balances fleet owners desires for broader TCM
exemptions against concerns about undermining the effectiveness of
TCMs, the lack of environmental benefits, and public reaction
concerns relative to California low-emission vehicles. This tier
establishes a Federal program known as the inherently low emission
vehicle (ILEV) program. As proposed, the ILEV program provides
both temporal and expanded TCM exemptions to CFFVs with near zero
evaporative emissions and decreased NOx emissions. This
requirement for inherently low evaporative emissions is the heart
of the program since in-use vapor emissions (evaporative and
refueling) approach and often surpass exhaust hydrocarbon emission
rates and yet are not controlled more stringently than conventional
vehicles by the clean fuel vehicle emission requirements.
For the second tier of TCM exemptions, EPA proposed that ILEVs
receive HOV lane exemptions. With this exemption, ILEVs would have
access to use freeway lanes now limited to high occupancy vehicles.
In the past, fleet vehicles have effectively been excluded from
using HOV lanes due to their operating characteristics. To provide
more incentive for the purchase of these vehicles, EPA intends to
study and promulgate additional select TCM exemptions for ILEVs in
future rulemakings.
The ILEV program is potentially a positive for all parties.
The vehicle will generate substantial emission reductions, states
will be able to claim these reductions in their state
implementation plans (SIPs), and fleet owners can qualify for
expanded TCM exemptions. Even looking beyond the benefits of this
program, low emission technology will be developed and employed on
in-use vehicles and the public will receive important exposure to
these extra clean vehicles in preparation for possible expansion of
the program by the state.
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b. Program Provisions and Requirements
One key goal of the clean fuel fleet program is a reduction in
ozone precursor emissions and air toxics. The fleet program
effectively addresses reductions in ozone precursors NMOG and NOx
emissions, but contains no additional provisions regarding vapor
emissions from CFFVs. The ILEV program continues this emphasis on
reducing ozone precursor emissions.
In order to qualify as ILEVs, vehicles would have to meet the
following requirements:
1) In addition to qualifying as CFFVs, ILEVs must pass additional
evaporative emission control requirements.
ILEVs have inherently low vapor emissions because even if
their evaporative emission controls were to fail, these
vehicles would still emit very low amounts of vapor emissions.
In order for vehicles to be certified as ILEVs, they must pass
a stringent evaporative emissions test with any evaporative
emission control hardware disconnected. The ILEV evaporative
emissions requirement was proposed at a level which would be
more than an order of magnitude less than the emissions from
an uncontrolled gasoline vehicle. Of course, the existing
evaporative standard would also have to be met, using a
control system if necessary.
In th« case of electric and gaseous-fuel vehicles, the nature
of their fuels and fuel storage reduces concern about
evaporative emissions from these vehicles. Dedicated electric
vehicles are not considered to make any direct contribution to
urban emissions. Gaseous fuels (CNG and LPG) are stored in
enclosed fuel systems under pressure and are characterized as
having zero evaporative emissions. If the pressurized fuel
system were to be breached, the vehicle would generally be
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rendered inoperative through the quick loss of fuel/ the owner
would then need to repair the vehicle before any future use.
EPA proposed that for these vehicles to qualify as ILEVs, the
manufacture would need to show through an engineering
evaluation, that the vehicles would meet the evaporative
emission requirement.
2) ILEVs must meet the exhaust emission requirements of CFFVs.
Light-duty ILEVs must meet the LEV exhaust standards for
carbon monoxide and nonmethane organic gas (NMOG).
Maintaining the focus on further reducing ozone precursor
emissions from that of conventional vehicles, light-duty ILEVs
must meet the ULEV NOx standards for that vehicle class.
Heavy-duty ILEVs must meet the combined nonmethane hydrocarbon
(NMHC) + NOx ultra low-emission standard for clean fuel heavy-
duty vehicles.
3) ILEVs must be dedicated fuel vehicles.
ILEVs can only operate on the fuel(s) on which the vehicle was
certified to meet the ILEV evaporative and exhaust emission
standards. Any fuel is eligible provided that the ILEV
requirements are met.
4) ILEVs must fall within the covered vehicle weight classes and
be operated by covered fleets.
Vehicles which may qualify as ILEVs must fall within the
weight classes covered by the fleet program, which are light-
duty vehicles, light-duty trucks, and heavy-duty trucks up to
26,000 Iba. GVWR. Furthermore, ILEVs may only be operated by
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fleets covered by the fleet program. The states, however, may
expand the ILEV program to vehicle classes and fleets not
initially covered by the fleet program.
IV. ILEV Emission Reductions
a. Background
Motor vehicle emissions are composed of hydrocarbons, oxides
of nitrogen (NOx), carbon monoxide, and other pollutants.
Hydrocarbons and NOx react together at ground level in the presence
of sunlight to form ozone. The chemical nature or reactivity of
the hydrocarbon emissions from the vehicle determines to a large
degree the extent that ozone will be formed from those emissions.
The reactivity of the fuels in use, or those being considered for
use, varies over two orders of magnitude, from electricity and
methane at the low end of the range, to gasoline at the high end of
the range.
For each class of clean fuel vehicles certified for the fleet
program, the hydrocarbon exhaust emissions must be adjusted for
reactivity. This reactivity adjustment requirement is described in
the Act under the definition of nonmethane organic gas (NMOG). As
required under that definition, the mass of hydrocarbon exhaust
emissions of vehicles using fuels other than gasoline must be
measured and speciated, and the mass of each specie adjusted for
reactivity. The aggregate reactivity-adjusted mass is then
compared against the applicable NMOG standard.
The ozone-forming emissions from motor vehicles generally fall
into three different categories: evaporative, refueling, and
exhaust. Evaporative emissions, which are hydrocarbon fuel vapors
emitted from the fuel storage and distribution system on the
vehicle, can be further subdivided into a number of different
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sources generally called diurnal, hot soak, running loss, and
resting loss emissions. Each of these sources is described below
in more detail:
• Diurnal emissions result from fuel vapors generated in the
fuel tank from daily ambient temperature and pressure
increases while the vehicle is parked.
• Hot soak emissions result from fuel vapors generated by
residual vehicle heat following vehicle operation.
• Running loss emissions result from fuel vapors generated by
the heating of the fuel in the fuel system while the vehicle
is in operation.
• Resting loss emissions result from fuel vapors continuously
emitted from the vehicle as the result of permeation through
rubber and plastic components of the fuel system or migration
from charcoal evaporative control canisters.
Similar to evaporative emissions, refueling emissions are fuel
vapors released directly into the ambient air from the fuel storage
system. The difference is that these emissions occur while the
vehicle is being refueled. In the case of a liquid-fueled vehicle,
the liquid entering the fuel tank displaces the air and fuel vapor
in the partially empty fuel tank, forcing them out of the tank.
The more volatile the fuel, the greater the refueling emissions.
Refueling and evaporative emissions, when both are being considered
together, will be referred to as vapor emissions for the remainder
of this document.
Exhaust emissions are generated by the combustion of fuel and
are discharged from the vehicle's tailpipe, usually after passing
through a catalytic converter. The primary components of exhaust
emissions are carbon dioxide, water vapor, carbon monoxide, NOx,
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and hydrocarbons. For some fuel types, particulate matter and
formaldehyde are also important. To place clean fuel vehicles into
production, manufacturers must certify that their vehicles emit
less NOx, carbon monoxide, hydrocarbons and other pollutants than
their respective standards. For hydrocarbon emissions from CFFVs,
the Act requires the emissions be measured as NMOG.
Evaporative and exhaust emissions from motor vehicles usually
increase (deteriorate) as the vehicles age. This deterioration
occurs for a number of reasons. These include the effects of the
aging of the vehicle's engine and the emission control hardware, as
well as malmaintenance, defects, and deliberate tampering. This
deterioration is responsible for a significant portion of the ozone
forming emissions emitted from motor vehicles.
The estimation of the deterioration is a key component of an
analysis to project emissions in the future. Because of the nature
of the evaporative control systems on motor vehicles and the fuel
vapors they control, vapor emissions do not change significantly
with age until a physical or mechanical failure occurs. Most
vehicle evaporative control system designs are similar and the
frequency and severity of these failures are fairly well
understood. Thus, future vapor emissions can be estimated with a
fairly high degree of confidence.
This is not true for exhaust emissions. Exhaust emissions are
dependent on the engine configurations and emission control
approach used and can vary drastically with simple changes in the
operational setpoints of the engine controls. This is further
complicated by the fact that the full range of types of vehicles
likely to qualify as ILEVs have not yet been manufactured and
tested for their exhaust emissions. This lack of exhaust emission
data precludes EPA from projecting the exhaust emission performance
of ILEVs relative to LEVs at this time. Therefore, exhaust
emissions will not be considered in this analysis, even though it
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is likely that some reductions are possible.
b. Base Case Vehicle Vapor Emissions
1. Emission Control Programs
CFFVs, which would be the vehicles purchased by fleets in lieu
of ILEVs, form the baseline of comparison to estimate ILEV vapor
emission reductions. These base case vehicles are expected to be
low-emission vehicles (LEVs) running on federal reformulated
gasoline.
