A work train (departmental train or engineering train/vehicles 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.

Several railroad vehicles are used to inspect tracks and infrastructure, identifying flaws and areas that need routine maintenance.

Track maintenance and renewal trains often consist of many separate pieces of equipment, each capable of servicing specific track components.

Trains are susceptible to issues related to low rail traction as well as being immobilized by significant snowfalls.

The uncontrolled growth of weeds and other vegetation along railroad right-of-ways can cause significant drainage issues, obstruct worker access, and become a nuisance to adjacent property owners.

In addition to specialized equipment above, most railroads have allocated regular rail cars and locomotives to railroad maintenance duties. This is often older equipment that has either reached the age limit that prohibits it from interchange with other railroad, and is required to stay on the railroad that owns it, or equipment that has been rendered obsolete by newer, often higher capacity versions: tank cars, flatcars, hoppers, gondola, boxcars as well as locomotives.

Railroads have historically kept rail-mounted cranes of various sizes to assist with maintenance work and major construction projects, and to respond to derailments and natural disasters. These have in large part been displaced by a mixture of road-biased mobile cranes and sideboom bulldozers.

Beyond typical railroad cars, hi-rail technology has allowed railroads to put conventional heavy equipment such as excavators, mobile cranes, bucket trucks, concrete mixers, etc, right onto the tracks.