Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration
Office of Planning, Environment, & Realty (HEP)

SAFETEA-LU Evaluation and Assessment Phase I

1. Introduction

Purpose of the Study

The Congestion Mitigation and Air Quality Improvement (CMAQ) Program provides funds to States for transportation projects designed to reduce traffic congestion and improve air quality, particularly in areas of the country that do not attain national air quality standards. Created by the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991, the program was reauthorized under the Transportation Equity Act for the 21st Century (TEA-21) in 1998 and again as part of the Safe, Accountable, Flexible, Efficient, Transportation Equity Act: A Legacy for Users (SAFETEA-LU) in 2005. From its beginning, the CMAQ program has been a key funding mechanism for helping urban areas meet air quality goals and supporting investments that encourage alternatives to driving alone and improve traffic flow. Since 1991, the Program has provided $22.7 billion in funding to States, metropolitan planning organizations (MPOs), and transit agencies to invest in projects that reduce criteria air pollutants regulated from transportation-related sources. The CMAQ program is also credited with gaining State and regional support for the mandates of the 1990 Clean Air Act Amendments (CAAA).1

In TEA-21, Congress funded a study to better understand the efficiency and effectiveness of the CMAQ program, which was undertaken by the Transportation Research Board (TRB). Building on this effort, the further reauthorization of the CMAQ program in Section 1808 of SAFETEA-LU requires the U.S. Department of Transportation, in consultation with the U.S. Environmental Protection Agency (EPA), to conduct an evaluation and assessment of a representative sample of CMAQ projects, for the purpose of: (A) determining their congestion and air quality benefits, and (B) ensuring effective implementation of the program. Moreover, SAFETEA-LU placed increased emphasis on funding cost-effective strategies, calling for States and MPOs to give priority in distributing funds to diesel retrofits and "cost-effective congestion mitigation activities that provide air quality benefits."2

The language of SAFETEA-LU Section 1808 requiring an evaluation and assessment of CMAQ projects is included below.

  1. (f) EVALUATION AND ASSESSMENT OF CMAQ PROJECTS. Section 149 of such title (as amended by subsection (e)) is amended by adding at the end the following:
    1. (1) IN GENERAL. The Secretary, in consultation with the Administrator of the Environmental Protection Agency, shall evaluate and assess a representative sample of projects funded under the congestion mitigation and air quality program to
      1. (A) determine the direct and indirect impact of the projects on air quality and congestion levels; and
      2. (B) ensure the effective implementation of the program.
    2. (2) DATABASE. Using appropriate assessments of projects funded under the congestion mitigation and air quality program and results from other research, the Secretary shall maintain and disseminate a cumulative database describing the impacts of the projects.
    3. (3) CONSIDERATION. The Secretary, in consultation with the Administrator, shall consider the recommendations and findings of the report submitted to Congress under section 1110(e) of the Transportation Equity Act for the 21st Century (112 Stat. 144), including recommendations and findings that would improve the operation and evaluation of the congestion mitigation and air quality improvement program.

This report is the first phase of a two phase effort being undertaken by FHWA, in consultation with EPA, in order to meet the requirements in Section 1808(f) of SAFETEA-LU. The purpose of this report is to examine the direct and indirect impacts of CMAQ-funded projects on air quality and congestion levels. This evaluation was conducted by gathering data reported in FHWA's national database of CMAQ projects, as well as additional background collected from States and MPOs to analyze the total annual costs (i.e., CMAQ and non-CMAQ funds), estimated annual emissions reductions, and congestion relief benefits for a small number of CMAQ funded projects. The report also contains an assessment of the air quality cost-effectiveness of these selected projects, and preliminary information on good practices being implemented by State DOTs and MPOs for prioritizing and selecting CMAQ projects. This preliminary information is followed by a Phase II report that involves case studies of a sample of State DOTs and MPOs to highlight approaches that advance the effective implementation of the program.

