(a) Conformity determinations and conformity redeterminations for transportation plans, TIPs, and FHWA/FTA projects must be made according to the requirements of this section and the applicable implementation plan.

(b) Frequency of conformity determinations for transportation plans.

(1) Each new transportation plan must be demonstrated to conform before the transportation plan is approved by the MPO or accepted by DOT.

(2) All transportation plan amendments must be found to conform before the transportation plan amendments are approved by the MPO or accepted by DOT, unless the amendment merely adds or deletes exempt projects listed in §93.126 or §93.127. The conformity determination must be based on the transportation plan and the amendment taken as a whole.

(3) The MPO and DOT must determine the conformity of the transportation plan (including a new regional emissions analysis) no less frequently than every four years. If more than four years elapse after DOT's conformity determination without the MPO and DOT determining conformity of the transportation plan, a 12-month grace period will be implemented as described in paragraph (f) of this section. At the end of this 12-month grace period, the existing conformity determination will lapse.

(c) Frequency of conformity determinations for transportation improvement programs.

(1) A new TIP must be demonstrated to conform before the TIP is approved by the MPO or accepted by DOT.

(2) A TIP amendment requires a new conformity determination for the entire TIP before the amendment is approved by the MPO or accepted by DOT, unless the amendment merely adds or deletes exempt projects listed in §93.126 or §93.127.

(3) The MPO and DOT must determine the conformity of the TIP (including a new regional emissions analysis) no less frequently than every four years. If more than four years elapse after DOT's conformity determination without the MPO and DOT determining conformity of the TIP, a 12-month grace period will be implemented as described in paragraph (f) of this section. At the end of this 12-month grace period, the existing conformity determination will lapse.

(d) Projects. FHWA/FTA projects must be found to conform before they are adopted, accepted, approved, or funded. Conformity must be redetermined for any FHWA/FTA project if one of the following occurs: a significant change in the project's design concept and scope; three years elapse since the most recent major step to advance the project; or initiation of a supplemental environmental document for air quality purposes. Major steps include NEPA process completion; start of final design; acquisition of a significant portion of the right-of-way; and, construction (including Federal approval of plans, specifications and estimates).

(e) Triggers for transportation plan and TIP conformity determinations. Conformity of existing transportation plans and TIPs must be redetermined within two years of the following, or after a 12-month grace period (as described in paragraph (f) of this section) the existing conformity determination will lapse, and no new project-level conformity determinations may be made until conformity of the transportation plan and TIP has been determined by the MPO and DOT:

(1) The effective date of EPA's finding that motor vehicle emissions budgets from an initially submitted control strategy implementation plan or maintenance plan are adequate pursuant to §93.118(e) and can be used for transportation conformity purposes;

(2) The effective date of EPA approval of a control strategy implementation plan revision or maintenance plan which establishes or revises a motor vehicle emissions budget if that budget has not yet been used in a conformity determination prior to approval; and

(3) The effective date of EPA promulgation of an implementation plan which establishes or revises a motor vehicle emissions budget.

(f) Lapse grace period. During the 12-month grace period referenced in paragraphs (b)(3), (c)(3), and (e) of this section, a project may be found to conform according to the requirements of this part if:

(1) The project is included in the currently conforming transportation plan and TIP (or regional emissions analysis); or

(2) the project is included in the most recent conforming transportation plan and TIP (or regional emissions analysis).

[62 FR 43801, Aug. 15, 1997, as amended at 67 FR 50817, Aug. 6, 2002; 69 FR 40072, July 1, 2004; 73 FR 4439, Jan. 24, 2008]