In addition to the reformulated gasoline program, a number of
other vehicle emission reduction programs are expected to be
implemented which will further reduce vapor emissions compared to
that from today's vehicles. These emission reduction programs
include Phase II Gasoline Reid Vapor Pressure Control, Improved
Evaporative Emissions Control, Onboard Diagnostics, and Enhanced
Inspection/Maintenance. These programs and their initiation dates
are summarized in Table 1.
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Table I - Summary of Future Emission Control Programs
Emission Control Program
Phase II Gasoline RVP
Control
Improved Evaporative
Emissions Control
Onboard Diagnostics
Enhanced I/M
Reformulated Gasoline
required for most areas
covered by fleet program
Planned or Anticipated Program
Start Date
May 1992
Proposed Phase-in 1995 - 1998
Model Year 1994
Proposed Phase-in 1994 - 1996
Assumed to be used by all base case
fleet vehicles starting in 1998.
Stage II refueling emission control, which is called for in
the Act, is expected not to apply to most of the fleets covered by
the fleet program. Stage II refueling emission control is a state
implemented program requiring most fuel dispensing facilities
located within moderate or worse ozone nonattainment areas to
install controls to reduce refueling emissions. In this case,
fleets are generally centrally fueled from their own facilities and
would only be covered if they dispense more than 10,000 gallons per
month. According to past EPA analysis, most fleets do not dispense
monthly volumes greater than this level; thus, they would not be
covered by the stage II requirements and their refueling emissions
would be uncontrolled. For this analysis, two approaches will be
taken concerning this issue: 1) that no fleet vehicles would be
covered by Stage II, and 2) 10 percent of fleet vehicles would be
covered by Stage II.
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2. Calculation Methodology
EPA assessed the benefits of the emission control programs
listed above to project the vapor emissions of base case vehicles.
Since the benefits of each of these programs on vehicle emissions
can diminish when the parallel effects of other programs are also
considered, it was necessary to use MOBILE 5.0 to account for the
synergistic effect of all the future programs implemented together.
The MOBILE emission modeling computer program was developed to
estimate the exhaust and vapor emissions from all classes and ages
of operating vehicles. The model incorporates a number of factors
that affect the level of emissions, including ambient temperature,
average vehicle speed, mileage accrual rates, emission control
hardware failure rates, and vehicle tampering. The benefits of
mobile source emission control programs implemented prior to the
CAA amendments, and projections of the benefits of programs
required in the Clean Air Act amendments, are incorporated into
this version of the MOBILE computer program.
Some of these MOBILE 5.0 input parameters and data output were
modified in the special version of the model to account for two
specific operating characteristics of fleet vehicles and the fleet
program. The high urban use of covered fleet vehicles was
accounted for by using an urban average driving speed. Because the
fleet program is primarily concerned with reducing ozone precursor
emissions, the analysis was modeled at 90.5 °F which considered
high summertime temperatures associated with ozone exceedances.
The MOBILE 5.0 model reports vapor emissions for each of the
separate sources discussed above for each vehicle class. The
various vapor emission sources are totaled for each class to derive
total vapor emissions for that class. After the emission control
programs in Table 3 are fully phased-in, the vapor emission factor
for each vehicle class is stable. This should occur in about 1998
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when the mandatory portion of the clean fuel fleet program begins,
so only one emission factor is necessary for each vehicle class
(see Table 12 in Appendix) .
These separate vehicle class emission figures are then
combined into a composite value using weighting factors. Unlike
the emission factors, the weighting factors do change as the fleet
program phases in and the mix of vehicle classes changes over time.
To provide sample figures for one year, the weighting factors for
the year 2000 class mix of fleet vehicles including the mileages
and number of vehicles are summarized in Table 2. The year 2000
was chosen because it falls in the middle of the early years of the
fleet program phase-in and would tend serve as an average for the
weighting factors for those years. Weighting factors for other
years can be calculated using the projected sales figures in
reference 1. A weighting factor for heavy-duty diesel vehicles is
not included in this table because diesel is low in volatility;
consequently, ILEV replacements of conventional diesels or diesels
qualifying as ILEVs replacing the existing fleet are not expected
to yield any reductions in vapor emissions.
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Table 2 - -Weighting Factors and their Base Data for Year 2000 Fleet
Vehicles
Category
Number of
Operating Fleet
Vehicles [1]
Average Annual
Mileage [1]
Weighting Factors
LDV*
302,000
17,600
0.58
LDT1*
118,000
15,700
0.21
LDT2*
24,000
15,700
0.04
HDGV*
50,000
31,700
0.17
* LDV is light-duty vehicle; LDT1 is light-duty truck under 6000
Ibs. gross vehicle weight rating (GVWR); LDT2 is light-duty truck
between 6000 and 8500 Ibs. GVWR; and HDGV is heavy-duty gasoline
vehicle.
Applying the weighting factors for any one year to the base
case emission factors yields composite emission factors for the
base case vehicles in that year. Emission factors for years prior
to 1998 were not analyzed for two reasons. First, base case
vehicle and ILEV purchases by fleets prior to 1998 are expected to
be less significant and the numbers more difficult to predict than
when the fleet program begins in 1998. And second, the inputs for
the MOBILE computer model were difficult to determine because the
final provisions and phase-in dates for some of the emission
control programs mandated by the Act have not been established.
Therefore, this analysis focused only toward the end of this decade
when the vehicle emission control and fleet programs are certain to
be implemented.
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3. Modeling Results
Using the analysis and weighting scheme described above, the
composite base case fleet vehicle emission factor for the year 2000
is calculated and summarized below in Table 3. The value of 0.50
grams/mile is based on the emission factor data summarized in
detail in Table 12 in the Appendix and the weighting factors listed
in Table 2 above. Composite emission factors for other select
years are summarized below in Table 5 for the purpose of projecting
the emission benefits of the ILEV program.
Table 3 - Projected Vapor Emissions from Low-Emission Vehicles in
grams/mile/vehicle (parentheses includes effects of Stage
II reductions)
Year
2000
LDV*
0.33
LDT1*
0.38
LDT2*
0.39
HDGV*
1.23
Weighted Total
0.50 (0.48)
* LDV is light-duty vehicle; LDT1 is light-duty truck under 6000
Ibs. gross vehicle weight rating (GVWR); LDT2 is light-duty truck
between 6000 and 8500 Ibs. GVWR; and HDGV is heavy-duty gasoline
vehicle.
c. ILEV Vapor Emissions
1. ILEV Vfchicles/Fuels
Projections of the in-use emissions from ILEVs are based on
vehicle technology/fuel combinations that are expected to meet an
evaporative emissions requirement of 5 grams/test with any control
system disconnected. The assumed vehicle technology/fuel
combinations are dedicated alternative-fuel and diesel vehicles
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running on the proven low-emitting vehicle technology/fuels. There
is no limit or specification on the fuel or technology which can be
used provided that the performance standard can be met. Possible
technologies/fuels include compressed natural gas, liquid petroleum
gas, electricity, neat alcohols such as methanol and ethanol, and
clean conventional fuel technologies.
Reformulated gasoline and alcohol blended fuels are also
eligible, however, they may have greater difficulty qualifying
because of their relatively high reid vapor pressure of over 8
pounds per square inch (psi). If vehicles using these fuels are
subjected to the ILEV evaporative emissions test, which requires
that the evaporative emissions control hardware be disconnected,
they could emit several times over the ILEV evaporative limit.
However, it would not be infeasible for these fuels to qualify as
ILEVs, if a fuel storage system can be designed which ensures that
evaporative emissions remain below the ILEV evaporative emissions
requirement.
Vapor emissions from ILEVs are not expected to increase or
deteriorate over time. This is based on the concept of vehicle
expected to meet the requirements to qualify as an ILEV. While the
vapor emissions from conventional vehicles are certified with the
use of vapor emission control hardware when required, and this
hardware can later fail in-use resulting in significant amounts of
in-use vapor emissions. The ILEV test procedure does not allow the
use of such hardware. Thus, the ILEV test procedure ensures that
the in-use vapor emissions will remain very, very low because only
inherently low emitting fuels and fuel storage configurations would
be permitted. ILEV fuels would either be naturally low in vapor
pressure, or totally enclosed in storage systems that would
preclude vapor emissions. Further descriptions of the inherently
low emitting qualities of the fuels expected to qualify as ILEV
fuels are included separate sections on each of the ILEV fuel
categories below.
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For this analysis, the alternative fuels expected to qualify
as ILEV fuels are categorized into four groups and evaluated in the
context of several parameters. The four groups are: 1) gaseous
fuels, which includes compressed natural gas and liquid petroleum
gas; 2) alcohol fuels, which includes neat methanol and neat
ethanol; 3) electricity; and 4) clean conventional fuel
technologies. These groupings were chosen because of the
similarities in the technologies and the ozone forming potential of
the fuel vapors. Each of these groups will next be evaluated for
their vapor emissions, their ozone forming potential, and their
expected penetration of the ILEV market.
