49 CFR 220.305: Use of personal electronic devices.

A railroad operating employee must have each personal electronic device turned off with any earpiece removed from the ear—

(a) When on a moving train;

(b) When any member of the crew is—

(1) On the ground, or

(2) Riding rolling equipment during a switching operation; or

(c) When any railroad employee is assisting in preparation of the train for movement.