Transportation Conformity

Transportation Conformity image

The U.S. Environmental Protection Agency (USEPA) defines Transportation Conformity as a bridge which connects air quality and transportation planning activities.

The Clean Air Act Amendments of 1990 (CAAA90) require the USEPA to establish National Ambient Air Quality Standards (NAAQS) for six common air pollutants that are found all over the United States. These pollutants can injure health, harm the environment and cause property damage. USEPA calls these pollutants criteria air pollutants because the agency has developed science-based guidelines as the basis for setting permissible levels. NAAQS have been established for each of the criteria pollutants. 

Areas where air quality monitoring shows a violation of the NAAQS are designated “nonattainment.”  Nonattainment means that an area has monitored air quality that does not meet the NAAQS.Once a nonattainment area is shown through air quality monitoring to have met a NAAQS, USEPA will designate the area as a "maintenance area."

Nonattainment and maintenance areas are subject to a requirement known as Transportation Conformity. The intent of Transportation Conformity is to fully coordinate transportation and air quality planning to ensure that the Regional Transportation Plan (the Plan) and the Transportation Improvement Program (TIP) projects which are analyzed will not 1) cause or contribute to any new violation of the NAAQS, 2) increase the frequency or severity of any existing NAAQS violations, or 3) delay timely attainment of the NAAQS or any required interim emissions reductions or other milestones in any area. Through Transportation Conformity Determinations, NYMTC quantitatively demonstrates how its Plan and TIP projects impact future motor vehicle emissions budgets.

Emissions Budgets and the State Implementation Plan

In order to improve air quality, states must draft a plan known as a State Implementation Plan (SIP) to improve the air quality in nonattainment areas. The SIP outlines the measures that the state will take to improve air quality.

In New York State, the New York State Department of Environmental Conservation (NYSDEC) is required to produce a SIP that details how the NAAQS will be achieved in specific nonattainment areas in the state.

SIPs are developed to demonstrate that a state has appropriate program components in place, and to identify emission control programs that the state will rely on to meet and maintain the NAAQS in air quality control regions designated by USEPA under CAAA90. State SIPs must also account for pollution that contributes to visibility impairment, otherwise known as regional haze.

The New York SIP is made up of many related actions that have been taken to meet these CAAA90 requirements, such as infrastructure assessments, rate-of-progress plans attainment demonstrations, and regulations. With regard to metropolitan transportation planning, it establishes motor vehicle emissions budgets for specific pollutants which are used in determining Transportation Conformity.

Nonattainment and Maintenance Areas Addressed by NYMTC

NYMTC’s Transportation Conformity Determinations address all nonattainment and maintenance areas that fall in whole or in part within the NYMTC planning area, including:

  • The New York-Northern New Jersey-Long Island, NY-NJ-CT PM2.5 Maintenance Area, which includes all NYMTC counties and boroughs except Putnam County, as well as Orange County;
  • The New York-Northern New Jersey-Long Island, NY-NJ-CT Ozone Nonattainment Area, which includes all NYMTC counties and boroughs except for Putnam County;
  • The Poughkeepsie, New York Ozone Nonattainment Area, which includes Dutchess, Orange and Putnam counties; and
  • The New York-Northern New Jersey-Long Island, NY-NJ-CT Carbon Monoxide Maintenance Area, which includes all NYMTC counties and boroughs except Putnam, Rockland and Suffolk.

For more information contact Sangeeta Bhowmick