(a) Pursuant to section 1308 of the Transportation Equity Act for the 21st Century, TEA-21 (Pub. L. 105-178), a State(s), MPO(s), or public transportation operator(s) may undertake a multimodal, systems-level corridor or subarea planning study as part of the statewide transportation planning process. To the extent practicable, development of these transportation planning studies shall involve consultation with, or joint efforts among, the State(s), MPO(s), and/or public transportation operator(s). The results or decisions of these transportation planning studies may be used as part of the overall project development process consistent with the National Environmental Policy Act (NEPA) of 1969 (42 U.S.C. 4321 et seq.) and associated implementing regulations (23 CFR part 771 and 40 CFR parts 1500-1508). Specifically, these corridor or subarea studies may result in producing any of the following for a proposed transportation project:

1. (1) Purpose and need or goals and objective statement(s);
2. (2) General travel corridor and/or general mode(s) definition (e.g., highway, transit, or a highway/transit combination);
3. (3) Preliminary screening of alternatives and elimination of unreasonable alternatives;
4. (4) Basic description of the environmental setting; and/or
5. (5) Preliminary identification of environmental impacts and environmental mitigation.

(b) Publicly available documents or other source material produced by, or in support of, the transportation planning process described in this subpart may be incorporated directly or by reference into subsequent NEPA documents, in accordance with 40 CFR 1502.21, if:

1. (1) The NEPA lead agencies agree that such incorporation will aid in establishing or evaluating the purpose and need for the Federal action, reasonable alternatives, cumulative or other impacts on the human and natural environment, or mitigation of these impacts; and

2. (2) The systems-level, corridor, or subarea planning study is conducted with:

   1. (i) Involvement of interested State, local, Tribal, and Federal agencies;
   2. (ii) Public review;
   3. (iii) Reasonable opportunity to comment during the statewide transportation planning process and development of the corridor or subarea planning study;
   4. (iv) Documentation of relevant decisions in a form that is identifiable and available for review during the NEPA scoping process and can be appended to or referenced in the NEPA document; and
   5. (v) The review of the FHWA and the FTA, as appropriate.

(d) In addition to the process for incorporation directly or by reference outlined in paragraph (b) of this section, an additional authority for integrating planning products into the environmental review process exists in 23 U.S.C. 168. As provided in 23 U.S.C. 168(f):

1. (1) The statutory authority in 23 U.S.C. 168 shall not be construed to limit in any way the continued use of processes established under other parts of this section or under an authority established outside this part, and the use of one of the processes in this section does not preclude the subsequent use of another process in this section or an authority outside of this part.
2. (2) The statute does not restrict the initiation of the environmental review process during planning.