Context for the CMAQ Program

Any evaluation of CMAQ projects should recognize the magnitude of the air quality and congestion problems in the United States and have realistic expectations concerning the influence one program can have on reducing transportation-generated pollution and mitigating traffic congestion. Despite substantial progress in improving air quality nationally since the 1970s, over 100 million Americans still live in areas of the country that do not meet EPA's National Ambient Air Quality Standards for one or more pollutants. Traffic congestion is a growing problem affecting urban areas of all sizes, with congestion affecting more trips, over more hours of the day, on more roadways than in the past. According to Texas Transportation Institute's Urban Mobility Study, traffic congestion creates a $78 billion annual drain on the U.S. economy in the form of 4.2 billion lost hours and 2.9 billion gallons of wasted fuel.3

While the CMAQ program provides targeted resources to address the role of transportation in these air quality and congestion challenges, the resources provided by the CMAQ program are modest in comparison to the overall Federal transportation program. In total, SAFETEA-LU provides $286.4 billion in guaranteed funding for Federal surface transportation programs over five years through FY 2009. This includes $193.6 billion in Federal-aid Highway program authorizations and $52.6 billion for Federal transit programs, as well as other projects. The CMAQ program is authorized at $8.6 billion, or 4.4 percent of the total Federal-aid Highway program (three percent of the total Federal surface transportation program funding). Given other State and local sources of funding, which make up about half of all highway and transit capital expenditure and the majority of operating expenses, the Federal CMAQ program represents less than two percent of total transportation spending in many metropolitan areas.

A single major transportation infrastructure project in an urban area can cost more than $1 billion, and there are a number of major highway and transit projects being constructed across the U.S. that cost in the multiple billions of dollars. At an authorized level of approximately $1.7 billion per year under SAFETEA-LU, the CMAQ program which provides funding to all 50 States and the District of Columbia is not able to substantially "solve" the air quality or congestion problems facing metropolitan areas across the country. However, the incremental benefits of the program are an important part of the solution.

The CMAQ program provides funds that are targeted to areas of the country with the most severe air quality problems, which tend to be the largest metropolitan areas experiencing some of the worst traffic congestion. Many metropolitan areas rely on the CMAQ program as a flexible funding source to support a wide range of projects that improve air quality, reduce traffic congestion, and support a multi-modal transportation system, and as a mechanism to help fund air quality mandates under the Clean Air Act. CMAQ funded projects are often small in scale e.g., a bicycle path, a park-and-ride lot, a new transit shuttle service, or a traffic signalization improvement. Still, they may have important benefits at a corridor or local level, where the benefits of a single project can make a difference. CMAQ funds also are used to leverage other Federal and State and local funding sources, and to support regional efforts such as regional ridesharing programs, incident management programs, and traveler information systems.

Establishment of the CMAQ Program

The Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 was a landmark surface transportation Act which, for the first time, emphasized intermodalism - the seamless linking of highway, rail, bicycle, pedestrian, and other modes. The Act included provisions and new programs designed to address the Nation's growing transportation challenges, such as improving safety, reducing traffic congestion, improving efficiency in freight movement, increasing intermodal connectivity, and protecting the environment. ISTEA opened the transportation planning process to more public involvement than ever before, bringing new players to the table when decisions were being made and increasing collaboration among existing stakeholders. This diversity in transportation decision-making has resulted in additional positive benefits for communities, because transportation investment decisions are built upon input from transportation stakeholders and the general public.

ISTEA also made funding available to new kinds of programs, and established the Congestion Mitigation and Air Quality Improvement (CMAQ) program the first federally funded transportation program explicitly targeting air quality improvement. Approximately 4 percent of total funding for the 1992-1997 Federal surface transportation program, or $6 billion, was authorized for CMAQ projects that would offer alternatives to single occupant vehicle (SOV) travel, improve travel efficiency as a means of addressing traffic congestion, and promote cleaner motor vehicles in the Nation's most polluted areas.4

From its inception, the primary policy focus of the CMAQ program has been on air quality improvement, reflecting the requirements placed on the transportation sector by the Clean Air Act Amendments (CAAA) of 1990 to help meet national air quality goals. It provides flexible funding for States to use in nonattainment areas to help them address air quality concerns from transportation sources. Over time, the CMAQ program has become a key funding mechanism to support investments that not only help urban areas meet air quality goals, but also help focus transportation planning on a more inclusive, environmentally sensitive, and multimodal approach.

Apportionment and Eligible Projects

Federal CMAQ funds are apportioned annually to each State according to the severity of the air quality problem and the population of each nonattainment or maintenance county (based upon Census Bureau data).5 Each State is guaranteed a minimum apportionment of one-half percent of the year's total program funding, regardless of whether the State has any nonattainment or maintenance areas. These minimum apportionment funds can be used anywhere in the State for projects eligible for either CMAQ or the Surface Transportation Program (STP).

