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Policy Guidance
Transportation
Conformity
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This page contains policy guidance issued by EPA and/or the U.S. Department of Transportation to assist state and local transportaton and air quality agencies implement the transportation conformity program. Policy guidance can be found on the following topics:
- Transportation Planning and Conformity Requirements
- Emission Models and Conformity
- State Implementation Plans (SIPs) and Conformity
- Quantifying Benefits of Control Measures in SIPs and Conformity
- Land Use and Conformity
- March 2, 1999 Conformity Court Decision
Transportation Planning and Conformity Requirements
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Transportation Conformity in PM10 Nonattainment and Maintenance Areas and the Revocation of the Annual PM10 Standard
On October 17, 2006, EPA issued a final rule that revoked the annual PM10 standard and retained the 24-hour PM10 standard. This guidance memo (PDF) (6 pp, 332K) addresses how transportation conformity is to be implemented in light of the revocation of the annual PM10 standard.
Contact: Laura Berry at 734-214-4858 or berry.laura@epa.gov - Transportation Conformity and the Revised 24-hour PM2.5 Standard
On October 17, 2006, EPA issued a final rule establishing revisions to the 24-hour and annual PM2.5 national ambient air quality standard. This guidance memo (PDF) (4 pp, 154K) addresses how transportation conformity will be implemented under the revised 24-hour PM2.5 standard.
Contact: Meg Patulski at 734-214-4842 or patulski.meg@epa.gov - Transportation Conformity Guidance for Qualitative Hot-spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas
This guidance document (PDF) (35 pp, 306K, EPA420-B-06-902, March 2006) is a companion document for the March 10, 2006, final rule that establishes the transportation conformity criteria and procedures for determining which transportation projects must be analyzed for local air quality impacts in PM2.5 and PM10 nonattainment and maintenance areas (71 FR 12468). The Environmental Protection Agency (EPA) and the Federal Highway Administration (FHWA) have developed this guidance to help state and local agencies meet the final rule's hot-spot analysis requirements.- Transportation Conformity Rule That Addresses Requirements for Project-level Conformity Determinations in PM2.5 and PM10 Nonattainment and Maintenance Areas Final Rule, published March 10, 2006.
- Interim Guidance for Implementing the Transportation Conformity Provisions in the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users
(SAFETEA-LU)
EPA and the US Department of Transportation are jointly issuing guidance (PDF) (52 pp, 291K, EPA420-B-06-901, February 2006) to nonattainment and maintenance areas that are subject to transportation conformity on implementing the transportation conformity-related provisions contained in the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU), which was signed into law on August 10, 2005. SAFETEA-LU revised a number of aspects of the Clean Air Act's transportation conformity provisions including:- providing an additional six months to re-determine conformity after new state implementation plan (SIP) motor vehicle emissions budgets are either found adequate, approved or promulgated;
- changing the frequency requirements for transportation conformity determinations;
- providing an option for reducing the time period covered by conformity determinations;
- providing procedures for areas to use in substituting or adding transportation control measures (TCMs) to approved SIPs;
- adding a one-year grace period for conformity lapses; and
- streamlining requirements for conformity SIPs.
Contact: Rudy Kapichak at 734-214-4574 or kapichak.rudolph@epa.gov - Companion Guidance for the July 1, 2004, Final Transportation Conformity Rule: Conformity Implementation in Multi-jurisdictional Nonattainment and Maintenance Areas for Existing and New Air Quality Standards (PDF) (47 pp, 917K, EPA420-B-04-012, July 2004)
This guidance document describes how the rule's requirements for conformity determinations apply in areas that contain more than one MPO, a donut area, parts of more than one state, or any combination. It expands on the July 1, 2004, final conformity rule by including additional detail, examples, and pictorial representations of boundary scenarios that are present in the field.
Please note that question 5 on page 27 (Are there circumstances under which an 8-hour area with 1-hour budgets would not use them?) is no longer applicable. On October 20, 2006, the DC Circuit Court of Appeals issued a decision related to the July 1, 2004 conformity rule (69 FR 40004). The Court ruled in favor of EPA on all issues except one, in which the Court vacated 40 CFR 93.109(e)(2)(v) of the conformity rule. This provision previously allowed the consultation process to be used to determine that an approved or adequate 1-hour ozone SIP budget was not appropriate to use for 8-hour ozone conformity determinations. This provision was subsequently removed from the Transportation Conformity rule on January 28, 2008 (73 FR 4434). Contact: Meg Patulski at 734-214-4842 or patulski.meg@epa.gov - EPA and DOT Joint Guidance on Use of Latest Planning Assumptions in Conformity Determinations (PDF) (11 pp, 73K)
This January 18, 2001 guidance memorandum clarifies EPA's and DOT's expectations for implementing the transportation conformity rule's requirements for use of latest planning assumptions in conformity determinations. This memorandum also reiterates EPA's expectations for using latest planning assumptions in the development of motor vehicle emission budgets in state implementation plans.
