104 STAT. 2410 PUBLIC LAW 101-549—NOV. 15, 1990 "(ii) increase the frequency or severity of any existing violation of any standard in any area; or "(iii) delay timely attainment of any standard or any required interim emission reductions or other milestones in any area. The determination of conformity shall be based on the most recent estimates of emissions, and such estimates shall be determined from the most recent population, employment, travel and congestion estimates as determined by the metropolitan planning organization or other agency authorized to make such estimates. Transportation. "(2) Any transportation plan or program developed pursuant to title 23, United States Code, or the Urban Mass Transportation Act shall implement the transportation provisions of any applicable implementation plan approved under this Act applicable to all or part of the area covered by such transportation plan or program. No Federal agency may approve, accept or fund any transportation plan, program or project unless such plan, program or project has been found to conform to any applicable implementation plan in effect under this Act. In particular— "(A) no transportation plan or transportation improvement program may be adopted by a metropolitan planning organization designated under title 23, United States Code, or the Urban Mass Transportation Act, or be found to be in conformity by a metropolitan planning organization until a final determination has been made that emissions expected from implementation of such plans and programs are consistent with estimates of emissions from motor vehicles and necessary emissions reductions contained in the applicable implementation plan, and that the plan or program will conform to the requirements of paragraph (I)(B); "(B) no metropolitan planning organization or other recipient of funds under title 23, United States Code, or the Urban Mass Transportation Act shall adopt or approve a transportation improvement program of projects until it determines that such program provides for timely implementation of transportation control measures consistent with schedules included in the applicable implementation plan; "(C) a transportation project may be adopted or approved by a metropolitan planning organization or any recipient of funds designated under title 23, United States Code, or the Urban Mass Transportation Act, or found in conformity by a metropolitan planning organization or approved, accepted, or funded by the Department of Transportation only if it meets either the requirements of subparagraph (D) or the following requirements— "(i) such a project comes from a conforming plan and program; "(ii) the design concept and scope of such project have not changed significantly since the conformity finding regarding the plan and program from which the project derived; and "(iii) the design concept and scope of such project at the time of the conformity determination for the program was adequate to determine emissions. "(D) Any project not referred to in subparagraph (C) shall be treated as conforming to the applicable implementation plan only if it is demonstrated that the projected emissions from such
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