To be eligible for CMAQ funds, a project must be included in the MPO's current transportation plan and Transportation Improvement Program (TIP) (or the current Statewide TIP, or STIP in areas without an MPO).6 In nonattainment and maintenance areas, the project also must meet the conformity provisions contained in Section 176(c) of the Clean Air Act and the transportation conformity rule at 40 CFR Part 93. In general, there are three types of CMAQ eligible activities:7

The CMAQ Interim Program Guidance dated October 31, 2006 lists 16 categories of projects eligible for CMAQ funding, which FHWA has traditionally grouped into the following categories:

CMAQ-funded projects or programs must reduce CO, ozone precursor (NOx and VOCs), PM, or PM precursor (e.g., NOx) emissions from transportation.8 These reductions should contribute to the area's overall clean air strategy.9 The traditional Federal share for most eligible CMAQ projects has been 80 percent. However, some projects that also focus on safety efforts have been funded at 100 percent Federal share.10 More recently, the 2007 Energy Independence and Security Act provides the option of 100 percent Federal share for all CMAQ projects in FY 2008 and FY 2009.11

State DOTs and MPOs, the key agencies for transportation planning at the local and regional level, operate under broad guidance regarding project eligibility when they determine project selection and implementation decisions. Notwithstanding the statutory formula for determining the apportionment amount, the State may use its CMAQ funds in any ozone, CO, or PM nonattainment or maintenance area. States may do so according to local preference; there is no obligation to allocate CMAQ funds in the same way they are apportioned.

CMAQ projects are usually proposed and evaluated at the MPO level and then chosen at the State level using a variety of selection processes. To support a transparent, open process, MPOs, State DOTs, and transit agencies are encouraged to establish and make available a project selection process that clearly identifies the basis for selecting projects, including emissions benefits, cost effectiveness, and additional selection factors such as congestion relief, greenhouse gas reductions, safety, system preservation, access to opportunity, sustainable development and freight, reduced SOV reliance, multi-modal benefits, or other criteria. At a minimum, projects should be identified by year and proposed funding source.12

Required Emissions Analyses

The CMAQ statute includes emissions reduction as a requirement for CMAQ-invested projects or programs.13 Project sponsors must estimate the expected emissions reductions for projects funded under the program, with particular attention to the pollutants of concern in the project implementation area (CO, VOCs, NOx, PM2.5 and PM10).14 According to the Interim Program Guidance, quantified emissions benefits (i.e., emissions reductions) and emissions increases should be included in all project proposals, except where it is not possible to quantify emissions changes, in which case a qualitative assessment may be provided. Emissions effects should be estimated and reported in a consistent fashion (i.e., kg/day) across projects to allow accurate comparison during the project selection process.

State and local transportation and air quality agencies may conduct CMAQ-project air quality analyses with different approaches; FHWA does not specify the emissions reduction methodologies to be used. However, FHWA stipulates that every effort should be taken to ensure that determinations of air quality benefits are credible and based on a reproducible and logical analytical procedure for inclusion in FHWA's national CMAQ database.15

Relevant Literature and Studies

While this study focuses on a set of CMAQ-funded projects from FHWA's national CMAQ database, it also builds upon and is intended to supplement past efforts to assess the impacts of CMAQ projects.

Since the program's inception, FHWA and EPA have developed several documents that have described the emissions benefits, congestion benefits, and other positive effects of CMAQ funded projects. For instance, FHWA developed a document in 1996, Congestion Mitigation and Air Quality Improvement Program Indirect Benefits, which highlights the CMAQ program's indirect benefits to MPOs and other stakeholders in the transportation planning process, and provided examples of specific projects and their benefits.16 In 1999, EPA created a brochure on the CMAQ program, "Creating Transportation Choices: Congestion Mitigation and Air Quality Improvement Program Success Studies," which highlights a set of examples of CMAQ-funded projects.17 In 2003, FHWA developed a report, CMAQ: Advancing Mobility and Air Quality, which describes the ways in which CMAQ projects can improve mobility.18 The report documents nine examples of CMAQ projects and how they have enhanced mobility, and includes information on the emissions benefits reported for these projects.

For over a decade, FHWA and EPA also have undertaken efforts to assess the effectiveness of the CMAQ program, to examine cost-effectiveness, and to provide information on recommended practices for estimating emissions effects. In 1997, FHWA sponsored a literature review on the Cost Effectiveness of Transportation Control Measures by CMAQ Category, which documented a range of studies summarizing the emissions benefits of projects funded under CMAQ.19 To address concerns about the effectiveness of the CMAQ program at reducing motor vehicle emissions during the deliberations that led to passage of TEA-21, the EPA in coordination with FHWA, conducted a detailed assessment of CMAQ project effects and costs (Costs and Emissions Benefits of CMAQ Project Types, 1999). The study documented emissions effects, costs, methodologies and assumptions for 24 CMAQ projects within six project categories.20

