37 U.S.C. § 408 : US Code - Section 408: Travel and transportation allowances: travel within limits of duty station

Search 37 U.S.C. § 408 : US Code - Section 408: Travel and transportation allowances: travel within limits of duty station

(a) A member of a uniformed service may be directed, by
regulations of the head of the department or agency in which he is
serving, to procure transportation necessary for conducting
official business of the United States within the limits of his
station. Expenses so incurred by the member for train, bus,
streetcar, taxicab, ferry, bridge, and similar fares and tolls, or
for the use of privately owned vehicles at a fixed rate a mile plus
parking fees, shall be defrayed by the department or agency under
which he is serving, or the member is entitled to be reimbursed for
the expense.
(b)(1) Under regulations prescribed by the Secretary concerned, a
member of a uniformed service who performs emergency duty described
in paragraph (2) is entitled to travel and transportation
allowances under section 404 of this title for that duty.
(2) The emergency duty referred to in paragraph (1) is duty that -

(A) is performed by a member under emergency circumstances that
threaten injury to property of the Federal Government or human
life;
(B) is performed at a location within the limits of the
member's station (other than at the residence or normal duty
location of the member);
(C) is performed pursuant to the direction of competent
authority; and
(D) requires the member's use of overnight accommodations.