Background

Transportation conformity is a Clean Air Act requirement that ensures federally supported highway and transit project activities are consistent with (“conform to”) a state’s plan for meeting and maintaining the national ambient air quality standards (NAAQS).   Conformity applies to areas of the nation the US EPA has designated as being in “nonattainment” (not meeting) the NAAQS.   

US EPA has designated Ohio non-attainment areas for ozone (smog) and small particulates (PM_2.5).

Ohio 8-Hour ozone nonattainment areas map

Ohio PM_2.5 nonattainment areas map

Transportation Plans, Programs (TIPs), and projects developed for these areas are required to demonstrate transportation conformity.  Conformity demonstrations ensure that federally financed transportation activities do not cause new air quality violations, worsen existing violations, or delay timely attainment of the air quality standards.   US EPA’s 8-Hour ozone and PM_2.5 nonattainment area designations include most of Ohio’s urbanized counties (MPO areas).  Many of these designations also encompass adjacent rural counties that are considered to contribute to the regional air quality problem.  Because these designations all include Ohio MPO counties, the respective MPO Plans and TIPs are key documents requiring conformity demonstrations.

Highway and transit expansion projects, referred to as “nonexempt” projects, in these air quality areas must be drawn from and consistent with conforming Transportation Plans and TIPs.

Conformity Procedures

The conformity process involves a series of analytical procedures that forecast mobile source emissions from vehicles traversing the transportation network identified in a regional Transportation Plan and TIP and compares these emissions against pre-established emission thresholds.   Conformity is demonstrated when the mobile source emissions are less than or equal to the emission thresholds. 

The emission thresholds are established based on a separate planning process called the State Implementation Plan (SIP).   The SIP defines the strategies and programs the state will implement to achieve emission reductions needed for the nonattainment area to meet and maintain the NAAQS.  The SIP planning process establishes emission reduction thresholds for mobile (transportation), industrial (point), and consumer activity (area) sources.  The conformity process addresses only the mobile source sector thresholds.

US EPA’s Conformity Rule, defining the transportation conformity procedures and regulations can be viewed at:
http://www.epa.gov/otaq/transp/conform/conf-regs.htm

Key requirements of the conformity process include:

·        Use of latest planning assumptions

·        Use of latest US EPA emissions modeling software

·        Interagency consultation to coordinate conformity procedures, data, and schedules

·        Timely implementation of SIP Transportation  Control Measures

·        Public Involvement

Contact Information

Questions concerning Transportation Conformity may be addressed to Dave Moore, at (614) 466-0754, in the ODOT Office of Systems Planning and Program Management.  Email at Dave.Moore1@dot.state.oh.us.