Clean Air
Through Transportation
Challenges in Meeting
National Air Quality Standards
TD
883. 1
C577
1993
A Joint Report from the United States
Department of Transportation and
Environmental Protection Agency
August 1993
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Contacts
For questions regarding the development or content of this report or for additional
copies, contact:
at the Department of Transportation:
• Federal Highway Administration: Noise and Air Quality Branch, (202) 366-2080
• Office of the Secretary: Environmental Division, (202) 366-4366
• Federal Transit Administration: Planning, Analysis and Support Division, (202) 366-4317
at the Environmental Protection Agency:
• Office of Mobile Sources: Emission Control Strategies Branch, (313) 668-4259
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r
,/
Clean Air ^ :-
Through Transportation:
Challenges in Meeting National Air Quality Standards
US EPA Region 8
Technical Library 80C-L
999 18th Street, Suite 300
Denver. 202-2466
A Joint Report from the United States Department of Transportation
and Environmental Protection Agency
Pursuant to
Section 108(f)(3) of the Clean Air Act
August 1993
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The Honorable Albert Gore, Jr.
President of the Senate
Washington, D.C. 20510
Dear Mr. President:
Enclosed is the Department of Transportation and Environmental
Protection Agency joint report titled, "Clean Air Through
Transportation: Challenges in Meeting National Air Quality
Standards." The report, required by Section 108(f)(3) of the
Clean Air Act, as amended in 1990, addresses the issues of motor
vehicles and air quality. The report discusses the challenges
faced in attempting to improve air quality through transportation
programs. It also provides a status report on meeting the
transportation provisions of the Clean Air Act Amendments of 1990
and the air quality provisions of the Intermodal Surface
Transportation Efficiency Act.
A copy of this report has also been sent to the Speaker of the
House of Representatives.
Sincerely,
S*~\
L3^2
Carol M. "/Browner Federico Pena
Administrator Secretary
Environmental Protection Agency Department of Transportation
Enclosure
-------
The Honorable Thomas S. Foley
Speaker of the House of
Representatives
Washington, D.C. 20515
Dear Mr. Speaker:
Enclosed is the Department of Transportation and Environmental
Protection Agency joint report titled, "Clean Air Through
Transportation: Challenges in Meeting National Air Quality
Standards." The report, required by Section 108(f)(3) of the
Clean Air Act, as amended in 1990, addresses the issues of motor
vehicles and air quality. This report discusses the challenges
faced in attempting to improve air quality through transportation
programs. It also provides a status report on meeting the
transportation provisions of the Clean Air Act Amendments of 1990
and the air quality provisions of the Intermodal Surface
Transportation Efficiency Act.
A copy of this report has also been sent to the President of the
Senate.
Sincerely,
Carol M. Browner Federico Pena
Administrator Secretary
Environmental Protection Agency Department of Transportation
Enclosure
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Table of Contents
Page
L INTRODUCTION 1
A. Purpose and Scope of Report -
The Provisions of Section 108(f)(3) 1
B. Summary 1
C. Background - CAA and ISTEA 4
H. CHALLENGES IN TRANSPORTATION AND AIR QUALITY PROGRAMS 7
A. MPOs Face Significant Challenges
in Meeting New CAA Requirements 7
B. Reducing Vehicle Emissions Through
TCMs is Difficult 9
C. By Themselves, Capital-Intensive Investments May
Not Be the Best Way to Address Air Quality Concerns 11
D. Technological Improvements Have Reduced
Vehicle Emissions Despite Increasing VMT 17
E. Better Data and Models Are Needed 19
F. Beyond Transportation - Land Use, Public Acceptance,
and Fiscal Constraints Figure Prominently 22
m. STATUS OF PROGRAMS 25
A. Full Funding of ISTEA Would Help Meet Mobility and Air Quality Goals 25
B. Limited CAA Funds Exist for Air Quality Operations and Management 27
C. Regulations and Guidance Implementing CAA and ISTEA
Have Been Issued 27
D. SIP Development, Revisions, and EPA Approvals Are Proceeding 31
E. Transportation Plans, TIPs, and Conformity
Determinations Are Also Proceeding 33
IV. CONCLUSIONS 37
APPENDICES 41
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I. INTRODUCTION
A. Purpose and Scope of Report -The
Provisions of Section 108(f)(3)
Section 108(f)(3) of the Clean Air Act (CAA) as
amended in 1990 requires the Secretary of Trans-
portation (DOT) and the Administrator of the Envi-
ronmental Protection Agency (EPA) to submit to
Congress by January 1,1993, and every 3 years
thereafter, a report that: "reviews and analyzes ex-
isting State and local air quality-related transporta-
tion programs...." The report is also required to
evaluate the adequacy of funding and make recom-
mendations regarding meeting the Act's require-
ments. (See Appendix A for the complete text of
Section 108(f)(3)).
This report is the first in that series. It provides
the Congress with: an identification of the chal-
lenges faced in attempting to improve air quality
through transportation projects and programs
(Chapter II), the status of implementing the new
transportation provisions of CAA and air quality
provisions of the Intermodal Surface Transporta-
tion Efficiency Act (ISTEA) (Chapter III), and con-
clusions (Chapter IV). This report generally covers
the 2-year timeframe beginning with the promulga-
tion of the 1990 CAA amendments, November 1990,
through the end of fiscal year (FY) 1992.
In many ways, it is too early to address whether the
legislated funding and approach will be successful
in meeting the goals of CAA. Federal guidance and
regulations continue to be developed, and most
States and local areas around the country are just
beginning to develop and implement transportation
plans, projects, and programs to meet their CAA re-
quirements. This report describes the challenges of
meeting the requirements; future reports will be
more comprehensive and address the relative suc-
cess of meeting CAA goals through transportation
programs.
B. Summary
Many areas that currently fail to meet the national
ambient air quality standards, as well as the trans-
portation and air quality agencies assisting them,
face formidable challenges if they are to meet the
CAA requirements. When they were enacted on
November 15,1990, the 1990 CAA amendments set
strict deadlines for these "nonattainment" areas to
meet the standards depending on the severity of
their air pollution problems for specific pollutants.
The most important pollutants for this report are
ozone, carbon monoxide (CO), and particulate mat-
ter of under 10 microns in size (PM-10) where mo-
bile sources have a significant impact. The areas
with the least serious problems must reach attain-
ment this year (1993); the most severe area, the
counties around and including Los Angeles, have
until 2010.
VOC Emissions Have Decreased 39%
and NOx Emissions Have Decreased 25%
(from Mobile Sources), 1982-1991
-
-
;:
Source
82 83 84 85 86 87 88 89 90 91
National Air Quality and Emissions Trends • 1991, EPA
Figure 1
Nonattainment areas must reduce emissions that
either directly cause or combine to form pollution
from three primary sources: stationary, "area"
(such as dry cleaning establishments), or mobile.
A great deal of attention has been focused on mo-
bile sources generally, and the role that trans-
portation facilities (roads, transit, bike-, and
pathways) play specifically, in part, because of
the emphasis CAA places on transportation mea-
sures as a means to reduce emissions. Mobile
source emissions can be significant; for urban
areas they are variously estimated at 40 to 50
percent for hydrocarbons (HC), which combine
with oxides of nitrogen (NOx) to form ozone, 50
percent for NOx, and 80 to 90 percent for CO, and
they can be higher in some areas. Reliable esti-
mates for PM-10 do not yet exist, but total PM-10
emissions are increasing.
As the effort to meet CAA requirements for trans-
portation-related pollution was undertaken across
the country, distinct challenges became evident,
and to place these challenges in context, several
points bear mention.
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Technological improvements have
reduced emissions from motor
vehicles despite increases in vehicle
travel.
Air quality, as measured in terms of CO, hydrocar-
bons and NOx emissions, has substantially im-
proved over the last 10 years. Between 1982 and
1991, total emissions from all sources have de-
creased substantially (32 percent for CO, 13 percent
for hydrocarbons, and 8 percent for NOx), almost
entirely from motor vehicles. But the improve-
ments have not been uniform from all sources. Sta-
tionary source emissions, for example, have actual-
ly increased for certain emissions over the last 10
years. By contrast, motor vehicle emissions gener-
ally declined between 1982 and 1991 due to im-
proved automobile technology, despite continued in-
creases in vehicle travel. According to EPA's report
titled, "National Air Quality and Emissions Trends
-1991," CO from mobile sources (highway, transit,
and off-road engines) has decreased by 40 percent;
NOx decreased by 25 percent; and volatile organic
hydrocarbons decreased by 39 percent (see Figures
1 and 2). Highway-related emissions showed even
greater reductions.
CO Emissions Have Decreased 40%
(from Mobile Sources), 1982-1991
'en'
c
0
=1 80
S 60
I 40
Metric Tons
ro
o
~^~^^" r~— ~ ~ ^
r-^
!2 83 84 85 86 87 88 89 90 91
Source: National Air Quality and Emissions Trends - 1 991 , EPA
Figure 2
Automobile travel has increased substantially. For
example, between 1983 and 1990, vehicle miles
traveled (VMT) increased by 41 percent, continuing
a century-long trend. A variety of trends con-
tributed to this growth: increases in the number of
workers, increases in vehicle ownership, longer av-
erage trip lengths, growth in suburb to suburb trav-
el, and continued decreases in the cost of driving.
The real cost of gasoline, for example, is now lower
than it was in 1950. Efforts to reduce travel in sin-
gle occupant vehicles (SOV) and VMT face tremen-
dous challenges in light of these trends.
Reductions from all sources will need to be consid-
ered in developing a strategy to meet the national
ambient air quality standards. In addition to sta-
tionary and motor vehicle sources, area sources can
contribute a third or more to emissions in nonat-
tainment areas. A specific type of area emissions,
nonroad engines can contribute between 7 and 17
percent of an area's hydrocarbon, NOx, and CO
emissions, and in the struggle to reduce all emis-
sions, new standards may be established for this in-
creasingly important source. Nonroad emissions
come from a variety of sources ranging from agri-
culture and construction machinery to lawn mowers
and garden equipment, and to recreational vehicles,
including pleasure boats.
While further reductions will be necessary from all
sources, the costs and benefits of specific air quality
strategies must be carefully weighed to ensure that
the most cost-effective strategies are selected from
among all sources of emissions.
Federal funding available for
transportation control measures
(TCMs) has increased dramatically—
but most TCMs produce small
emission reductions.
The experience to date indicates that efforts to re-
duce emissions through traditional TCMs have not
generated significant air quality benefits. (See Ap-
pendix E for a description of traditional TCMs as
defined by Section 108(f)(l) of CAA). Previously the
lack of funds at the local level to develop and imple-
ment competitive alternatives to automobile travel
was seen as a major impediment to reducing mobile
source emissions. This was addressed by ISTEA.
Authorized at $155 billion, ISTEA represents a sig-
nificant shift in the way transportation funds are
used nationwide. It expands planning and research
funds, establishes a new program, the Congestion
Mitigation and Air Quality Improvement (CMAQ)
Program, to improve air quality, and enhances the
flexibility that State and local governments have in
using other Federal funds. However, even with this
funding increase, traditional measures are expected
to have limited benefits.
Low densities and high travel demand in suburban
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areas, low automobile user costs, and an increasing
number of trips generated by an eclectic American
lifestyle lead to relatively low participation rates in
alternative forms of travel to the automobile. While
transit is a crucial component of the Washington,
B.C., transportation network, for example, it car-
ries only 13 percent of regional commuter trips.
And as a percentage of total regional travel, tran-
sit's share is even lower. Making matters worse,
the percentage of travelers using higher occupancy
forms of travel (transit, ride sharing) has declined
nationwide, and single-occupant automobile travel
has increased since 1983. Across the country, the
share of commuting trips made by driving alone in-
creased from 64.4 percent of all trips in 1980 to 73.3
percent in 1990. Average vehicle occupancy de-
creased by 16 percent since 1977.
Recent modeling by MPOs shows that combinations
of congestion reduction measures, including high-
way capacity expansion, and improvements to
ridesharing programs, transit, and other TCMs,
produce only 1- to 2-percent reductions in emissions
without concomitant travel reduction efforts such
as increased travel costs or restrictions and policies
to increase land use density. Despite an $11 billion
package of transportation initiatives in the San
Francisco area, for example, emissions are expected
to decline by less than 1 percent compared to sim-
ply maintaining current facilities and services.
More effective measures exist, including pricing
and other incentives to stop driving alone, but these
are politically unpopular and are uncharted territo-
ry in most urban areas. Other control measures
that target emissions from every trip, such as in-
spection and maintenance programs, are likely to
be more productive ways of making significant
emission reductions. Measures that target the ve-
hicles having disproportionately high emissions
may also be effective.
The modeling tools and technical
information available to States and
metropolitan planning
organizations (MPOs) are imperfect.
Within this overall framework, other challenges
also face the transportation and air quality commu-
nity that arise from the dramatic changes brought
about by CAA and ISTEA. One challenge is caused
by the complexity of analyzing the effects of atmos-
pheric changes and geography on air quality and
predicting the impacts of changes in human behav-
ior on transportation and emission rates.
Both the transportation and air quality communi-
ties have collected data and developed sophisticated
tools for analyzing such effects, generally aided by
computer models. But models to determine trans-
portation impacts on emissions have their short-
comings. Transportation models were not designed
to develop emissions estimates, and both trans-
portation and emissions models rely on approxima-
tions that only yield accurate predictions within
certain parameters. Work is continuing in this
area, but the lack of adequate data and models
poses a significant analytical challenge.
Related to the need for better tools is the need for
better technical information. States and local areas
must meet several requirements that necessitate
high quality transportation/air quality information.
They report that better data are needed on trends
in travel demand, emission levels from cars and
trucks in their areas, the effectiveness of technolog-
ical improvements to reduce tailpipe and other
emissions, and relative contributions from station-
ary, area, and mobile source inventories. Most im-
portantly, States and local areas need better infor-
mation on what they can expect to achieve through
TCMs. While Federal agencies have attempted to
provide as much data as possible, better informa-
tion can be developed only as better tools and more
comprehensive data become available.
There has been a great need for
guidance and direction, and Federal
agencies have struggled to provide as
much information as is available.
Another need that has been often expressed by
State and local officials is for more, and more time-
ly, guidance from Federal agencies. Enactment of
two major pieces of legislation, CAA and ISTEA, in
a relatively short period of time has challenged
EPA's and DOT's abilities to develop timely trans-
portation/air quality guidance, but has also fostered
a close working relationship between the agencies.
The need to realistically address the requirements of
these Acts has caused a convergence of purpose and
precipitated a greater understanding between them.
DOT and EPA have provided detailed guidance in
many areas. Substantial effort has been made to
package and disseminate relevant information,
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jointly sponsor national conferences and regional
workshops, develop coordination mechanisms
through the National Association of Regional Coun-
cils (NARC), and respond to individual State and
local requests for information through site visits
and telephone communications. Guidance and reg-
ulations have been published on VMT forecasting,
transportation and air quality planning, State im-
plementation plan development, motor vehicle in-
spection and maintenance, the CMAQ Program,
TCMs, and conformity.
The conformity requirement bears special mention
because it significantly changes the relationship be-
tween transportation and air quality agencies, and
failure to meet it can bring transportation pro-
grams and projects, both highway and transit, to a
halt. Under CAA, transportation plans and pro-
grams using Federal funds must "conform" to State
plans to improve air quality, called State Imple-
mentation Plans, or SIPs. (See Section I.C.) If they
fail to meet the conformity test, projects contained
therein cannot advance, with some exceptions.
EPA and DOT jointly published interim guidance
on June 7,1991, and EPA published a Notice of
Proposed Rulemaking (NPRM) with DOT concur-
rence on January 11,1993. The final rule is expect-
ed in the fall of 1993.
CAA and ISTEA have substantially
increased the coordination
requirements for transportation and
air quality decisionmaking,
entailing greater complexity and
requiring more staff time.
ISTEA and CAA not only changed the goals of
transportation planning and implementation, they
also altered State and local responsibilities, and
broadened the number of public agencies and pri-
vate interest groups involved in the process. Local
areas have been greatly empowered under ISTEA,
and decisions over transportation priorities are now
the joint responsibility of local MPOs and states.
With expanded responsibilities, many nonattain-
ment areas discovered the need for more staff and
better training. Almost 69 percent of recently sur-
veyed MPOs in nonattainment areas cited the need
for more staff to meet their obligations. Many had
recently added staff. Approximately the same num-
ber said their personnel also required training in
critical areas to develop effective transportation
programs to improve air quality. The most impor-
tant areas where training is needed were cited as:
enhancement of technical skills, such as predicting
the impacts of transportation programs (through
computer modeling, etc.), and enhancement of poli-
cy development skills to manage interagency nego-
tiations and consensus-building. Similarly, ade-
quate staff and resources are concerns with other
Federal, State, and local agencies involved in trans-
portation and air quality.
With changing relationships and new partners in
plan development, the need for productive coordina-
tion has been greatly multiplied. State transporta-
tion and air quality agencies must work together
with MPOs to meet their air quality needs. Air
quality agencies must successfully collaborate in
the development of transportation priorities, just as
transportation agencies must gain entree in the SIP
development process. The traditional relationships
that have separated these agencies must be recon-
structed toward mutual understanding and cooper-
ation. This pertains not only to State and local of-
fices, but to Federal agencies as well.
Similarly, as more community, citizen action, and
private interest groups have become involved in
transportation plan development and the setting of
environmental priorities, they have brought new
points of view and new agendas, further changing
the decisionmaking process. While such changes
have greatly diversified the approach and added
new perspective and information to the setting of
transportation priorities, they have also increased
the potential for confrontation. Legal actions have
already been threatened or initiated against States
as well as DOT. Managing the coordination process
poses a considerable challenge and must be a high
priority for agencies at all levels of government.
Finally, major budget shortfalls are common across
the Nation. Many States, localities, and metropoli-
tan areas must focus their attention and resources
on many other real and pressing priorities, includ-
ing crime, education, health care, homelessness, un-
employment, and poverty.
| C. Background - CAA and ISTEA
i
CAA and ISTEA provide complementary approach-
es to decrease transportation-related emissions.
CAA sets air quality requirements and milestones,
mandates further improvements to vehicles and
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fuels, requires greater integration of transportation
and air quality planning procedures, and establish-
es penalties for failing to meet its requirements.
The ISTEA provides funding and the flexibility to
use it to improve air quality through development
of a balanced transportation program.
