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Last Updated: Tuesday, April 30, 2013 7:52 AM

Federal Clean Air Act Transportation Conformity

"Transportation Conformity" is a process set up by the Federal Clean Air Act to ensure that federal actions are consistent with plans to achieve and maintain Federal air quality standards. Specific requirements for highway and transit projects are set by US Environmental Protection Agency (EPA) regulations in 40 CFR 93 Subpart A, US EPA and US DOT (FHWA) guidance , and local procedures set up by Metropolitan Planning Organizations and Air Pollution Control Districts. The map and table below illustrate the areas which are subject to Transportation Conformity requirements in California in early 2013. For other types of federal actions, not related directly to highways and transit, conformity requirements are based on 40 CFR 93 Subpart B (General Conformity) .

Conformity requirements for ozone are in transition between the 1997 and 2008 national standards. Nonattainment areas were designated by EPA in May 2012, effective 7/20/2012, for the 2008 standard. Conformity requirements for the new standards go into effect on 7/20/2013, and the 1997 ozone standard will be revoked on that date for conformity purposes. (77 FR at 30088, May 21, 2012 )

 

 

Click on the graphic image at left for an enlarged image, or use one of the following links to download the map image. Save the file using the method appropriate for your browser:

GIF format (96 dpi, 114 KB file size)

PDF format (363 KB file size)

Or view a Table of Areas Subject to Transportation Conformity Requirements

Table of Conformity Areas with Regional Conformity Status

For statewide interagency consultation information and records of Statewide Conformity Working Group meetings, see the Statewide Conformity Working Group page at this site.

Transportation Conformity Overview

Transportation Conformity applies in areas that are "nonattainment" or "attainment-maintenance" for National Ambient Air Quality Standards, and only for the standards that actually are or previously were violated. The number of standards violated varies by area, from only one (some ozone, PM2.5, or PM10-only areas) to nearly the entire possible range (South Coast air basin); conformity analysis must be done for all of the standards that are or (in maintenance areas) were violated.

This summary is necessarily abbreviated. For more details see the Caltrans Standard Environmental Reference (Chapter 11 - Air Quality and air quality forms and templates), the EPA Transportation Conformity web site , and the FHWA Conformity web site . Nonattainment and "maintenance" areas in California can be identified through the EPA Region 9 Air Quality Maps web site , the EPA "Green Book" , and the Conformity Areas Table at this web site.

Conformity analysis and determinations are done at statewide, regional (Metropolitan Planning Organization - MPO - or isolated rural area), and project scales.

Statewide Analysis

California's State Transportation Plan is a policy-only product that does not identify and analyze specific projects. It is not, therefore, subject to conformity requirements. A statewide interagency consultation process is maintained; see the Statewide Conformity Working Group section of this site.

Regional Analysis

Regional analysis considers the effect of all regionally significant projects in a nonattainment area, and normally addresses emission budgets set in an EPA-approved State Implementation Plan. The regional analysis considers the Design Concept (what type of project it is) and scope (how long, capacity, etc.) of all projects to be implemented by various analysis years. Regional analysis also addresses implementation of Transportation Control Measures contained in the EPA-approved State Implementation Plan. Regional conformity must be determined not less often than every 4 years by a MPO with a nonattainment or maintenance area, and usually is analyzed more often as various Regional Transportation Plan (RTP) and Transportation Improvement Program (TIP) amendments happen.

Project-Level Analysis

Project-level analysis is done at the time a NEPA document is prepared, and a project-level conformity determination must be done at the time the NEPA document is approved, and is reaffirmed or re-done at each federal action point (usually funding approvals) after that. Project-level conformity normally applies only to projects that are not exempt from conformity (40 CFR 93.126, 128, and in ozone-only areas 127) and are regionally significant (see definition at 40 CFR 93.101). References are to the "eCFR" web site at the U.S. Government Printing Office web site . A project-level analysis usually includes the following:

• Regional Conformity: document that the project's Design Concept, Scope, and open-to-traffic Delivery date match those assumed for regional analysis purposes. If something changes, project-level conformity cannot be determined until the RTP and TIP are amended with revised conformity determinations.
• Hot Spot Analysis: if a project is in a carbon monoxide (CO), PM10, or PM2.5 nonattainment or maintenance area, analysis must confirm that the project will not cause or worsen a localized violation of the standard. This is done in two ways:
  • CO areas: a project is analyzed using the Caltrans/UCD CO Protocol, and modeled if necessary using the CALINE4 model. This process documents whether or not the project will cause a new CO violation in the project vicinity. Since all CO areas in California are currently attainment-maintenance, there currently are no violations of the CO standard, so it is not possible to worsen an existing violation.
  • Particulate Matter (PM10 and/or PM2.5) areas: a project is initially reviewed with a regional interagency consultation process to determine whether it's a "project of concern" or "POAQC". If it is not, public notice may be required of that decision and the results of that process (and the finding that the project is not a POAQC) will be documented as part of a conformity analysis report or section of the NEPA document. If a project is determined to be a POAQC, detailed quantitative analysis is required based on EPA Guidance, using EPA's approved dispersion models (CAL3QHCR or AERMOD). To meet conformity requirements in this case, the project must not cause or worsen violations of the PM standard(s) at issue.

More details regarding project-level analysis methods used in California and related information can be found in the Analysis Tools section of this web site, and in the Caltrans Standard Environmental Reference sections noted above.

 

 

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