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Congestion Mitigation and Air Quality (CMAQ) Program Interim Guidance


The Congestion Mitigation and Air Quality Improvement (CMAQ) program was established by ISTEA of 1991. The CMAQ program provides a flexible funding source to State and local governments for transportation projects and programs to help meet the requirements of the Clean Air Act. Funding is available to reduce congestion and improve air quality for areas that do not meet the National Ambient Air Quality Standards (NAAQS) for ozone, carbon monoxide, or particulate matter-nonattainment areas-and for areas that were out of compliance but have now met the standards-maintenance areas[1].

The CMAQ program supports two important goals of the Department of Transportation: improving air quality and relieving congestion. This program was particularly designed to help States and metropolitan areas meet their Clean Air Act obligations in nonattainment and maintenance areas and to prevent areas from falling into nonattainment. Additionally, MAP-21 puts an increased focus on addressing PM-2.5.

The effective date of this MAP-21 CMAQ program eligibility guidance is October 1, 2012. The CMAQ program requirements in effect on October 1, 2012 will apply to all related funding obligated on or after that date, whether carryover or new.


Section 1113 of MAP-21 establishes several important changes to the CMAQ program at 23 U.S.C. 149. In addition, section 1105 of MAP-21 provides for the apportionment of funds to the CMAQ program in 23 U.S.C. 104.

The following sections of Title 23 are applicable to the CMAQ program.

  1. 23 U.S.C. 104 Apportionment
  2. 23 U.S.C. 120 Federal share
  3. 23 U.S.C. 126 Transfers
  4. 23 U.S.C. 134 Metropolitan transportation planning
  5. 23 U.S.C. 135 Statewide transportation planning
  6. 23 U.S.C. 149 Congestion Mitigation and Air Quality Improvement Program
  7. 23 U.S.C. 217 Bicycle transportation and pedestrian walkways
  8. 23 U.S.C. 150 National Goals and Performance Management Measures


Authorization Levels under MAP 21: Section 1101 of MAP-21 authorizes funds for the CMAQ program and Section 1105 amends 23 U.S.C. 104(b)(4) and provides for the apportionment of funds.

MAP-21's approach to distribution of formula funds is based on the amount of formula funds each State received in FY 2012.

Once each State's total Federal-aid apportionment is calculated, an amount is set aside for the State's CMAQ program through a calculation based on the size of the State's FY 2009 CMAQ apportionment relative to the State's total FY 2009 apportionments.

The following amounts are the total national estimated apportionments (before set-asides) for the CMAQ program:

FY 2013 $2.21 billion
FY 2014 $2.23 billion
TOTAL $4.44 billion

Overall MAP-21 funding tables can be accessed at http://www.fhwa.dot.gov/map21/funding.cfm. Amounts for State Planning and Research and the Transportation Alternatives Program are set aside from each State's CMAQ apportionment.

The Fiscal Management Information System (FMIS) program codes will be provided in a memorandum to the FHWA Division Offices and States once the process is finalized.

Period of Availability: CMAQ funds are contract authority from the Highway Account of the Highway Trust Fund. They are available for obligation for a period of three years after the last day of the fiscal year for which the funds are authorized.

Obligation Limitation: CMAQ funds are subject to the annual obligation limitation imposed on the Federal-aid highway program.

Federal share: The Federal share for CMAQ funds is governed by 23 U.S.C. 120. It is generally 80 percent, subject to the upward sliding scale adjustment for States containing public lands (See page 16 of Financing Federal-Aid Highways, FHWA- PL-07-017). Certain safety projects that include an air quality or congestion relief component, e.g. carpool/vanpool projects, as provided in 23 USC 120(c) may have a Federal share of 100 percent , but this provision is limited to 10 percent of the total funds apportioned to a State under 23 U.S.C. 104.


Generally, projects eligible under the CMAQ program prior to enactment of MAP-21 remain eligible with the new authorization. All CMAQ projects must demonstrate the three primary elements of eligibility: transportation identity, emissions reduction, and location in or benefitting a nonattainment or maintenance area. While project eligibilities are continued, there is some modification with new language placing considerable emphasis on select project types including electric and natural gas vehicle infrastructure and diesel retrofits. As in past authorizations of the program, projects must be included in a Metropolitan Planning Organization (MPO) transportation plan and transportation improvement program (TIP), or the current Statewide TIP in areas that are not part of an MPO. The MPO plans and programs must also have a transportation conformity determination in place, where applicable. In addition, CMAQ investments must comply with the appropriate Federal cost principles, such as 2 CFR 225, the guidelines for State, local, and tribal governments[2].

Eligible Activities Include:

  1. Acquisition of diesel retrofits, including tailpipe emissions control devices, and the provision of diesel-related outreach activities.

