A rubber-tired, manually steered, electrically-powered passenger vehicle operating on city streets drawing power from overhead lines. (The overhead contact wire system which supplies the power from a central power source is called a catenary.) The power is generated by the use of a grooved metallic wheel or pulley carried on the end of a pole by an electric motorized vehicle and held in contact with an overhead conductor, usually a suspended wire, from which it collects the current for the propulsion of the vehicle. A dual-mode trolley bus also has an on-board power source which can be used in emergencies or to extend the route beyond the end of the overhead wires. A trolley is generally 30 to 35 feet in length.