7. The following jobs are essential for rail safety:
(1) the rail operating foreman;
(2) the track maintenance foreman;
(3) the locomotive engineer;
(4) the brakeman; and
(5) the signalman.
The locomotive crew consists of an engineer and at least one brakeman. Notwithstanding the foregoing, the engineer alone may use a portable locomotive control device without being part of a crew.
Only a locomotive engineer may use a portable locomotive control device.
A person may hold more than one job essential for rail safety.