CAA classifies nonattainment areas according to
the severity of their air quality problems. For
ozone, these classifications in order of increasing
severity are: marginal, moderate, serious, severe 1,
severe 2, and extreme. For CO, they are: low mod-
erate (<12.7 ppm), high moderate (>12.7 ppm), and
serious. For PM-10, they are: moderate and seri-
ous. As the classification increases, so do the num-
ber of CAA-required actions the areas must take
(see Appendices B, C, and D) and the time intervals
they have to meet the national ambient air quality
standards (NAAQS). Depending on their classifica-
tions, some nonattainment areas will have to meet
mobile source requirements relating to:
• inspection and maintenance programs,
• vapor recovery systems,
• clean fuel fleet programs,
• VMT limitations,
• employer trip reduction programs,
• reformulated gasoline, or
• oxygenated fuels.
All areas must determine and document the magni-
tude of the problem, set emission reduction targets,
and specify the means by which these targets will
be reached, including TCMs. TCMs are not general-
ly mandated under CAA, but Employee Commute
Option Programs—a TCM listed in Section 108(f)(l),
are required in areas classified as severe and above
for ozone and serious for CO. These elements must
be included in the SIP. In addition, these areas
must implement TCMs to offset any growth in emis-
sion due to growth in VMT or vehicle trips.
Under CAA, the SIP is the means by which a State
monitors, controls, maintains, and enforces compli-
ance with the NAAQS. The SIP is intended to set
realistic numerical goals for each emissions sector
and enforceable measures to attain them, with
input from those responsible for development of
emission reduction plans, as well as implementa-
tion of those plans.
Other plans and programs are also affected by
CAA, specifically the metropolitan transportation
plan and transportation improvement program
(TIP). As noted above, CAA requires that the
plans, programs, and projects contained in these
transportation documents "conform" to the purpose
of the SIP. The conformity requirement significant-
ly changes the way transportation plans are devel-
oped in nonattainment areas. In essence, trans-
portation plans and programs must ensure that the
transportation sector contributes its planned share
of emission reductions. If they fail to do so, either
they must be modified or the SIP must be modified
to offset the disparity in projected emissions, or
they cannot advance. What this means is that if
transportation plans and programs fail to meet the
conformity requirements, they must be amended
before they can be implemented. With some excep-
tions, this provision can hold up virtually the entire
Federal highway and transit program until confor-
mity is demonstrated.
Generally, if a nonattainment area fails to meet its
deadline for attaining the standards, it is automati-
cally bumped up into the next worse category. For
example, all nonattainment areas designated as
marginal for ozone must either meet CAA require-
ments for attainment by November of this year or
they will be redesignated as moderate areas.
If a nonattainment area fails to meet the SIP sub-
mittal requirements, EPA must apply sanctions to
DOT's highway program or sanctions that require a
2:1 offset for new major stationary source emis-
sions. Highway sanctions entail the withholding of
Federal highway funds, except those targeted for
exempted safety or environmentally beneficial pro-
jects, and can be applied for SIP deficiencies related
not only to mobile sources but stationary sources as
well. Under certain conditions, EPA may extend
the boundaries within which highway sanctions are
applied to include the entire State.
Two-to-one emissions offsets are applied to new sta-
tionary sources where each ton of emissions gener-
ated must be offset by a two-ton reduction through
additional control measures on existing stationary
sources. EPA must apply highway or offset sanc-
tions after 18 months to areas for failure to submit
a SIP or a portion of a SIP, disapproval of a SIP by
EPA, failure to implement the provisions of an ap-
proved SIP, or failure to meet any other provisions
required by CAA. Six months after the imposition
of highway or offset sanctions, EPA must apply
both if the requirements have not been met. EPA
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interprets the CAA to give it authority to apply
sanctions earlier on a discretionary basis in order to
ensure that CAA requirements are met.
As CAA prescribes the goals and procedures for
achieving the standards in nonattainment areas,
ISTEA provides funding for reducing transporta-
tion-related emissions. Previously, the lack of
funds at the local level to develop and implement
competitive alternatives to automobile travel and
the dedication of most Federal fuel tax revenue to
highways were seen as major impediments to re-
ducing motor vehicle emissions. This was ad-
dressed by ISTEA through establishment of the
CMAQ Program and by enhancing the flexibility
that State and local governments have in using
Federal funds.
Rather than narrowly categorized programs for
highways, mass transit, and other forms of trans-
portation, recipients can now use broadly flexible
funds for a variety of transportation purposes. The
largest program under ISTEA is the Surface Trans-
portation Program (STP), authorized at $23.9 bil-
lion over a 6-year period. STP funds can be used at
the discretion of State and local officials for many
different types of transportation programs, includ-
ing highways, transit, TCMs, and planning and re-
search. Further, ISTEA allows for transfers from
national highway system, bridge, and interstate
maintenance programs to STP, greatly increasing
the flexibility with which many Federal program
funds are used.
Authorized at $6 billion over 6 years, the CMAQ
Program directly funds transportation projects to
improve air quality and provides nonattainment
areas with necessary resources to reduce congestion
and provide or improve alternative forms of travel,
including transit, ridesharing, bicycling, and even
walking. ISTEA precludes CMAQ funding for cer-
tain TCMs listed in CAA, specifically programs to
reduce extreme cold start emissions and vehicle
scrappage programs, despite emission reduction po-
tential of such measures at least in the short run.
About $340 million of an authorized $809 million
was obligated in FY1992, and well over half of this
(58 percent) was used for transit. While the FY
1992 obligation rate for this program was low by
DOT standards at 42 percent, it is appropriate that
nonattainment areas carefully consider how best to
spend these funds. Other typical projects under the
Program included development of highway and
road projects such as high-occupancy vehicle lanes,
traffic signalization and incident management, and
establishment of a statewide coordinator for bicycle
and pedestrian transportation, ridesharing pro-
grams, and park-and-ride lots.
CMAQ Obligations by Type of Project
(FY1992)
Ped./Bike 0.03%
Transit 57.76%
Highway/Road 40.40%
Other 1.80%
Figure 3
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II. CHALLENGES IN TRANSPORTATION
AND
AIR QUALITY PROGRAMS
A. MPOs Face Significant Challenges in
Meeting New CAA Requirements
J
ISTEA significantly increased the responsibility of
MPOs in the development of transportation and air
quality planning and programming. Their tradi-
tional transportation planning responsibilities have
been increased to include expanded roles in pro-
gram and project selection. Because of these added
responsibilities, some have questioned the current
ability of the MPOs to evaluate and implement
transportation control measures and effectively ad-
vance these plans as part of the overall political
process.
In an effort to identify MPO concerns, NARC, the
American Association of State Highway and Trans-
portation Officials (AASHTO), and the University of
North Carolina-Charlotte (UNCC) conducted sur-
veys of MPOs, and the Federal Highway Adminis-
tration (FHWA) surveyed its field offices. These
surveys were aimed at determining what issues are
of most concern to MPOs, and to identify ways in
which the Federal Government can assist MPOs in
implementing the air quality requirements embod-
ied in ISTEA and CAA. Results of the surveys were
incorporated into a DOT effort, in coordination with
EPA, to develop an action plan that could be used to
assist MPOs in carrying out their new transporta-
tion and air quality planning responsibilities. What
follows is a general compilation of specific issues
that were identified as being areas of concern that
are crucial to the MPOs' effective implementation of
the transportation and air quality requirements
embodied in the two acts.
1. Staffing and Training
Given the fundamental changes in the nature and
responsibilities facing MPOs and States involved in
the planning process, it is appropriate to consider
whether their professional staffing and training are
sufficient to carry out their expanded roles and re-
sponsibilities. Based on its 1992 survey, UNCC es-
timated that 18 percent of MPO staff in nonattain-
ment areas were working on CAA issues, and that
as many as 50 percent of staff in severe nonattain-
ment areas were working on CAA issues. According
to the NARC survey, nearly 70 percent of MPOs
thought they needed greater staffing to carry out
new responsibilities under both the ISTEA and
CAA. It should be emphasized that staffing re-
sources in these areas generally have been static or
declining over the past several years due to a level-
ing off of Federal funds for transportation planning.
Since MPO staff commitments are directed by an-
nual planning work programs set in advance, new
priorities in staffing and organization will take time
to implement.
As might be expected, many MPOs think their
staffs need substantial training to carry out the
transportation planning and air quality mandates
established in the ISTEA and CAA. Again, since
most MPOs had few or no ongoing air quality plan-
ning responsibilities, developing strong technical
and policy competence will take time. Nearly 80
percent of MPOs responding to AASHTO and
NARC surveys said they could draw on staff and
technical support from various State agencies in the
short run.
In the near term, MPOs may be forced to shift
staffing priorities towards their new ISTEA and
CAA responsibilities at the expenses of some tradi-
tional functions. In addition, they are using avail-
able State technical support in lieu of in-house
training for staff and full integration of air quality
software into their transportation modeling capabil-
ities. Although there is no requirement that MPOs
perform all such tasks themselves, most appear to
prefer having the required technical capabilities
more immediately available from in-house expertise.
2. Data, Models, and Technical
Information
The results of the FHWA field scan, as well as the
NARC, AASHTO, and UNCC surveys, document a
widely perceived need for better information and
analytical tools for transportation controls mea-
sures. TCMs will be under consideration in most
nonattainment areas. Nevertheless, the develop-
ment of political or technical consensus and support
for certain TCMs will be difficult because of their
effects on travel alternatives and their cost, travel
behavior, and the perceptions that various parties
bring with them to the deliberative process. TCM
selection and implementation will require a clear
understanding of the air quality benefits that can
-------
be achieved, as well as an examination of other con-
sequences. Hence, the need for better information
and analytical tools for TCMs.
In the area of transportation planning models,
there is an urgent need to raise the state-of-the-
practice in many metropolitan areas, and a need to
create a new generation of transportation models
which can better reflect the dynamics of travel deci-
sion processes. There also is a wide disparity
among MPOs relating to the timeliness of their
travel demand data bases. There is a strong need
to expand data collection to improve accuracy in
VMT tracking, real-time output from the Highway
Performance Monitoring System (HPMS), and esti-
mates of mode split, vehicle occupancy, volume-to-
capacity ratios, and commercial vehicle activity.
With regard to air quality models, there seems to be
a desire among MPOs to improve understanding of
EPA's MOBILES emission model and EPA's region-
al air quality model, since their outputs are so criti-
cal to transportation system decision tradeoffs.
3. Institutional Coordination - State and
Local Agencies
The MPO planning responsibilities within metro-
politan regions are focused on development of
TCMs, and making conformity determinations on
TIPs and Transportation Plans. State DOTs and
MPOs need to be involved in the development of
SIPs and in monitoring local attainment of national
standards. However, there is little consistency
among the States in the coordination between
transportation agencies (State DOTs, MPOs, tran-
sit agencies, or local governments) and the SlP-de-
veloping agency. Of particular concern is the lack
of MPO or State DOT involvement in emission in-
ventory and budget development in many States.
Some MPOs even report that they are not involved
in project and program development.
It is not entirely clear to what extent MPOs have
been excluded from a process that is well underway
and to what extent the process itself is not advanc-
ing as well as it should be. Since MPO and DOT
commitments to TCMs in approved SIPs will even-
tually be required, and since consistency between
the transportation plan and the SIP is necessary to
meet CAA's requirements for enforceability and ad-
equate measures for implementation (at the time of
SIP approval), it is important that DOTs and
MPOs be involved.
Another area of varied MPO responsibility is that of
growth management and land use control. Tradi-
tionally, these functions have been the responsibili-
ty of local governments. And while there is a grow-
ing belief that land use and growth management
can be important in the long run to achieving trans-
portation system efficiency, mobility, and reducing
mobile source emissions, there is also a growing be-
lief that local governments acting individually do
not achieve optimal regional results. Federal agen-
cies must do everything possible to support and dis-
seminate research and information in this area to
appropriate State, regional, and local organizations.
4. Funding
The NARC survey found that nearly half of the
MPOs thought they needed greater planning and
research funds to fully implement their new air
quality responsibilities. Nearly one-third respond-
ed that they have a backlog of transportation and
air quality planning activities delayed due to insuf-
ficient funding. Traffic monitoring and data collec-
tion were cited as areas specifically needing signifi-
cantly increased resources. In the case of TCM im-
plementation, almost half of the MPOs believed in-
creased funding would be needed to fully implement
all TCMs planned.
Even though ISTEA substantially increased trans-
portation funding levels and eliminated many of the
restrictions on the use of Federal assistance, there
remain many unmet transportation system needs.
For instance, although STP and NHS funds may be
used for planning activities, there are many un-
funded construction and operations projects com-
peting for these limited resources, including reha-
bilitation and reconstruction of aging transit and
highway infrastructure, traffic signalization, con-
gestion alleviation, and safety needs.
5. Public Awareness and involvement
ISTEA mandates an opportunity for strong public
input and review of transportation plans and pro-
grams. Further, the public, as well as State and
local elected officials, need to understand the CAA
requirements, the benefits of reduced emissions,
and the effectiveness of various measures to
achieve those benefits.
Even though ISTEA will result in substantially ex-
panded public participation in State and MPO plan-
8
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ning and programming processes, achievement of
general public consensus will be difficult. In the
case of air quality, the public will undoubtedly de-
mand to know that increasing its transportation
costs or reducing mobility will result in cleaner air.
Also those who perceive themselves to be adversely
affected by transportation infrastructure projects in
any way will very likely raise air quality issues.
The expanded public involvement can be expected
to assist elected officials in understanding the na-
ture of impacts associated with their decisions. It
will also require a full knowledge of the implica-
tions of their proposed actions on the part of staff as
well as decisionmakers.
B. Reducing Vehicle EmissionsThrough
TCMs is Difficult
Despite the significant emission reductions that
have been achieved, many areas of the United
States have not attained the NAAQS for one or
more specific pollutants. While nonattainment
areas have gleaned emission reductions from tech-
nological controls of stationary and mobile sources,
many of them must now consider additional strate-
gies for emission reductions necessary to attain the
NAAQS. TCMs are being considered as part of
those strategies. TCMs must be part of a balanced
transportation plan that meets both air quality and
mobility objectives. However, based on preliminary
indications, the traditional methods of altering
transportation behavior by offering alternatives
have not yet been shown to significantly reduce
emissions.
TCMs are intended to decrease mobile source emis-
sions by eliminating or reducing motor vehicle
trips, cold start emissions, VMT, and highway con-
gestion. And they are usually meant to affect indi-
vidual behavior by inducing transportation mode
shifts or shifting travel to off-peak times, which can
result in a decrease in mobile source emissions.
Certain TCMs are listed in Section 108(f)(l) of CAA
and, with two exceptions, identified as eligible
strategies under the Surface Transportation and
CMAQ Programs of ISTEA. The CAA list offers a
sample of the traditional control measures available
to State and local governments which includes im-
proved public transit, development of bicycle and
pedestrian facilities, trip reduction ordinances, ve-
hicle access restrictions, and traffic flow improve-
ments, among others. Of the Section 108(f*)(l)
TCMs, only the employer-based transportation
management plans (employer trip reduction/em-
ployee commute options) are specifically required
and then only in Severe and Extreme ozone- and
Serious CO nonattainment areas.
Despite the emphasis placed on these TCMs, it will
probably be necessary for many State and local gov-
ernments to look beyond these TCMs in order to at-
tain the ozone and CO NAAQS. In particular,
TCMs that focus on providing more attractive alter-
natives to SOV travel are limited in effectiveness.
(See also Chapter II.C.) Preliminary indications
from around the country indicate that traditional
TCMs will yield only a 1- to 2-percent reduction in
mobile source emissions, far short of what some
areas will need.
Historically, decreasing emissions from mobile
sources mean that TCMs will incur emission reduc-
tions off a shrinking base, at least for HC and CO.
More generally, the transportation sector's ability
to contribute to regional emission reductions
shrinks with its portion of total regional emissions.
In many areas these trends will continue resulting
in smaller and smaller TCM impacts on regional
emissions. In other areas, continuing increases in
travel could lead to an increasing share of total
emissions by the transportation sector. Here, the
types of TCMs employed will be critical—trip-
based, VMT-based, work trips—and will determine
the effectiveness of different kinds of emission re-
duction strategies.
Substantial changes in the level of TCM effective-
ness will require all levels of government to look be-
yond traditional TCMs to economic/market-based
TCMs, such as congestion pricing, increases in
parking prices, emissions charges, etc., which show
greater emission reduction potential. The introduc-
tion of economic/market-based TCMs into the trans-
portation supply and demand decisionmaking
process can and must be designed to improve mobil-
ity and air quality, and at the same time not de-
tract from regional economic growth.
Regulatory TCMs included in Section 108(0(1) and
others which place restrictions on automobile travel
show greater emission reduction potential than
TCMs that increase the supply of transportation al-
ternatives. But economic/market-based TCMs have
some important advantages as emission reduction
strategies over strictly regulatory TCMs. For ex-
-------
ample, economic/market-based TCMs can apply to
all types of drivers and all kinds of trips—not just
employment-related travel—as employer trip reduc-
tion programs are structured. In that work trips
only constitute 26 percent of all trips, almost three
times more trips are unaffected by TCMs targeting
commuting trips.
While providing a disincentive to SOV travel, eco-
nomic/market-based TCMs can alter travel behav-
ior and, at the same time, maintain individual
choice concerning travel mode. For necessary
work- or other-related travel, absolute restrictions
are not imposed, and those who would be burdened
the most by abandoning their cars (e.g., people who
rely on their cars for business) need not do so. Per-
haps the greatest advantage of economic/market-
based TCMs over traditional TCMs is that econom-
ic/market-based TCMs can enhance ridership on
conventional travel alternatives—rail, bus, carpool-
ing—and offer individuals and businesses the in-
centive to develop innovative options such as
telecommuting and vanpools. Other advantages
can include greater economic efficiency and re-
duced congestion.
VMT/emissions pricing is one method that uses eco-
nomic/market-based incentives to bring about be-
havioral changes many traditional TCMs fail to
achieve. A tax on VMT or emissions can theoreti-
cally provide a significant incentive to drive less
and use cleaner vehicles. Congestion/road pricing
is another way which uses market disincentives po-
tentially providing benefits that traditional TCMs
cannot. It can be argued, for example, that
road/congestion pricing is more effective and fair
when compared to indirect pricings such as fuel or
registration fees because road pricing can be tai-
lored to the location, level, and duration of traffic
congestion or emission problems. In addition, the
external and unaccounted costs of driving—pollu-
tion, congestion, accidents—which vary with dri-
ving conditions and have the highest impacts dur-
ing congested periods on specific roadways, may be
accounted for in some congestion/road pricing
plans.
