53 Pa. Stat. § 15551
The words "transit facilities," as used in this act, shall be taken to mean and to include railways, and extensions thereof, for the transportation of persons and property over, under, upon, through, and across any streets, highways, avenues, bridges, viaducts, rivers, waters, and public and private lands; or partly over, under, upon, through, and across all or any of the same. They shall also be taken to mean and to include tunnels, subways, bridges, elevated structures, tracks, poles, wires, conduits, power-houses, sub-stations, lines for the transmission of power, car-barns, shops, yards, sidings, turn-outs, switches, stations, and approaches thereto, cars and motive equipment; and all works, buildings, appliances, and appurtenances necessary and convenient for the proper construction, equipment, maintenance, and operation of such transit facilities, or any one or more of them.
53 P.S. § 15551