Contact: Meg Patulski at 734-214-4842 or patulski.meg@epa.gov
Emission Models and Conformity
- Use of EMFAC2007 Model in California
On January 18, 2008, the Federal Register Notice of Availability for the newest EMFAC model was published, Official Release of EMFAC2007 Motor Vehicle Emission Factor Model for Use in the State of California | PDF version (4 pp, 112K). This notice describes EPA's approval of the model for SIP and transportation conformity purposes in California. EPA's approval of the model does not affect MOBILE model users in other states. EPA intends to approve EMFAC2007 in the future for PM2.5 and PM10 hot-spot analyses in California, once EPA issues quantitative hot-spot modeling guidance for such analyses in that state.
Contacts: Karina O'Connor, Region 9, at 775-833-1276 or oconnor.karina@epa.gov, for further information about the Federal Register notice.
Meg Patulski at 734-214-4842 or patulski.meg@epa.gov, for further information regarding the future development of quantitative PM2.5 and PM10 hot-spot modeling guidance in California. - Policy Guidance on the Use of the November 1, 2006, Update to AP-42 for Re-entrained Road Dust for SIP Development and Transportation Conformity (PDF) (7 pp, 173K, EPA420-B-07-055, August, 2007)
This guidance provides details about the changes made to the AP-42 methods for road dust and how and when to use them in PM2.5 state implementation plan development and transportation conformity determinations. This guidance supersedes the AP-42 portions of EPA's February 24, 2004, guidance, which addressed both MOBILE6.2 and AP-42 (next item, below). The portions of the February 2004 guidance addressing MOBILE6.2 remain in effect. - Policy Guidance on Use of MOBILE6.2 for SIP Development and Transportation Conformity (PDF) (13 pp, 672K)
This memorandum describes how and when to use MOBILE6.2 in state implementation plan development and transportation conformity determinations. The time period requirements set forth in this policy document became effective upon publication of the May 19, 2004 Federal Register notice of availability that announced EPA's approval of the new model for official purposes. Note that the AP-42 portions of this guidance are no longer in effect as they have been replaced by the August, 2007 memo found immediately above.Federal Register Notice of Availability: Official Release of MOBILE6.2 Motor Vehicle Emissions Factor Model, | PDF version (3 pp, 45K)
Contact: Gary Dolce at 734-214-4414 or dolce.gary@epa.gov - Clarification of Question 5 of Policy Guidance for MOBILE6 SIPs in Mid-course Review Areas (PDF) (2 pp, 113K)
This memorandum clarifies the approach for determining that attainment SIPs in mid-course review areas continue to demonstrate attainment with revised MOBILE6 inventories. The EPA memorandum was issued on February 12, 2003.
Contact: Gary Dolce at 734-214-4414 or dolce.gary@epa.gov - Policy Guidance on Use of MOBILE6 for SIP Development and Transportation Conformity (PDF) (14 pp, 105K)
This memorandum describes how and when to use MOBILE6 in state implementation plan development and transportation conformity determinations. The time period requirements set forth in this policy document became effective upon publication of the January 29, 2002 Federal Register notice of availability that announced EPA's approval of the new model for official purposes.January 29, 2002, Federal Register Notice of Availability: Official Release of the MOBILE6 Motor Vehicle Emissions Factor Model | PDF version (4 pages, 48K)
Contact: Meg Patulski at 734-214-4842 or patulski.meg@epa.gov
State Implementation Plans (SIPs) and Conformity
- Phase 2 8-hour Ozone Implementation Rule Provision for RFP Reductions Obtained From Outside a Nonattainment Area
EPA issued a memorandum(PDF) (2 pp, 95K) on October 11, 2007 stating that the Agency cannot approve 8-hour ozone reasonable further progress (RFP) state implementation plans (SIPs) that have obtained VOC or NOx reductions from outside an 8-hour nonattainment area. The memorandum also advises that motor vehicle emissions budgets cannot be found adequate if contained in these RFP SIPs. When EPA issued the memorandum, the U.S. Court of Appeals for the District of Columbia Circuit had not yet responded to EPA's request for a partial remand and Plaintiff's request for vacatur. On November 2, 2007, the Court issued an order that vacates and remands the portion of the Phase 2 8-hour implementation rule for which EPA had previously sought a voluntary partial remand. The October 11, 2007 memorandum remains applicable as it is consistent with the Court's order. - Court Decision on the Phase 1 Ozone Implementation Rule
On June 8, 2007, the U.S. Court of Appeals for the District of Columbia Circuit responded to our petition for rehearing on the Court's December 22, 2006, decision on the Phase 1 Rule to implement the 8-hour ozone national ambient air quality standard (NAAQS). To assist Regions, Federal, State, local agencies, and Tribes, a memo (PDF) (4 pp, 827 K) was issued to the EPA regional offices on June 15, 2007. The memo summarizes the Court's opinion, and its implications for transportation conformity and the June 15, 2007, due date for submission of state implementation plans for nonattainment areas.