A pricing strategy need not, however, begin by
charging for these externalities. Charging users
the full cost of road construction and maintenance
on local roads, for example, could constitute an effi-
cacious incentive and produce revenues which
might then be used to lower taxes or increase other
services. A broad-based pricing mechanism such as
this is likely to be more effective since it targets all
trips and not just work trips.
Despite these advantages, economic/market-based
mechanisms must be implemented carefully to en-
sure equity and to realize the air quality benefits.
For example, raising the costs of SOV travel could
have disproportionate impacts on the working poor.
Where such impacts occur, mitigation measures
such as tax rebates, transportation vouchers, or
new cost-effective transportation alternatives can
offset them and should be considered. (It should be
noted, though, that many current transportation
costs and benefits are also not distributed equally).
Moving to a system which charges those who bene-
fit is likely to improve the fairness of the trans-
portation system by shifting costs to those who cre-
ate them. In any case, a more efficient use of infra-
structure would decrease transportation-related
costs and externalities generally.
Other implementation issues are also important.
Most pricing mechanisms need to be implemented
uniformly throughout a nonattainment area or SOV
travelers will be able to find and use alternate
roads, parking, and other facilities to avoid the
higher costs, causing problems in other areas. Fi-
nally, such mechanisms require strong political will
to be implemented. Recent experience has shown
that many consumers balk at the notion of higher
fees and taxes without a clear understanding of the
benefits. All levels of government will need to sup-
port an economic/market-based approach if it is to
assist in reducing emissions, maintain mobility,
and gain public acceptance.
While an individual TCM may only provide a small
emissions reduction, a grouping of selected TCMs
which includes economic/market-based TCMs could
yield greater emissions reductions. Accordingly,
complementary TCMs should be developed and
evaluated as part of a coordinated strategy with
particular attention on intermodal alternatives.
Although TCMs can assist in reducing emissions,
the level of their effectiveness varies across the
country because of geographic, meteorological, de-
mographic, and economic differences. Therefore,
neither DOT nor EPA can assign uniform effective-
ness values to either individual TCMs or groups of
TCMs. Furthermore, the state-of-practice and data
on which to conduct analyses are inadequately de-
10
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veloped in many areas to assess all TCMs which
maybe of interest.
While the ability to evaluate a TCM's effectiveness
for reducing mobile source emissions is not an exact
science, EPA has individually, and jointly with
DOT, undertaken several projects aimed at increas-
ing the accuracy and amount of information con-
cerning TCMs. (See Chapter III.C.) In addition,
EPA is currently preparing guidance on methodolo-
gies for estimating emissions and travel activity ef-
fects of TCMs. EPA has provided a grant to the
University of Michigan to do research on human be-
havioral characteristics as they relate to trans-
portation choices.
These projects, although beneficial, will probably
not produce definitive information needed to accu-
rately estimate the emissions reduction benefits di-
rectly attributable to TCMs in all cases. Additional
research into the emission reduction potential of
TCMs is warranted. The combination of market
disincentives to SOV use coupled with attractive al-
ternatives should be pursued, including their poten-
tial costs and benefits. Finally, every effort must be
made to share relevant information among Federal,
State, and local agencies and raise the state-of-
practice in areas where it is needed.
C. By Themselves, Capital-intensive
Investments May Not Be the Best Way
to Address Air Quality Concerns
An important question in developing transporta-
tion/air quality projects and programs is how to
best use Federal and other funding. Some TCMs
require large capital investments and a great deal
of funds in new or expanded high occupancy vehicle
(HOV) lanes, transit, or intermodal facilities. Oth-
ers may be of relatively low capital intensity such
as pricing and regulatory mechanisms or rideshar-
ing. Of course, many TCMs will fall between these
extremes, and different nonattainment areas will
undoubtedly use the increased funding under
ISTEA to finance a wide variety of projects to ad-
dress their transportation and air quality needs. It
will be important for each area to decide among the
capital alternatives based on the relative costs and
benefits, but there is little evidence that capital in-
vestments in new transportation facilities, particu-
larly large investments, are the best way to im-
prove air quality. In fact, available information and
analysis suggest that capital investments when
made without disincentives to SOV use have negli-
gible impacts on air quality.
Information to judge the effectiveness of different
transportation investments or control strategies in
reducing emissions is limited. This is partly be-
cause the emissions consequences of transportation
capital projects are difficult to evaluate systemati-
cally and virtually impossible to actually measure
in isolation from other influences. Most analyses of
the effectiveness of capital investments and TCMs
are based on simulations using regional transporta-
tion and vehicle emissions models rather than on
the measured impacts of actual projects or controls.
These models usually have at least some structural
or conceptual simplifications which leave room for
doubt about the accuracy of their predictions.
Nevertheless, useful estimates of the potential ef-
fectiveness of new investment as an emissions-re-
ducing strategy can be inferred. And the evidence
suggests that capital investments in transportation
facilities are not likely to produce significant emis-
sion reductions by themselves, although they may
be more effective when undertaken in conjunction
with pricing or regulatory mechanisms to reduce
SOV travel.
1. Evidence from California
Because of the severity of the air quality problems
in California, TCM effectiveness has been the sub-
ject of considerable analysis there. This section re-
ports on four studies that show the relatively low
emission benefits of capital-intensive TCMs. In one
study done for the 1991 Clean Air Plan for the San
Francisco Bay area, over 22 TCMs were evaluated.
Of these, the market-based mechanisms (smog fees,
congestion pricing, gas taxes, and increased park-
ing charges) showed the greatest air quality, reduc-
ing mobile source emissions from about 4.5 to 7.6
percent. In comparison, the capital-intensive TCMs
were much less effective. For example, an expan-
sion of the regional rail system, including an exten-
sion of the Bay Area Rapid Transit (five stations)
and the Tasman light rail (12 miles), would reduce
HC and CO by only 0.86 percent each. Similarly,
adding 300 miles of HOV lanes to the existing net-
work would reduce HC and CO by only 0.64 and
0.62 percent, respectively.
Table 1 reports the results from two other analyses
that attempt to predict the emission reductions
11
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from transportation controls and related programs.
These estimates are drawn from a variety of
sources with varying degrees of precision, tend to be
optimistic, and need to be interpreted cautiously.
Nevertheless, the table supports the idea that only
small emission reductions will result from TCMs
generally and further indicates that high-capital
TCMs are not expected to be among the most effec-
tive in reducing emissions.
The statistics from Los Angeles are based on the
Air Quality Management Plan (July 1991 update)
developed by the South Coast Air Quality Manage-
ment District (AQMD). It offers emission reduction
goals that would be necessary to bring Los Angeles
into compliance by the year 2010. The total cost of
such measures is difficult to estimate, but the direct
costs of the transportation investments needed to
meet these goals is projected to be $5.16 billion per
year until 2010. The emission reduction goals esti-
mated by Los Angeles are considerably larger than
the projections by San Diego. According to MPO
personnel, whether they can achieve such targets
remains to be seen.
The analysis done for San Diego was an effort spon-
sored by CALTRANS to determine the effectiveness
of potential TCMs that could be implemented to
meet the NAAQS. The TCM costs and the time
needed to implement the selected TCMs were not
provided in the analysis but would be considerable
for many of them, especially those targeting land
use management and transit expansions.
For both San Diego and Los Angeles, the most capi-
tal-intensive investments resulted in the smallest
percentage decreases in emissions. For example, a
20-mile extension of San Diego's light rail line is ex-
pected to reduce HC and CO emissions (from mobile
sources) by less than 0.4 percent and 0.6 percent,
respectively. Similarly, construction of an exten-
sive rail transit system in southern California is ex-
pected to reduce HC emissions by about 1 percent
and CO emissions by 3 percent, even in conjunction
with areawide adoption of measures to encourage
its use.
Another study by the Metropolitan Transportation
Commission, San Francisco's MPO, showed that an
$11 billion investment in transportation initiatives
will yield a 0.9 percent and 0.8 percent reduction in
CO and HC emissions, respectively. San Francis-
co's investments were primarily composed of new
transit lines, HOV lanes, and local arterial im-
provements. The analysis showed little difference
between large mass transit and large highway pro-
jects.
The low projected emission reduction is unsurpris-
ing. San Francisco and many other nonattainment
areas have massive transportation infrastructures
already in place. Further investment, even $11 bil-
lion worth, only marginally changes the existing in-
frastructure and consequently has a marginal im-
pact on emissions as well.
Control measures that generally have lower capital
costs, such as increased prices for parking and vehi-
cle use, and telecommuting, are anticipated to be
somewhat more effective. Such measures will like-
ly have variable costs associated with them, rang-
ing from net benefits to very high compliance costs
on firms or individuals. But, as suggested above,
revenues generated by these mechanisms can be
used to mitigate the impacts on particular groups.
In any case, these measures do appear to offer po-
tential for greater emissions reductions.
2. Interim Conformity Findings
Most nonattainment areas have now been through
two rounds of transportation conformity determina-
tions under CAA. Taken together, they indicate
that transportation infrastructure programs alone
will make little difference in changing regionwide
mobile source emissions. Further, detail on what
many areas included in their TIPs needs to be ex-
plored. And while much is known about the exten-
sive programs in California, other areas may not
have incorporated programs to influence land use,
TDM measures, or other more stringent efforts in
their TIPs. Further, their analyses may not fully
examine the impact increasing congestion can have
on travel behavior. Still, the programs put forth so
far show that expanded infrastructure will yield
less than a 2 percent emission reduction in most
cases.
By contrast, most nonattainment areas anticipate
that even without new capital investment, mobile
source HC and CO emissions will decline by 4-5
percent each year and in some areas considerably
more, according to an analysis of the first round
conformity determinations. But it should be noted
that realizing these estimated emission reductions
will depend on future VMT increases and that such
12
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Table 1
Emission Restriction Targets for Selected TCMs
(from Mobile Sources)
San Diego
TCM
Transit Expansion
Ridesharing
Flexible Work Schedule/
Telecommuting
Land Use Impacts
Traffic Flow Improvements
Parking Management
Los Angeles
TCM
Transit Expansion
Traffic Flow Improvements
Flexible Work Schedule/
Telecommuting
Land Use Impacts
Description
20-mile rail extension, double bus service
Increase vehicle occupancy 25%
15% participating in telecommuting
5% shift work hours
10% reduction in overall home-work distance
Regionwide signal control
60% increase in costs
Description
Add 300 miles to rail system, expand bus
service by 50%
Signal control, truck restrictions
Eliminate 3 million work trips
60% participation in flexible schedules
25% reduction in overall home-work distance
% Reduction
HC CO
0.4
0.4
0.8
1.4
2.2
2.4
0.6
0.7
1.1
2.0
2.5
4.1
% Reduction
HC CO
0.9
2.1
2.2
4.1
3.1
4.9
6.9
11.8
Sources:
1. From Loudon and Dagang, "Predicting the Impact of Transportation Control Measures on Travel Behavior and Pollutant Emissions, "JHK
Associates, 1992.
2. South Coast Air Quality Management District, "Air Quality Management Plan," Appendix IV-G, 1989.
reductions are not expected for PM-10 emissions
that are increasing. These reductions will come pri-
marily from newer vehicles with additional emis-
sion control features and from reductions in gaso-
line volatility, a major contributing factor to evapo-
rative emissions.
Under the Interim Conformity Determination pro-
cedures established by EPA and DOT, nonattain-
ment areas are required to submit estimates of fu-
ture year emissions levels under two sets of condi-
tions: first, assuming that no additions to their re-
gional transportation networks would be made (the
"no-build" case); and second, assuming that all in-
frastructure projects and TDM programs included
in their Regional Transportation Plans and/or TIPs
were fully implemented (the "build" scenario).
These estimates were required for both the mile-
stone year (1995 or 1996) and for the horizon year,
by which each area is expected to comply with the
NAAQS. (See Appendices B, C, and D for a list of
deadlines by nonattainment status.) Since it is un-
likely that many TDM measures were included so
soon after passage of the 1990 CAA amendments,
13
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the "build" versus "no-build" comparison predomi-
nantly serves to examine the impact of new transit
and highway infrastructure.
The anticipated differences in emissions levels be-
tween the "build" and "no-build" scenarios are quite
modest. Anticipated reductions in HC emissions by
the milestone year were greater than 2 percent in
only a few cases, and most nonattainment areas es-
timated a 0- to 1-percent decrease. Similar, though
somewhat larger, decreases were estimated for CO
emissions. Still, in only a very small number of
areas were CO decreases expected to be more than
5 percent. By the horizon year, considerably more
nonattainment areas expected emission reductions
greater than 2 percent, but well over half expected
that implementation of their current TIPs would re-
duce emissions by less than that. While current an-
alytical techniques preclude greater precision, it is
clear that the impact of the measures included in
the determinations is small.
Among the tasks facing some MPOs and DOTs is
the need to develop new and innovative approaches
to reduce mobile sources and to insure that their
modeling methods can predict the air quality im-
pacts as well as possible.
3. Investments in New Rail Transit
Further evidence about the emissions reduction
potential of one important category of capital in-
tensive TCM is the construction of rail transit fa-
cilities. Rail transit is of particular interest due to
its high visibility and high cost, and due to the
availability of examples in several areas. Despite
the significant investment in rail transit, ridership
increases that would significantly affect emissions
levels have not materialized. While rail projects
in Washington, B.C., Atlanta, and Baltimore
added significantly to transit ridership—67 per-
cent, 18 percent, and 14 percent, respectively—in-
creases in other locations were very modest or
failed to occur. Such increases in ridership, how-
ever, are not reflective of concomitant emissions
reductions since the proportion of regional travel
carried by transit is typically very small. In the
Washington, D.C., metropolitan area, for example,
transit's share of commuter trips is 13 percent,
and Washington's Council of Governments in its
"1982 Regional Air Quality Plan" estimated that
Metrorail's impact on emissions from all trips com-
bined was about a 1-percent reduction.
Analyses from the Boston metropolitan area also
suggest the high cost of emission reductions from
new rail services. One study examined the cost-ef-
fectiveness of various alternatives including an ex-
pansion of a subway line (one station) and rehabili-
tation of the commuter rail line (four stations). The
analysis shows that these transit investments were
not cost-effective means of reducing emissions, with
HC reductions costing $100,000 per ton when all
costs were assigned to HC reduction. Others were
far more productive. Even the addition of 20,000
more park-and-ride spaces was somewhat more
cost-effective, although this study did not consider
the effects of policies over time.
Noninvestment transportation measures tend to
be more cost-effective because they affect the
whole fleet, and the rate at which the fleet pol-
lutes. According to the Boston study, inspection
and maintenance (I/M) programs, for example, af-
fect the entire fleet and yield greater cost-effec-
tiveness, between $1,400 and $5,300 per ton. I/M
programs can even be more cost-effective. Accord-
ing to recent EPA estimates, I/M programs could
be as cost-effective as $500 per ton. This wide
variation in control costs is not unique to trans-
portation-related emissions; stationary source con-
trol costs also cover a wide range, from net savings
to costs of $20,000 per ton.
Further along the cost-effectiveness scale, reducing
a travel subsidy can have net benefits. For exam-
ple, over 95 percent of U.S. employees receive a tax-
free parking subsidy at work. Offering them the
cash value of that subsidy gives them a choice: con-
tinued subsidized parking or cash. Such an ap-
proach was examined by Shoup in 1992 and shown
to help people save money (by carpooling or walking
without forcing them to do so), decrease a subsidy,
and decrease emissions.
One reason for the modest air quality effects attrib-
uted to new rail transit is that only part of the addi-
tional ridership of these systems is drawn from
SOV users. Others are drawn from buses, carpools,
and latent demand. In addition, many riders access
rail stations by automobile, meaning that their
trips still entail engine cold starts and subsequent
cooling down. This generates the bulk of HC emis-
sions—65 percent from a 10-mile trip—because of
an automobile's relative inefficiency and higher
emission rates while warming up and higher gaso-
line evaporation rates when cooling down.
14
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Table 2
Cost-Effectiveness of HC Emission Control Measures
Measure
investment
Regulation
Market Incentive
Rail Extension and Rehabilitation
Park & Ride Spaces
Inspection and Maintenance
Cashing Out Parking Subsidies
$/ton
> 100,000
> 50,000
1 ,400-5,300
Net Benefits
Sources: "The Mass Transit Air Quality Link, "Antonioli, 1992; and "Cashing Out Employer-Paid Parking,'
Shoup, 199S.
Of course, this is not to say that existing rail ser-
vices should be allowed to deteriorate or even that
further investments should not be made as part of a
comprehensive strategy or for other reasons. In
Northeastern cities with long-established rail
transit systems, there is little doubt these urban-
ized areas would suffer much worse congestion
and air pollution if these rail systems ceased oper-
ating. In the greater New York metropolitan area,
for example, there is virtually no alternative to a
viable rail system. Subway ridership is over 3 mil-
lion passengers per day, and this does not include
patronage from two of the largest commuter rail
systems in the country. No combination of auto-
mobile travel and other transportation alterna-
tives could accommodate this level of demand for
the foreseeable future. It should also be noted
that new rail systems and extensions are justified
on the basis of fulfilling a range of objectives be-
sides air quality improvement: improved accessi-
bility and travel time, reinforcement of desired
land use patterns and densities, energy considera-
tions, etc. When viewed in this broader context,
the very modest air quality effects are seen as an-
cillary benefits of these systems, not the primary
reason for implementing them.
Experience with bringing new rail systems on line
over the past 20 years has shown that they cannot
approach their carrying capacity unless accompa-
nied by measures that would allow transit to com-
pete more effectively with SOVs. The experience
in Washington, B.C., over the past decade is a case
in point. There, despite having a fairly built-out
rapid transit system and land use controls that
are generally supportive of transit use, the system
was not able to increase its share of journey-to-
work trips throughout the region. From 1980 to
1990, the Washington Metrorail system grew from
30 to 73 miles of line and opened an additional 30
stations. And the number of workers using rail
transit grew from 69,000 to 143,000, a significant
increase. However, the number of people driving
alone to work in the Washington metropolitan
area also increased dramatically from 980,000 to
1,394,000, and overall transit's mode share de-
clined slightly. The situation in Washington with
respect to personal travel trends is mirrored in
other urban areas as well. To the extent that cost-
ly new rail projects are relied on as transportation
control measures to improve air quality, it is clear
that their effectiveness depends largely on a com-
prehensive, regionwide program that makes tran-
sit a more attractive option relative to single-occu-
pant driving.
4. Supply of Alternatives versus Demand
for SOV Travel
Even if capital investment in transportation is not
the most effective emissions-reduction strategy
taken alone, it may still represent an important
complement to other measures. Capital invest-
ments in new HOV facilities, expanded transit ser-
vice, or widespread facilities for exclusive use by bi-
cyclists and pedestrians increase the supply and at-
tractiveness of transportation alternatives to SOV
travel.
