A rubber-tyred tram (also known as tramway on tyres, ) is a development of the

guided bus Guided buses are buses capable of being steered by external means, usually on a Bus lane, dedicated track or roll way that excludes other traffic, permitting the maintenance of Public transport timetable, schedules even during rush hours. Unl ...

in which a vehicle is guided by a fixed rail in the

road surface A road surface (British English) or pavement (North American English) is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, macadam, ...

and draws current from overhead electric wires (either via

pantograph A pantograph (, from their original use for copying writing) is a Linkage (mechanical), mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a se ...

trolley pole A trolley pole is a tapered cylindrical pole of wood or metal, used to transfer electricity from a "live" (electrified) overhead line, overhead wire to the control and the electric traction motors of a tram or trolley bus. It is a type of current ...

s). Two incompatible systems using physical guide rails exist: the guided light transit (GLT) designed by

Bombardier Transportation Bombardier Transportation was a Canadian rolling stock and rail transport manufacturer, with headquarters in Toronto and Berlin. It was one of the world's largest companies in the rail vehicle and equipment manufacturing and servicing industry. ...

, and the translohr from Lohr Industrie (currently made by

Alstom Alstom SA () is a French multinational rolling stock manufacturer which operates worldwide in rail transport markets. It is active in the fields of passenger transportation, signaling, and locomotives, producing high-speed, suburban, regional ...

and FSI). There are no guide bars at the sides but there is a central guidance rail that differs in design between the systems. In the case of Translohr, this rail is grasped by a pair of metal guide wheels set at 45° to the road and at 90° to each other. In the GLT system, a single double-

flange A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of a steel beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer o ...

d wheel between the rubber tires follows the

guidance Guidance may refer to: Arts and media * Guidance (album), ''Guidance'' (album), by American instrumental rock band Russian Circles * Guidance (film), ''Guidance'' (film), a Canadian comedy film released in 2014 * Guidance (web series), ''Guidance ...

rail. In both cases, the weight of the vehicle is borne by rubber tires to which the guide wheels are attached, which make contact with the road on concrete roll ways designed to minimise impact on the ground. Power is usually supplied by

overhead line An overhead line or overhead wire is an electrical cable that is used to transmit electrical energy to electric locomotives, Electric multiple unit, electric multiple units, trolleybuses or trams. The generic term used by the International Union ...

s, rechargeable batteries, or

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal comb ...

s where there are no overhead wires.

Characteristics

The Translohr system operates as a guided vehicle at all times, while with the Bombardier system the vehicles can be driven independently as requirements dictate, such as journeys to the depot. Consequently, the Bombardier vehicles are legally considered buses, and must bear

rear-view mirror A rear-view mirror (or rearview mirror) is a, usually plane mirror, flat, mirror in automobiles and other vehicles, designed to allow the driver to see rearward through the vehicle's rear window (rear windshield). In cars, the rear-view mirror ...

s, lights and number plates, and are controlled with

steering wheel A steering wheel (also called a driving wheel, a hand wheel, or simply wheel) is a type of steering control in vehicles. Steering wheels are used in most modern land vehicles, including all mass-production automobiles, buses, light and hea ...

s and pedals like ordinary buses, though the steering wheel is not used when following the guidance rail. On the other hand, Translohr vehicles operate like standard

tram A tram (also known as a streetcar or trolley in Canada and the United States) is an urban rail transit in which Rolling stock, vehicles, whether individual railcars or multiple-unit trains, run on tramway tracks on urban public streets; some ...

s and cannot move without guidance, so they are not classified as buses and are not equipped with number plates. The ART system can be diverted by virtual track by the driver using a conventional steering wheel. These systems have been likened to the tram equivalent of

rubber-tyred metro A rubber-tyred metro or rubber-tired metro is a form of rapid transit system that uses a mix of road transport, road and rail transport, rail technology. The vehicles have wheels with rubber tires that run on a roll way inside guide bars for tr ...

s, and they are also less efficient than steel-wheeled light rail vehicles. There is no evidence to prove the superiority of either guidance system. Both Bombardier and Translohr have had

derailment In rail transport, a derailment is a type of train wreck that occurs when a rail vehicle such as a train comes off its rails. Although many derailments are minor, all result in temporary disruption of the proper operation of the railway sys ...

s during operation.

Operation systems

File:Scambio Translohr Deposito Favaro 071120.jpg, Translohr flexible single rail switch File:Scambio Translohr Padova Santo 041015.jpg, Translohr rigid two-rail

switch In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type o ...

File:Translohr-rail-crossing.jpg, Translohr rail crossing File:Tramway de Caen Rail.jpg, Guide rail section

Retired systems

Bombardier Guided Light Transit (GLT)

* Nancy Guided Light Transit, France (2001–2023) – 40% of the line ran as a driver-steered

trolleybus A trolleybus (also known as trolley bus, trolley coach, trackless trolley, trackless tramin the 1910s and 1920sJoyce, J.; King, J. S.; and Newman, A. G. (1986). ''British Trolleybus Systems'', pp. 9, 12. London: Ian Allan Publishing. .or troll ...

, and was part of the Nancy trolleybus system. The entire route was to be replaced by a tramway,"Worldwide Review egular news section (November 2017). '' Tramways & Urban Transit'', p. 431. UK: LRTA Publishing. . but those plans were dropped in 2021, and it is being converted back into a conventional trolleybus system because of the higher cost of a tramway. * Caen Guided Light Transit, France (2002–2017) – GLT closed in 2017 and converted to

light rail Light rail (or light rail transit, abbreviated to LRT) is a form of passenger urban rail transit that uses rolling stock derived from tram technology National Conference of the Transportation Research Board while also having some features from ...

which opened in 2019."Alstom trams to replace Caen TVR" (January 2017). '' Tramways & Urban Transit'', p. 7. UK: LRTA Publishing. .

Translohr

* Zhangjiang Tram, Shanghai, China (STE3, 2010–2023); closed due to high operating costs and low ridership. * TEDA Modern Guided Rail Tram, Tianjin, China (STE3, 2007–2023); closed due to maintenance issues.

Proposed systems

Cambridge Cambridge ( ) is a List of cities in the United Kingdom, city and non-metropolitan district in the county of Cambridgeshire, England. It is the county town of Cambridgeshire and is located on the River Cam, north of London. As of the 2021 Unit ...

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

. One of the three systems under consideration for the proposed Cambridge Autonomous Metro utilises a "fully autonomous, battery-powered road transport vehicle". (The other options are a

personal rapid transit Personal rapid transit (PRT), also referred to as podcars or guided/railed taxis, is a public transport mode featuring a network of specially built guideways on which ride small automated vehicles that carry few (generally less than 6) passenge ...

and a guided bus. An upgrade bus service is also being considered.)

References

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