a rigid contact conductor that provides a sliding contact for the current collector of rolling stock (an electric locomotive or motorized car). It is made of soft steel, and its shape and cross-sectional dimensions are similar to those of standard track rails. The contact rail is fastened by insulators to brackets located on the ties.
Contact rails provide reliable contact for the current collectors of motorized cars or electric locomotives, which are fastened to their undercarriages. Vibration of the current collectors or separation from the contact rail must be prevented to avoid interruptions of the current-carrying circuit, sparking, and arcing, which damage the contact surfaces. Contact rails are used predominantly in underground railroads or subway systems and less frequently for open lines operated at a relatively low voltage (not exceeding 1,500 volts).