Wikipedia
Work train
A work train or departmental train (engineering train in the UK) is one or more rail cars intended for internal non-revenue use by the railroad's operator. Work trains serve functions such as track maintenance, maintenance of way, revenue collection, system cleanup and waste removal, heavy duty hauling, and crew member transport.
Usage examples of "work train".
A work train loaded with construction materials was pulling away from an expansive underground rail yard with the tracks converging at the main tunnel entrance that Mancuso judged was four meters in diameter.
The driver of the work train slewed out of the way, ramming into the rocky wall of the tunnel.
A tripping device failed to work and their train, braking late, ran into the rear of a stalled work train.