For such TCMs to be effective at reducing emis-
sions, however, large numbers of trips must be
shifted from SOV to non-SOV travel alternatives,
15
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and experience has shown that increases in supply
alone will not produce these shifts. In addition to
increasing the supply of non-SOV options, the de-
mand for SOV travel needs to be reduced. In many
cases, high demand for SOV travel is a direct result
of free parking and other distortions in the trans-
portation marketplace, and successful demand
management can reduce those distortions. Travel-
ers act to minimize a combination of time and
money costs, and thus eliminating subsidies has
shown significant effects. The simple act of charg-
ing for, rather than giving away, parking has
shown 20-45 percent decreases in SOV commuting
rates for individual employers (Shoup 1992), al-
though similar regional impacts have not yet been
shown. This is even true in poorly transit-served
areas of suburban Los Angeles.
TCMs that increase the cost of commercial parking,
reduce or offer a cashing out of employer-provided
parking, establish road and congestion pricing
mechanisms or VMT restrictions can be effective
means of reducing the demand for SOV travel.
Such measures will impose variable costs which can
be quite high. For understandable reasons, such
measures are unpopular with those bearing the di-
rect costs when they are.
Some people argue for simultaneously increasing
the supply and attractiveness of alternatives
through capital investments and creating disincen-
tives to SOV travel as a way to create an integrated
program that maximizes emission reductions. Such
a program will not eliminate resistance to SOV dis-
incentives but may reduce it because the program
includes more visible and widely supported ele-
ments, such as capital investments in transit,
ridesharing, bikeways, and other transportation al-
ternatives and critical elements necessary to
achieve emission reduction targets. Others argue
that all too often the attractive and sometimes cost-
ly TCMs are offered without the tougher disincen-
tives to SOV travel.
Resistance to SOV disincentives has varied but
can be significant. In Washington, D.C., and
many areas around the country, major political
battles have been fought over the implementation
of parking or roadway restrictions. In the Nation's
capital, the opposition has come despite major in-
vestments in bus and rail transit and two major
HOV corridors. A more encouraging example
comes from Portland, Oregon, which over the past
20 years has removed a major freeway, canceled
construction of another, imposed a parking mora-
torium, and passed transit-supportive zoning
changes and bond initiatives, all with significant
public support. Yet even the Oregon Legislature
declined to take the next step to implement con-
gestion pricing and vehicle emission fees, as rec-
ommended by a special State task force.
5. Long-Term Emissions Consequences
of Capital Investment
While the short- to mid-term emissions impacts of
transportation capital investments are modest,
their longer-term effects may be more pronounced.
Because of their durability, these investments con-
tinue to influence urban travel patterns over a
prolonged period and in turn have an impact on
the location of homes and businesses. Households
and businesses base their location decisions in
part on the accessibility and convenience provided
by the regional transportation network. As trans-
portation investments are made, certain locations
are made more desirable which, as new businesses
and residences relocate, increases utilization of
the transportation facility. Of course other vari-
ables, such as building costs, crime, schools, and
other amenities, also play a significant role in
household and business location decisions. (See
Chapter II.F for more information.)
Certain types of investments may decrease emis-
sions over time. The benefits of this longer-term
strategy, however, may not be realized in time to
assist nonattainment areas meet the NAAQS ac-
cording to the deadlines set out in CAA. The first
deadlines occur this year and most areas are sup-
posed to reach attainment before the year 2000.
Even the Los Angeles area only has until 2010 to
meet the standards. These are relatively short
timeframes to effect such land use changes.
In summary, if large reductions in vehicle travel
are sought, State and locally elected officials will
need the political will to make tough decisions nec-
essary to adopt and implement the kinds of TCMs,
such as stringent and economically viable pricing
mechanisms, that will reduce the attractiveness of
SOVs in their region, yet preserve mobility. Previ-
ous emphasis has been on reducing commuter trav-
el, and strategies that affect every trip—commuter
and nonwork—will be necessary if significant emis-
sion reductions are to be realized.
16
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D. Technological Improvements Have
Reduced Vehicle Emissions Despite
Increasing VMT
*
The CAA provisions intended to reduce SOV travel
and VMT pose tremendous challenges for trans-
portation, air quality, and land use planners, par-
ticularly in light of the travel trends in the United
States. Efforts to control VMT have mostly concen-
trated on eliminating work trips, but given the ris-
ing importance of other trip purposes, such efforts
are destined to be marginally effective alone. Ef-
forts to control total VMT require broad support to
pass enabling State legislation, making them be-
yond the jurisdiction of the transportation and air
quality communities. Other ways exist to reduce
highway emissions, such as inspection and mainte-
nance programs and other programs targeted at so-
called "gross-emitters."
1. Transportation Trends
Vehicle travel is by far the predominant travel mode
in the country. Of 250 million daily passenger trips,
94 percent are made in automobiles or trucks and
only 2 percent by public transportation. Automobile
travel as measured by VMT has increased marked-
ly, far outpacing population growth and household
formation in the recent past. Between 1983 and
1990, passenger VMT increased by 41 percent, com-
pared to relatively slight increases in population
and households (6 and 9 percent, respectively).
Average Vehicle Occupancy Has Declined
1977-1990
2
1.8
1.4
1.2
1
<^^
*" •» Total
+MM»««S«™^^i(^
Work
1977 1983 1990
Total 1.8 1.7 1.6
Work Trip 1.3 1.3 1.1
Source: NTPS, 1990
Figure 4
The reasons for increased VMT are varied. The
1990 National Personal Transportation Survey
identified several major national trends in travel
patterns that offer a partial explanation. First,
there has been a dramatic increase in the number
of workers, particularly women, up 58 percent since
1969, which means an increase in commuter travel.
Second is an increase in the number of jobs located
in the suburbs where generally fewer travel alter-
natives are offered and distances are greater than
suburb-to-city travel. Suburb-to-suburb travel is
now the dominant commuting pattern in the United
States. Third, vehicle ownership has increased sig-
nificantly between 1969 and 1990. Nationwide,
households with two or more vehicles increased
from 31 percent to 58 percent. And finally, average
automobile occupancy continued to decline to 1.5 in
1990, from 1.9 in 1977. Vehicle occupancy for work
trips is even lower and dropped under 1.1 persons
per vehicle in the last 10 years.
The cost of gasoline has also been a significant fac-
tor in VMT growth. Gasoline costs in real terms
are now lower than they were in 1950. Fuel effi-
ciency has also increased dramatically. Low fuel
costs combined with high fuel efficiencies means
that marginal per-mile driving costs are among the
lowest they have ever been.
While more people are driving more cars for more
miles, highway capacity has been practically con-
stant since 1970. Depicted in Figure 5, highway
road-miles have increased slightly, 4 percent, since
1970, although it should be noted that in urban
areas capacity has increased more significantly.
One consequence of this is clear—increasing conges-
tion. Furthermore, many have become concerned
that these trends mean worsened air quality.
These data suggest the continued dominance of per-
sonal vehicles for passenger travel. The large in-
creases may slow as vehicle ownership approaches
saturation and female participation in the work
force levels off. Nevertheless, the multiple trends
contributing to growth show how difficult it will be
to reduce traffic congestion and the resulting air
pollution. This difficulty is reinforced by the cur-
rent land use patterns of dispersed residences and
jobs, with the corresponding heavy reliance on auto-
mobiles and limited alternatives.
2. Control Mechanisms
Because of the above trends, increasing attention
has been focused on ways of controlling VMT, with
particular emphasis on controlling work trips.
17
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VMT Has Grown Markedly
Despite Constant Capacity
2,500
2,000
1.500
1,000
VMT (billions)
1970
Road Miles (0,000s)
1975 1980 1985
1991
Source: FHWA
Figure 5
Work trips, however, have dropped to only 26 per-
cent of all trips, down from 32 percent in 1969.
Similar trends are demonstrated for purpose-specif-
ic VMT. So, if controlling VMT is a necessary and
desirable way of reducing mobile source emissions,
targeting work trips alone limits the overall effec-
tiveness of the strategy.
As work trips decreased as a percentage of all trips,
other trip purposes increased. The share of trips
made on family or personal business increased from
14 percent to 24 percent, for example, between 1969
and 1990; shopping trips increased from 15 percent
to 20 percent in the same period. Clearly if VMT is
going to be effectively controlled, trips for every pur-
pose, not just journey to work, need to be targeted.
Effecting changes in travel behavior can be accom-
plished by adjusting the comparative advantage
each offers, particularly through the disincentives
discussed above, i.e., regulatory or market-based
initiatives. Unlike providing new infrastructure or
better services, such initiatives often require en-
abling legislation at the State level. Winning the
public support necessary for enactment has shown
to be extremely difficult. Enabling legislation re-
quires not only the consent but the active participa-
tion of elected officials. In this sense, such initia-
tives are substantially beyond the control of either
air quality or transportation officials and the com-
munities they represent, and a much broader base
of support is necessary to implement them.
Another means to control mobile source emissions
is to target those vehicles producing the greatest
amount of emissions. Only 10 percent of all vehi-
cles on the road produce between 50 to 60 percent of
highway CO emissions. (Less dramatic impacts are
demonstrated for other emissions: 10 percent of the
vehicles produce 40-50 percent of HC emissions and
20-30 percent of NOx emissions. These considera-
tions may not apply to PM-10 in a significant way).
Since such gross emitters are the predominant
source of highway emissions and not only increase
the formation of CO hotspots but ambient pollution
as well, reducing their impacts can effectively im-
prove air quality without radically disrupting
American economic and lifestyle choices.
3. Emissions Consequences and Control
Strategy Implications
Even as VMT increased, mobile source emissions
declined as stricter tailpipe measures were estab-
lished and enforced. Since 1982, hydrocarbon, CO,
and NOx all decreased by substantial margins; hy-
drocarbons are down 39 percent, CO decreased 40
percent and NOx declined 25 percent, according to
the EPA report, "National Air Quality and Emis-
sions Trends -1991." Given the growth in VMT,
however, the environmental and transportation
communities are concerned that rising VMT may
eventually overtake the emission improvements re-
alized over the last 10 years.
Technology has improved the emission rates of new
cars considerably. For example, 1990-model vehi-
cles emit hydrocarbons and CO at only one-third
the rate of 1975-model vehicles. In the near term,
further emission reductions can be expected as
older vehicles are retired and replaced with newer,
cleaner ones. But even with these technological im-
provements, the total vehicle emissions could once
again increase if VMT rises rapidly. Some esti-
As VMT Increased, Emissions Declined
1982-1991
1982
1984
1986
1988
1991
Source: FHWA. National Air Quality and Emission Trends -1991. EPA
Figure 6
18
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mates predict that mobile source emissions will
again rise on or about the year 2005. Others sug-
gest that VMT growth will subside and negative
emissions impacts may be averted.
Whether and when emissions rise again with VMT
(under uncontrolled conditions), and to what level,
depends in part on what is done in the future to re-
duce the emissions per mile of travel. The 1990
Clean Air Act has resulted in the implementation of
even stricter tailpipe and evaporative emission con-
trols that will increasingly benefit all areas over the
next two decades. Enhanced inspection and main-
tenance programs, now required in nonattainment
areas designated serious and above for ozone (or
high moderate and above for CO), use high technol-
ogy emissions testing on an annual or biennial
basis along with supplemental on-road emissions
testing to ensure that vehicles meet the standards.
If they do not, maintenance is required to bring
them into compliance. EPA estimates that en-
hanced I/M programs can yield a 28-percent emis-
sion reduction. Areas not specifically required to
adopt enhanced I/M can choose to do so for greater
emissions reductions and to reduce the need to con-
trol VMT. Similarly, States and nonattainment
areas variously must or may choose (depending on
classification) to implement other technology-ori-
ented measures such as reformulated gasoline, oxy-
genated gasoline, California vehicle standards,
clean fuel fleets, or other measures.
Nevertheless, VMT reductions (uncontrolled)
through control mechanisms described earlier
may be part of the preferred long-term strategy.
The overall emissions control strategy that is
right for an area will depend on the overall emis-
sion reduction that is required, as well as on local
preferences among all the control possibilities. To
the extent that vehicle technology and fuel mea-
sures cause smaller per-mile emissions, they tend
to shift the logical focus for additional emission
reductions away from VMT and on to trips and
nonvehicle sources. It should be noted that in
many areas, congestion reduction and quality of
life are also reasons to consider many VMT con-
trol strategies.
Except for fuel changes and inspection and mainte-
nance programs, the technology measures' benefits
will phase in gradually and will not provide much of
a contribution to meeting the requirement to reduce
VOC emissions by 15 percent by 1996. Because
growth in emissions from rising VMT must also be
offset in addition to the 15 percent reduction, the
rate at which VMT will grow naturally is a crucial
question to determine the importance of reductions
from new efforts to limit VMT growth, fuel changes,
enhanced I/M, and non-vehicle control measures.
The affected States are considering their emission
reduction targets and options at this time, with SIP
revisions due on November 15,1993.
E Better Data and Models Are Needed
Several steps are required to analyze the emissions
consequences of regional transportation plans or
measures designed to control travel behavior.
First, based on the existing development and land
use patterns, a regional transportation modeling
system is typically used to estimate a baseline vol-
ume and pattern of travel. Second, the resulting es-
timate of total travel broken down by vehicle type,
time period, speed, or other important category is
used in conjunction with a vehicle emissions model
to predict regionwide emissions of different pollu-
tants. Next, these same steps are repeated with the
transportation plan or control measure in effect,
and the predicted emissions are compared to the
baseline estimates. (See Appendix F for a complete
description of the transportation and emissions
modeling processes.)
The regional transportation modeling system cur-
rently used to estimate travel volumes and pat-
terns was designed 30 years ago. This system
was originally intended to forecast the need for
new highway facilities, and today has far greater
demands placed on it with such CAA and ISTEA
policy implications as air quality modeling.
Though useful when applied in the traditional
role of determining how many lanes are necessary
to serve a particular region, these models are not
sensitive to many of the inputs and parameters
needed for their adaptation to air quality model-
ing. Short-term improvements to the current
transportation model set have the potential of sat-
isfying many of the gaps in the air quality model
link. Other deficiencies, however, point to a need
for more in-depth research into new procedures
and algorithms.
The ability to translate a transportation plan to in-
fluence travel behavior into changes in inputs for
the regional models is a critical step in this process.
Each individual project in a transportation plan or
19
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TIP can potentially alter the configuration or capac-
ity of the regional transportation network. Any
changes are reflected in the computerized represen-
tation of the network by altering the capacity or
performance characteristics. The results of a num-
ber of such changes implemented together, such as
would occur if all of the projects included in a re-
gional transportation plan were constructed, are es-
timated by operating the system of regional trans-
portation models with the reconfigured network
substituted for the original network.
Translating many TCMs into corresponding
changes in regionwide travel patterns and vehicle
emissions is more challenging. The average travel
and emissions impacts of capital-intensive TCMs,
such as new transit facilities or HOV lanes, are
usually evaluated in much the same way as individ-
ual elements of the regional transportation plan.
However, expressing the effects of measures such
as mandates for employers to encourage or require
flexible work schedules or mandates for employer-
based ridesharing promotion programs in a regional
modeling system is considerably more difficult. As-
sessing the emissions consequences of these mea-
sures is likely to require more creative, detailed,
and localized analysis, which in many cases can be
conducted most effectively outside the framework of
conventional regional transportation and vehicle
emissions modeling.
Taken together, both transportation and emissions
models must make various technical and behavioral
assumptions. Such assumptions often fall short of ac-
curately representing an extremely complex reality.
1. Uncertainty in Transportation,
Emissions, and Concentration Models
Inaccurate estimates of regional vehicle emissions
associated with urban travel can result from errors
in either the detailed estimates of traffic volumes
and speeds produced by transportation models, or
the emissions rates for the fleet of vehicles operating
in an urban area. The accuracy of these estimates is
tied to the data inputs, mathematical structure, and
solution procedures of commonly used regional
transportation and vehicle emissions models.
There are three primary sources for inaccuracy in
the execution of regional transportation models:
limitations to the inputs on which these models
rely, areas where the models need to be expanded,
and shortcomings in the models themselves. As an
example of the first, the forecasted distribution of
regional population and employment is often an
erroneous input because such information is depen-
dent on fluctuating political compromises more than
on technical expertise. Local officials who want
forecasts to reflect positive growth and development
within their jurisdictions sometimes assume suc-
cessful implementation of land-use plans that later
prove difficult to adopt or enforce. Aside from their
unavoidably controversial nature, the future geo-
graphic distributions of human activity are likewise
inherently difficult to predict at the level of detail
demanded for input into regional transportation
models. In practice, errors sometimes occur if ad-
justments are not made to improve accuracy. Fore-
casting can be improved by including additional
transportation alternatives in the models. For ex-
ample, incorporating variables for, and better esti-
mates of, bike and pedestrian mode shares can pro-
vide more reliable results than is sometimes done.
Nevertheless, many of the errors which occur lie in
the nature of adopting a process for a purpose other
than for which it was originally intended. As an il-
lustrative point—travel by time of day is not neces-
sary for the traditional travel model to estimate re-
gional demand, though it is a critical input for air
quality modeling. The handling of time of day vari-
ables lies outside the basic structure of the regional
transportation model.
Input errors also arise from the reliance of many re-
gional model systems on incomplete or outdated
databases. In particular, information on the vol-
ume, geographic pattern, and timing of tripmaking
is often estimated from household surveys admin-
istered 20 or more years earlier. Though an attempt
is sometimes made to update such data with limited
surveys or public sources such as the U.S. Census,
the availability of variables which explain travel be-
havior and changing trends may be insufficient.
One particularly significant gap between the re-
gional transportation models and those used for air
quality planning lies in the area of speed estimates.
Though accurate speeds are a critical input for esti-
mating emissions, the traditional travel model
process was not intended as a source for such infor-
mation. The accuracy of volume and speed esti-
mates from a regional transportation model may
become increasingly unreliable under congested
conditions; this serves as an area of concern for
20
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many urban highway networks with prevalent con-
gestion and high volumes in the peak hour. The
limitation of unreliable speed estimates is also seri-
ous for areas with major arterial streets because
congestion-related delays on these facilities stem
from a complex interaction between directional traf-
fic volumes and traffic signal phasing. The repre-
sentation of such complexities is an application
which goes beyond the design of the traditional
travel model system.
