49 C.F.R. § 299.3
(c) The following Federal railroad safety regulations found in Title 49 of the Code of Federal Regulations, and any amendments are applicable to the railroad.
(24) The following parts shall apply to the railroad's maintenance-of-way equipment as it is used in work trains, rescue operations, yard movements, and other non-passenger functions:
(iii) Part 229, Railroad Locomotive Safety Standards, except—