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Executive Summary
Overview
The concept of transportation conformity was introduced in the Clean Air Act (CAA) of 1977 which included a provision to ensure that transportation investments conform to a state's air quality plan for meeting the Federal air quality standards. Conformity requirements were made substantially more rigorous in the CAA Amendments of 1990. The transportation conformity regulations1 that detail implementation of the new requirements were first issued in November 1993, and have been revised numerous times since. The regulations detail the process for transportation agencies to demonstrate and ensure that air pollutant emissions from transportation sources are consistent with air quality goals. This document was prepared for State and local officials who are involved in decision making on transportation investments.
What is Transportation Conformity?
Transportation conformity is a way to ensure that Federal funding and approval goes to those transportation activities that are consistent with the air quality goals: to eliminate violations, reduce the frequency and severity of violations and reach attainment in a timely manner.
What Actions are Subject to Conformity?
Conformity applies to long-range transportation plans, shorter-term transportation improvement programs (TIPs) and transportation projects funded or approved by the Federal Highway Administration (FHWA) or the Federal Transit Administration (FTA). Conformity requirements apply in areas that either do not meet or previously have not met certain air quality standards.
What is a Conformity Determination?
A conformity determination is a demonstration that the emissions from travel on an area's transportation system are consistent with goals for air quality found in the State Implementation Plan (SIP).
Who is Responsible for Making a Conformity Determination?
Metropolitan Planning Organization (MPO) policy boards make initial conformity determinations in metropolitan areas, while State Departments of Transportation (DOTs) usually do so in areas outside of metropolitan areas. Conformity determinations must also be made at the Federal level by FHWA/FTA. A formal interagency consultation process is required for developing SIPs, transportation plans, TIPs, and making conformity determinations, and includes the Environmental Protection Agency (EPA), FHWA, FTA, and State and local transportation and air quality agencies.
How Frequently are Conformity Determinations Required?
Conformity determinations must be made at least every three years, or when transportation plans or TIPs are updated. Also, conformity determinations must be made within 18 months of certain actions on the state's air quality plan. In addition, conformity determinations must be made within 12-months of an area being designated by EPA as nonattainment for ozone (O3), carbon monoxide (CO), particulate matter (PM-10 and PM-2.5), or nitrogen dioxide (NO2), the pollutants for which conformity is required.
How do we Involve the Public?
A conformity analysis is made available to the public as part of the MPO and/or State DOT transportation planning process. MPOs are required to make transportation plans, TIPs, and conformity determinations available to the public, to accept and respond to public comment, and to provide adequate notice of relevant public meetings. Project sponsors must also include appropriate public involvement during project development.
How do we Determine Conformity?
Regional emissions are estimated based on projected motor vehicle travel on existing and planned highway and transit facilities consistent with an area's transportation plan and TIP. The projected emissions must not exceed the emissions limits ("motor vehicle emissions budgets") established by the SIP. Also, the MPO is required to demonstrate that Transportation Control Measures (TCMs) in EPA-approved SIPs are implemented in a timely fashion.
What are Emissions Budgets?
The state air quality plan assigns emission reductions for each pollutant or precursor for each source type (on-road motor vehicles, nonroad equipment and vehicles, stationary and area sources). The level of emissions for on-road motor vehicles, such as cars, trucks, and buses, is called a "motor vehicle emissions budget". For conformity, projected emissions from highway and transit use must be less than or equal to the budget. Budgets are developed as part of the air quality planning process by State air quality or environmental agencies, and approved by EPA. Transportation agencies participate in this process in accordance with required interagency consultation procedures.
What are Transportation Control Measures (TCMs)?
TCMs are specific projects or programs designed to reduce emissions from transportation sources by reducing vehicle use, changing traffic flow or congestion conditions. Examples include programs for improving public transit, developing high occupancy vehicle (HOV) facilities, and ordinances to promote non-motorized vehicle travel. Areas can include TCMs in their SIPs.
What is Project-level Conformity?
In nonattainment and maintenance areas, projects must come from a currently conforming transportation plan and TIP that have undergone a conformity determination which has been approved by FHWA and FTA. In carbon monoxide and particulate matter nonattainment and maintenance areas, additional analysis may be necessary for Federally funded or approved projects, to determine if a project has localized or micro-scale air quality impacts as part of project-level conformity. This analysis is sometimes referred to as "hot-spot" analysis.
What Happens if an MPO Cannot Make a Conformity Determination?
When a conformity determination is not made by one of the deadlines described above, there is a conformity lapse and the use of Federal transportation funds is restricted. Exceptions include: safety projects, TCMs in EPA-approved SIPs, and project phases that are already authorized by the FHWA/FTA.
What Options do States and MPOs have to Reduce Emissions?
A variety of projects and programs can be implemented to reduce emissions. Options include traditional investments like transit, high-occupancy vehicle (HOV) lanes, and signal timing, and technology-based measures such as retrofitting, repowering, and/or replacing heavy-duty diesel trucks or implementing idling reduction programs.
Purpose of this Guide
This Guide was prepared to help State and local officials understand transportation conformity and how conformity requirements relate to transportation investments in their communities. Specifically, we discuss the implications of conformity on transportation plans, transportation improvement programs (TIPs), and transportation projects. The Guide provides overview information on the major elements of the conformity process and provides answers to basic questions2. Several exhibits are included in the Guide to illustrate key elements of the conformity process. Appendices are also included that discuss the health effects of pollutants, options to reduce on-road mobile source emissions, and resource agency contacts. A glossary is also included.
1 Title 40 C.F.R., Parts 51 and 93.
2 Many additional documents and training materials are available at: www.fhwa.dot.gov/environment/conform.htm that address the technical requirements of transportation conformity.
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