Vehicle emissions models can err in basic emission
rates for individual vehicles, as well as in the cor-
rection factors used to adjust these measured
rates. Basic emission rates are measured for a
simulated pattern of "typical" city driving, which
does not accurately reflect the variety of road facil-
ities, vehicle types and traffic flow conditions en-
countered in urban travel. Most important, the
overall average speed (19.6 mph) of the test cycle
may not reflect the actual mix of speeds on local
roads and highways. It is excessive for local trips
primarily on collector and arterial streets and un-
derrepresents travel at freeway speeds which now
constitutes much of urban travel, particularly off-
peak.
Another source of error is that basic emission rates
for specific vehicles, categorized by type, model
year, and age, represent test measurements from a
small sample of vehicles. This is particularly true
for rate estimates for emissions due to fuel vapor.
Yet emission rates among individual vehicles with-
in any category vary widely even under laboratory
conditions, so that a small sample may not produce
a reliable estimate of emissions.1 It may be possi-
ble to reduce this problem by using test results
from State vehicle emissions inspection and mainte-
nance programs, once they introduce more realistic,
mass based test procedures and standardized re-
porting requirements take effect.
The correction factors used to adjust measured
emissions rates may also be a source of error, par-
ticularly the adjustment factors intended to correct
for speeds different from the 19.6 mph average in
the Federal Test Procedure (FTP). MOBILE model
speed correction factors are developed by interpolat-
ing between FTP-measured emission rates and
those measured for other test driving cycles, each of
which generates a different average speed. Howev-
er, actual patterns of urban driving may differ from
test cycles in other critical aspects, even with simi-
lar average speeds. Frequency and duration of high
acceleration periods, for example, may be different
from test cycles. EPA has a major effort underway
to better characterize cycle aspects, which will be
reflected in the emissions model in 2 years.
2. Improving Transportation, Emissions,
and Concentration Models
In November 1994, nonattainment areas designated
serious and above for ozone must submit SIP revi-
sions that demonstrate their plans are sufficient to
achieve attainment of the NAAQS by the CAA-man-
dated dates. That demonstration will be done in part
through use of transportation, emission, and concen-
tration models. But it is not certain that strategies
developed with these models will ensure attainment.
This goal of emission estimations beyond planning
for mobility stretches the state of the art in trans-
portation/air quality modeling to its limits.
Current regional transportation and air quality
models are unlikely to perfectly reflect actual emis-
sions impacts of transportation plans and programs.
There is a need for broader application and greater
responsiveness in the models which increases the
practitioners' ability to analyze air quality impacts,
as well as other aspects of transportation projects.
To this end, efforts to improve the reliability of cur-
rent models have been widely initiated.
presence of extremely high-emitting vehicles in most model year cohorts suggests that small differences in their repre-
sentation between the national test sample and any urban area's local fleet can cause the MOBILE model to misestimate the
local emission rate for some vehicle type and age categories substantially (usually by underestimating the true rate, since the
sample selection procedure tends to exclude high-emitting vehicles); see W.R. Pierson et al., "Comparison of the SCAQS
Tunnel Study with Other On-Road Vehicle Emissions Data," 1495ff; and D.R. Lawson et al., "Emissions from In-Use Motor
Vehicles in Los Angeles: A Pilot Study of Remote Sensing and the Inspection and Maintenance Program," Journal of the Air
and Waste Management Association, Volume 40 (1990), pp. 1096ff. This source of potential error has recently become more
important, as the number of vehicles tested to estimate the model's basic emission rates for used vehicles has declined, while
the representation of these vehicles in the nationwide fleet has increased; see U.S. General Accounting Office, Reliability of
EPA's Mobile Source Emissions Model Could be Improved, GAO/RCED-90-138, May 1990.
21
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A priority initiative has been launched to improve
the current regional travel forecasting models, and
to better handle the land use/transportation rela-
tionship. Jointly funded by FHWA, FTA, and
EPA, this initiative is significant; under FHWA's
lead, the project is likely to encompass many
years. Research has begun, and the final plan for
the effort is currently being prepared. The overall
effort includes an outreach program, improving ex-
isting procedures, researching new procedures,
and a focus on data collection. Included will be re-
search into the "supply side" of different modes, fo-
cusing on the access of both activities and differ-
ent times of day. Revised network procedures, in
response to changing forecasting needs, will in-
clude incremental loadings by time of day, embed-
ded in a simulation procedure which will feedback
network information to an "activity generation"
step. This feedback process should increase the
reliability of speeds and volumes under congested
conditions. The overall model design must be flex-
ible and sensitive to changes in needs of decision
makers and to changes in air pollution control
technology.
Vehicle emissions models can also be improved,
and EPA conducts an ongoing program of research
and testing that has led to continuing improve-
ments in its MOBILE emissions model. A source
of potential error in vehicle emissions models has
been the inability of the test driving cycle to repre-
sent the variety and mix of vehicle operating con-
ditions encountered in typical urban driving. Cur-
rently, EPA is working to correct this potential
error through a large-scale research effort to de-
termine actual in-use driving behavior and the
emission impacts as compared to the FTP. To en-
sure that vehicles are being tested under circum-
stances which reflect the actual current driving
conditions, EPA found potential concerns with the
FTP's treatment of acceleration, speed, soak time,
and cold start driving behavior during an earlier
review.
EPA was unable to sufficiently address the afore-
mentioned problems before the CAA deadline for
correcting and producing a new FTP. Consequent-
ly, EPA is operating under a court-mandated sched-
ule to complete the new FTP. Under the court-
mandated schedule EPA must: produce a first draft
of the FTP NPRM by October 1993, publish the
NPRM by March 30,1994, and promulgate the final
rule by December 31,1994.
F. Beyond Transportation - Land Use, \
Public Acceptance, and Fiscal
Constraints Figure Prominently
The Clean Air Act and ISTEA set forth challenging
goals which become even more challenging when
taken together. ISTEA clearly sets forth a policy
that transportation investments and strategies
must meet social, environmental, and economic ob-
jectives while meeting the Nation's mobility goals.
The Clean Air Act, as amended, is designed to at-
tain and maintain the NAAQS. The combination of
these Acts has changed the way transportation
planning will be done in areas failing to meet the
NAAQS.
The challenges to air quality and transportation
planners in jointly meeting these objectives are nu-
merous and complex. There are important factors
which are part of the background in which trans-
portation and air quality planners must operate,
but which are beyond control of any single govern-
ment entity. These factors include the importance
of land use in influencing transportation demand
and air quality, the lack of public understanding of
benefits of clean air, and competing urban priorities
under constrained fiscal conditions.
1. Land Use
We are becoming increasingly aware of the interre-
lationships of land use and transportation. Low
density development often means that the prepon-
derance of trips can only be made by the automo-
bile. This limits travel for those who cannot drive
or afford an automobile. Similarly, higher density
land use better supports public transit services.
"The pattern of urban development dictates
whether people can walk or cycle to work or
whether they must travel dozens of miles; it
also determines whether a new bus or rail line
can attract enough riders. Despite this obvious
link, city layouts often are too dispersed to fos-
ter efficient transportation." [Marcia D. Lowe,
Worldwatch Institute, in Surface Transporta-
tion Policy Project Bulletin, October 1992.]
While transportation facilities influence growth
patterns, there are many variables which combine
to influence growth and land use. Land use is regu-
lated by local governments, usually under authority
granted by State governments. However, policies
22
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at all levels of government affect land use decisions
and individual preferences to live or conduct busi-
ness at a specific location. Economic factors such
as demand for housing and office space are particu-
larly important. Tax policies at all levels of govern-
ment have an influence on land use. For example,
income tax deductions for mortgage interest have
provided a major incentive for purchase of single
family homes. Local real estate taxes, especially
differences in taxes among local jurisdictions, also
have an influence on location decisions. The extent
of land use regulation is often a factor in decisions
by developers. Availability of water, sewer, and
other infrastructure also influences development
decisions.
ISTEA requires metropolitan and State transporta-
tion plans to reflect consideration of land use plans.
This will be an important step. Better understand-
ing of the relationships among land use patterns,
travel patterns and air quality will be needed to re-
spond to the challenge of reducing transportation's
contributions to air quality. Cities such as Port-
land, Oregon, are studying what can be done to en-
courage land use patterns which support more effi-
cient transportation. Changing land use poses sig-
nificant political challenges and may not yield re-
sults within the CAA timeframes.
2. Public Acceptance
Transportation control measures seek to provide in-
centives to use more efficient, less polluting modes
of transportation and/or disincentives to use of au-
tomobiles with single occupants. Local decision-
makers in some areas have difficult choices to make
in the near future as to transportation plans and
transportation control measures in SIPs if they are
to achieve significant emission reductions from
TCMs.
The public needs to understand the overall emis-
sions requirements of CAA, benefits of reduced
emissions, and the ability of various strategies to
achieve the benefits. Public acceptance of measures
that impose higher costs or constraints on SOV
travel will be important to the success of the trans-
portation control measure and its effectiveness in
reducing emissions.
A recent example in the Washington, D.C., area
highlights how the failure to gain public support
can lead to a measure's demise. On September 1,
1992, the Virginia Department of Transportation
(VDOT) started operating new lanes on the Dulles
Toll Road in the HOV mode, as agreed to by rele-
vant transportation agencies. The toll road, built to
handle 47,000 vehicles per day, was carrying 76,000
in 1992, with projected volumes to double by the
year 2010 unless mitigation measures (HOV opera-
tion) were adopted. The operation limited the left
lane to carpools of three or more persons. While the
facility accommodated about 650 3-person carpools
during its first weeks of operation, the closure of
the lane to general traffic caused greater congestion
on the other two lanes. This created a furor among
SOV users, worsened by a lack of support from traf-
fic reporters and a perception that the new lanes
were underutilized. Neither environmental organi-
zations nor local politicians rallied to support the
HOV proposal. Bowing to overwhelming pressure
from congressional representatives and motorists,
Virginia's Commonwealth Transportation Board
suspended the HOV restrictions on October 5,1992.
To give HOV lanes and other control measures a
greater chance of success and to avoid commitments
to measures where they cannot succeed, the public
must have an opportunity to participate in the
transportation and air quality planning processes.
ISTEA expands opportunities for public participa-
tion in State and MPO transportation planning.
3. Fiscal Constraints
At all levels of government, there is a paradox of in-
creasing requirements for staff time, analysis, and
other resources while at the same time fiscal con-
straints are increasing. For example, the analysis
required to support determinations that transporta-
tion plans and programs conform to air quality
plans will be extensive. For most areas, this will
cost about $50,000 for the conformity determination
alone. However, costs can be very significant, per-
haps reaching hundreds of thousands of dollars, as
in the case of Los Angeles. Further, the conformity
analysis will have to be repeated each time revi-
sions to a plan or program are proposed. Develop-
ment of emissions inventories, budgets, and other
elements of State implementation plans also re-
quire substantial expenditures by air quality agen-
cies. At the same time, all levels of government are
facing hard decisions about budget shortfalls.
Other concerns not related to transportation and
air quality are important and fighting for limited
resources.
23
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III. STATUS OF PROGRAMS
A. Full Funding oflSTEA Would Help
Meet Mobility and Air Quality Goals
1. Funding Levels for Title I Programs
(Surface Transportation)
Expensive, capital-intensive projects may not be the
best use of transportation funds for air quality, but
current funding is still needed to improve alterna-
tives to SOV travel and reduce emissions through
effective programs like enhanced inspection and
maintenance, among others. Funding levels are au-
thorized in ISTEA, and yearly limits are placed on
total expenditures by the Congress through the ap-
propriations process. In 1993, appropriated
amounts for Title I Programs (for Surface Trans-
portation) were considerably less than the ISTEA-
authorized levels, forcing the States with nonat-
tainment areas to make hard choices regarding how
to meet both their mobility and air quality goals de-
spite overall increases in authorized funding levels.
ISTEA substantially increased funds for air quality
purposes in two ways: by creating a dedicated
source of funds in the $6 billion CMAQ Program
and by providing the flexibility to use funds for
transportation projects which may improve air
quality. ISTEA's flexibility allows $23.9 billion in
Surface Transportation Program funds to be used
for transit and other transportation projects and
programs that can have a positive impact on air
quality. Furthermore, funds from other ISTEA pro-
grams can be transferred to STP and used for eligi-
ble purposes under that program. Fifty percent of
NHS funds can be transferred to STP without Fed-
eral approval, and 100 percent can be transferred
with DOT approval. Forty percent of Bridge funds
and 20 percent of Interstate Maintenance funds can
also be transferred to STP.
ISTEA also increased the quantity of funds avail-
able for planning purposes, needed to support both
transportation and environmental programs. Met-
ropolitan planning is funded by a legislated set-
aside from NHS, STP, CMAQ, Interstate Mainte-
nance, and Bridges. The percentage of planning
funds doubled from 0.5 percent to 1.0 percent under
ISTEA and the actual dollar amount more than
doubled ($47 million in FY1991 to $117 million in
FY 1992) because of the higher authorization level.
Highway Planning and Research (HPR) funds simi-
larly increased from 1.5 percent to 2.0 percent. Fi-
nally, planning and research are eligible activities
under both NHS and STP.
Table 3
Summary of Major ISTEA/Title I Programs
Surface Transportation Program
National Highway System
Interstate Maintenance
Bridges
Interstate Construction
CMAQ
Interstate Substitution
$23.9 billion
21.0 billion
17.0 billion
16.1 billion
7.2 billion
6.0 billion
1.0 billion
Source: FHWA
The ISTEA-authorized levels, however, have not
been realized. In the appropriations for FY 1993,
the obligation ceiling—the maximum amount of an-
nual Federal aid funds the states are allowed to
spend under all programs—was set significantly
below the authorized amount. As Table 4 shows, an
additional $2.9 billion could have been included in
the obligation ceiling and spent on needed trans-
portation and air quality projects.
Current funding is needed for transportation pro-
grams to improve air quality, but setting the obliga-
tion ceiling below authorized levels further con-
strains the already difficult choice that States must
make to meet both their mobility and air quality
needs. Priorities will differ from State to State, but
by appropriating less than authorized levels, Con-
gress makes those choices all the more difficult.
And even though $967 million was apportioned to
the States under the CMAQ Program in 1993, the
States will not have the opportunity to make full
use of the funds for air quality purposes if their
obligation ceiling is reached by advancing other
needed transportation projects.
2. Funding Levels for Title III Programs
(Federal Transit Act)
In FY 1992, the total authorized funding level under
Title III of ISTEA (which amends the Federal Tran-
sit Act) was $3.64 billion, including $2.29 billion
25
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Table 4
Authorized vs. Appropriated Levels
for Title I Programs -1993
Authorized Funding Levels
Obligation Ceiling
Difference
$16.410 billion
13.51 9 billion
2.891 billion
Source: FHWA
for the formula grants program and $1.34 billion
authorized for discretionary grants. The enacted
budget for FY 1992 very nearly matched authorized
funding levels for that year.
For FY 1993, the funding picture changed marked-
ly. FTA's total authorization for FY 1993 increased
significantly to $5.23 billion, including $3.2 billion
for the formula grants program and $2.03 billion for
discretionary grants. The FY 1993 enacted budget,
however, provided only $1.7 billion for formula
grants and $1.72 billion for discretionary grants.
The greatest shortfall in appropriations was in the
formula grant program where $758.26 million was
appropriated for capital grants under the Section 9
urban formula program as compared to a total of
$1.02 billion for the previous fiscal year. This level
of funding for the Section 9 capital program in FY
1993 detracted from the ability of transit agencies
to advance needed capital improvement projects.
Funding was insufficient to allow transit agencies
to upgrade and expand service at a time when
Clean Air Act requirements would encourage an ex-
panded role for transit in nonattainment areas.
The disparity between authorized and appropriated
funding levels is also evident for transit's metropoli-
tan planning. MPOs rely heavily on FTA's Section
8 planning funds to conduct long- and short-range
transportation planning which meets CAA require-
ments. In FY 1993, $70.67 million was authorized
for metropolitan planning but only $38.25 million
was appropriated.
The magnitude of this shortfall for metropolitan
planning seriously undercut the ability of MPO's to
acquire the technical capabilities that they need in
order to satisfy the new CAA requirements. Un-
questionably, CAA placed a significantly greater
analytical burden on State DOTs and MPOs in
demonstrating that their plans and programs con-
form to the objectives of the SIP.
3. The CMAQ Program
ISTEA created a $6 billion authorization for the
CMAQ Program over 6 years. Approximately $1.8
billion has been apportioned among the States
based on the severity of ozone pollution and the
number of people affected. During FY 1992, $340
million was obligated under the CMAQ Program,
more than 50 percent of which was assigned to
transit capital projects and about 40 percent for
highway purposes (including HOV lanes, traffic
surveillance and incident management, and signal-
ization and intersection improvements). (See Figure
7.) Other typical projects and programs included:
• establishment of inspection and maintenance
programs,
• projects to enhance pedestrian and bicycle
transportation,
• ridesharing programs, and
• park-and-ride lots.
As noted above, the CMAQ Program has clearly
been the most utilized source of flexible funds under
ISTEA to date, based on FY 1992 obligations. By
contrast, the nationwide total of STP funds which
States made available for transit use was only $24
million, or about 0.5 percent of the total STP funds
available in FY 1992. Thus, at least during the first
year of the current authorization, the STP program
was generally used for traditional highway projects,
while the CMAQ Program provided the great bulk of
Title I funds that were put to transit use.
The CMAQ Program is tightly focused on the need
to bring nonattainment areas into attainment, but
each State receives a minimum apportionment of at
CMAQ Obligations by Type of Project
(FY1992)
Ped./Bike 0.03%
Transit 57.76%
Highway/Road 40.40%
Other 1.80%
Figure 7
26
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least 0.5 percent of each year's authorization.
Twenty-six States, the District of Columbia, and
Puerto Rico received the minimum apportionment
specified by law (almost $9 million each so far).
Thirteen of these have no ozone or carbon monoxide
nonattainment areas and may, therefore, spend the
funds on any project eligible under either the
CMAQ or STP Program. Only 24 States receive
more than the minimum apportionment because of
their air quality problems. Due to the statutory ap-
portionment formula, which gives added weight to
the more seriously polluted nonattainment areas,
these States received 86 percent of all the CMAQ
Program funds distributed thus far.
The States have been slow to obligate their avail-
able funds. In FY 1992, approximately $340 million
was obligated for programs and projects, represent-
ing a 42-percent obligation rate. The low obligation
rate is due to the fact that the program breaks new
ground, and initially nonattainment areas strug-
gled with how to best use the funds. As States and
MPOs become more familiar with the program gen-
erally—and specifically, DOT guidance on project
eligibility—and the needed coordination is fostered
between transportation and air quality agencies,
the obligation rate is expected to increase. Further-
more, as TCMs are included in SIPs which are sub-
sequently approved by EPA, the demand for CMAQ
funds will increase, also raising the obligation rate.
