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Last Updated: Thursday, April 7, 2016 1:39 PM

Conformity References and News

Announcements are courtesy of various conformity working group members. Most links on this page are to sites external to Caltrans. Exit Caltrans website PDF files require Acrobat Reader software from Adobe; DOC and XLS files require recent (generally 2000 version or later) Microsoft Office or compatible software, or Word or Excel viewer software from Microsoft. DOCX and XLSX files require Microsoft Office 2007 or later, or compatible software.

Note: PDF files may have been converted from word processing or spreadsheet formats supplied by Conformity Working Group members or others, for consistency of presentation and accessibility. PDF files should retain the print formatting of the original document. Files in other formats may not follow the original documents print formatting, and are provided for content accessibility only.

Electronic Mail List

The Statewide Conformity Working Group email list has moved to the Caltrans email lists web site. List subscriptions can be managed directly by users at that site rather than by sending emails to the group chair. See:

NOTE name change in group. Previous email group had to be removed due to system issues. Previous group archives are no longer available. (3/6/2013)


Key Conformity Web Sites Exit Caltrans website

EPA's Conformity Web Site:

Federal Highways' conformity web site:

Conformity Rule References

Section 176(c) of the Clean Air Act (42 USC 7506(c)) Exit Caltrans website (January 2008, PDF file)
with updates per SAFETEA-LU, maintained by EPA

Conformity Regulations web site maintained by EPA.Exit Caltrans website

An online version of the Transportation Conformity rule (40 CFR 93) is available in the experimental eCFR section of the Federal Digital System at the GPO (all Exit Caltrans website).


FHWA now has detail maps for all PM2.5 and Ozone nonattainment areas. EPA and ARB also have maps. ARB and EPA also have GIS versions of many of their maps available at their web sites. See Exit Caltrans website:

PM Hot Spot Guidance (updated 2/6/2014)


EMFAC 2011 must be used for hot spot analysis for new studies started after 9/6/2013.

Qualitative Analysis Guidance was published on EPA's website 3/29/2006. Quantitative analysis guidance was published in the Federal Register in December /2010 and updated in November 2013, replacing the qualitative (emission analysis) procedures for projects of concern. Project-level conformity resources can be found at EPA's project-level analysis page: Exit Caltrans website

EPA Webpage with Baseline Years for Various NAAQS (3/22/2010)

EPA has posted a web page listing the conformity analysis baseline years for various standards. See: Exit Caltrans website


A short training session entitled “What is Transportation Conformity?” is now available from FHWA as an on-demand webinar.This session was developed by the FHWA Resource Center Air Quality Technical Services Team in coordination with the Office of Human and Natural Environment. You can access the training at this link: Handouts are available for download at the same site.

The training will provide an understanding of the basics of transportation conformity. It provides a general overview of the transportation conformity process and its major requirements. It is intended for transportation and air quality practitioners who are new to transportation conformity, those looking for a refresher, or others who only need a brief overview of the rule. The session is approximately 27 minutes long.

SIP Sanctions Clocks in California

EPA does not maintain a public summary of sanctions clocks. Caltrans and FHWA lists are maintained on a staff & time-available basis.

A good description of how "sanctions" under the Clean Air Act work is at the FHWA Environmental web site Exit Caltrans website. If highway sanctions go into effect (cutting off highway funding), a conformity lapse also occurs (cutting off other transportation funding) if the issue was a control strategy SIP disapproval. Otherwise, there is little connection between the sanctions process and conformity. The exception/exemption lists for transportation projects under sanctions and conformity are very different.

Other Items


JANUARY 30, 2014 - EPA PM10/2.5 Quantitative Hot Spot Analysis Guidance UPDATED


On December 20, 2010, notice of EPA's final release of the quantitative PM hot spot guidance was published in the Federal Register (text and PDF versions Exit Caltrans website). Publication starts a 2-year grace/phase-in period for use of the new emission models (MOVES in most of the country, EMFAC 2007 in California) and the new procedures. EPA and FHWA will deliver training during the first half of 2011 regarding the new procedures.

This guidance replaces the 2006 guidance document, and qualitative (emission) analysis based cannot be started for Projects of Concern after 12/20/2012. Proponents of Projects of Concern that will not have final NEPA action before the end of the 2-year grace period should consider doing or re-doing PM hot spot analysis using the new procedures. Criteria for determining whether a project is a Project of Concern needing detailed analysis have not changed.

For more information, see the PM Hot Spot Guidance item in the References section above, which has been updated to refer to EPA's current guidance and web pages.