A. Gaseous-Fuel ILEVs
Gaseous-fuel vehicles do not emit diurnal, running loss, or
hot soak emissions because the storage systems are completely
enclosed.[2,3] The refueling emissions are also expected to be
essentially zero because quick disconnect fittings are expected to
be required hardware for future refueling installations. It is
unknown whether gaseous fueled vehicles emit resting losses because
they have never been measured. Because the fuel system is under
pressure, the walls of the fuel lines are thicker than today's
vehicles which would tend to eliminate the bleeding through the
fuel line walls seen in today's vehicles. Thus, resting loss
emissions are projected to be essentially zero as well.
Gaseous fuels are much less reactive than gasoline vapor.
This is because the components of the fuels are much more inert.
Compressed natural gas is composed primarily of methane and ethane
(a typical fuel would contain about 95 and 2 percent, respectively,
plus minor amounts of other hydrocarbons and inerts) which are much
lower in reactivity.[4,5, 6] Liquid petroleum gas for automotive
fuel is composed primarily of propane and butane (a typical fuel
will contain about 95 percent and 5 percent, respectively, plus
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trace amounts of other constituents), which is also relatively low
in reactivity.[4,5,6] Thus, the ozone-forming potential of both
these vehicle/fuel combinations is substantially lower than that
for gasoline-type vehicles.
Compared to the other fuels considered, gaseous fuels are
projected to capture the largest share of the ILEV market early on.
Gaseous fuels are now available as conversions, and OEM models are
planned. This positions gaseous fueled ILEVs to take advantage of
the large benefits such as the much lower fuel price and the
already widespread accessibility of the fuels.[7]
B. Alcohol-Fuel ILEVs
The alcohol fuel emissions used in this analysis are those
estimated for neat methanol (M100),[8] and are assumed to apply to
neat ethanol (E100) as well which has about the same ozone-
producing potential. Although ethanol's vapor pressure is about
one half of methanol's (2.5 psi versus 4.6 psi. at 100 °F)[9], its
reactivity is about two times higher (1.34 versus 0.56);[5]
therefore, reactivity adjusted emissions for ethanol would be about
the same. Since alcohols and gasoline are both liquid fuels and
would use similar fuel system designs, alcohol fuels are assumed to
emit the same amount of resting losses as gasoline-powered
vehicles. The vapor emissions from alcohol fuel-vehicles are
summarized below in Table 4. To relate the ozone forming potential
of these emissions to those of base case vehicles, a reactivity
adjustment factor was applied. California's reactivity adjustment
factor of 0.29, adjusted to that of gasoline, is used here.[5,6]
Neat alcohol fuels are estimated to comprise another large
segment of the ILEV market. The cold start drawbacks related to
neat alcohol fuels have shown some promise of being resolved. A
direct injected methanol engine has been developed which cold
22
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starts at temperatures previously obtainable only through glow plug
technology or with methanol blended with gasoline. This technology
is assumed in this report to be further developed for both methanol
and ethanol to allow the alcohols to make inroads into the ILEV
market.
Table 4 - Projected Emissions from Alcohol-Fuel Inherently Low-
Emission Vehicles (Grams/Mile)
Emission Category
Hot Soak and
Diurnal
Running Loss
Resting Loss
Refueling Loss
Total Vapor
Emissions
Reactivity
Adjusted Vapor
Emissions (g/mi)
Alcohol Fuels
(M100 and E100)
.030
.025
.01
.017
.077
.022
c.
Electric ILEVs
Electric vehicles are expected to emit no measurable amounts
of any pollutants. The basis for this is that emissions related to
power generation are not considered. Also, electric ILEVs would
need to be dedicated electric vehicles, or if hybrid, the vehicles
will use a secondary fuel which is also essentially zero emitting,
23
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such as another alternative fuel meeting the ILEV qualification
procedures. When hybrids are developed, test procedures and other
requirements will need to be developed to assess more fully their
evaporative and exhaust emission characteristics.
Electric vehicles are projected to comprise a relatively small
fraction of the operating ILEVs. This assumption is based on their
much greater purchase cost, shorter operating range, and more time
consuming "refueling" (recharging) requirement, as compared to
other alternative-fuel vehicles.
D. Clean Conventional Fuel Technologies
Diesel vehicles emit very low amounts of evaporative emissions
and would thus easily meet the ILEV evaporative emission
requirement. This conclusion is based on data which establishes
diesel's reid vapor pressure to be about 0.4 pounds per square
inch,[10] which is over one order of magnitude lower than that of
methanol. This difference in vapor pressure indicates that diesel
vapor emissions would also be about one order of magnitude lower
than that of methanol, [11] which would put the total emissions
value at about 0.008 grams per mile. Because clean diesel is a
petroleum-based fuel which includes many reactive compounds, the
little fuel which does evaporate is considered to be very reactive.
Diesel vehicles may not qualify early on as ILEVs. This
projection is based on the current difficulty diesels have in
trying to meet more stringent NOx standards. As diesel emission
control technology advances, which is expected to occur as the
sulfur content is reduced, then new catalyst technology can then be
used allowing diesels to meet more stringent NOx standards, and
potentially qualify as ILEVs. Also helping clean diesel's chances
for being adopted as an ILEV fuel are its current advantages as
being fuel efficient and widely available. However, in the
24
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aggregate the overall number of diesel ILEVs is expected to be
relatively small.
Low vapor pressure grades of reformulated gasoline, or that
type fuel coupled with new fuel storage technologies, could
conceivably be invented to permit gasolines to meet the ILEV
evaporative emission requirements. If this technology can be
developed and implemented, the amount of vapor emissions would
still need to be lower than the ILEV evaporative emission standard.
Therefore, any such technology would emit evaporative emissions
similar to that expected for methanol, which would probably just
qualify for the ILEV evaporative emission requirement without any
new technology.
2. Composite Vapor Emissions
For this analysis, the first step in projecting the vapor
emissions from ILEVs was to estimate the aggregate emissions from
each technology/group. "This aggregate figure was determined by
totaling the estimated vapor emissions emitted from each emission
source (i.e., refueling, diurnal, hot soak etc.). As described
above, gaseous-fuel, and electric ILEVs are considered to emit zero
evaporative emissions, and the nonblended alcohol and diesel
vehicle vapor emissions are estimated to be 0.022 and 0.008 grams
per mile, respectively. Finally, the emission figures were next
weighted together using an assumed in-use mix of alternative fuels
projected to be used by ILEVs. This assumed mix is 50 percent
gaseous fueled, 5 percent of electric, and 40 percent composed of
pure alcohol (neat alcohol) and clean conventional fuel
technologies with less than 5 percent of this expected to be
diesel.
This assumed mix of fuels/technology results in a vapor
emission factor of 0.01 grams per vehicle-mile and will be used in
25
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the following comparison between ILEVs and base case vehicles.
Even assuming that all the ILEVs are alcohol fueled or used a
technology which just met the ILEV standard, the vapor emissions
would only rise to 0.022 grams per mile. Conversely, if all ILEVs
were zero emitting such as electric or the gaseous-fuel type, the
vapor emissions would be zero. From this data it is clear that the
use of ILEVs in place of base case vehicles would essentially
eliminate vapor emissions.
d. ILEV Emission Benefit
1. Individual Vehicle Benefit
The projected, per vehicle hydrocarbon vapor emission benefit
from the use of ILEVs is simply the difference between the ILEV
composite emission factor and the base case vehicle composite
emission factor. As summarized in Table 5 for several years
starting in 1998, ILEVs are expected to realize vapor emission
reductions in the range of 0.47 - 0.57 grams/mile/vehicle.
Considering the total hydrocarbon emission inventory (vapor and
exhaust emissions) as currently estimated for base case vehicles
and assuming no reduction in ILEV NMOG exhaust emissions over other
CFFVs, ILEVs would be expected to be about 50 percent lower
emitting in NMOG emissions than base case vehicles. If ILEVs are
indeed lower in exhaust emissions as expected, then the emissions
reduction would be even greater.
If some of the fleets are required to implement Stage II
refueling emission controls at their refueling facilities (coverage
may extend to 10 percent of fleet vehicles), the vapor emission
benefit would be somewhat reduced. The above stated emission
benefit figures for year 2000 base case vehicles would be reduced
about 4 percent to 0.47 g/mi/vehicle. The relative significance of
the ILEV vapor emission benefit remains essentially the same.
26
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2. Aggregate Benefit
The annual emission benefit from all operating ILEVs is the
product of the emission benefit per ILEV, the projected number of
operating ILEVs, and the average annual mileage of ILEVs. This
calculation is shown in the following equation:
(eBase Case GILEv) X n
iLEV
EB ILEV = Total ILEV Emission Benefit
e Ba.« ca.« = Emission Factor for Base Case Vehicle
e ILEV = Emission Factor for ILEV
n ILBV = Number of ILEVs
VMT riMt = Annual Miles Travelled by Fleet Vehicles
The future number of operating ILEVs is difficult to predict.
The reasons for this difficulty stem from the uncertainty
surrounding the future cost and availability of ILEVs and their
fuels, the public acceptance of such vehicles, and the
effectiveness of expanded TCM exemptions and other incentives to
encourage their purchase. Because of the difficulty in assessing
these issues, a wide range of in-use ILEVs population will be
assumed to be operating, to encompass the various possible ILEV
purchase scenarios that could unfold. Certain points within this
range are computed as fractions of the total CFFVs which EPA
estimates will be purchased for the fleet program.[1] The middle
value in this range is based on the fraction of fleet vehicles in
wholesale and retail delivery fleets, which is about 1/15 of the
total number of fleet vehicles.[12] These fleets would most likely
want to take advantage of the HOV lane incentives. The range of
operating ILEVs encompassing the 1/15 value starts at 1/50 of
operating CFFVs at the low end, and extends to 1/5 at the high end.