  2. Intermodal equipment and facility projects that target diesel freight emissions through direct exhaust control from vehicles or indirect emissions reductions through improvements in freight network logistics.

  3. Alternative fuel projects including participation in vehicle acquisitions, engine conversions, and refueling facilities.

  4. Establishment or operation of a traffic monitoring, management, and control facility, including the installation of advanced truck stop electrification systems.

  5. Projects that improve traffic flow, including efforts to provide signal systemization, construct HOV lanes, streamline intersections, add turning lanes, improve transportation systems management and operations that mitigate congestion and improve air quality, and implement ITS and other CMAQ-eligible projects, including efforts to improve incident and emergency response or improve mobility, such as through real time traffic, transit and multimodal traveler information.

  6. Projects or programs that shift travel demand to nonpeak hours or other transportation modes, increase vehicle occupancy rates, or otherwise reduce demand through initiatives, such as teleworking, ridesharing, pricing, and others.

  7. Transit investments, including transit vehicle acquisitions and construction of new facilities or improvements to facilities that increase transit capacity. The MAP21 provision on operating assistance (23 USC 149(m)) is being reviewed and guidance interpreting the provision will be issued in the future.

  8. Non-recreational bicycle transportation and pedestrian improvements that provide a reduction in single-occupant vehicle travel.

  9. Vehicle inspection and maintenance programs.

Ineligible Activities:

No funds may be used to add capacity except for HOV facilities that are available to SOV only at off-peak times.


The CMAQ program has new performance-based features. The Secretary will establish measures for States to use for assessing traffic congestion and on-road mobile source emissions.

Each MPO serving a Transportation Management Area (TMA) with a population of more than one million and also representing a nonattainment or maintenance area is required to develop a performance plan to achieve emission and congestion reduction targets. The MPO plans must be updated biennially and each update must include a retrospective assessment of the progress made toward the air quality and traffic congestion performance targets through the last program of projects.


  1. A State without a nonattainment or maintenance area may use its CMAQ funds for any CMAQ- or Surface Transportation Program (STP)-eligible project.

  2. States with a nonattainment or maintenance area that received a minimum apportionment in FY 2009 may use part of their current CMAQ funds for any STP-eligible project. The amount is based on the proportion of the State's FY 2009 CMAQ apportionment that could be obligated in any area of the State for STP-eligible projects.

  3. The amount that may be obligated in any area of the State for STP-eligible projects is to be adjusted if a new nonattainment area is designated, a nonattainment area redesignated as an attainment (including maintenance) area, or a standard is fully revoked in an existing nonattainment or maintenance area.


The legislation calls for a State that has PM 2.5 (fine particulate matter) nonattainment and maintenance areas to use a portion of its CMAQ funds for projects that reduce PM 2.5 in such areas. Diesel retrofits are highlighted in MAP-21 as eligible to effect such mitigation. Further information on this section will be provided in the future.


MAP-21 changed the approach to transfer of CMAQ funds to other elements of the Federal-aid program. Transfers of CMAQ funds no longer are subject to a special statutory formula but follow the maximum 50 percent transfer guideline provided in Transferability of Federal-aid at 23 U.S.C. 126.

Exercising this transfer authority could impact traffic congestion and on-road mobile source emissions, the progress of which will be reported once performance measures are established under 23 U.S.C. 150.

States continue to have the ability to transfer (or "flex") CMAQ funds to FTA for award as a grant under Chapter 53 of Title 49, as they did under SAFETEA-LU [see 23 U.S.C. 104(f)].


A State may obligate funds apportioned under section 104(b)(2) in an area of such State that is otherwise eligible for obligations of such funds for operating costs under chapter 53 of title 49 or on a system that was previously eligible under this section. This section is being reviewed and information on how it is to be interpreted will be provided in the future.


The Secretary must maintain and disseminate a cumulative database describing the impacts of projects, including project name, location, sponsor, cost, and cost-effectiveness (based on reduction in congestion and emissions) to the extent already measured.

The Secretary, in consultation with EPA, shall evaluate cost effectiveness of projects periodically, for use by States and MPOs in project selection.


  1. The Secretary, in consultation with the Environmental Protection Agency (EPA), will assess, among other items, air quality and health impacts of projects funded under the CMAQ program since the enactment of SAFETEA-LU.

  2. The study is to be conducted by an independent scientific research organization.

  3. Funded at up to $1 million from Administrative Expenses, a final report is due within two years of MAP 21 enactment

[1] A list of non-attainment and maintenance areas is maintained by EPA and can be accessed at http://www.epa.gov/airquality/greenbook/ .

[2] FHWA maintains an active database system of CMAQ investments which can be accessed at https://fhwaapps.fhwa.dot.gov/cmaq_pub/HomePage/default.aspx.

Page last modified on September 12, 2013.
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