A tram (also tramcar; and in North America streetcar, trolley or trolley car ) is a rail vehicle which runs on tramway tracks along public urban streets, and also sometimes on a segregated right of way. The lines or networks operated by tramcars are called tramways. Tramways powered by electricity, the most common type, were once called electric street railways (mainly in the United States ) due to their being widely used in urban areas before the universal adoption of electrification. In the United States, the term tram has sometimes been used for rubber-tyred trackless trains, which are not related to the other vehicles covered in this article.
Tram vehicles are usually lighter and shorter than conventional trains and rapid transit trains. Today, most trams use electrical power, usually fed by an overhead pantograph sliding on an overhead wire ; in some cases by a sliding shoe on a third rail, a trolley pole or a bow collector sliding on an overhead wire. If necessary, they may have dual power systems— electricity in city streets, and diesel in more rural environments. Trams are now commonly included in the wider term " light rail", which also includes grade-separated systems.
Tram lines may also run between cities and towns (for example, interurbans, tram- train ) or even countries ( Basel, Strasbourg ), or be partially grade-separated even in the cities ( light rail). Very occasionally, trams also carry freight.