B. Limited CAA Funds Exist for Air
Quality Operations and Management
Four sections of CAA allow the EPA Administrator
to provide funding to State and local governments,
and other public and private groups and individuals:
• Section 103 - provides grants for research and
demonstrations relating to the causes, effects,
and control of air pollution.
• Section 105 - provides grants for general air pol-
lution mitigation. For FY 1993, $94.1 million
was allocated for Section 103,105, and 106 pro-
grams.
• Section 106 - provides for the development of
interstate air quality agencies or commissions.
• Section 175 - provides funds for developing a
plan revision. Although authorized, no appro-
priations have been made under Section 175.
Two additional EPA programs are designed specifi-
cally to reduce mobile source emissions: The CAA
Increments Program and Selected National Priori-
ties program. The CAA Increments Program sets
aside $9.0 million (FY 1993) for program develop-
ment of I/M programs, Stage II regulations, plan-
ning studies, enhanced monitoring activities, and
public outreach. The Selected National Priorities
Program was allocated $1.8 million for emission re-
duction demonstration projects based on market
and other initiatives.
C. Regulations and Guidance
Implementing CAA and ISTEA
Have Been Issued
1. CAA Regulations and Guidance
This summarizes the status of EPA and DOT ef-
forts to implement the transportation-related CAA
requirements. Regulations and guidance in several
areas are covered below, including: transportation
conformity, transportation control measures, VMT
forecasting and tracking guidance, transportation
and air quality planning guidelines, motor vehicle
inspection and maintenance, mobile source model-
ing, clean fuel fleet programs, and other related
provisions.
1.a. Transportation Conformity
CAA requires that the Federal Government shall
not support or approve any activity which does not
conform to an approved SIP. No metropolitan plan-
ning organization (MPO) shall approve any trans-
portation plan, program, or project which does not
conform to the applicable implementation plan.
The assurance of conformity is an affirmative re-
sponsibility of DOT and the affected MPO.
They also require EPA to publish regulations, with
the concurrence of DOT, which lay out the criteria
and procedures for determining conformity of trans-
portation plans, programs and projects that are de-
veloped, funded, or approved under Title 23 of the
United States Code (USC) or the Federal Transit
Act. Interim guidance was distributed on June 7,
1991. A notice of proposed rulemaking (NPRM)
was published in the Federal Register on January
11,1993. The final rule is expected to be promul-
gated by October 1993.
27
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1 .b. Transportation Control Measures
CAA requires EPA, in consultation with DOT, to
publish guidance on updated information on 16
broadly defined TCMs. The Agency has pro-
duced a group of documents to satisfy the afore-
mentioned CAA requirements, including the
Transportation Control Measure Information
Documents and the Transportation Control Mea-
sure: State Implementation Plan Guidance. The
availability of these documents was announced
on May 29, 1992. These documents are designed
to assist State and local officials in planning and
evaluating transportation control measures. In-
formation is provided through discussions of im-
plementation issues, variations of measures, de-
gree of effectiveness, and institutional processes.
More quantitative information is provided on
current methods, strategies, and variables for
making estimates on how transportation control
measures affect the number of vehicle trips, ve-
hicle miles traveled, and vehicle speed.
EPA is currently working on several documents
to augment the guidance listed above, including
information on the estimation of emission and
travel activity effects of TCMs expected in 1993.
Guidance on the reduction of work-related trips,
titled the Employee Commute Options (ECO)
program, were issued in January 1993. Three
workshops were held in the spring of 1992 to
provide additional guidance. In addition, EPA,
DOT, and NARC are sponsoring additional TCM
analysis and information dissemination for State
and local governments.
1.c. VMT Forecasting
and Tracking Guidance
CAA requires EPA to publish guidance, in con-
sultation with DOT, on forecasting VMT. EPA
published the Section 187 VMT Forecasting and
Tracking Guidance on March 19,1992. This
guidance addresses how to forecast and track
VMT in moderate and serious CO nonattainment
areas with design values greater than 12.7 parts
per million (ppm). The guidance States that es-
timates of actual annual VMT in areas subject to
the Section 187 requirements should be obtained
from the Highway Performance Monitoring Sys-
tem (HPMS), maintained by DOT. The HPMS
VMT estimates will be used to track actual
VMT.
1 .d. Transportation and
Air Quality Planning Guidelines
CAA mandates that EPA update and publish the
1978 guidelines on Transportation and Air Quality
Planning, in consultation with DOT. EPA pub-
lished the updated 1992 Transportation and Air
Quality Planning Guidelines. This document is
designed to provide guidance to State and local
government officials and to assist them in planning
for transportation-related emissions reductions
that will contribute to the attainment and mainte-
nance of the NAAQS for ozone, CO, and PM-10.
The notice of availability for the Transportation
and Air Quality Planning Guidelines was pub-
lished in the Federal Register on August 18,1992.
I.e. Clean Fuel Fleet Programs
CAA requires the establishment of a program to re-
quire certain centrally fueled fleets to include some
clean fuel vehicles in their new vehicle purchases.
As defined in CAA:
'a clean alternative fuel' means any fuel (including
methanol, ethanol, or other alcohols (including any
mixture thereof containing 85 percent or more by
volume of such alcohol with gasoline or other fuels),
reformulated gasoline, diesel, natural gas, liquefied
petroleum gas, and hydrogen) or power source (in-
cluding electricity) used in a clean fuel vehicle that
complies with the standards and requirements ap-
plicable to such vehicle under this title when using
such fuel or power source.
Clean fuel vehicles will be required to meet strin-
gent emissions standards.
The Clean Fuel Fleet Programs involve two rule-
makings. The first establishes guidelines for a
Clean Fuel Fleet credit program, regulations for
governing transportation control measure exemp-
tions for Clean Fuel Fleet Vehicles, and provi-
sions affecting Federal Fleet Facilities. The sec-
ond rulemaking will include regulations govern-
ing the conversion of conventional vehicles to
meet the clean fuel standards for all vehicle/en-
gine classes, heavy duty engine standards, and
general provisions for State implementation of the
Clean Fuel Fleet program.
EPA issued an NPRM for TCM exemptions to the
Clean Fuel Fleet program on October 3,1991, and a
28
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final rule on March 1,1993. The rule specifies
which clean fuel vehicles are exempt from trans-
portation control measures, such as time-of-day and
HOV lane restrictions. Work on the second rule-
making, concerning emission and conversion re-
quirements, is underway but no forecast of a pro-
mulgation date has been released.
1.f. Mobile Source Emissions Modeling
Section 130 of CAA requires EPA to review and re-
vise the emission factors used to estimate the emis-
sions of CO, VOC, and NOx from mobile sources.
EPA has produced a series of computer programs
which incorporate emission factors known as the
MOBILE series.
In response to CAA, EPA announced the release of
MOBILE 4.1 on January 4,1991, and an updated
version MOBILE 5.0 on December 4,1992. This
updated model superseded all previous MOBILE se-
ries models. MOBILES will be used for all projec-
tion year ozone inventories, and for consistency,
1990 inventories in ozone areas will have to be rees-
timated with MOBILES also. It may also be used
for projection-year CO inventories.
1.g. Motor Vehicle Inspection
and Maintenance
Each State containing a moderate ozone nonattain-
ment area, and under certain conditions a margin-
al area, as well as certain CO nonattainment
areas, is required to submit a SIP revision, due
immediately after enactment of the 1990 CAA
amendments, that includes provisions necessary to
provide for a basic vehicle inspection and mainte-
nance program. Additionally, each State contain-
ing serious ozone nonattainment areas or high-
moderate CO nonattainment areas, or areas of
higher level classifications, is required to submit a
SIP revision to provide for an enhanced vehicle in-
spection and maintenance program for urban areas
of 200,000 or more within 2 years of the enactment
of the 1990 amendments. States with metropolitan
areas greater than 100,000 population in an Ozone
Transport Region must also submit SIP revisions
for this purpose.
CAA directs EPA to publish guidance for motor ve-
hicle inspection and maintenance programs within
12 months of enactment. EPA's guidance on vehicle
inspection and maintenance is required to include
information on the frequency of inspections, the
types of vehicles to be inspected, vehicle mainte-
nance required by owners and operators, audits by
the State, test methods and measures to include
whether testing is centralized or decentralized, in-
spection methods and procedures, quality of inspec-
tion components covered, assurance that a vehicle
under recall from a manufacturer has complied
with that notice, and effective implementation and
enforcement, including assurance that any vehicle
retesting after a failure shall include proof of cor-
rective action.
The language in CAA concerning the vehicle inspec-
tion and maintenance guidance is of a legally bind-
ing nature not often associated with guidance.
After consultation with EPA's Office of General
Counsel and after public hearing and comment,
EPA concluded that it was required to pursue a
rulemaking instead of the publication of guidance
for enhanced I/M programs.
EPA promulgated a rule for both basic and en-
hanced vehicle inspection and maintenance on No-
vember 5,1992.
1.h. New Bus Emission Standards
CAA contains several provisions relating to buses
which include: a new particulate matter stan-
dard, a requirement for retrofitting of 1993 and
earlier model year urban buses, and new require-
ments for an "in-use" urban bus test. In addition
to and associated with the bus programs, a re-
vised NOx standard for all 1998 and later year
heavy-duty engines is also contained in CAA.
EPA has responded to the aforementioned re-
quirements by pursuing two separate rulemak-
ings, a retrofit rule which was promulgated on
April 22, 1993, and a rule containing 1994 re-
quirements which was published in the Federal
Register on March 24,1993.
1 .i. Related Provisions
Preamble
General
EPA published the General Preamble for Title I of
CAA in the Federal Register on April 16,1992. This
document provides guidance to States on how to
prepare SIPs that comply with CAA provisions re-
lating to the attainment of the NAAQS. It address-
es State submittals under Title I due during the
first 6 years after enactment.
29
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2. ISTEA Regulations and Guidance
The following section provides the status of DOT
regulations and guidance relating to air quality.
2.a. Procedures for Flexible Funding
FHWA and FTA released procedures which govern
the use of STP and Interstate Substitution-High-
ways Program funds for transit projects, and the
use of FTA Section 9 Program funds for highway
projects in March 1992. This was followed in July
1992 by the publication of procedures for using
CMAQ funds for transit programs and projects.
2.b. CMAQ Guidance
FHWA and FTA issued interim guidance on the
CMAQ program in February 1992 and comprehen-
sive guidance in October 1992. The guidance States
that TCMs contained in the SIPs have the highest
priority for CMAQ funding. In addition, the guid-
ance clarifies what is eligible under CMAQ and em-
phasizes the need for cooperation among Federal,
State, and local governments and agencies in decid-
ing which projects to fund under the CMAQ pro-
gram.
2.c. Metropolitan and Statewide Planning
Regulations
FHWA and FTA issued interim guidance on
ISTEA's new metropolitan planning requirements
in April 1992. This guidance covers several issues
related to CAA compliance such as the need for a
coordinated approach on regional emissions analy-
sis. Additionally, the guidance requires that pro-
jects covering the first 3 years of the TIP be priori-
tized. An NPRM for the metropolitan planning reg-
ulation was published on March 2,1993, along with
an NPRM for statewide planning. The comment pe-
riod closed on May 3. A final rule is being devel-
oped and is expected to be issued in late summer
1993.
2.d. Management Systems Regulations
ISTEA requires DOT to issue regulations on the
State of development and implementation of sys-
tems for managing: (1) pavement of Federal-aid
highways, (2) bridges on and off Federal-aid high-
ways, (3) highway safety, (4) traffic congestion, (5)
public transportation facilities and equipment, and
(6) intermodal facilities and systems. Three of the
management systems (traffic congestion, public
transportation, and intermodal) relate to air quality
considerations. ISTEA requires that the results of
these management systems be considered in mak-
ing project selection decisions under Title 23 of the
United States Code and the Federal Transit Act.
FHWA and FTA published an NPRM in the Federal
Register on March 2,1993. It requires States to im-
plement the aforementioned management systems
by FY1995. The NPRM would require identifica-
tion of areas where congestion occurs and its caus-
es, evaluation of strategies to manage it, and rec-
ommended congestion reduction strategies. In the
NPRM, priority is given to measures which both re-
duce SOV travel and improve the efficiency of the
existing system. Issuance of a final rule is expected
by late summer 1993.
The public transportation management system pro-
poses a system of data collection on the age, condi-
tion, useful life, and replacement value of transit fa-
cilities and equipment as the basis for choosing the
most cost-effective strategies for providing and
maintaining transit assets. The proposal envisions
an ongoing process of assessing the conditions of
the assets of a transit system in order to identify
the areas of greatest need.
The current proposal of the intermodal manage-
ment system requires the identification of inter-
modal facilities and the use of efficiency measures
to gauge the performance of facilities and the sys-
tem as a whole. Data collection at both the project
and system level would be necessary to evaluate
what measures or actions will promote maximum
connectivity and more efficient linkages across the
air, water, and various land-based transportation
systems.
2.e. Congestion Pricing Pilot Program
In May 1992, FHWA published a Federal Register
Notice announcing a congestion pricing pilot pro-
gram, administered by FHWA, and designed for the
establishment, maintenance, and monitoring of con-
gestion pricing projects. FHWA published a. second
Federal Register Notice on November 24,1992,
which formally solicited proposals and outlined
evaluation and rating criteria. Competing propos-
als received by the close of the proposal period on
January 25,1993, are being evaluated and rated by
30
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Table 5
A Summary of Current Guidance/Regulations and Other
Documents Published in Fulfillment of ISTEA and CAA
Act
CAA
CAA
CAA
ISTEA
ISTEA
ISTEA
CAA
CAA
ISTEA
ISTEA
CAA
CAA
CAA
CAA
CAA
CAA
Subject
Bus Emission Standards (Retrofit)
Bus Emission Standards (1994 Reqs.)
Employee Commute Options Guidance
Metropolitan Planning NPRM
Statewide Planning NPRM
Management Systems NPRM
TCM Exemptions to Clean Fuel Programs
Conformity NPRM
CMAQ Program Guidance (issued 10/16/92)
Congestion Pricing Program
Inspection and Maintenance Rule
Sanction NPRM (Section 110(m))
1992 Transportation and Air Quality Guidelines
TCM Information Guidance
Title I/General Preamble
VMT Forecasting Guidance
Date
4/22/93
3/24/93
3/1 2/93
3/2/93
3/2/93
3/2/93
3/1/93
1/11/93
1/4/93
11/24/92
11/5/92
9/28/92
8/18/92
5/29/92
4/16/92
3/19/92
FR Notice
58 FR 21 359
58 FR 15781
58 FR 13596
58 FR 1 2064
58 FR 12084
58 FR 1 2096
58 FR 11 888
58 FR 3768
58 FR 128
57 FR 55293
57 FR 52950
57 FR 44534
57 FR 371 62
57 FR 22746
57 FR 13498
57 FR 9549
an interagency review committee. A second solici-
tation could take place, should the initial period re-
sult in fewer than the five cooperative agreements
permitted under ISTEA.
D. SIP Development, Revisions, and
EPA Approvals Are Proceeding
This section describes the status of transportation-
related SIP submittals under CAA. A SIP is a
legally enforceable document submitted by the Gov-
ernor or designee consisting of rules and regula-
tions demonstrating attainment of the NAAQS by
the dates set forth in the Act. States are required
to submit SIP revisions at specified points between
1991 and 1994 to meet specific clean air require-
ments. EPA expects States to have submitted fully
adopted, technically and administratively complete
SIPs and SIP elements by the required due dates.
In a limited number of circumstances, EPA may ac-
cept "committal SIPs" in lieu of a fully adopted SIP
which consists of a commitment by the State to
adopt specific enforceable measures within 1 year of
the promulgation of EPA's conditional approval of
the commitment.
If a State fails to make a SIP submittal by the due
date, EPA must make a finding of failure to submit
a SIP, or an element of a SIP. If a finding is made,
it will start the 18-month clock for purposes of im-
posing one of two sanctions provided for in section
179(b) of CAA. This action also activates the 24-
month period for Federal Implementation Plan
(FIP) promulgation.
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1. SIP Revisions for "Reasonably
Available Control Technology"
(RACT)
States were required to submit SIP revisions in
May 1991 that demonstrate their plans to imple-
ment emission control technology on existing sta-
tionary sources that are acceptable to EPA. These
revisions are noted in this report because of the po-
tential for the imposition of highway sanctions (see
below). EPA published its finding that 12 areas in
5 States had failed to adequately comply with the
RACT SIP revisions in the Federal Register on Oc-
tober 22,1991. EPA has a nondiscretionary duty to
apply sanctions to any of the 12 areas which had
not submitted complete and acceptable SIPs before
April 22,1993. State efforts are underway to cor-
rect deficiencies in SIP submittals even while ad-
ministrative procedures are put in place to impose
sanctions.
2. PM-10 SIP Revisions
The first of the mobile source SIP revisions was due
on November 15,1991, in which States were re-
quired to demonstrate how they will reach attain-
ment for PM-10 by December 31,1994. Sixty-seven
areas were required to submit SIP revisions. Forty
SIPs were submitted on time; 27 were not. During
1992, eight additional SIPs were submitted. Of the
remaining 19 areas, 3 were incomplete and 16 were
missing. Sanctions are required to be imposed on
the 16 areas after June 15,1993. Sanctions will be
due in one area submitting an incomplete SIP in
September 1993, and the last two in November
1993,
3. Ozone and CO SIP Submittals
Required on November 15,1992
CAA also required certain SIP submittals for ozone
and CO nonattainment areas by November 15,
1992. Ozone and carbon monoxide SIPs that have
met the November 15,1992, submittal deadline
have undergone a review to determine the com-
pleteness of both the SIP elements and the entire
SIP, Letters of failure to submit a SIP element or
an entire SIP were sent from the EPA Regions to 33
States, the District of Columbia, and Puerto Rico on
January 15,1993.
In the aforementioned letters, EPA summarized the
findings. In general terms, if a State failed to sub-
mit any plan elements, the letter identified the
nonattainment areas for which the State did not
make a submittal, identified the specific require-
ments that were not met, and made a finding of
State failure to submit a required plan or plan ele-
ment. The letters also explained the statutory con-
sequences of failure to make a submittal, and the
statutory consequences of EPA disapproval of any
submittal. These letters start the 18-month sanc-
tions clock and the 2-year FIP clock. The number of
States receiving a letter for failure to submit a SIP
is shown in Table 6. They have until July 15,1994,
before sanctions are due to be imposed.
