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Transportation Conformity: A Basic Guide for State and Local Officials

Frequency Requirements for Transportation Conformity

Conformity determinations must be made at least every four years, but may occur more often if metropolitan transportation plans or TIPs are updated more frequently or amended with non-exempt projects. In addition, certain SIP actions relating to motor vehicle emissions budgets may also require an updated conformity determination within 24 months. Also, conformity must be demonstrated within 12 months of EPA's designation of an area as nonattainment for any transportation-related criteria pollutant. Project-level conformity must be determined prior to the first time a non-exempt Federal project is adopted, accepted, approved or funded.

Updated: 3/14/2012
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