In TEA-21, Congress called for an evaluation of the benefits and cost-effectiveness of projects funded under the CMAQ program. The Transportation Research Board (TRB) conducted this study, which examined the emissions benefits of CMAQ-funded projects, based on available literature and conducted a comparison against other pollution reduction measures to evaluate the program's cost effectiveness. Overall, the TRB study (published as Special Report 264) concluded that the CMAQ program had been valuable to its designed objectives, and supported its continuation subject to some targeted findings and recommendations. Perhaps the most critical finding in the review was the inability to evaluate performance of funded projects due to poor or absent information. This resulted in a recommendation for a more formal evaluation component attached to future funding of the CMAQ program. The study noted that the CMAQ program had not been structured to be evaluated in a rigorous way (local flexibility was an important feature of the program), thus making it impossible to perform a rigorous scientific analysis of benefits of CMAQ-funded projects.21

This study is designed to supplement the findings of previous research by examining a small number of CMAQ-funded projects, with a focus on projects funded in years 2000 and later. By examining CMAQ projects that have been implemented, this study provides information on the estimated impacts that have been achieved on congestion levels and air quality.

Report Organization

This report is organized into three major sections:

Appendixes provide additional information on assumptions used in the calculations, and include short write-ups of each project in a standardized template.

  1. 1 Transportation Research Board. Special Report 264: The CMAQ Program: Assessing 10 Years of Experience. 2002. Page 19.
  2. 2 SAFETEA-LU 1808(d) amending 23 USC 149 (f)(3)(A)(ii).
  3. 3 Texas Transportation Institute, 2007 Urban Mobility Report. September 2007. Available at:
  4. 4 See Transportation Research Board. Special Report 264: The CMAQ Program: Assessing 10 Years of Experience. 2002. Page 19.
  5. 5 23 USC 149(b)-(c).
  6. 6 23 USC 134-35, 149(d).
  7. 7 FHWA Memorandum. October 31, 2006. "Guidance on the Congestion Mitigation and Air Quality Improvement (CMAQ) Program Under the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users." Pages 10 11, interpreting 23 USC 149(b).
  8. 8 23 USC 149(b).
  9. 9 FHWA Memorandum. October 31, 2006. "Guidance on the Congestion Mitigation and Air Quality Improvement (CMAQ) Program Under the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users." Page 11, interpreting 23 USC 149(b).
  10. 10 23 USC 120(c).
  11. 11 See Section 1131 of the Energy Independence and Security Act of 2007 (P.L. 110-140, H.R. 6).
  12. 12 See FHWA Memorandum. October 31, 2006. "Guidance on the Congestion Mitigation and Air Quality Improvement (CMAQ) Program Under the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users." Page 26, interpreting 23 USC 149(b).
  13. 13 The exception is for states receiving minimum apportionment that do not have, and have had, a nonattainment area designed under the Clean Air Act, in which case the State may use funds for any project eligible under the Surface Transportation Program. 23 USC 149(b)-(c).
  14. 14 23 USC 149(b)-(c).
  15. 15 See FHWA Memorandum. October 31, 2006. "Guidance on the Congestion Mitigation and Air Quality Improvement (CMAQ) Program Under the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users." Page 25.
  16. 16 Federal Highway Administration, Congestion Mitigation and Air Quality Improvement Program: Indirect Benefits. Publication No. FHWA-PD-97-045, 1997.
  17. 17 Hagler Bailly, "Creating Transportation Choices: Congestion Mitigation and Air Quality Improvement Program Success Studies," for U.S. EPA, 1999.
  18. 18 Federal Highway Administration, CMAQ Advancing Mobility and Air Quality. Publication No. FHWA-EP-03-045, 2003.
  19. 19 Center for Transportation and the Environment (CTE), North Carolina State University, Cost Effectiveness of Transportation Control Measures by CMAQ Category, FHWA, 1997.
  20. 20 Hagler Bailly, Costs and Emissions Impacts of CMAQ Project Types, U.S. EPA, 1999.
  21. 21 Transportation Research Board. Special Report 264: The CMAQ Program: Assessing 10 Years of Experience. 2002.
  1. Table of Contents
  2. Executive Summary
  3. Section One
  4. Section Two
  5. Section Three
  6. Section Four
  7. Appendix A
  8. Appendix B
  9. Appendix C
  10. Appendix D
Updated: 10/20/2015
HEP Home Planning Environment Real Estate
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000
Turner-Fairbank Highway Research Center | 6300 Georgetown Pike | McLean, VA | 22101