(a) All Tribal transportation facilities listed in the approved NTTFI must be open and available for public use as required by 23 U.S.C. 101(a)(31). However, the public authority having jurisdiction over these roads or the Secretary, in consultation with a Tribe and applicable private landowners, may restrict road use or close roads temporarily when:

(1) Required for public health and safety or as provided in §170.116.

(2) Conducting engineering and traffic analysis to determine maximum speed limits, maximum vehicular size, and weight limits, and identify needed traffic control devices; and

(3) Erecting, maintaining, and enforcing compliance with signs and pavement markings.

(b) Consultation is not required whenever the conditions in paragraph (a) of this section involve immediate safety or life-threatening situations.

(c) A Tribal transportation facility owned by a Tribe or BIA may be permanently closed only when the Tribal government and the Secretary agree. Once this agreement is reached, BIA must remove the facility from the NTTFI and it will be ineligible for expenditure of any TTP funds.