A tram is a type of urban rail transit consisting of rail vehicles, either individual railcars or self-propelled trains coupled into multiple units that run on tramway tracks on urban public streets; some include segments on segregated right-of-way. The tramlines or tram networks operated as public transport are called tramways or simply trams/streetcars. Trams are now commonly included in the wider term light rail, which also includes grade-separated systems.
A trolleybus is an electric bus that draws power from dual overhead wires using spring-loaded trolley poles. Two wires, and two trolley poles, are required to complete the electrical circuit. This differs from a tram or streetcar, which normally uses the track as the return path, needing only one wire and one pole. They are also distinct from other kinds of electric buses, which usually rely on batteries. Power is most commonly supplied as 600-volt direct current, but there are exceptions.
An overhead line or overhead wire is an electrical cable that is used to transmit electrical energy to electric locomotives, electric multiple units, trolleybuses or trams. The generic term used by the International Union of Railways for the technology is overhead line. It is known variously as overhead catenary, overhead contact line (OCL), overhead contact system (OCS), overhead equipment (OHE), overhead line equipment, overhead lines (OHL), overhead wiring (OHW), traction wire, and trolley wire.
A third rail, also known as a live rail, electric rail or conductor rail, is a method of providing electric power to a railway locomotive or train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway track. It is used typically in a mass transit or rapid transit system, which has alignments in its own corridors, fully or almost fully segregated from the outside environment. Third-rail systems are usually supplied from direct current electricity.
An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor. Locomotives with on-board fuelled prime movers, such as diesel engines or gas turbines, are classed as diesel–electric or gas turbine–electric and not as electric locomotives, because the electric generator/motor combination serves only as a power transmission system.
Railway electrification is the use of electric power for the propulsion of rail transport. Electric railways use either electric locomotives, electric multiple units or both. Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines, but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches, and transformers.
The use of a third rail in rail transport modelling is a technique that was once applied, in order to facilitate easier wiring.
The Snaefell Mountain Railway is an electric mountain railway on the Isle of Man in Europe. It joins the village of Laxey with the summit of Snaefell, at 2,036 feet (621 m) above sea level the highest point on the island. It connects with the Manx Electric Railway (MER) in Laxey. The line is 5 miles (8 km) long, is built to 3 ft 6 in gauge and uses a Fell Incline Railway System centre rail for braking on the steep gradients. It is electrified using overhead wires at 550 volts direct current, with bow collectors.
A trolley pole is a tapered cylindrical pole of wood or metal, used to transfer electricity from a "live" (electrified) overhead wire to the control and the electric traction motors of a tram or trolley bus. It is a type of current collector. The use of overhead wire in a system of current collection is reputed to be the 1880 invention of Frank J. Sprague, but the first working trolley pole was developed and demonstrated by Charles Van Depoele, in autumn 1885.
Ground-level power supply, also known as surface current collection or, in French, alimentation par le sol, is a concept and group of technologies whereby electric vehicles collect electric power at ground level from individually-powered segments instead of the more common overhead lines. Ground-level power supply was developed for aesthetic reasons, to avoid the presence of overhead lines in city centres.
A pantograph is an apparatus mounted on the roof of an electric train, tram or electric bus to collect power through contact with an overhead line. The term stems from the resemblance of some styles to the mechanical pantographs used for copying handwriting and drawings.
Conduit current collection is an obsolete system that was used by some electric tramways to pass current to streetcars via a "conduit", a small tunnel under the roadway. Modern systems fall under the term ground-level power supply.
A bow collector is one of the three main devices used on tramcars to transfer electric current from the wires above to the tram below. While once very common in continental Europe, it was replaced by the pantograph or the trolley pole, itself often later replaced by the pantograph.
Guided Light Transit was the name of guided bus technology and associated infrastructure designed and manufactured by Bombardier Transportation. It was installed in two French cities: Nancy and Caen. The Caen system was closed in 2017 and replaced by conventional trams, while the Nancy system was closed in March 2023 and is to be replaced by trolleybuses.
A trolleytruck is a trolleybus-like vehicle used for carrying cargo instead of passengers. A trolleytruck is usually a type of electric truck powered by two overhead wires, from which it draws electricity using two trolley poles. Two current collectors are required in order to supply and return current, because the return current cannot pass to the ground since trolleytrucks use tires that are insulators. Lower powered trucks, such as might be seen on the streets of a city, tend to use trolley poles for current collection. Higher powered trucks, such as those used for large construction or mining projects, may exceed the power capacity of trolley poles and have to use pantographs instead. Trolleytrucks have been used in various places around the world and are still in use in cities in Russia and Ukraine, as well as at mines in North America and Africa. Because they draw power from the mains, trolleytrucks can use renewable energy sources – modern trolleytrucks systems are under test in Sweden and Germany along highways using diesel–electric hybrids to reduce emissions.
The history of trams, streetcars, or trolleys began in the early nineteenth century. It can be divided up into several discrete periods defined by the principal means of motive power used.
The stud contact system is an obsolete ground-level power supply system for electric trams. Power supply studs were set in the road at intervals and connected to a buried electric cable by switches operated by magnets on the tramcars. Current was collected from the studs by a "skate" or "ski collector" under the tramcar. The system was popular for a while in the early 1900s but soon fell out of favour because of the unreliability of the magnetic switches, largely due to friction and rapid corrosion affecting its cast iron moving components.
A rubber-tyred tram is a development of the guided bus in which a vehicle is guided by a fixed rail in the road surface and draws current from overhead electric wires.
Torquay Tramways operated electric street trams in Torquay, Devon, England, from 1907. They were initially powered by the unusual Dolter stud-contact electrification, but in 1911 was converted to more conventional overhead-line supply. The line was extended into neighbouring Paignton in 1911 but the whole network was closed in 1934.
The Cantono Frigerio system was an Italian electric power supply for trackless trolleybuses with two wires about 20 inches (510 mm) apart being contacted by a four-wheeled collector on a single trolley pole. In English publications it was often described as Filovia system although the Italian term filovia means literally wire way, i.e. a trolleybus line or a trolleybus system.
