The FRA recommendation was if a locomotive is equipped they should be on at all times (unless prohibited by company regulations) for both crossing protection and roadway worker protection (track workers, signal maintainers etc.)
for GCOR rule see:
5.9.5 Displaying Ditch Lights
Display ditch lights, if equipped, to the front of the train when headlight is on bright.
Locomotives must not be operated as the lead unit out of a train’s initial terminal unless both
ditch lights are operating. However, if no units are equipped with ditch lights, do not exceed 20
MPH over public crossings until occupied.
If one ditch light fails enroute, the train may proceed, but repairs must be made by the next daily
inspection. If two ditch lights fail enroute, the train may proceed, but not exceeding 20 MPH over
public crossings until occupied, but must not travel beyond the first point where repairs may be
made or until the next daily inspection, whichever occurs first.
If Conductors are in charge, why are they promoted to be Engineer???
Retired Triebfahrzeugführer. I am not a moderator.