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:
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:
Transportation activities subject to transportation conformity are: