A rail adhesion car or rail adhesion train is a modified vehicle used on a rail adhesion system where the standard equipment does not have locomotives' rail sanding ability. In particular, it may involve tanks and dispensing equipment installed in an electric subway or rail car that is run over the rails alone or in a train to dispense sand when needed. Because of space limits under the cars, the sand or gel/sand mix tanks are installed inside the passenger space.
In the New York City Subway, for example, rail adhesion cars were created from older equipment. As of 2013[update], three such cars existed in the subway system:[1]