27
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The weighted average annual mileage of fleet vehicles was
calculated to be 19,500 miles per year based on the figures in
Table 2 for the average fleet mileage and projected number of
vehicles for the four vehicle classes involved. The projected
number of ILEVs, the vapor emission 'reduction of ILEVs, and the
composite average annual mileage figure combine together in Table
5 to project the hydrocarbon vapor reduction benefit of the ILEV
program. The gram/mile emission reduction benefit for ILEVs varies
over the years because of the change in the vehicle mix in the
fleet.
28
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Table 5 - Calculation of Total Vapor Emission Benefits from the ILEV Program
Year
1998
1999
2000
2005
2010
Projected
Number of
Operating
CFFVs
106,000
270,000
498,000
996,000
1,130,000
Fraction of
CFFVs as
ILEVs
1/50
1/15
1/5
1/50
1/15
1/5
1/50
1/15
1/5
1/50
1/15
1/5
1/50
1/15
1/5
Projected
Number of
Operating
ILEVs
2,100
7,100
21,200
5,400
18,000
54,000
10,000
33,200
100,000
20,000
66,400
199,000
22,600
75,300
226,000
Emission
Reduction
of ILEVs
(g/mi)
0.57
0.52
0.49
0.47
0.47
Composite
Mileage of
Fleet
Vehicles
(mi/year)
20, 800
20,100
19,500
20,100
19,000
Total
Emission
Benefit
from ILEVs
(tons/year)
28
93
280
62
210
620
105
350
1050
210
690
2100
230
750
2300
29
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The figures indicate a range of vapor reductions from 105 to
1050 tons per year in the year 2000, and 230 to 2300 tons per year
in the year 2010. Since the projected number of ILEVs operating is
linked to the number of operating CFFVs, the increase in emission
reductions associated with the phase-in of the program plateaus by
the year 2005. After that point, smaller increases in emission
benefits which are expected would result from the growth of the
fleet industry, although there could be additional expansions of
the program through state initiatives.
The projected aggregate emission benefit of the ILEV program
would be smaller if Stage II refueling emission controls affected
a portion of the fleet vehicles. Considering that 10 percent of
the vehicles could be affected, the projected aggregate emission
reduction would be reduced by about 4 percent.
Conversely, the emissions benefit would be much larger if
fleets resell their ILEVs to the general public. Up to this point,
ILEVs were assumed to be held by the fleet to the end of the
vehicle's useful life. This approach was chosen because the fuels
projected to be used by ILEVs may not be available to the general
public. However, if the fuels are made widely available, (which is
likely where local alternative fuel programs or the National Energy
Strategy is implemented), if fleets continue their current
practices of reselling their vehicles prior to reaching their
useful life, and if states offer incentives to noncovered fleets
and the public, then ILEV resale prior to full useful life is
probable.
Such ILEV sales to the public would increase the number of
ILEV purchases and also yield associated emission benefits. In the
most optimistic scenario, all ILEVs would be sold off to the public
at the same rate currently seen by the fleet industry, which is
about 3 years for LDVs, 4 years for LDTs and 5 years for HDVs.[l]
At these turnover rates and using average fleet mileage, LDVs, LDTs
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and HDTs would be sold with about 45,000 miles, 60,000 miles and
75,000 miles on the vehicle, respectively. Comparing these mileage
figures with those of useful life would give a sense for the
potential increase in the number of operating ILEVs and associated
emission reductions which could be realized. The useful lives of
LDVs, LDTs and HDTs are 100,000 miles, 120,000 miles, and 120,000
miles, (the weighted average for light and medium heavy-duty
vehicles), respectively.[13]
The ratio of mileage to useful life indicates that fleets
typically sell their fleet vehicles with about half of the useful
life left for those vehicles. Since half of accrued mileage would
occur outside of fleets, the effective ILEV fleet size would double
as a result. The total impact of the increased ILEV fleet would be
observed when the entire fleet turns over. After the start of the
fleet program in 1998 when the number of ILEVs sold is expected to
increase, and if current fleet resale practices apply, then the
resale of light-duty ILEVs would begin as soon as three years later
in 2001. The number of ILEVs operated in the public sector would
catch up to the sales to fleets 10 years after 1998 when the heavy-
duty fleet vehicles would have completely turned over. The
emissions impact of ILEVs depends on the increased number of ILEVs
which would begin immediately and would increase until the fleet
size stabilizes in 2008.
Based on the scenario laid out above, the ILEV emission
benefit figures determined above would be adjusted upwards to
include the potential additional ILEV sales and associated air
benefits. Thus, the above projected year 2010 ILEV VOC emission
benefits of 230 - 2300 tons per year would increase to 460 - 4600
tons per year.
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e. Conclusion
The projected composite hydrocarbon vapor emission factor
(0.01 g/mi/vehicle) for ILEVs is very low compared to the projected
composite emission factor for base case CFFVs (0.50
grams/mile/vehicle). The purchase of ILEVs by fleets would
essentially eliminate vapor emissions relative to base case vehicle
purchases. Preliminary exhaust emission calculations shows base
case vehicles to emit about equal quantities of hydrocarbon exhaust
emissions as evaporative emissions. Even assuming equal exhaust
hydrocarbon emissions from ILEVs (which would seem to be a
conservative assumption), the purchase of ILEVs is projected to cut
NMOG emissions by over one half. Thus, ILEVs would be much cleaner
vehicles than base case vehicles, and are justified in receiving
the additional TCM exemptions and other incentives extended to
them.
Compared to other emission control programs, the per vehicle
benefit of ILEVs is significant. Reformulated gasoline and
enhanced inspection/maintenance programs are two emission control
programs currently being considered for implementation, and EPA
estimated either to reduce exhaust and evaporative nonmethane
emissions by about one quarter. Based only on evaporative
emissions, the ILEV program would be incrementally twice as
effective as these other programs.
If ILEVs are resold by fleets to noncovered fleets and to the
private sector before the vehicles reach their full useful life,
the aggregate number of ILEV sales and related emission benefits
would increase. The extent of the increase would seem to depend on
the availability of ILEV fuels and the degree to which states make
incentives available to noncovered fleets and the public. This
analysis demonstrates how this effect could potentially double ILEV
sales and emission benefits.
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The aggregate emission benefits of the ILEV program would
increase following promulgation of additional transportation
control measure exemptions for ILEVs. EPA proposed in the
rulemaking process to study other incentive programs and promulgate
additional TCM exemptions that make good policy sense. These
additional exemptions would be expected to result in more ILEV
purchases and, as more conventional vehicle or LEV purchases are
supplanted by ILEVs, the total emission benefit will rise.
V. Affects of ILEV Use of HOV Lanes
a. Background
Now that the ILEVs have been shown to be much lower emitting
than the base case vehicles, the next task is to compare that
benefit with any implications of ILEVs using HOV lanes.
1. What are HOV Lanes?
High-occupancy vehicle (HOV) lanes are special lanes of the
road restricted for use by vehicles carrying multiple occupants,
such as carpools, vanpools, and buses. Several different types of
HOV lanes have been implemented and each of these types could be
affected by the ILEV program. These include freeway HOV lanes,
arterial HOV lanes, and bus-only lanes. Other HOV lane lanes are
really variations of the above, and include freeway ramps and
bridge and toll road HOV lanes. Because bus-only lanes are
generally not open to vehicles other than buses, they would not be
available for use by ILEVs under the federal program. The state
and local governments, however, could choose to open up such lanes
to ILEVs on a case-by-case basis. This report will focus on
freeway HOV lanes because of their relative high usage and
widespread implementation, and because data are much more available
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on their operation. It is reasonable to assume that the impact on
other types of HOV lanes would be similar to that expected for
freeway HOV lanes, since they are all used in essentially the same
ways.
Two conditions must be present for HOV lanes to be successful
as transportation control measures. First, the volume of traffic
in the general purpose lanes (non-HOV lanes) must be great enough
to cause frequent congestion problems during the heavy traffic or
peak periods. Second, the volume of HOV lane traffic flow must be
sufficiently low to avoid congestion even during the rush period.
This difference in traffic flow would then provide a twofold
incentive for single occupancy drivers to join a carpool and use
the HOV facility. The first incentive is that the daily commute
takes less time, and second is the greater reliability of arriving
at one's destination on time (i.e., fewer or no traffic jams).
2. HOV Lane Benefits
HOV lanes can produce a range of benefits. One benefit is
motor vehicle emission reductions, which can be separated into
primary and secondary reductions. The primary emission reduction
is the elimination of emissions from vehicles the drivers of which
become passengers in other vehicles. These reductions are
significant, since potentially each additional rider eliminates a
vehicle trip. The secondary emission reduction results from the
reduced congestion brought about by the reduced number of vehicles
on the road. More efficient traffic flow decreases total vehicle
emissions because vehicles are spending less time in inefficient
stop-and-go operation. For several reasons the emission reductions
from HOV lane use have not been perhaps as large as originally
anticipated by those studying the effectiveness of HOV lanes.[14]
However, the use of HOV lanes is positive from an environmental
prospective.