Table 6
Number of States Failing to Meet
11/15/92 SIP Submittals
Required SIP Submittal Finding
Emission Inventory
- Ozone
- Carbon Monoxide
Basic I/M Program
Enhanced I/M Program
Stage II vapor recovery program
TCMs to offset growth in emissions
Employee Commute Options (ECO)
program
Contingency Measures
Oxygenated Fuels
of Failure
to Submit
4 States
5 States
7 States
3 States
10 States
4 States
8 States
6 States
2 States
4. Future SIP Revisions
By November 15,1993, States with moderate ozone
nonattainment areas must submit SIP revisions
that demonstrate emission reductions of at least 15
percent in the first 6 years for volatile organic com-
pounds (VOC) and attainment demonstration SIPs.
By November 15,1994, serious, severe, and ex-
treme ozone areas must submit SIP revisions that
demonstrate VOC reductions that average 3 per-
cent per year each consecutive 3-year period after
the initial 6-year period and attainment demon-
stration SIPs.
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5. Sanctions
Under Section 179(a) of CAA, EPA must impose
sanctions on any State which fails to submit a
SIP or a portion of a SIP. Under Section 179(a),
EPA must impose sanctions 18 months after it
makes a finding of a missing, incomplete, or in-
adequate SIP for the purpose of ensuring that
the requirements of the Act are met. In unusual
circumstances EPA may be able to impose sanc-
tions earlier than at the end of the 18-month pe-
riod under Section 110(m). EPA published a
proposed rule in the Federal Register on Septem-
ber 28,1992, explaining the criteria for sanction
determinations. A final rule is expected in late
1993.
One of two sanctions is applied to States not
meeting the relevant CAA requirements: sanc-
tions on Federal highway funds or sanctions on
new stationary source emissions ("2:1 offsets").
If highway sanctions are applied, no Federal
highway funds, with some exceptions, may be
obligated for projects in the area failing to meet
SIP submission requirements. Nine categories,
describing projects largely related to TCMs and
safety, are exempt from sanctions. After 24
months following the SIP submittal deadline,
EPA can impose highway sanctions statewide.
If 2:1 offset sanctions are imposed, EPA requires
a 2-ton emission reduction for each ton of emis-
sions coming from new or modified stationary
sources that increase emissions in the area. If
the deficiency has not been corrected within 24
months, EPA must impose both sanctions.
As of March 1993, EPA had notified 37 States
that they had failed to meet deadlines for sub-
mittal of various CAA requirements and are
under threat of sanctions. Sanctions were due
in five States as of April 22, 1993.
For EPA to impose sanctions, EPA must select
whether the highway sanction or the general off-
set ratio sanction will be applied first. EPA has
determined that this selection is a rule under
the Administrative Procedures Act, which
means EPA must propose and allow the public
to comment on its selection. Sanctions will
begin to apply in the affected areas when EPA
completes this selection rulemaking.
E Transportation Plans, TIPs, and
Conformity Determinations Are
Also Proceeding
Enactment of CAA and ISTEA significantly
changed the way Transportation Plans and TIPs
are developed in nonattainment areas. Where pre-
viously they were developed primarily to address a
region's mobility needs, now these Plans and TIPs
must also contribute to improvements in air quality
in nonattainment areas.
This section describes the status of Plan and TIP
development in nonattainment areas since enact-
ment of CAA and ISTEA. This section also summa-
rizes conformity determinations made on TIPs by
MPOs and DOT.
1. Plan and TIP Development
Based on a survey of MPOs done under the aus-
pices of NARC in September 1992, most nonattain-
ment areas are in the process of developing trans-
portation strategies to improve air quality. These
strategies can include various projects and pro-
grams to reduce emissions, including transporta-
tion control measures. However, development and
implementation of new strategies to improve air
quality are still in their early stages, particularly
in ozone areas. This is understandable because
MPOs in nonattainment areas are not expected to
update their Transportation Plans until later this
year (October 1993), and further SIP revisions are
not required until November 1993 and 1994. As
such, not many MPOs have as yet incorporated
these TCMs into their Plans, TIPs, or transporta-
tion elements of SIPs.
The overwhelming majority of MPOs in ozone
nonattainment areas are currently developing new
strategies (and TCMs where necessary) to address
their air quality needs. Over 90 percent of the sam-
pled MPOs in areas designated as moderate and
above are developing transportation measures to
improve their air quality. Even those MPOs in
areas with less critical air quality problems are de-
veloping transportation/air quality plans. In areas
designated as marginal, approximately 76 percent
of the MPOs report that TCM development is un-
derway, even though marginal areas are expected
to reach attainment largely through fleet turnover.
33
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Once transportation projects to improve air quality
have been developed and determined to be appropri-
ate from an effectiveness and financial standpoint,
they are included in the SIP (in areas where TCMs
are necessary) and specifically identified. CAA re-
quires these TCMs to receive priority consideration
and expeditious implementation. While MPOs are
required to only include FHWA/FTA-funded or -ap-
proved projects in their Plans and TIPs, the status of
all SIP transportation control measures is covered in
the TIP submission because of the need to demon-
strate expeditious implementation of TCMs in mak-
ing conformity determinations on Plans and TIPs.
Despite the large proportion of nonattainment area
MPOs seeking ways to effectively reduce emissions,
so far only a small proportion report that they have
incorporated any transportation measures devel-
oped as a part of this process into the Plan (25 per-
cent) or TIP (37 percent). Some of the reasons for
this relatively low percentage are that either SIPs
have not been completed or EPA has not yet ap-
proved them; or SIPs may address air quality needs
through strategies solely targeting stationary or
area sources; or mobile source reductions may be
achieved through technological means rather than
transportation programs, and SIPs would not neces-
sarily include specific TCMs that would be included
in the Plans and TIPs. On the other hand, if emis-
sion reductions from transportation projects and
programs are a part of their strategies, these efforts
will most likely be included in Plans and TIPs.
2. Conformity Determinations
The conformity provisions of CAA will be the most
challenging for transportation planners. Conformity
provisions were first added to the Clean Air Act by
Section 176(c) of the Act as amended in 1977. This
section makes it the affirmative responsibility of the
Federal agency supporting an action to ensure that
its activities conform to an approved or promulgated
air quality implementation plan. It also prohibits the
MPO from approving any transportation plan, pro-
gram, or project which does not conform to such a plan.
To ensure continuing conformity between transporta-
tion plans and programs and SIPs, CAA requires
that conformity determinations be made no less fre-
quently than every 3 years. The actual frequency
rate will be established by the EPA conformity regu-
lation. A conforming plan or program must be con-
sistent with the area's emissions budget, not cause,
create, or worsen violations, not obstruct attainment,
and demonstrate timely TCM implementation.
At the project level, the following four conditions
need to be demonstrated in order to make a confor-
mity determination:
• The project must come from a conforming Plan
and TIP;
• the design concept and scope of the project
should not have changed significantly since the
Plan and TIP were found to conform;
• the design concept and scope of the project must
be sufficiently developed to determine emissions
at the time of the conformity determination for
the TIP; and
• in CO and PM-10 nonattainment areas, the
project must not create or worsen hot spot
violations.
CAA allows a case-by-case conformity determina-
tion for projects not coming from a Plan and TIP.
Most State agencies and MPOs in nonattainment
areas have now been through two rounds of con-
formity determinations under CAA. Most of these
agencies spent a considerable amount of staff re-
sources and funds to complete the required analy-
sis; and some are currently under a threat of liti-
gation by environmental groups that see the con-
formity process as a means of forcing a change in
the transportation decisionmaking process.
In most areas, the conformity requirement has
made a major difference in the development and ac-
ceptance of Transportation Plans and TIPs. This
has occurred in various ways, and can be best illus-
trated by the following examples.
• FHWA and FTA withheld acceptance of certain
TIPs from the Great Lakes area for 4 months
until the public had the opportunity to comment
on them and the MPOs responded. Future im-
provements in MPO modeling and technical
process was also a condition for TIP acceptance
in these nonattainment areas.
• In several Midwest areas, only the "neutral"
projects within the TIPs were found to be in con-
formity. Neutral projects are defined as those
with minimal air quality impacts and can pro-
ceed without a conformity analysis. MPOs in
these areas were required to improve their mod-
34
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els used to make conformity determinations. In
other areas in Ohio and Indiana, for example,
MPOs themselves submitted TIPs composed
only of neutral projects while they adjusted to
the new analysis requirements.
• In the Southeast and Northwest parts of the
country, highway projects were delayed until
the TIP containing the conformity analysis was
completed. In some cases, this meant that pro-
jects were withheld from the statewide TIP
until a TIP conformity analysis was completed.
• One area in the Southwest reported that innova-
tive projects contributing to improved air quality
have been accelerated as a result of the confor-
mity requirements.
Throughout the United States, MPOs report that
they have had to drop or delay projects previously
scheduled for implementation to meet the confor-
mity requirements. The impact of this is that
most plan and TIP amendments now consist of
only neutral projects due to the constraints of this
complex process.
Due to the working relationship that exists among
DOT, the States, and MPOs, no nonconformity de-
terminations have been made to date. In their an-
alytical processes, the MPOs themselves alleviate
most potential nonconformity situations prior to
formal submission to Federal agencies. In addi-
tion, informal Federal review of Plan and TIP de-
velopment typically avoids the inclusion of pro-
jects failing to meet the conformity test.
35
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IV. CONCLUSIONS
CAA together with ISTEA calls for significant
changes in the way we go about meeting trans-
portation and air quality goals. CAA seeks to re-
duce vehicle emissions through a combination of
cleaner vehicles, cleaner fuels, and transportation
programs and projects to help achieve national air
quality goals. Transportation control measures
may play a role in many State air quality imple-
mentation plans. The requirements to determine
conformity of transportation plans, programs and
projects to State air quality plans dictate considera-
tion of air quality concerns in transportation plan-
ning and project development.
The ISTEA complements the Clean Air Act by giv-
ing State and local transportation officials the flexi-
bility to use Federal transportation funds in ways
that will help develop a balanced, environmentally
sound, intermodal transportation system. ISTEA
increases the emphasis on multimodal considera-
tions, land use decisions, and air quality problems
in the transportation planning process and on pub-
lic participation in transportation planning. New
ISTEA programs, such as the Congestion Mitiga-
tion and Air Quality Improvement Program, were
established to help fund transportation control
measures and other projects intended to help meet
standards in air quality nonattainment areas.
Other programs such as the congestion pricing pilot
program may also offer air quality benefits, al-
though the details of implementing these projects
remain to be worked out.
These two statutes together call for fundamental
changes in the transportation and air quality plan-
ning processes. It is too early to judge the extent to
which the intended process changes have occurred.
Transportation agencies are just beginning to take
advantage of the flexibility and new programs of-
fered by ISTEA. New players in the transportation
planning process are just beginning to become in-
volved in many areas. Development of State air
quality implementation plans will continue for
ozone and other pollutants at least until late 1994.
Because we are still assessing how transportation
and air quality agencies are responding to CAA and
ISTEA, this report does not offer conclusions on
how well new programs and requirements are
working. Legislative recommendations are not of-
fered at this time. But tremendous challenges re-
main to be met in responding to these new require-
ments, including the following:
• Mobile source emissions have decreased consid-
erably since the early 1970s due to the improve-
ments in automobile technology, but future
long-term reductions are in doubt. Transporta-
tion trends show increasing VMT, while shared
rides and transit are decreasing. VMT increases
could counteract important progress made over
the last 10 years in producing cleaner vehicles
and retard attainment efforts.
• Traditional methods of altering transportation
behavior such as construction of transit and
high occupancy vehicle lanes have not been
shown to substantially reduce pollution. Pre-
liminary indications from several areas in the
country show that traditional transportation
control measures alone will only yield a 1- to 2-
percent reduction in air pollutant emissions.
Significant potential for further progress can
also be made through technological improve-
ments by reducing cold start, tailpipe, and evap-
orative emissions.
Substantial changes in the level of TCM effec-
tiveness will need to offer a comprehensive pro-
gram of TCMs, including both the traditional
TCMs and economic/marketing based TCMs
such as congestion/road pricing, increases in
parking prices, and emissions or VMT charges.
Such a comprehensive program would need to
combine transportation choices and measures to
discourage trips in single-occupant vehicles.
• The complex requirements of CAA and ISTEA
have increased the burdens on staffs of local
transportation and air quality agencies, as well
as Federal agencies, and increased the complexi-
ty of issues which need to be considered by deci-
sionmakers.
• Transportation and air quality modeling tools
need to be upgraded to be useful in meeting
these increased requirements.
• Our knowledge of the interrelationships among
land use, economics, demography, and trans-
portation is still developing, but the reciprocal
interaction of two factors seems to be a signifi-
cant driving force. Land use densities and trav-
37
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el costs have decreased simultaneously across
the country. Even as lower densities increased
reliance on the auto, real decreases in the cost of
driving and travel subsidies caused further den-
sity decreases. The resulting growth in travel
produced increases in emissions (prior to the in-
troduction of tailpipe standards). Because both
economics and development patterns contributed
to our current pollution levels, changes in both
may be necessary for improvements in air quali-
ty. These will require a sustained effort over
many years and will take meaningful land man-
agement policies at the local level.
Progress is being made in addressing these chal-
lenges, but substantial continued efforts are
needed.
DOT and EPA are working with groups like the
National Association of Regional Councils and
the Surface Transportation Policy Project to ed-
ucate State and local agencies on the provisions
of the acts through the NARC Clean Air Project
and the STPP Livable Communities confer-
ences. These organizations are also involved in
helping to develop new coordination and public
involvement processes in transportation and air
quality planning. Continuation of these efforts
will be important.
• DOT and EPA are working to develop and dis-
tribute guidance to assist areas in meeting the
new requirements. Guidance has been issued,
but some important regulations have not yet
been finalized.
While future success depends on our response to
the challenges facing us, significant progress has
been made. EPA's Air Quality Trends Report for
1991 showed that 41 of the 97 nonattainment areas
for ozone and 13 of the 42 areas for CO have met
the standards for the last 3 years. Smog decreased
by 8 percent, and CO levels are down 30 percent, al-
though not all areas have demonstrated such im-
provements and some new nonattainment areas are
appearing, especially for PM-10. Major reductions
in vehicle emissions have been made, and further
reductions continue as fleet turnover occurs and
more stringent emissions standards come into ef-
fect. Implementation of basic and enhanced inspec-
tion and maintenance programs in many areas will
substantially assist this effort and reduce the dis-
proportionate impacts of gross emitters. Increasing
use of reformulated fuels, oxygenated fuels, fuel
with lower vapor pressure limits, and improve-
ments in alternative fuels will further reduce vehi-
cle emissions. All of these will make important con-
tributions to attainment of national ambient air
quality standards.
38
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References
• Antonioli, David L., "The Mass Transit Air Quality Link," John F. Kennedy School of Government, Har-
vard University, April 17,1992.
• Bae, Chang-Hee Christine, "Air Quality and Travel Behavior: Untying the Knot," Journal of the Ameri-
can Planning Association, Vol. 59, No. 1, Winter 1993.
• Bay Area Air Quality Management District, "Bay Area '91 Clean Air Plan," Volume II, Appendix F, Octo-
ber 1991.
• Clean Air Act Amendments of 1990, PL 101-549, November 15,1990.
• Dittmar, Hank, "Beyond Conformity: Transportation, Air Quality and Community Values," paper pre-
sented to the AASHTO Standing Committee on the Environment, Rapid City, SD, October 1992.
• Hartgen, David A., et al., "Nonattainment Areas Speak," University of North Carolina at Charlotte, re-
port prepared for the Federal Highway Administration, May 18,1993.
• Howitt, Arnold and Alan Altshuler, "The Challenges of Transportation and Clean Air Goals," John F.
Kennedy School of Government, Harvard University, report prepared for the US Department of Trans-
portation, October 1992.
• Intermodal Surface Transportation Efficiency Act of 1991, PL 102-240, December 18,1991.
• Kessler, Jon and William Schroeer, "Meeting Mobility and Air Quality Goals: Strategies that Work," Of-
fice of Policy Analysis, US Environmental Protection Agency, forthcoming in Transportation —An Inter-
national Journal.
• Lawson, D.R., et al., "Emissions from In-Use Motor Vehicles in Los Angeles: A Pilot Study of Remote
Sensing and the Inspection and Maintenance Program," Journal of the Air Quality and Waste Manage-
ment Association, Volume 40,1990.
• Loudon, William R. and Deborah A. Dagang, "Predicting the Impacts of Transportation Control Mea-
sures on Travel Behavior and Pollutant Emissions," JHK and Associates, paper presented to the 1992
meeting of the Transportation Research Board, January 1992.
• Lowe, Marcia D., Surface Transportation Policy Project Bulletin, Worldwatch Institute, October 1992.
• Metropolitan Washington Council of Governments, "Final Washington Metropolitan Air Quality Plan for
Control of Ozone and Carbon Monoxide," December 1982.
• Pierson, W. R., et al., "Comparison of the SCAQS Tunnel Study with Other On-Road Vehicle Emissions
Data," Journal of the Air Quality and Waste Management Association, Volume 40,1990.
• Shoup, Donald, "Cashing Out Employer-Paid Parking," Report FTA-CA-11-0035-92-1, December 1992.
• Shrouds, James M., "Challenges and Opportunities for Transportation: Implementation of the Clean Air
Act Amendments of 1990 and the Intermodal Surface Transportation Efficiency Act," Transportation in
the ISTEA Era, Institute of Transportation Engineers, Orlando FL, January 15,1993.
39
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• South Coast Air Quality Management District, "Air Quality Management Plan," Appendix IV-G, 1989.
• US Department of Transportation, Federal Highway Administration, "1990 National Personal Trans-
portation Survey," FHWA-PL-92-027, March 1992.
• US Department of Transportation, Federal Highway Administration, "Highway Statistics, 1991,"
FHWA-PL-92-025, October 1992.
• US Department of Transportation, Volpe National Transportation Systems Center, "NARC Survey
Analysis," forthcoming report prepared for the National Association of Regional Councils and the Feder-
al Highway Administration.
• US Environmental Protection Agency, "National Air Quality and Emissions Trends, 1991," October
1992.
• US General Accounting Office, "Reliability of EPA's Mobile Source Emissions Model Could be Improved,"
GAO/RCED 90-138, May 1990.
• US General Accounting Office, "Urban Transportation: Reducing Vehicle Emissions with Transporta-
tion Control Measures," GAO/RCED 93-169.
