23 C.F.R. § 625.3 – Application.

(a) Applicable Standards.
1. (1) Design and construction standards for new construction, reconstruction, resurfacing (except for maintenance resurfacing), restoration, or rehabilitation of a highway on the NHS (other than a highway also on the Interstate System or other freeway) shall be those approved by the Secretary in cooperation with the State highway departments. These standards may take into account, in addition to the criteria described in § 625.2(a), the following:
  1. (i) The constructed and natural environment of the area;
  2. (ii) The environmental, scenic, aesthetic, historic, community, and preservation impacts of the activity; and
  3. (iii) Access for other modes of transportation.
2. (2) Federal-aid projects not on the NHS are to be designed, constructed, operated, and maintained in accordance with State laws, regulations, directives, safety standards, design standards, and construction standards.
(b) The standards, policies, and standard specifications cited in § 625.4 of this part contain specific criteria and controls for the design of NHS projects. Deviations from specific minimum values therein are to be handled in accordance with procedures in paragraph (f) of this section. If there is a conflict between criteria in the documents enumerated in § 625.4 of this part, the latest listed standard, policy, or standard specification will govern.
(c) Application of FHWA regulations, although cited in § 625.4 of this part as standards, policies, and standard specifications, shall be as set forth therein.
(d) This regulation establishes Federal standards for work on the NHS regardless of funding source.
(e) The Division Administrator shall determine the applicability of the roadway geometric design standards to traffic engineering, safety, and preventive maintenance projects which include very minor or no roadway work. Formal findings of applicability are expected only as needed to resolve controversies.
(f) Exceptions.
1. (1) Approval within the delegated authority provided by FHWA Order M1100.1A may be given on a project basis to designs which do not conform to the minimum criteria as set forth in the standards, policies, and standard specifications for:
  1. (i) Experimental features on projects; and
  2. (ii) Projects where conditions warrant that exceptions be made.
2. (2) The determination to approve a project design that does not conform to the minimum criteria is to be made only after due consideration is given to all project conditions such as maximum service and safety benefits for the dollar invested, compatibility with adjacent sections of roadway and the probable time before reconstruction of the section due to increased traffic demands or changed conditions.