(f)
Specific Rules.—
The Secretary may, by regulation, provide that the following crossings over railroad lines shall be subject, in whole or in part, to the regulations required under this section:
(1)
Private highway-rail grade crossings.
(2)
Pedestrian crossings.
(3)
Crossings utilized primarily by nonmotorized vehicles and other special vehicles.
Regulations issued under this subsection shall not apply to any location where persons are not authorized to cross the railroad.