- Urban rail transit
Urban rail transit is an all-encompassing term for various types of local rail systems serving urban or older
suburb an areas. The vast majority of modern urban rail vehicles run onelectricity . The set of urban rail systems can be roughly subdivided into four categories, which sometimes overlap, causing some systems or lines to have aspects of each.Urban rail transit types
Trams
Tram s are systems that runs mainly or completely along streets, with low capacity and frequent stops. Passengers usually board at street- or curb-level (but low-floor trams and level boarding platforms may be used). These can be called "trams", "streetcars", or "trolleys", while the longer-distance lines which have now mostly vanished were called "interurbans" or "radial railways".Light Rail
Light rail is a relatively new term, as an outgrowth of trams/streetcars. Speeds are usually higher, andarticulated vehicles may be used to increase capacity. Note that some systems called "light rail" have most or all of the characteristics of "rapid transit" (see below) and may be better placed in that category, while others are essentially trams referred to as light rail for political reasons.Rapid Transit
A rapid transit, underground, subway, tube, elevated, or metro(politan) system is a
railway —usually in anurban area —with a high capacity and frequency of service, andgrade separation from other traffic. In most parts of the world these systems are known as a "metro", inLondon ,England the system is called the "underground", while in most ofNorth America and in Glasgow,Scotland it is a "subway".Monorail
Monorail is a metro orrailroad with a track consisting of a single rail (actually a beam), as opposed to the traditional track with two parallel rails. Monorail vehicles are wider than the beam they run on.Variations
Terms typically used for one type of system are sometimes used for the other. For example,
Boston 's Green Line is referred to as a "subway", despite having street-running portions. TheDocklands Light Railway inLondon is a predominantly-elevated system which provides a metro-style service with more in common with the rapid transit definition above than that of light rail; it is so named to distinguish it from theLondon Underground , which uses longer trains of heavier vehicles to provide more frequent service.Many cities use names such as "subway" and "elevated railway" to describe their entire systems, even when they combine both methods of operation. Slightly less than half of the
London Underground 's tracks, for example, are actually underground; New York City's subway also combines elevated and subterranean stations, while theChicago El andVancouver SkyTrain use tunnels to run through central areas.Other types of services
Passenger rail
Other types of passenger rail include the following:
*"Funicular s" are inclined railways that carry passengers up and down steep slopes.
*"Regional rail " or "commuter rail" runs on trackage often shared withintercity rail and freight trains, typically serving newersuburb s andrural areas. Commuter rail trains are typically built to higher standards, as they run at higher speeds are at risk of more severe crashes. This distinguishes commuter rail from interurbans, which use light-rail vehicles on tracks through lower density areas.Bus
A
bus shares many characteristics with light rail, but does not run on rails.Trolleybus es are buses that are powered byoverhead wire s.Railbus es, vehicles that can travel both on rails and on roads, have been tried experimentally, but are not in common use. The termbus rapid transit is used to refer to various methods of providing faster bus services, but the systems which use it are usually more equivalent tolight rail than torapid transit . Some cities experimenting withguided bus technologies, such as Nancy have chosen to refer to them as 'trams on tyres' (rubber tyred trams) and given them tram-like appearances.References
For terminology, see
passenger rail terminology .
* [http://flyvbjerg.plan.aau.dk/Publications2007/URBANRAIL61PRINT.pdf Flyvbjerg, B. "Cost Overruns and Demand Shortfalls in Urban Rail and Other Infrastructure," Transportation Planning and Technology, vol. 30, no. 1, February 2007, pp. 9-30.]External links
* [http://www.nautf.com NAUTF | North American Urban Transit Forum]
* [http://www.eastsiderailnow.org/myths.html Rail Transit Myths -- And Realities]
* [http://metrobits.org metrobits.org world metro database]
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