Transportation conformity is required by the Clean Air Act (CAA) Section 176(c) which ensures that Federal (FHWA/FTA) funding and approval are given to transportation (highway/transit) activities that are consistent with air quality goals. It is a link between Transportation and Air Quality planning ensuring that transportation improvement programs (TIPs) and Federal projects must conform to the purpose of the SIP.
Conformity to a SIP means that such activities will not:
- Cause or contribute to any new violations of the national ambient air quality standards (NAAQS)
- Increase the frequency of severity of NAAQS violations
- Delay timely attainment of the NAAQS or any required interim milestone
Transportation conformity only addresses air pollution from on-road mobile sources such as cars, trucks and transit in areas that are designated as non-attainment or maintenance for the following pollutants and their appropriate precursors.
- Ozone (O3);
- Particulate matter (PM10 and PM2.5);
- Nitrogen dioxide (NO2); and
- Carbon monoxide (CO)
Transportation activities subject to transportation conformity are:
- Metropolitan transportation plans
- Metropolitan transportation improvement programs (TIPs)
- Federal projects receiving FHWA/FTA funding or approvals