(a) When a single environmental document is not prepared for a proposed major Federal action, an agency may rely upon an existing environmental document, or element thereof, to document compliance with NEPA as follows:

(1) Any Federal agency may rely upon an environmental document prepared in accordance with 23 U.S.C. 139 to the same extent such Federal agency could adopt or use a document prepared by another Federal agency.

(2) The Administration may rely upon an existing environmental document not prepared in accordance with 23 U.S.C. 139 if the Administration determines that the proposed action is substantially the same as the action covered in the existing environmental document and that the environmental issues were adequately identified and addressed.

(3) The Administration may rely upon an existing categorical exclusion decision by another Federal agency if the Administration determines that a proposed major Federal action is substantially the same as the action that another Federal agency determined is categorically excluded from NEPA.

(4) A Federal land management agency may rely upon an existing environmental document or categorical exclusion decision prepared by FHWA for a project addressing substantially the same major Federal action proposed for approval by the Federal land management agency.

(b) Adoption of Categorical Exclusions under 42 U.S.C. 4336c:

(1) FHWA, FRA, or FTA may establish a new categorical exclusion by adopting a category of action listed as a categorical exclusion in another agency's NEPA procedures.

(2) A State functioning as FHWA, FRA, or FTA in carrying out responsibilities delegated or assigned to the State in accordance with 23 U.S.C. 326 or 327 may not establish a new categorical exclusion through adoption.

(3) To establish the new categorical exclusion, the Administration will:

(i) Identify the categorical exclusion listed in another agency's NEPA procedures that covers a category of proposed actions or related actions;

(ii) Consult with the agency that established this categorical exclusion to ensure that the proposed adoption of the categorical exclusion to a category of Administration actions is appropriate; and

(iii) Provide public notification that the Administration plans to use the categorical exclusion for its proposed actions by documenting its adoption.

(4) The Administration may begin to apply the newly adopted categorical exclusion to proposed major Federal actions upon completion of sub-paragraphs (b)(3)(i)-(iii).