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Other benefits of HOV lanes which result from congestion
relief include decreased energy consumption, increased economic
efficiencies related to transport of people and goods, and reduced
need to expand freeway capacity. When realized, these benefits
increase economic efficiency by reducing the cost or time it takes
to do business. In addition, to the extent that congestion is
reduced, HOV lanes may also lower public frustration from traffic
j ams.
3. HOV Lane Utilization
HOV lane traffic flow is considered undesirable if it is
either too high or too low. In the case of freeways, a rule of
thumb which has been established is that the flow is considered too
high if it increases above 1500 vehicles per hour.[15] Above this
level, the lane begins to appear full and the HOV lane incentive
that lures potential carpoolers to participate begins to be less
inviting. The maximum of any lane carrying a normal mix of
vehicles under normal weather conditions is accepted to be about
2000 vehicles per hour. At this point unstable flow or stop-and-go
traffic usually begins.[16] The second issue occurs when the HOV
lane drops to about 800 vehicles per hour or lower. At these lower
traffic flows, the HOV lane appears practically empty and
objections by the general public to the lane can arise. The most
optimum flow would seem to occur around 1500 vehicles per hour at
which point all lanes of the freeway are carrying the maximum
numbers of persons and vehicles.
b. Method of Analysis
The HOV lane analysis presented here projects the increase in
HOV lane traffic flow arising from the use of ILEVs and assesses
whether current vehicle volume would be increased above the 1500
vehicles per hour threshold thought to be the indicator of optimum
35
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flow for HOV lanes. The analysis further quantifies the impact of
allowing ILEVs access to HOV lanes by assessing how the increased
flow may decrease HOV lane speed. To best predict the actual
impact of ILEVs, the analysis used lane-use data collected from
existing HOV lanes.
The analysis of the impact of ILEVs on HOV lanes was made in
three steps, and each step often involved several substeps. First,
several urban areas with HOV lanes were chosen for study. Then, to
project the number of operating ILEVs in each of those areas, the
number of operating CFFVs in each area was projected and, the same
broad range used in the ILEV emission reduction section above
(1/50, 1/15, 1/5) was applied here. In addition, however, the ILEV
range was adjusted by the fraction of urban freeways in each area
projected to have HOV lanes. This adjustment brings the projected
number of ILEVs more in line with the estimated amount of available
incentives. Finally, the third step was to assess the impact of
ILEVs on the traffic flow in HOV lanes during the peak traffic
period. Each of these steps is detailed below.
To project the impact of ILEVs on HOV lanes, several urban
areas with HOV lanes were chosen for study. Houston, Texas;
District of Columbia; Los Angeles, California, and Seattle,
Washington were chosen because HOV lanes are already functioning in
these areas, and data on their use patterns have been collected and
were readily available. The entire urban area was studied because
each HOV lane and associated freeway lanes are part of a traffic
management strategy for the urban area where they are located.
Furthermore, these areas, except for Seattle, are all covered by
the clean-fuel fleet program. Although Seattle is not a covered
area, it was chosen because it is similar in population and highway
characteristics to Atlanta and Baltimore, which do not currently
have HOV lanes to analyze. Like Baltimore and Atlanta, Seattle has
about 2 million inhabitants, and about 10 freeways entering and
encircling the urban area.
36
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The next step was to project the number of operating CFFVs in
each of the chosen areas. This number was found by adjusting the
projected nationwide number of CFFVs in all areas covered by the
fleet program by the area fuel use fraction of the area being
studied.[1] Table 6 below summarizes these steps and resulting
numbers.
Table 6 - The Number of CFFVs in Particular Urban Areas for the
Years 2000 and 2010.
Area Being
Studied
Houston
Texas
District of
Columbia
Seattle
Washington
Los Angeles
California
Area Fuel
Fraction
0.059
0.050
0.033
0.193
Year
2000
2010
2000
2010
2000
2010
2000
2010
Number of
CFFVs*
30,500
69,400
25,800
58,800
16,900
38,300
99,800
227,000
* Number of CFFVs for entire U.S. was estimated to be 516,900
cars and trucks in the year 2000, and 1,176,000 in 2010.[1]
Next, the number of operating ILEVs was determined for each
area studied. Consistent with Section IV above, the number of
ILEVs is projected to fall within a relatively broad range based on
37
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fractions - of the projected number of operating CFFVs. The same
range of fractions (1/50, 1/15, 1/5) is used as a starting point;
however, in this case the range is adjusted lower by the fraction
of freeways in that particular urban area expected to have
operating HOV lanes by the year 2000. This fraction was
established with the HOV lane information summarized in Table 13 in
the Appendix,[17] and the use of a recent road atlas. In effect,
this approach reasonably supposes that only fleet operators near
HOV lanes will purchase and use ILEVs.
The third step was to determine the extent that ILEVs might
increase HOV traffic flow during the heaviest traffic periods of
the day. To conduct this analysis, information was needed on how
the ILEV population would be dispersed throughout the heavy traffic
period and to determine the duration of that period. The
dispersion of ILEVs was determined from the operating
characteristics of fleets in general. Based on the operating
characteristics, it is reasonable to believe that fleet vehicle use
of HOV lanes would be equally dispersed throughout the commute
period. These vehicles are used for various delivery purposes such
as raw and finished material deliveries; mail, package and
administrative paperwork deliveries and each application would tend
to demand a different vehicle use schedule. Furthermore, fleets
try to minimize their costs by accomplishing multiple tasks in the
immediate area of their destination prior to returning to their
central location. This requires additional time in the destination
area. Based on these characteristics, fleet use of HOV lanes would
be limited to perhaps one trip per vehicle during each commute
period, and the tendency is that the trips would be dispersed.
The heaviest traffic period was identified by studying the
characteristics of urban highways and current HOV lanes. Urban
highway traffic flows tend to be highest during the commute
periods, and the absolute highest during the peak-hour of those
periods. For the HOV lanes analyzed, the peak-hour flow during the
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morning commute, was generally found to be the maximum flow period
of the entire day. [18] The morning commute period is usually
reported to occur from 6:00 a.m. to 10:00 a.m.[18]
Based on the discussion above, it was then possible to
estimate HOV lane use by ILEVs during the heavy traffic periods.
Fleet vehicles would be expected to make only one trip during the
heavy traffic period and based on the variety of fleet
applications, these trips would be spread out over the entire heavy
traffic period. Information suggests that the heavy traffic period
is about 4 hours. Therefore, the ILEV population using HOV lanes
is divided by 4 to estimate the number of ILEVs which would be
added to an HOV lane during the peak-hour traffic period.
The impact of ILEVs on HOV lane traffic flow in each studied
area was analyzed with the use of a commonly used highway design
diagram. This diagram, reproduced in Figure 1 in the appendix, was
developed by transportation engineers to relate the traffic speed
in any one lane to the traffic flow.[14] For this analysis, the
diagram was used to determine the change in average vehicle speed
which might occur from a given increase in the flow of traffic.
The far right point of the diagram's curve indicates the "maximum
flow point" of about 2000 vehicles per hour. When the "maximum
flow point" is reached, further traffic demand begins to result in
a drastic decrease in lane flow and speed. This resulting
condition is termed unstable flow.[16]
This analysis methodology was applied to each of the four
urban areas studied. This next section summarizes the specific
information used in making the analysis for each urban area, and
the results of the individual analyses.
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c. Case-^by-Case Analyses
I. Houston, Texas
The Houston area provides an especially good case to evaluate
for this analysis because several HOV lanes are already implemented
and designs are complete to add more HOV lanes. Figure 2 in the
Appendix shows the existing and planned HOV lanes for the Houston
urban area.[19] The future highway HOV lane system serves almost
every quadrant surrounding the city center, except for 1-10 to the
east and SH 288 to the south.
As described in the subsection above, the previously used
broad range of fractions (1/50, 1/15, 1/5) was adjusted by the
fraction of freeways with HOV lanes and applied to the number of
CFFVs in Table 6 to project a range of operating ILEVs. The
Houston area has 10 total highways and 6 of these are expected to
have HOV lanes;[17,19] the previously used fractions are therefore
adjusted downward by 6/10 to 1/80, 1/25, and 1/8. The range of
ILEVs operating in each HOV lane is determined by dividing the
projected range of ILEVs for the entire area by the number of HOV
lanes. Finally, the number of ILEVs operating during the morning
peak hour was determined by multiplying the calculated range of
ILEVs expected to be operating in each HOV lane by the 1/4
adjustment factor discussed in the previous section. The results
of these calculations are summarized below in Table 7.
