Transportation Conformity

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.

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 nonattainment or maintenance for the following pollutants and their appropriate precursors:

Ozone (O₃);
Particulate matter (PM₁₀ and PM_2.5);
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