Premetro
Type of tramway or light rail From Wikipedia, the free encyclopedia
Premetro (or pre-metro) is a type of light rail system designed as a precursor to full metro/rapid transit.[1][2] It has partially dedicated infrastructure, such as tunnels and viaducts, to separate it from other traffic. Initially, trams or light rail vehicles operate on the system, generally with the long-term goal of upgrading to rapid transit trains.[3] To accommodate this future transition, premetro infrastructure is built with specific properties, such as wider track radii and gentler gradients than those for ordinary trams.[4][5] A number of light rail lines are, or have been, called a Pre-metro by their operators, such as in Brussels[6][7] and Antwerp.[8][9] Additionally, Buenos Aires has a line light rail line named Premetro, [10][11] however this operates as a feeder line to the metro network, and was not built with plans for conversion to full rapid transit.[12]
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History
Summarize
Perspective
An early example of was the Tremont Street subway (1897) in Boston, today part of the MBTA Green Line. This tunnel was intended solely to reduce streetcar congestion on surface streets, not for later conversion to metro service.[13] However between 1901 and 1908, two out of four tracks were used for rapid transit service including high platforms.[14] Several early streetcar tunnels, including the Steinway Tunnel and East Boston Tunnel, were later converted to metro operation. However, the small loading gauge, tight curves, and steep grades of the streetcar tunnels required shorter metro cars than otherwise desirable.[13] In 1950 Stockholm converted a 1920s tram tunnel for its first rapid transit line.[15]
Second generation
The modern premetro concept Stadtbahn began in 1960s Germany, as rising traffic congestion due to auto ownership led to the construction of new transit systems. Rather than building costly metro lines immediately, some cities built only the downtown tunnels. They could be used by existing tram lines in the short term, with the intention of full metro conversion later - hence "pre-metro".[16] The idea spread to other European countries in the 1970s, especially Belgium, where such systems were explicitly named premetros.[16] Also one segment of Vienna's U2 metro line (Rathaus-Museumsquartier) is an in 1980 converted underground tramway line, which was constructed in 1966.
Terminology
The use of tram vehicles in tunnels originated in the United States in the nineteenth century and was often called "subway–surface line". Later, in the second half of the twentieth century the term "semi-metro" was coined for tram systems with some sections in tunnels and on viaducts. Only when a semi-metro section is designed for later use of heavy rapid transit trains, it falls in the premetro category. The large scale report "Light Rail Transit: A State of the Art Review" describes on page 9 the relationship of premetro systems to broader terms as follows:
Certain design features distinguish these systems from semi-metro or conventional light rail transit systems[1]
The same distinction is made in glossaries.[2][17] During the period when tram vehicles are used, the specific line falls into the light rail category.[18][19]
Examples
Previously converted lines
- Line 2 (Rio de Janeiro) in Brazil[20]
- Two stations of the line Roma – Fiuggi – Frosinone were converted to metro standards to become part of the Rome Line C.
- Vienna Pre-metro in Austria
Lines being converted
Lines without plans to be converted
See also
References
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