40
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Table 7 --Projected Number of ILEVs Operating in Houston HOV Lanes
During Peak Hour
Area Being
Studied
Houston
Texas
Year
2000
2010
Adjusted
Range of
Fractions
1/80
1/25
1/8
1/80
1/25
1/8
Number of
Operating
ILEVs
380
. 1,220
3,810
870
2,800
8,700
ILEVs
Operating
in Each
HOV Lane
60
200
635
140
460
1,400
ILEVs
Operating
During
Peak Hour
15
50
160
36
120
360
The impact on HOV lane volume caused by the use of ILEVs was
projected by adding the estimated ILEV peak-hour operating volume
to that recently recorded for an existing HOV lane. The Houston
highway labeled 1-10, which is also called the Katy Highway, has
been studied extensively and that available data was used for study
in this analysis and reasonably assumed to apply to the other
Houston HOV lanes as well. The data reveal that the Katy highway
peak-hour flow is about 1050 vehicles per hour.[19] Adding the
range of ILEVs projected to be operating during the peak hour in an
HOV lane in the year 2000 to the current volume of 1050 vehicles
per hour yields a range of 1065 - 1200 vehicles per hour. The same
calculation performed for the year 2010 yields a range of 1085 -
1400 vehicles per hour.
The impact of this projected increased volume in HOV lanes
during peak hour can be estimated by using the vehicle speed versus
traffic flow diagram (see Figure 1 in the Appendix). By dividing
the initial flow of 1050 vehicles per hour by the potential maximum
flow of 2000 vehicles per hour, a volume/capacity ratio of 0.53
41
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results. This value forms the baseline of comparison, for the
projected increased traffic flows after the introduction of ILEVs.
Using the potential maximum HOV and ILEV traffic volume in the year
2000 of 1200 vehicles per hour and dividing by 2000 vehicles per
hour, a volume/capacity value of 0.60 is produced. The 0.53 value
corresponds with 57 miles per hour, while the 0.60 value
corresponds with the value of about 56 miles per hour (using the
non-California curve in the diagram) , or a 1 mile per hour decrease
in speed. The impact on traffic speed determined from the other
value for the year 2000, and the upper and lower values of the
range for the year 2010 were calculated in the same fashion. These
calculations show that the projected increase in traffic volume
would cause average vehicle speed to be reduced by 0-1 miles per
hour in the year 2000, and 0-2 miles per hour in the year 2010.
These projected changes in flow are essentially insignificant,
especially considering the hourly and daily variations in traffic
flow typically seen on these roads.
2. District of Columbia
The District of Columbia currently has three operating HOV
lanes and tentatively plans to implement one more as indicated in
Figure 3 in the Appendix.[19] The HOV lane which has been studied
and documented extensively is called the Shirley Highway, or 1-395;
the others are 1-66, 1-95 (which is an extension of 1-395), and the
Dulles tollroad.[15,19] There are a total of ten major highways
entering and connecting the D.C. urban area. Using these figures,
the previously used fractions are adjusted downward by 4/10 to
1/125, 1/40, and 1/12. The peak hour volume is reported to be 2460
vehicles per hour for two HOV lanes of traffic, or 1230 vehicles
per hour in each lane.[19] These figures and assumptions as they
apply to the D.C. HOV lanes are summarized below in Table 8.
42
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Table 8 - Projected Number of ILEVs Operating in District of
Columbia HOV Lanes
Area Being
Studied
District of
Columbia
Year
2000
2010
Adjusted
Range of
Fractions
1/125
1/40
1/13
1/125
1/40
1/13
Projected
Number of
Operating
ILEVs
210
650
1,980
470
1,470
4,520
ILEVs
Operating
in Each
HOV Lane
50
160
500
120
370
1,130
ILEVs
Operating
During
Peak Hour
13
40
125
30
90
280
Using the methodology used for Houston above, the HOV lane
traffic for Washington DC is expected to increase from 1230
vehicles per hour to 1243 - 1355 vehicles per hour in the year
2000, and to 1260 - 1510 vehicles per hour in 2010. Using the lane
speed versus flow diagram, these flow increases correspond to
average vehicle speed reductions of 0 - 1 mile per hour in the year
2000, and 0-3 miles per hour in 2010. Once again, this effect is
essentially insignificant.
3. Seattle, Washington
The HOV lane in Seattle which has been adequately studied is
1-5 North. Other existing and planned HOV lane lanes are: 1-90,
1-5 South, 1-405, SR 167, SR 522, and SR 520. There are a total of
10 major highways entering and connecting the Seattle urban area.
The highways with and without HOV lanes are shown in Figure 4 in
the Appendix.[19] Using these figures, the initial range of
43
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fractions was adjusted by 7/10 to 1/70, 1/20, and 1/7. . The peak
hour volume for 1-5 was reported to be 500 vehicles per hour, which
is below the undercapacity point for freeway HOV lanes. Since the
data was collected, the HOV lane occupancy was modified from 3 to
2 minimum occupants per vehicle, and the lane volume has very
likely increased. However, this report will evaluate the data
available at this point in time. These figures and assumptions as
they apply to the Seattle HOV lanes are summarized below in Table
9.
Table 9 - Projected Number of ILEVs Operating in Seattle HOV Lanes
During Peak Hour
Area Being
Studied
Seattle
Washington
Year
2000
2010
Adjusted
Range of
Fractions
1/70
1/20
1/7
1/70
1/20
1/7
Number of
Operating
ILEVs
240
800
2,400
550
1,920
5,470
ILEVs
Operating
in Each
HOV Lane
34
110
340
80
270
780
ILEVs
Operating
During
Peak Hour
10
30
80
20
70
200
The effect of ILEVs using 1-5 and the other HOV lanes, based
on the higher occupancy threshold, can be evaluated by the same
methodology used earlier. The HOV lane traffic would be expected
to increase from 500 vehicles per hour to 510 - 580 vehicles per
hour in the year 2000, and to 520 - 700 vehicles per hour in 2010.
Using the speed versus flow diagram, these volume increases
correspond to no vehicle speed reduction in the year 2000 and a 0 -
1 mile per hour reduction in 2010. Obviously, even if the number
of current vehicles using HOV lanes doubled as a result of the
44
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recent change in the occupancy requirement, the effect of ILEVs
would still be insignificant.
4. Los Angeles, California
Los Angeles has three HOV lanes operating at this time: the
San Bernardino freeway (1-10)/ the Newport/Costa Mesa freeway
(Route 55) / and the Artesia freeway (Route 91) . Another 18 HOV
lanes are planned which would increase the total number of freeways
with HOV lanes to 21 out of a total of 24 freeways. [17,19] ] These
freeways are shown in Figure 5 in the Appendix.[19] Using the
numbers of highways with and without HOV lanes, the initial range
of fractions is adjusted by 21/24 to 1/60, 1/17, and 1/6. Because
of the severity and complexity of the traffic problem in Los
Angeles, HOV lanes are used extensively. The highest flow can be
in afternoon or morning or near equal for both; therefore, the
entire data set of morning and afternoon peak hour flow will be
used in lieu of just one data set for all lanes. [19] The averaging
of the HOV lane peak hour traffic flows is 1370 vehicles per hour,
and this data is summarized in Table 10 below.
45
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Table 10 - Average Peak Hour Flow for HOV Lanes in Los Angeles[19]
HOV Lane
San Bernardino
Route 55
1-405
Route 91
Average Peak
Hour Flow
Morning Peak
Hour Flow
1,445
1,298
1,294
-
Afternoon Peak
Hour Flow
1,267
1,578
1,082
1,629
Average Peak
Hour Flow
1,370
The result of the HOV lane calculations are summarized in Table 11
below.
Table 11 - Projected Number of ILEVs Operating in Los Angeles HOV
Lanes During Peak Hour
Area Being
Studied
Los Angeles
California
Year
2000
2010
Adjusted
Range of
Fractions
1/60
1/17
1/6
1/60
1/17
1/6
Number of
• Operating
ILEVs
1,660
5,900
16,600
3,780
13f 400
37,800
ILEVs
Operating
in Each
HOV Lane
80
280
790
180
640
1,800
ILEVs
Operating
During
Peak Hour
20
70
200
45
160
450
46
-------
The -analysis shows that HOV lane traffic is expected to
increase from the current average of 1370 vehicles per hour to 1390
- 1570 vehicles per hour in the year 2000, and to 1415 - 1820
vehicles per hour in 2010. Using the California-specific curve of
the speed versus diagram, these flow increases correspond to
average speed decreases of 0 - 2 miles per hour in the year 2000,
and 0-3 miles per hour in 2010.
This analysis of the Los Angeles area, based on the average of
HOV lane data available, indicates that for the high end estimate
(1/6) in the out years (2010) ILEVs may increase the HOV traffic
flow beyond the range which transportation engineers would consider
optimal. As already stated, engineers generally design HOV lanes
to maintain the volume of traffic in those lanes at or under 1500
vehicles per hour, and absolutely keep the flow in HOV lanes under
the maximum flow of 2000 vehicles per hour. At the high end of the
estimated range of operating ILEVs, traffic volume would increase
to values beyond the optimal range. This impact on HOV lane flow
would be offset, however, by the commensurate decrease in flow in
the general purpose lanes.
The 1500 vehicle per hour design optimum, however, does not
appear to be a hard and fast rule. According to the data available
on HOV lanes, there are 8 cases where the average peak-hour flow
exceeds the 1500 vehicle per hour value, and four of those are
greater than 1600 vehicles per hour.[19] If HOV lane traffic flow
above the recommended threshold was indeed a significant problem in
those cases, then steps to correct those situations would have
already been taken.
d. Conclusion
The city-specific HOV lane analysis presented in this report
shows that ILEV use of HOV lanes would not cause a significant
47
-------
vehicle volume increase for three of the four cases .analyzed.