April 17, 2013 - EPA Memo Regarding PM2.5 AreA Boundary Determination Process

EPA Region 9 signed a memo describing the PM2.5 (2012 standard) nonattainment area boundary-setting process. State recommendations are due in December 2013, and area designations based on existing monitors will be done in late 2014. Data from new near-road monitors is not expected to be available in time to be used for the initial area designations. For more information see (both website Exit Caltrans website and PDF files):

March 6, 2013 - EPA Availability Notice for EMFAC 2011


EPA Region 9 signed the availability notice and forwarded it to the Federal Register for publication, happened on March 6, 2013. Publication in the Register starts a grace period of 6 months for transition from EMFAC 2007 to EMFAC 2011. Conformity analyses started during the grace period may use either version of EMFAC, with concurrence by Interagency Consultation. Analyses done with EMFAC 2011 may be approved after the notice is published. After the end of the grace period, new analyses MUST use EMFAC 2011. ARB has released a project-level analysis tool for EMFAC 2011, and EPA plans to release revised hot spot analysis guidance incorporating EMFAC 2011. See:

Federal Register Notice (PDF) Exit Caltrans website

ARB EMFAC 2011 web site: Exit Caltrans website

March 22, 2010 - EPA Publishes Final Rule for PM2.5 and PM10 CONFORMITY Amendments

From EPA:

The final rule entitled, "Transportation Conformity Rule PM2.5 and PM10 Amendments" (aka "PM Amendments rule") was signed by the Administrator on March 10, 2010 and will be published in the Federal Register on March 24, 2010. You can find the signed version and a factsheet about the final rule on our website at this location: Exit Caltrans website

As a reminder, conformity requirements apply for the 2006 PM2.5 NAAQS by December 14, 2010. On its effective date of April 23, the PM Amendments final rule will supersede the November 2009 Interim Guidance Exit Caltrans website. The final rule's requirements for the 2006 PM2.5 NAAQS areas are consistent with the interim guidance; however, note that the final rule establishes 2008 as the baseline year for the 2006 PM2.5 areas that use the baseline year test.


From FHWA by email:

On March 29, 2006, the Environmental Protection Agency (EPA) and the Federal Highway Administration (FHWA) issued joint guidance on how to perform qualitative hot-spot analyses in PM2.5 and PM10 nonattainment and maintenance areas titled “Transportation Conformity Guidance for Qualitative Hot-spot Analysis in PM2.5 and PM10 Nonattainment and Maintenance Areas” (March 2006 guidance) ( Exit Caltrans website). The guidance provides information for State and local agencies to meet the PM2.5 and PM10 hot-spot analysis requirements established in the March 10, 2006, final transportation conformity rule (71 FR 12468). Since issuing the March 2006 guidance, a lawsuit was filed challenging a project’s conformity determination, including the project’s PM2.5 hot-spot analysis that relied on “Method A” (comparison to another location with similar characteristics). Method A is described in question 4.1 of the March 2006 guidance. As part of a settlement agreement on that lawsuit (Environmental Defense, et al. v. USDOT, et al., No. 08-1107 (4th Cir., dismissed Nov. 17, 2008)), FHWA agreed to issue a clarification on a specific schedule, in coordination with EPA, to the March 2006 guidance. This clarification does not supersede the March 2006 guidance or the March 10, 2006, final transportation conformity rule; it only further explains how to implement the existing guidance and the hot-spot analysis requirements in the final rule. The clarification also does not create any new requirements and does not serve as guidance for PM2.5 and PM10 quantitative hot-spot analyses.

FHWA sent an email and the draft clarification on February 10, 2009, to certain transportation stakeholders and environmental interests groups for review and comment before FHWA finalized the guidance clarification. FHWA did not receive any comments during the comment period.

Copies of the Final Clarification and the March 2006 guidance are attached. The final Clarification will be posted on FHWA's website at Exit Caltrans website next week. I encourage you to share this final document with your State and local transportation and air quality agencies.

The referenced documents can be downloaded from this site as PDF files:

January 7, 2009 - Updated Conformity Guidance on Use of Latest Planning Assumptions

The Federal Highway Administration has issued updated guidance on use of the latest planning assumptions Exit Caltrans website for transportation conformity determinations. The document updates and supersedes guidance issued in January 2001 based on changes implemented in the Environmental Protection Agency’s July 1, 2004, final conformity rule.

April 17, 2008 - FHWA NEPA-RTP-TIP Guidance

FHWA circulated a memo (PDF file) in February 2008 that appears to change how projects must be listed in the RTP and TIP before environmental and preliminary engineering work starts. A prior (2003) FHWA memo also still applies (PDF file Exit Caltrans website).

FHWA noted in a March meeting (from CFPG meeting notes):

This issue pertains to Planning and the relationship to the information that needs to be in the FTIP. If the project is programmed in the TIP, but is not fully funded in the RTP, you must have at least an environmental process/study funded in the RTP. This actually allows more flexibility, especially for the earmarks. This allows you to get near the end of the environmental process before full funding for the project is required in the RTP. There must be an indication of the project in the Plan or some reference to the project if leading to NEPA document. This may have conformity implications if a project is in PE in the TIP and considered a study in the RTP – conformity will be required when additional funds are added in the RTP.

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