Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration
Office of Planning, Environment, & Realty (HEP)

Transportation Conformity Highlights

October 2004

TEA-21 Extended for Eight Months. On September 30, the Surface Transportation Extension Act of 2004, Part V (STEA04-V) was enacted which completes the authorization process for FY 2004 and provides an 8-month extension of the Federal-aid Highway Program for FY 2005. For further information: see:

EPA Reclassifies Nine Ozone Nonattainment Areas. On September 17, 2004 U.S. EPA announced the reclassification of nine areas to "marginal" instead of "moderate" nonattainment of 8-hour ozone standard. The reclassified areas are: Cass County, MI; Muskegon County, MI; the eight-county Detroit, MI metro area; Greensboro County, NC; Kent and Queen Anne counties, MD; Lancaster County, PA; LaPorte County, IN; the counties surrounding Memphis, TN; and the counties surrounding Richmond, VA. Although the new classification lifts some CAA mandates, including auto tailpipe emissions testing, it mandates faster compliance, requiring standards to be met by 2007 instead of 2010. For transportation conformity, these areas (except Greensboro, NC, which is an Early Action Compact area) will be allowed to choose between either the no-greater-than-2002 test or the build no-greater-than-no-build test to demonstrate 8-hour conformity if interim emissions tests are applicable in these areas. However, it should be noted that the effective date of the nonattainment designation has not changed from June 15, 2004, and the 1-year grace period for conformity will expire on June 15, 2005 for these areas (except Greensboro). For more information, see:

Implications of the Implementation of the MOBILE6 Emissions Factor Model on Project-Level Impact Analyses Using the CAL3QHC Dispersion Model. A recently completed FHWA research study on project-level impacts of the MOBILE6 model is now available. The CAL3QHC roadway intersection model is typically employed to determine potential air quality impacts for project-level analysis. CAL3QHC uses both an idle emission factor and an appropriate emission factor based on each link's free flow speed. The recent changes incorporated in MOBILE6 may produce changes in the idle and free-flow speed emission rates. Because these two emission rates are the input parameters for CAL3QHC, the modeling output may be different using MOBILE6 versus earlier versions of MOBILE. This study explores how the use of MOBILE6 impacts project-level analyses. The study is divided into three main components addressing the following three questions: 1) How will changes in MOBILE6 impact project-level results? 2) How will changes in MOBILE6 affect the process for project-level analysis? 3) Will changes in MOBILE6 significantly impact screening assessment procedures? For study results, see:

EPA Sued Over the July 2004 Transportation Conformity Rule. A lawsuit was recently filed against EPA concerning the July 2004 Transportation Conformity Rule. The petitioners include Environmental Defense, Natural Resources Defense Council, Sierra Club and TRANSDEF. The petitioners raised four issues: 1) EPA's failure to finalize rules for PM2.5 hot-spot analysis; 2) the provision that allows 8-hour ozone nonattainment areas to use the interim emissions tests instead of budgets from the applicable 1-hour SIP; 3) the change to provisions related to reliance on a previous regional emissions analysis; and, 4) the change to latest planning assumptions requirements that allows areas to use the assumptions that are available when the area begins the regional emissions analysis rather than when U.S. DOT makes the conformity determination. Later this month EPA will be providing information to the Court on the issues.

NTI Course: Introduction to Transportation Conformity. Courses will be offered in Newington, CT on November 8-10; Memphis, TN on December 14-16; and Houston, TX on March 21-23, 2005. Additional courses are to be scheduled in January and/or February. For information and to register go to:

If you have any suggestions for future monthly conformity highlights, please email:

FHWA Resource Center Air Quality Team Contacts:

Updated: 10/20/2015
HEP Home Planning Environment Real Estate
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000