Estimates of ILEV use in Houston, District of Columbia, and Seattle
(representing Baltimore and Atlanta) suggests that the probable
traffic flow increase in HOV lanes is well below the desired
optimal flow of 1500 vehicles per hour. The HOV traffic flow was
so low in Seattle's situation at the time the data was being
collected that the addition of ILEVs might actually improve any
public perception of underutilization. Further analysis shows that
such increases in flow for these three areas would decrease average
vehicle speed only two miles per hour or less. Data collected from
most other HOV lanes currently operating appear to be similar to
these three cases analyzed here. [19] The increase in HOV lane flow
would be offset by the commensurate decrease in flow in the general
purpose lanes.
The analysis of the HOV lanes in Los Angeles demonstrates that
there could be some instances where ILEV use of a highly-used HOV
lane could increase the flow to a level somewhat beyond the design
optimum for a HOV lane. Several important points need to be made
concerning this case. First, this analysis conservatively assumed
that the 18 lanes to be added would all receive use at the same
level as the 3 current lanes. And even using this assumption,
potential impacts were projected only at the high end estimate in
the out years.
Second, the modifications currently employed by transportation
authorities to relieve increasing HOV demand could also be
implemented for any similar case created in part by ILEVs. One
option for accommodating increased demand for HOV lanes is to
increase the minimum number of occupants that will qualify a
vehicle to use a particular lane. This method was employed by
Houston for the Katy freeway. The facility was opened as a four-
person-per-vehicle HOV facility and then was eventually reduced to
a two-person facility to encourage participation.[18] When the
participation increased to extreme levels, the minimum vehicle
48
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occupancy was increased to a three-person HOV lane during the peak
period. [19] The Seattle HOV lane analyzed was only recently
changed from a three-person facility to a two-person facility to
increase its usage and carrying capacity.
Another way to accommodate increased demand for HOV lanes is
to increase the number of lanes available. The Shirley freeway is
an example of a two lane HOV facility. This obviously allows for
twice the capacity as a single lane facility. Another possibility
is to convert an existing general purpose lane to another HOV lane.
Also, increased enforcement of HOV lane requirements could help to
reduce use by eliminating ineligible vehicles. This would have
salutary effects m lane use and in public perception regarding HOV
lanes.
If ILEV overuse of HOV lanes were to be widespread, there
could be other ways in which the use of ILEVs could be curtailed.
One method would be to require that ILEVs be designed to operate
even cleaner than currently proposed. For example, more stringent
inspection and maintenance testing requirements for exhaust
emissions could be required for ILEVs. This more stringent
requirement would guarantee cleaner vehicles, with the subsequent
result of increasing the owner's responsibility of operating these
vehicles. Added future requirements such as these, if found to
make good economic sense, could help to limit the ILEV program to
a truly advanced technology program.
Third, even though there are many potential remedies, EPA is
allowing any state to seek a waiver from EPA to allow them to
discontinue the HOV exemption for part or all of a particular HOV
lane where ILEVs are the direct cause of extreme HOV lane
congestion. EPA would carefully -consider waiver requests in which
requesting states demonstrate that other solutions are either too
costly or too unreasonable to pursue.
49
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V. Additional TCM Exemptions for ILEVs
During the course of this analysis, two reasons made it
apparent that the HOV lane exemption proposed for ILEVs may not
offer an incentive sufficient enough to encourage widespread
purchases of ILEVs. First, not all nonattainment areas covered by
the fleet program have such lanes or firm plans to implement them.
As summarized in Table 14 in the Appendix, of the 22 nonattainment
areas covered by the fleet program, only 11 have committed plans to
have HOV lanes by the end of this decade. [17,19] And of these 11
areas, only three have committed plans to implement HOV lanes for
more than half of the major highways in the urban area. More HOV
lanes are expected to be implemented, however, as states finalize
plans on how to meet the urban airshed improvement goals specified
in the Act. Second, during the rulemaking process, the fleet
industry expressed some concern that the HOV lane exemption does
not offer an equal incentive to each fleet. Apparently, fleets use
highways to varying degrees and the HOV lane exemption would tend
to favor those fleets which use highways more. Based on these two
reasons, many fleets may not be encouraged to purchase ILEVs.
To offer all fleets an equal playing field to participate in
the ILEV program, EPA intends to propose to exempt ILEVs from
additional TCMs. EPA will study the effectiveness of each
potential TCM exemption to determine which of the additional
exemptions would provide the broadest possible incentive while
minimizing any related negative repercussions. After such
evaluations, EPA would promulgate those select TCM exemptions in
rulemakings giving the public the opportunity to comment on the
proposed exemptions. EPA intends to consider all TCM exemptions
including those suggested by the fleet industry during the
rulemaking process which established the ILEV program.
As additional TCM exemptions are promulgated and phased in,
the number of ILEV purchases are expected to increase resulting in
50
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associated air quality benefits. EPA intends to estimate and
summarize these benefits during the rulemaking process.
51
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References
1. Memorandum: "Estimated Number of Fleet Vehicles Affected by
the Clean Fuel Fleet Program," from Sheri L. Dunatchik,
Standards Development Support Branch, EPA, to Docket A-91-25,
June 11, 1991.
2. "Analysis of the Economic and Environmental Effects of
Compressed Natural Gas as a Vehicle Fuel, Volume I, Passenger
Cars and Light Trucks," Special Report of the Office of Mobile
Sources, Office of Air and Radiation, Environmental Protection
Agency, April 1990.
3. "Analysis of the Economic and Environmental Effects of
Compressed Natural Gas as a Vehicle Fuel, Volume II, Heavy-
Duty Vehicles," Special Report of the Office of Mobile
Sources, Office of Air and Radiation, Environmental Protection
Agency, April 1990.
4. "Gaseous Fuel Vehicle Technology, State of the Art Report,"
Revised Draft, Prepared for U.S. Department of Energy by EA
Mueller Incorporated, December 1988.
5. "Notice of Public Availability of Modified Text and Supporting
Documents and Information, Public Hearing to Consider
Amendments Regarding the Calculation and Use of Reactivity
Adjustment Factors for Low-Emission Vehicles..." State of
California, Air Resources Board, April 21, 1992.
6. EPA Memorandum: "Speciation for SAI Runs/" Lindhjem, C.;
Carey. P.; Somers, J. to Charles Gray Jr.; April 14, 1992.
7. "An Assessment of Propane as an Alternative Transportation
Fuel in the United States," Main Report, R.F. Webb, June 1989.
52
-------
8. "Analysis of the Economic and Environmental Effects of
Methanol as an Automotive Fuel," Special Report of the Office
of Mobile Sources, Office of Air and Radiation, Environmental
Protection Agency, September 1989.
9. "Analysis of the Economic and Environmental Effects of Ethanol
as an Automotive Fuel," Special Report of the Office of Mobile
Sources, Office of Air and Radiation, Environmental Protection
Agency, April 1990.
10. Machiele, Paul A., Flammability and Toxicity Tradeoffs with
Methanol Fuels, Technical Paper Prepared for SAE International
and Lubricants Meeting and Exposition, November 2-5 1987.
11. EPA Memorandum: Gasoline, Diesel, and Methanol Refueling
Emissions - Data Collection; from F. Peter Hutchins to Charles
L. Gray Jr., August 24, 1989.
12. Fleet Marketing Handbook, Number Eight; Fleet Owner, New York,
NY, 1987.
.13. Code of Federal Regulations, Part 86, Section 86.094-2.
14. "High Occupancy Vehicle System Plans, As Air Pollution Control
Measures," California Air Resources Board, May 1991.
15. Fuhs, Charles A., "High-Occupancy Vehicle Facilities: A
Planning, Design, and Operation Manual," Parsons,
Brinckerhoff, Quade and Douglas, Inc., New York, NY, 1990.
16. Homburger, Wolfgang, ed., "Transportation and Traffic
Engineering Handbook," Institute of Transportation Engineers,
Prentice Hall, Inc., New Jersey, 1982.
53
-------
17. Funs,. Charles A., List of Existing and Planned High-Occupancy
Vehicle Lanes, Parsons, Brinckerhoff, Quade and Douglas, Inc.,
May 1992.
18. Lancaster, Ann, and Lomax, Timothy, "Conference Proceedings:
Second National Conference on High-Occupancy Vehicle Lanes and
Transitways," Texas Transportation Institute, College Station,
Texas, 1987.
19. Turnbull, Katherine F., and Russell Hanks, "A Description of
High-Occupancy Vehicle Facilities in North America," Final
Report DOT-T-91-05, Texas Transportation Institute, College
Station, July 1990.
