Section 672.3 - [Effective until 11/1/2024] Scope and applicability(a) In general, this part applies to all recipients of Federal financial assistance under 49 U.S.C. chapter 53.(b) The mandatory requirements of this part will apply only to State Safety Oversight Agency personnel and contractors that conduct safety audits and examinations of rail fixed guideway public transportation systems, and designated personnel and contractors who are directly responsible for the safety oversight of a recipient's rail fixed guideway public transportation systems.(c) Other FTA recipients may participate voluntarily in accordance with this part.