Contact: Meg Patulski at 734-214-4842 or patulski.meg@epa.gov or
Rudy Kapichak at 734-214-4574 or kapichak.rudolph@epa.gov - Guidance for Creating Annual On-Road Mobile Source Emission Inventories for PM2.5 Nonattainment Areas for Use in SIPs and Conformity (PDF) (17 pp, 181K, EPA420-B-05-008, August 2005)
This guidance document describes how state and local agencies should prepare annual inventories for PM2.5 SIPs or regional conformity analyses. It provides a range of methods for producing those inventories and guidance on how to decide which method is most appropriate. For state and local agencies currently preparing a regional conformity analysis before a SIP is developed, this guidance provides the option of using a simpler inventory approach than what they might eventually use in the SIP. This document also addresses the possible use of the National Mobile Inventory Model (NMIM) in SIPs and conformity analyses.
Contact: Gary Dolce at 734-214-4414 or dolce.gary@epa.gov - Guidance for Determining the "Attainment Year" for Transportation Conformity in New 8-Hour Ozone and PM2.5 Nonattainment Areas (PDF) (12 pp, 144K, EPA420-B-05-002, March 2005)
This document provides guidance for 8-hour ozone and PM2.5 nonattainment areas in selecting attainment dates for use in transportation conformity determinations both before and after state implementation plans (SIPs) are submitted. This guidance also describes some flexibilities that are available to areas using interim emission or budget tests in choosing which years to perform a regional emissions analysis.
Contact: Rudy Kapichak at 734-214-4574 or kapichak.rudolph@epa.gov - Conformity SIP Guidance (PDF) (23 pp, 251K, EPA420-B-04-017, November, 2004)
This document provides guidance on the requirement that states adopt their own criteria and procedures for determining transportation conformity (known as "conformity SIPs"). This will help areas that have approved conformity SIPs know which provisions of the July 1, 2004, conformity rule amendments apply immediately and which provisions cannot apply until conformity SIPs are revised. It also includes information on other aspects of conformity SIPs.See Interim Guidance for Implementing SAFETEA-LU for updated conformity SIP information.
Contact: Rudy Kapichak at 734-214-4574 or kapichak.rudolph@epa.gov - 2001 Limited Maintenance Plan for moderate PM10 (PDF) (11pp, 335K)
- 1995 Limited Maintenance Plan for nonclassifiable CO Nonattainment Areas(PDF) (7pp, 1.3M)
Quantifying Benefits of Control Measures in SIPs and Conformity
- SmartWay SIP and Conformity Guidance (PDF) (35 pp, 306K, EPA420-B-07-004, June 2007)
This document describes how to quantify and use reductions in nitrogen oxides (NOx) that result when trucks are outfitted with two specific SmartWay fuel-efficient technologies: trailer aerodynamic kits and low-rolling resistant tires.- Fact Sheet | PDF version 3 pp, 106K, EPA420-F-07-045, June 2007)
Gary Dolce at 734-214-4414 or dolce.gary@epa.gov - Diesel Retrofits: Quantifying and Using Their Benefits in SIPs and Conformity - Guidance for State and Local Air and Transportation Agencies (PDF) (69 pp, 531K, EPA420-B-06-005, June 2006)
This document provides guidance on quantifying and using emission reductions from highway and nonroad diesel vehicles, engines, and equipment that have been retrofitted. The guidance discusses how emission reductions from diesel retrofit projects can be used in a SIP and in transportation conformity and general conformity determinations.- Fact Sheet | PDF version (7 pp, 195K, EPA420-F-06-034, June 2006)
Gary Dolce at 734-214-4414 or dolce.gary@epa.gov - Guidance for Quantifying and Using Emission Reductions from Best Workplaces for Commuter Programs in State Implementation Plans (SIPs) and Transportation Conformity Determinations
This guidance describes how to credit commuter benefit programs, such as EPA's Best Workplaces for Commuters, in a SIP or transportation conformity determination. The guidance also includes instruction on using EPA's 2005 COMMUTER Model (ZIP XLS, 13M), a tool for quantifying emissions and emission reductions associated with commuter benefit programs.