54
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Appendix
55
-------
Table 12 - Emission Factors for Base Case Vehicles Operating in 1998 and Thereafter
(figures in parentheses includes effects of Stage II reductions)
Vehicle
Class
LDV
LDT1
LDT2
HDGV
Weighted
Average
Hot Soak and
Diurnal
Emissions
0.04
0.05
0.05
0.51
Running Loss
0.08
0.07
0.07
0.32
Resting Loss
0.04
0.04
0.04
0.04
Refueling
Emissions
0.17 (0.16)
0.22 (0.20)
0.23 (0.21)
0.36 (0.33)
Total Vapor
Emissions
0.33 (0.32)
0.38 (0.36)
0.39 (0.37)
1.23 (1.20)
0.50 (0.48)
56
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Table - 13
Operational Characteristics of
Freeway/Highway HOV Facilities in Areas
Covered by the Fleet Program and Seattle, Washington
Area/HOV Facility
Houston
Existinq:
1-10 (Katy)
1-45 (Gulf)
US-290
(Northwest)
1-45 (North)
Planned
Number of Lanes
Project
Length
(Miles)
Eligibility
Requirements
Facility Type
1 (Reversible)
1 (Reversible)
1 (Reversible)
1 (Reversible)
13
6.5
13.5
13.5
3 + Peak Hours
2 + Other Times
2 + HOVs
2 + HOVs
2 + HOVs
Barrier-Separated;
Reversible-Flow
Barrier-Separated;
Reversible-Flow
Barrier-Separated;
Reversible-Flow
Barrier-Separated;
Reversible-Flow
57
-------
US 59
(Southwest)
US-59 (Eastex)
1-45 (North)
1-45 (Gulf)
District of
Columbia
Exist inq:
1-86 (Northern
Virginia)
1-395 (Shirley)
1-95 (Interim)
1 (Reversible)
1 (Reversible)
Extension to
Reversible
Extension to
Reversible
2-3 each
direction
2 (Reversible)
1 each direction
13.8
20
6.2
9
9.6
11
3 + HOVs
3 + HOVs
3 + HOVs
Flow Lane and
Ramps
Flow Lane and
Ramps
Flow Lane
Flow Lane
Barrier-Separated;
Reversible-Flow
Barrier-Separated;
Reversible-Flow
Concurrent-Flow;
Buffer-
Separated/Non-
Separated
58
-------
Planned:
1-95
1-66
Dulles Toll Road
Seattle
Existing:
1-5 (North)
1-5 (North Express
Lanes)
1-90 (Interim)
Extension to
Reversible
Concurrent
Concurrent
19
7.5
10
Flow Lanes
Flow Lanes
Flow Lanes
1 each direction
1 (Reversible
w/mixed Flow)
1 (WB only)
5.9 SB
6.2 NB
6
5
2 + HOVs
2 + HOVs
2 + HOVs
Concurrent-Flow;
Buffer-
Separated/Non-
Separated
Concurrent -Flow;
Buffer-
Separated/Non-
Separated
Concurrent-Flow;
Buffer-
Separated/Non-
Separated
59
-------
1-5 (South)
1-405
SR-167
SR-509
SR-15 (Gig Harbor)
Various Entry
Ramps
Ferry terminal
docks
Planned:
1 each direction
1 each direction
1 (WB only)
1 (MB only)
1
1 .
1
6.7 MB
5.0 SB
8.5
1.1
0.8
0.7
0.1
0.1
3 + HOVs
2 + HOVs
2 + HOVs
2 + HOVs
3 + HOVs
Mostly 3 + HOVs
2 + HOVs
Concurrent-Flow;
Buffer-
Separated/Non-
Separated
Concurrent-Flow;
Buffer-
Separated/Non-
Separated
Concurrent-Flow;
Buf fer-
Separated/Non-
Separated
Queue Bypasses
Queue Bypasses
Queue Bypasses
Queue Bypasses
60
-------
1-405
1-5 (South)
1-90
SR-520
SR-522
SR-167
Los Angeles
Existing:
Los Angeles, CA,
1-10 (El Monte)
Los Angeles, CA,
Rte. 91
Extensions to
Concurrent
Extensions to
Concurrent
Reversible and
Concurrent
Concurrent
Extensions to
Concurrent
Extensions to
Concurrent
1 each direction
1 (EB only)
31
39
14
6
2.1
12.5
12
8
3 + HOVs
2 + HOVs
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Barrier-Separated :
Two-Way
Concur rent -Flow;
Buffer-
Separated/Non-
Separated
61
-------
Rte. 55
1-405
Over 250 Entry
Ramps
Planned:
1-210
Rte. 91
1-10 (San
Bernardino)
1-10 (Santa
Monica)
1-710 (Harbor)
1 each direction
1 each direction
1
11
24
0.1
2 + HOVs
2 + HOVs
2 + HOVs
Concurrent— Flow;
Buffer-
Separated/Non-
Separated
Concurrent-Flow;
Buffer-
Separated/Non-
Separated
Queue Bypasses
Concurrent
Westbound
Concurrent
Extension to
Concurrent
Concurrent
Trans itway and
Ramps
45
13
10
12
14.5
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
62
-------
1-105 (Century)
Rte. 118
1-405
1-605
1-5
Route 2
Route 14
Route 57
Route 60
Route 101
Route 134
Route 170
Route 1-5
Route 1-5
Routes 55/405,
57/91, 55/91
Route 57
Concurrent
Concurrent
Concurrent
Concurrent
Concurrent
Concurrent
Concurrent
Concurrent
Concurrent
Concurrent
Concurrent
Concurrent
Concurrent
Barrier
Concurrent
18
44
25
20
34
7.5
10
11
32
30
13
5.5
46
3.3
6
10
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Flow Lanes
Separated Lanes
HOV Interchanges
Flow Lanes
63
-------
Route 91
Route 91
Route 215
Baltimore
Existinq :
NONE
Planned:
1-270
Boston
Existinq:
NONE
Planned:
1-90
1-93 (South)
1-93 (North)
Concurrent
Concurrent
Concurrent
19
10
14
Flow Lanes
Flow Lanes
Flow Lanes
Concurrent
Not
Available
Flow Lanes
Concurrent
Barrier
Concurrent
1
1.5
0.5
Flow Lanes
Separated Lanes
Flow Lanes
64
-------
Denver
Existing:
U.S. 35 (Boulder
Turnpike)
1 (EB Only)
4.1
Buses Only
Queue Bypasses
Planned;
1-25
Reversible
12
Flow Lanes and
Ramps
Greater
Connecticut
Existing:
Hartford, CT, 1-84
1 each direction
10
3 + HOVs
Concurrent-Flow;
Buffer-
Separated/Non-
Separated
65
-------
Hartford, CT, 1-91
Planned:
1-91
New York
Exist inq:
Rte. 495 (Lincoln
Tunnel)
Long Island Expy.
Gowanus Expy .
Ft. Lee, MJ (New
York City) 1-95
1 each direction
10
3 + HOVs
Concurrent-Flow;
Buffer-
Separated/Non-
Separated
Concurrent
9
Flow Lanes
1
1
1
1 (EB Only)
2.5
4
2
1
Buses Only
Buses, vanpools,
taxis
Buses/ vanpools,
taxis
3 4- HOVs
Contraflow
Contraflow
Contraflow
Queue Bypasses
66
-------
Rte. 495 (Lincoln
Tunnel)
Planned:
1-495 (Long Island
Expy . )
Sacramento
Exist ina:
NONE
Planned:
Route 99
San Dieqo
Exist ina:
San Diego, CA
1
0.3
Buses Only
Queue Bypasses
Concurrent
23
Flow Lanes
••
Concurrent
2 (Reversible)
11
8
2 + HOVs
Flow Lanes
Barrier-Separated;
Reversible-Flow
67
-------
Various Entry
Ramps
Planned:
1-5
1-15
1
0.1
2 + HOVs
Queue Bypasses
Concurrent
Concurrent
21
12
Flow Lanes
Flow Lanes
Fleet program covered areas currently without HOV facilities or plans for such facilities
Atlanta/ GA
Beaumont - Port Arthur, TX
El Paso, TX
Philadelphia, PA
San Joaquin Valley, CA
Springfield, MA
Baton Rouge, LA
Chicago, IL
Milwaukee, HI
Providence, RI
Southeast Desert, CA
68
-------
I
o
UJ
UJ
Q.
CO
Figure 1
SPEED-FLOW RELATIONSHIP
From 1985 Highway Capacity Manual (70 mph design speed, 8-lane curve)
With Typical California Operation Shown
Lower portion of curve j
represents unstable flow
More typical of
California operation
20
10
0.4 0.5 0.6 0.7
VOLUME / CAPACITY RATIO
-------
Figure 2
Houston Transitways
Eaatex Freeway
Northweat Freeway
North
Tranaitway
Northwest
Transitway
Freeways with
HOV Unea
Southwest Freeway
-------
Figure 3
Washington D.C./Northern Virginia
HOV Lanes
Shirley Hwjr
(1-305)
HOV Lane*
1-99
HOV Uoee
Freeway
Freeway with
HOV Lane
--•— WMhinfton O.C.
Boundary
Rlrer
-------
Figure 4
Seattle HOV Lanes
1-6 BO*
Coast Un«
-------
Figure 5
Los Angeles/Orange County
HOV Lanes
San Bernadino
Freeway (I-10)
Burway
Rt 91
Commuter Lane
Rt 55
Commuter Lane
freeway with
HOV Lane
Coast Line
1-405
Commuter Lane
------- |