A tram is a rail vehicle that runs on tramway track public urban streets; some include segments of segregated right-of-way. The lines or networks operated by tramcars as public transport are called tramways or simply tram/streetcar. Historically the terms electric street railways and trolley were also used in the United States. In the United States, the term tram has sometimes been used for rubber-tired trackless trains, which are unrelated to other kinds of trams.