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Appendix A
CLEAN AIR ACT
SECTION 108(f)(3)
(3) The Secretary of Transportation and the [EPA] Administrator shall submit to Congress by January 1,
1993, and every 3 years thereafter a report that -
(A) reviews and analyzes existing State and local air quality-related transportation programs, including
specifically any analyses of whether adequate funding is available to complete transportation projects
identified in State implementation plans in the time required by applicable State implementation plans
and any Federal efforts to promote those programs;
(B) evaluates the extent to which the Department of Transportation's existing air quality-related trans-
portation programs and such Department's proposed budget will achieve the goals of and compliance
with this Act; and
(C) recommends what, if any, changes to such existing programs and proposed budget as well as any
statutory authority relating to air quality-related transportation programs that would improve the
achievement of the goals of and compliance with the Clean Air Act.
(4) In each report to Congress after the first report required under paragraph (3), the Secretary of Trans-
portation shall include a description of the actions taken to implement the changes recommended in the pre-
ceding report.
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Appendix B
SPECIFIC TRANSPORTATION-RELATED PROVISIONS
OF THE CLEAN AIR ACT AS AMENDED IN 1990
FOR OZO/VENONATTAINMENT AREA CLASSIFICATIONS
Marginal
- These areas exceed the ozone standard of .12 parts per million (ppm) by 15 percent or less (.121 ppm up
to .138 ppm), and are required to attain the standard within 3 years of enactment (11/15/93).
- Emission inventories are due within 2 years of enactment. Revised emission inventories are required at
the end of each 3-year period until attainment.
- These areas must correct existing or previously required inspection/maintenance (I/M) programs.
- These areas will be reclassified as moderate nonattainment areas if they fail to attain the standard by
the deadline (plus up to two 1-year available extensions).
Moderate
- These areas exceed the standard by 15 percent to 33 percent (.138 ppm to .160 ppm), and are required to
attain the standard in 6 years (11/15/96). Moderate areas must meet marginal area requirements.
- In addition to meeting marginal area requirements, moderate areas have to submit SIP revisions within
3 years of enactment demonstrating volatile organic compound (VOC) reductions, within 6 years of en-
actment of at least 15 percent from 1990 baseline emissions, while accounting for any growth in emis-
sions after enactment. (Additional requirements for major NOx sources apply in certain areas).
- Contingency measures to be implemented if the area fails to make reasonable further progress or attain
the NAAQS by the attainment date; these measures are to be included in the SIP and are to take effect
without further action by the State or EPA.
- These areas must adopt basic I/M programs.
- These areas will be reclassified as serious nonattainment areas if they fail to attain the standard by the
deadline (plus up to two 1-year available extensions).
Serious
- These areas exceed the standard by 33 percent to 50 percent (.160 ppm to .180 ppm), and are required to
attain the standards in 9 years (11/15/99). Serious areas must meet moderate area requirements.
- In addition to meeting moderate area requirements, these areas have to submit SIP revisions within 4
years of enactment that demonstrate VOC reductions that average 3 percent per year each consecutive
3-year period beginning 6 years after enactment.
- These areas must submit SIP revisions within 42 months of enactment establishing clean-fuel vehicle
programs, mandating that certain percentages of new fleet vehicles be clean fuel vehicles and use clean
fuels within the nonattainment area, including measures to make the use of clean alternative fuels eco-
nomical to clean-fuel vehicle owners.
43
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- Beginning 6 years after enactment and each 3-year period thereafter, the State has to submit a demon-
stration as to whether vehicle emissions, congestion levels, vehicle miles traveled (VMT), and other rele-
vant parameters are consistent with those used in the SIP; if not the State has 18 months to submit SIP
revisions that include transportation control measures (TCMs) to reduce emissions to levels consistent with
SIP levels.
- In addition to the contingency provisions required under Section 172(c)(9), the SIP shall provide for im-
plementation of specific measures to be undertaken if the area fails to meet any applicable milestone.
- These areas must adopt enhanced I/M programs if the 1980 urban population exceeds 200,000.
- These areas will be reclassified as severe nonattainment areas if they fail to attain the standard by the
deadline (plus up to two 1-year available extensions).
Severe
- These areas exceed the standard by 50 percent to 133 percent (.180 ppm - .280 ppm). Areas with design
values from .180 - .189 ppm are required to attain the standards in 15 years (11/15/05). Areas with de-
sign values from .189 - .280 ppm are required to attain the standards in 17 years (11/15/2007). Severe
areas must meet serious area requirements.
- In addition to meeting serious area requirements, these areas must submit SIP revisions within 2 years
of enactment, which identify and adopt TCMs to offset growth in emissions from growth in trips or VMT.
- Within 2 years of enactment, SIP revisions are due that require employers of 100 or more to increase the
average passenger occupancy per vehicle for work trips by not less than 25 percent above the average for
all work trips in the area. The average vehicle occupancy for the nonattainment area needs to be estab-
lished at the time of the SIP submittal. The affected employers have to submit compliance plans within
2 years of the SIP revision (within 4 years of enactment) demonstrating compliance not later than 4
years after the revision (within 6 years of enactment).
- Severe areas which fail to attain the standard by the deadline are subject to mandatory fees on station-
ary emission sources and the more stringent new source review requirements applicable to extreme
areas.
Extreme
- The area exceeds the standard by more than 133 percent (.280 ppm and above), and has 20 years to at-
tain (11/15/2010).
- Extreme areas must meet severe area requirements.
- In addition to meeting severe area requirements, each SIP revision may contain measures to reduce the
use of high polluting vehicles or heavy-duty vehicles during heavy traffic hours.
- Extreme areas which fail to attain the standard by the deadline must submit a SIP revision within
9 months to implement a program of economic incentives and transportation controls.
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Appendix C
TRANSPORTATION-RELATED PROVISIONS
OF THE CLEAN AIR ACT AS AMENDED IN 1990
FOR CARBON MONOXIDE (CO) NONATTAINMENT AREA CLASSIFICATIONS
Moderate
These areas exceed the 8-hour CO standard of 9 parts per million (ppm) by not more than 82 percent (9.1
ppm to 16.4 ppm), and are required to attain the standard by December 31,1995.
Emissions inventories are due within 2 years of enactment with revised inventories no later than Sep-
tember 30,1995, and no later than the end of each 3-year period thereafter until attainment.
States with CO nonattainment areas which have CO design values of 9.5 ppm and above based on 1988
and 1989 data, or for any 2-year period after 1989, must submit SIP revisions requiring any gasoline
sold in the metropolitan statistical area (MSA) or consolidated metropolitan statistical area (CMSA) to
contain not less than 2.7 percent oxygen by weight. This requirement must be in effect for not less than
4 months per year. Those areas with design values of 9.5 ppm or more on the date of enactment of CAA
must provide for the requirement to take effect no later than November 1,1992. Areas that reach the
design value after enactment must provide for the requirements to take effect no later than November 1,
of the third year after the 2-year period for which the design value is determined.
For those areas with design values above 12.7 ppm, State Implementation Plan (SIP) revisions (due no
later than 2 years of enactment) have to contain vehicle miles traveled (VMT) forecasts for each year
until the attainment date, based on the Environmental Protection Agency's guidance; SIPs have to pro-
vide for annual updates of forecasts, and annual reports regarding the forecast accuracy. SIPs must in-
clude contingency provisions to be undertaken if actual or projected VMT exceed the prior forecast.
These areas are required to correct existing or previously required inspection and maintenance (I/M) pro-
grams, with those areas with design values above 12.7 and a 1980 urban population greater than
200,000 being required to adopt enhanced I/M programs.
These areas will be reclassified as serious nonattainment areas if they fail to attain the standard by the
deadline (plus two 1-year available extensions).
Serious
These areas exceed the 8-hour CO standard by 83 percent or more (16.5 ppm and higher), and are re-
quired to attain by December 31, 2000. Winnebago and Steubenville-Weirton may apply for waivers
from mobile source controls, based on a determination, yet to be made, that mobile sources do not con-
tribute significantly to CO levels.
Serious areas have to meet the requirements for moderate areas with design values of 12.7 ppm or
greater.
In addition to meeting moderate area requirements, States with serious areas have to submit SIP revi-
sions within 2 years of enactment that include transportation control measures to reduce CO emissions
and offset emission increases from growth in VMT, employer trip reduction programs, and require the
seasonal use of oxygenated fuel for the MSA or CMSA, whichever is larger. The oxygen content must be
sufficient, in combination with other measures, to provide for attainment of the CO standard by the applic-
able attainment date. The oxygenated fuels requirement is to be in effect no later than October 1,1993.
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- Attainment demonstrations have to include annual emission reduction milestones; if the areas fail to
meet the milestones, a SIP revision to implement economic incentives and a transportation control pro-
gram is required.
While the relationship of the aforementioned SIP elements to transportation is not always well defined, sev-
eral programs requiring SIP revisions clearly have an impact upon transportation. For example, the confor-
mity provisions of CAA, which are part of a general movement towards considering social, economic, and
environmental goals in planning the transportation system, require that transportation plans and programs
ensure and support the SIP's goal of attaining the NAAQS. A more complete description of the conformity re-
quirements and the other transportation-related programs of CAA are contained in Section II of this report.
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Appendix D
TRANSPORTATION-RELATED PROVISIONS
OF THE CLEAN AIR ACT AS AMENDED IN 1990
FOR PM-70 NONATTAINMENT AREA CLASSIFICATION
Areas designated nonattainment for PM-10 and classified moderate, on November 15,1990, are required by
Section 189 of the amended act to submit a SIP no later than November 15,1991. Among other require-
ments, this SIP must include the following two elements:
1) Either a demonstration that the plan will provide for attainment on or before December 31,1994, or
a demonstration that attainment by that date is impractical.
2) Provisions to assure that reasonably available control measures (RACM) for the control of PM-10 are
implemented by December 10,1993.
Areas designated nonattainment for PM-10 after November 1990 must submit a SIP within 18 months after
being designated nonattainment. States with a moderate nonattainment area are required to submit a plan
that includes, among other provisions, a demonstration of attainment, quantitative milestones, and provi-
sions to guarantee that RACM are implemented. Specific requirements are set forth in subparts 1 and 4 of
TitlelofCAA.
Serious Areas
The Administrator of the EPA may classify as a serious PM-10 nonattainment area any moderate PM-10
nonattainment area that the Administrator determines cannot practicably attain the NAAQS for PM-10 by
the attainment date or if the Administrator finds that the area has failed to attain the standard. Once re-
classified as a Serious PM-10 nonattainment area, the State must reach attainment of the NAAQS for PM-
10 as expeditiously as practicable but no later than the end of the 10th calendar year beginning after the
area's redesignation as nonattainment. However, areas designated nonattainment for PM-10 under Section
107(d)(4) of the Clean Air Act must reach attainment of the NAAQS for PM-10 by December 2001.
If a Serious PM-10 nonattainment areas fails to attain the NAAQS for PM-10 by the prescribed attainment
date, the State shall, after providing for both notice and an opportunity for public comment, submit within
12 months after the attainment date, a SIP revision which provides for attainment of the PM-10 NAAQS.
From the date of the SIP submission until attainment, the SIP shall provide for an annual reduction in PM-
10 or PM-10 precursor emissions of not less than 5 percent of the total amount of such emissions as reported
in the most recent inventory prepared for the area.
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Appendix E
TRANSPORTATION CONTROL MEASURES
FROM SECTION 108(f)(1) OF CAA
i programs for improved public transit;
ii restrictions of certain roads or lanes to, or construction of such roads or lanes for use by passenger
buses or high occupancy vehicles;
iii employer-based transportation management plans, including incentives;
iv trip reduction ordinances;
v traffic flow improvement programs that achieve emission reductions;
vi fringe and transportation corridor parking facilities serving multiple occupancy vehicle programs or
transit service;
vii programs to limit or restrict vehicle use in downtown areas or other areas of emission concentration
particularly during periods of peak use;
viii programs for the provision of all forms of high occupancy, shared-ride services;
ix programs to limit portions of road surfaces or certain sections of the metropolitan area to the use of
non-motorized vehicles or pedestrian use, both as to time and place;
x programs for secure bicycle storage facilities and other facilities, including bicycle lanes, for the conve-
nience and protection of bicyclists, in both public and private areas;
xi programs to control extended idling of vehicles;
xii programs to reduce motor vehicle emissions consistent with Title II, which are caused by extreme cold
start conditions;
xiii employer-sponsored programs to permit flexible work schedules;
xiv programs and ordinances to facilitate non-automobile travel, provision and utilization of mass transit,
and to generally reduce the need for single-occupant vehicle travel, as part of transportation planning
and development efforts of a locality, including programs and ordinances applicable to new shopping
centers, special events, and other centers of vehicle activity;
xv programs for new construction and major reconstruction of paths, tracks, or areas solely for use by
pedestrian or other non-motorized means of transportation when economically feasible and in the pub-
lic interest; and
xvi programs to encourage the voluntary removal from use and the marketplace of pre-1980 model year
light duty vehicles and pre-1980 light duty trucks.
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Appendix F
TRANSPORTATION AND EMISSIONS MODELING
Regional transportation models were originally developed for use in designing major capital investments in
urban highway facilities to accommodate anticipated growth in automobile travel. The modeling process
employs observed regularities in the patterns of household and business activity to make reliable inferences
about the volume, location, means, and timing of travel within an urban area, and to simulate the perfor-
mance of its transportation system in accommodating different volumes and patterns of travel.
Conducting an analysis of regional travel behavior and transportation system performance requires in-
formation describing the number and geographic distributions of households, businesses, and other ac-
tivity locations, as well as the demographic and economic characteristics of households and individuals,
and a detailed description of the spatial configuration and performance characteristics of the regional
transportation network. A complete set of these inputs is required for each period to be analyzed; thus
forecasts for each of these areas must be prepared for each future year under consideration. Analyzing
regional travel behavior and transportation system performance also requires an integrated set of models
and procedures for translating the spatial distributions and activity patterns of households and business-
es into regional travel demands, and for analyzing the interaction of these demands with the capacity of
the regional transportation system to accommodate them.
Regional travel demand analysis typically proceeds through a sequence of four modeling steps. In the
first of these (termed trip generation), the number of trips originating in and destined for each geograph-
ic zone in the region is calculated. Separate calculations are generally performed for different travel
purposes, such as commuting to work, shopping, or recreational travel.
The second step links the numbers of trip origins and destinations predicted for each zone into a specific
geographic pattern of travel volumes or origin-to-destination flows. Such "trip distribution" models typ-
ically represent the flow of trips between zones as a function of total zone trips, and some measure of
the "difficulty" in traveling between them, usually reflecting a combination of the time and cost entailed
in doing so.
In the third modeling step, the interzonal travel flows for each trip purpose are split among travel modes
(hence the term "mode split"), using information on the personal characteristics of travelers, as well as
on the comparative costs and performance (speed, frequency, etc.) of the available modes, and is used to
produce a total daily travel matrix by mode. Using external information, this can then be separated into
tables for each time period of interest, most commonly separate morning and evening peak travel peri-
ods and a single off-peak period.
In the final modeling step, the trip flows between zone pairs made by each travel mode during one of
these time periods are assigned (hence "traffic assignment") to routes or paths through a regional net-
work of transportation facilities. The regional automobile network is composed of interconnected road
and highway segments, while the transit network consists of individual routes and services, intercon-
nected at passenger transfer points. Assignment procedures generally assume that travelers choose
routes to minimize travel time. The traffic assignment process is usually conducted in stages, in an at-
tempt to simulate the diversion of travelers to alternate routes in response to congestion on preferred
routes.
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One major complication in the four-step modeling process arises from the fact that earlier modeling
stages—trip distribution and mode split—require as inputs the travel times between zone pairs that are
the final outputs of the fourth modeling step, traffic assignment. A common response to this interdepen-
dence is to estimate provisional interzonal travel times for use in those earlier stages, and then to repeat
those steps if the more definitive travel times calculated from the traffic assignment process differ signif-
icantly from provisional estimates. How many times to repeat this process is currently a matter of de-
bate.
An important product of the regional transportation modeling process for developing vehicle emission
estimates is an inventory of total travel by vehicle type for each time period included in the analysis.
Most traffic assignment models produce estimates of the number of vehicle miles traveled (VMT) on fa-
cilities represented in the regional network (such as major arterial streets, highways, and limited-access
expressways), together with estimates of the resulting average speed of travel on each type of facility. If
information regarding the typical mixes of automobiles and trucks utilizing different types of facilities at
different time periods within the day is available, or if parallel regional modeling processes are conduct-
ed for automobile and truck travel, separate estimates of VMT by type of vehicle and time period can
also be developed for each facility type. This information can be used in conjunction with a vehicle
emissions model to estimate total emissions generated by the calculated pattern of regional travel.
Vehicle emission models calculate the rates at which different pollutants are emitted per mile of travel
by various types of vehicles. These emissions include exhaust gases generated by operation of their in-
ternal combustion engines, and evaporative losses from their fuel systems occurring during vehicle oper-
ation, refueling, and storage. Two vehicle emission models are currently in widespread use, the EPA's
MOBILE model and the EMFAC model developed by the California Air Resources Board (CARB).
Vehicle emissions models consist of an extensive database of emissions of each pollutant per vehicle-
mile of travel measured under controlled operating and environmental conditions, together with proce-
dures for modifying these rates to reflect actual on-road operating conditions. Measured emission rates
differ among types of vehicles (passenger automobiles, light and heavy-duty trucks, and motorcycles),
as well as by model year and age, reflecting changes in new-vehicle emission standards and the increase
in emission rates that typically occurs with accumulated mileage. The MOBILE model uses measured
emission rates from a sample of vehicles run through the Federal Test Procedure (FTP).
Actual per-vehicle mile emission rates are calculated by adjusting these basic emission rates to reflect
differences between the test and actual conditions. These differences include tampering with emissions
control equipment, variation in driving patterns from those used to measure emissions rates, and air tem-
peratures different from that (75 degrees) at which emissions testing is conducted. Applying the appro-
priate correction factors to the basic emission rate produces an estimate of its actual exhaust emissions
rate in urban driving. Finally, evaporative hydrocarbon emissions from vehicles' fuel systems are added
to these tailpipe emission rates to determine total emissions per mile of operation. The resulting total
emission factors are supplemented with information on the age distribution and utilization of each type
of vehicle to estimate the average emissions per mile of each pollutant generated by the total number of
such vehicles operating in the urban area.
Total vehicle emissions are estimated by applying the per-mile vehicle rates (from emissions models) to
estimates of VMT. Separate contributions to total vehicle emissions can be estimated for different time
periods of the day, vehicle types, and transportation facilities.
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