Transportation Conformity

National Information

Overview

Transportation conformity is a way to ensure that Federal funding and approval are given to those transportation activities that are consistent with air quality goals. It ensures that these transportation activities do not worsen air quality or interfere with the purpose of the State Implementation Plan (SIP), which is to meet the National Ambient Air Quality Standards (NAAQS). Meeting the NAAQS often requires emissions reductions from mobile sources.

According to the Clean Air Act (CAA) transportation plans, programs, and projects cannot:

Create new NAAQS violations
Increase the frequency or severity of existing NAAQS violations; or
Delay attainment of the NAAQS

The State Implementation Plan and the Motor Vehicle Emission Budget

The State Implementation Plan (SIP) outlines a state's air quality goals (e.q. attaining or maintaining the NAAQS), and how they intend to achieve those goals. One component of a SIP is the Motor Vehicle Emission Budget (MVEB). For certain budget years, the MVEB sets the maximum amount of emissions of selected pollutants, such as Nitrogen Oxides (NOx), Volatile Organic Compounds (VOC), and/or Carbon Monoxide (CO), allowed from on-road mobile sources.

Region 4 State Implementation Plans

Transportation Plans

A Long Range Transportation Plan (LRTP) is a planning document that contains an area's transportation projects and goals over a 20-25 year period. The LRTP is updated every three years. A Transportation Improvement Program (TIP) is a subset of the LRTP and is updated every two years. It contains a 3 to 5-year listing of the projects funded and scheduled for construction/ROW acquisition. Both the LRTP and TIP must be shown to conform to the SIP's air quality goals. The Federal Highway Administration (FHWA) approves the final conformity determination with concurrence from EPA. Metropolitan planning organizations' web sites typically contain information on the current LRTP/TIP (see state links below).

Partners in the Conformity Process

The conformity process involves consultation between several agencies, including metropolitan planning organizations, state and local departments of transportation, state and local air agencies, transit operators, the Federal Highway Administration (FHWA), the Federal Transit Administration (FTA), and EPA.

Click on a state below for links to the conformity partners: