Regional agencies guiding metropolitan planning organizations making conformity determinations

Northeastern Illinois is currently designated as a nonattainment area for the 8-hour Ozone National Ambient Air Quality Standards. The region is subject to transportation conformity requirements in the Clean Air Act; federally funded highway and transit projects must be consistent with (“conform to”) the air quality goals established by a state air quality implementation plan.

As part of the transportation planning and programming process, the Chicago Metropolitan Agency for Planning (CMAP) evaluates the impact of proposed transportation projects on the region’s air quality. This evaluation, called a conformity determination, must demonstrate that the long-range regional transportation plan or Transportation Improvement Program (TIP) conforms before it is approved by the metropolitan planning organization (MPO) or accepted by the U.S. Department of Transportation.

The conformity determination must show that the emissions resulting from the long-range regional transportation plan or TIP demonstrate that implementation of that metropolitan transportation plan, TIP, or project will not cause any new violations of the air quality standard, increase the frequency or severity of violations of the standard, or delay timely attainment of the standard.

Interagency consultation is an important — and required — part of this process. In northeastern Illinois, that happens through the Tier II Consultation process and through the work of CMAP’s committees and working groups as described in the region’s public participation plan.

Tier II consultation process

The consultation process supports the regional planning process in several ways:

  • Assures early and proactive participation by the U.S. Environmental Protection Agency, Federal Transit Administration, and Federal Highway Administration in the long-range transportation plan or TIP development process.
  • Serves as a forum for interagency communication and coordination, along with a clear understanding of participating agencies’ roles and responsibilities in the conformity process.
  • Provides expertise from federal agency representatives for interpreting air quality regulations, as well as long-range transportation plans and TIP requirements.

In northeastern Illinois, consultation involves the MPO, Illinois Environmental Protection Agency, Illinois Department of Transportation, the Regional Transportation Authority, Federal Highway Administration, Federal Transit Administration, and U.S. Environmental Protection Agency.

Tier II consultation facilitates the local, regional, and state decision-making process by providing a forum for all affected federal, state, regional, and local agencies to discuss and resolve important issues. Decisions made by this interagency consultation process guide the MPO in making the conformity determination. 

The consultation team meets on an as-needed basis. No decision is put into effect until all parties involved in the consultation process agree.


Tier II consultation meetings are held as needed, and materials will be posted below.

May 10, 2024