Contact: Meg Patulski at 734-214-4842 or patulski.meg@epa.gov - Guidance on Quantifying NOx Benefits for Cetane Improvement Programs for use in SIPs and Transportation Conformity (PDF) (32 pp, 253K, EPA420-B-04-005, June 2004)
This document, issued in June 2004, provides guidance on quantifying emission reductions from the use of cetane improvement additives in diesel fuel. These emission reductions may be used either to meet state implementation plan requirements such as reasonable further progress or attainment or in transportation conformity determinations. - Guidance for Quantifying and Using Long Duration Truck Idling Emission Reductions in State Implementation Plans and Transportation Conformity (PDF) (33 pp, 379K, EPA420-B-04-001, January 2004)
The January 2004 Long Duration Truck Idling Emission Reduction Guidance provides information on quantifying emission reductions from the use of technologies which reduce long duration truck idling emissions. These emission reductions may be used either to meet state implementation plan requirements such as reasonable further progress or attainment or in transportation conformity determinations. - Comparing Methodologies to Assess Transportation and Air Quality Impacts of Brownfields and Infill Development (PDF) (49 pp, 17K, EPA-231-R-01-001, August 2001)
This document describes four methods for characterizing the air quality benefits resulting from infill development, compares these methodologies, and examines their advantages and disadvantages. It also includes the June 7, 2001 guidance memo listed directly below. - Guidance on Applicable Methodologies to Account for the Benefits of Infill in SIPs and Conformity Determinations (PDF), June 7, 2001 (7 pp, 113K)
This memo guides the use of the four methods in preparing SIPs and transportation conformity determinations.
Contact: Laura Berry, OTAQ, at 734-214-4858 or berry.laura@epa.gov or
Mary Kay Santore, OPEI, at 202-260-8745 or santore.marykay@epa.gov - Final Policy Guidance: Improving Air Quality Through Land Use Activities. January 2001
This document discusses how to include land use activities in a SIP. It includes examples of land use activities and discusses requirements. (See Chapter 8 for conformity requirements and examples.)- Announcement (PDF) (1p, 10K)
- Brochure: Improving Air Quality Through Land Use Activities (PDF) (4pp, 3M)
- Complete Report: Improving Air Quality Through Land Use Activities (PDF) (110 pp, 1.1MB, EPA420-R-01-001, January 2001)
Land Use and Conformity
March 2, 1999 Conformity Court Decision
(subsequently incorporated into July 2004 rulemaking)- EPA's Conformity Guidance on Implementation of March 2, 1999, Conformity Court Decision (PDF) (11 pp, 46K, EPA420-F-99-025, May 1999)
This guidance includes details about using submitted budgets in conformity, EPA's new adequacy review process, non-federal projects, SIP disapprovals, and certain safety margins consistent with the court decision. EPA released this guidance on May 14, 1999. - U.S. DOT's Revised Guidance for the Implementation of March 2, 1999, Conformity Court Decision
This guidance document was released on January 2, 2002, and supersedes and replaces all previous FHWA and FTA guidance implementing the Court's decision, including the supplemental guidance issued on June 18, 1999. It covers projects that can proceed during a conformity lapse. - Revised Guidance for Implementing the March 1999 Circuit Court Decision Affecting Transportation Conformity | PDF version (4 pp, 48K)
U.S. DOT's February 7, 2002 Federal Register Notice announcing their revised guidance on projects that can proceed during a conformity lapse. This notice provides DOT's rational and justification for revising the guidance. - May 20, 2003, FHWA/FTA Guidance: Clarification of Transportation Conformity Requirements for FHWA/FTA Projects Requiring Environmental Impact Statements (PDF) (2 pp, 107K)
- April 9, 2003, FTA Guidance: Revised FTA Procedures for a conformity lapse (PDF) (2 pp, 2.3MB) Addresses funding and approval of FTA projects during a conformity lapse.
- June 10, 1999, Federal Register Notice: Adequacy Status of Submitted State Implementation Plans for Transportation Conformity Purposes
Contact: Laura Voss Berry at 734-214-4858 or berry.laura@epa.gov