Transportation Conformity


Areas designated as air quality nonattainment or maintenance areas for the transportation-related pollutants have special meaning to transportation professionals. Transportation improvements projects in these areas must undergo a rigorous analytical process to demonstrate that they do not negatively impact air quality.

Transportation conformity ("conformity") is a way to ensure that Federal funding and approval goes to those transportation activities that are consistent with air quality goals. Conformity applies to transportation plans, transportation improvement programs (TIPs), and projects funded or approved by the Federal Highway Administration (FHWA) or the Federal Transit Administration (FTA) in areas that do not meet or previously have not met air quality standards for ozone, carbon monoxide, particulate matter, or nitrogen dioxide. These areas are known as "nonattainment areas" or "maintenance areas," respectively. Regulations governing transportation conformity are found in Title 40 of the Code of Federal Regulations (40 CFR Parts 51 and 93).

Please visit the FHWA Transportation Conformity website for detailed information.

The Decision Guide provides detailed information on the individual key decisions at which these processes are integrated. Explore the graphic below to learn about this relationship:

  • Hover over the highlighted key decisions to understand the specific relationship of transportation conformity to the decision.
  • Click on any highlighted key decision for more information concerning transportation conformity and this decision. You will find useful information in the "Data" and "Integrated Planning" tabs.

Key Decisions that are grayed-out have no specific relevance to the individual application or topic area but are still accessible from this graphic.