Re: Flagging

This should answer to question regarding Class 1s and flagging, from FRA regs:
(2) Flag protection against following trains on the same track is
not required if--
(i) The rear of the train is protected by at least two block
signals;
(ii) The rear of the train is protected by an absolute block;
(iii) The rear of the train is within interlocking limits; or
(iv) A train order specifies that flag protection is not required.
(v) A railroad operates only one train at any given time.
(b) Each railroad shall designate by timetable or other instruction
for each territory the specific distance which a crew member providing
flag protection must go out in order to provide adequate protection for
his train.