A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport are called tramways or simply trams/streetcars. Many recently built tramways use the contemporary term light rail. The vehicles are called streetcars or trolleys (not to be confused with trolleybus) in North America and trams or tramcars elsewhere. The first two terms are often used interchangeably in the United States, with trolley being the preferred term in the eastern US and streetcar in the western US. Streetcar or tramway are preferred in Canada. In parts of the United States, internally powered buses made to resemble a streetcar are often referred to as "trolleys". To avoid further confusion with trolley buses, the American Public Transportation Association (APTA) refers to them as "trolley-replica buses". In the United States, the term tram has sometimes been used for rubber-tired trackless trains, which are unrelated to other kinds of trams. Tram vehicles are usually lighter and shorter than main line and rapid transit trains. Today, most trams use electrical power, usually fed by a pantograph sliding on an overhead line; older systems may use a trolley pole or a bow collector. In some cases, a contact shoe on a third rail is used. If necessary, they may have dual power systems—electricity in city streets and diesel in more rural environments. Occasionally, trams also carry freight. Trams are now commonly included in the wider term "light rail", which also includes grade-separated systems. Some trams, known as tram-trains, may have segments that run on mainline railway tracks, similar to interurban systems. The differences between these modes of rail transport are often indistinct and a given system may combine multiple features. Ultra Light Rail ULR trains are trams are a developing light weight rail type, around <5T/axle (empty), for use in smaller cities and towns to replace main bus routes e.g. Coventry Very Light Rail, ULR Partners future-light-rail or lower use branch train lines. They may be normal trams, rail motor sized and/or smaller modular units capable of platooning. They offer all the advantages of traditional trams but their lower weight, prefabricated beam type tracks offer the possibility of avoiding costly services diversions, lightweight OHL Over Head Lines and/or onboard power options e.g. hydrogen, biomethane, battery, may mean reduced/eliminated OHL. Thus installation