Semi-metro explained

Semi-metro should not be confused with Light metro.

Semi-metro (also known as subway-surface[1] [2] [3] [4] [5] line or hybrid[6] streetcar/light rail line) is a form of public rail transport in which trams run partly on a conflict-free track, by using tunnels and/or viaducts.[7] These stretches of track are designed to function like a regular metro or rapid transit line.[8] [9] Semi-metro lines run with tram cars because they are usually developed from an existing tram network.[10] [11]

One key difference with metro/rapid transit is that semi-metro lines only partially run in tunnels and/or on viaducts.[12] A metro line has an entirely conflict-free track, often completely grade separated. Semi-metro routes are operated by regular trams (with or without low floor) or with specially developed streetcars/tramcars (light rail vehicles), such as the Stadtbahn-car 'type B'.[13]

Features

The term semi-metro falls under the umbrella term light rail,[14] which includes many kinds of modern tram transport. Semi-metro is in itself a container concept in which premetro and Stadtbahn fall. Although cheaper than a metro line, the construction of infrastructure for semi-metro routes was often still too expensive. Therefore sections were sometimes not constructed or realised in phases. The entanglement with the existing tram network is an advantage compared to constructing a separate light metro line.[15] [16] Often several tram branches at grade are needed in order to make fully use of the high capacity tunnels.[17]

Right-of-way category

A rail transit system is firstly determined by its main right-of-way category and secondly bij other parameters like power supply and operating speed.[13] There are three major right-of-way categories, having been labelled A, B and C. Category A: independent right-of-way, without level road or pedestrian crossings resulting in conflict free sections. Catergory B: reserved right-of-way to avoid traffic congestion, but with level road or pedestrian crossings. Category C: street running lines in mixed traffic. Typically, a tram/streetcar line has mostly category C, a light rail line has mostly category B and a semi-metro line has some of category A (combined with category B and sometimes C).[18] Whenever light rail vehicles operate only using category A, then it's defined as Light rail rapid transit (LRRT) and is part of the greater light metro class.[19]

History

The first city in Europe to carry a portion of a streetcar line through the city center in a tunnel was Marseille, France, in 1893, with its Noailles subterranean station (see Marseille tramway). It was initially operated by horse-drawn wagons. An prominent example is the Tremont Street subway (1897) in Boston,[20] [21] today part of the MBTA Green Line. Brussels, Cologne and Frankfurt pioneered in Europe in the 1960s.

Subtypes

Besides regular semi-metro networks, two subtypes exist. Both terms refer to tram networks where tram vehicles use viaducts and/or run through tunnels under city centres, but with key differences:

Premetro

Premetro is largely similar to semi-metro: a type of public transport in which trams run partly grade separated, by using tunnels and/or viaducts. However, there is one clear distinguishing factor: premetro uses infrastructure that has been explicitly constructed with the ambition to transfer to use metro trains in the future.[13] [22] [23] It is usually also developed from an existing classic tram network. One prominent example is the premetro in Brussels, where several premetro lines have been or will be converted into full heavy rail metro lines.

U-Stadtbahn

The U-Stadtbahn is also an intermediate transportation form between metro and tram. It has originated in Germany, adapting the existing tram networks. Here specially developed trams run underground through tunnels in central urban areas.[13] [24] [25] Stadtbahn lines can be subdivided by looking at the types of rolling stock.

Examples

There are many regions with forms of light rail, but only few where light rail uses tunnels and/or viaducts. In the United States, the most prominent examples are the San Francisco Muni Metro and Green Line in Boston.[26] [13] The Buffalo Metro Rail, Seattle's Link light rail[27] and the light rail lines in Cleveland[28] are also considered semi-metro.

Notable examples in Germany are the Hanover Stadtbahn,[29] Essen Stadtbahn,[30] Bonn and Cologne Stadtbahns, and the Frankfurt tramways. In the United Kingdom, the Tyne and Wear Metro is by definition a semi-metro system due to eight level crossings.[31] Over several decades a semi-metro system was constructed in the Dutch city of The Hague.[32] [33]

More recent examples are the Madrid Metro Ligero, the Málaga Metro and Alicante Metropolitan-Tram in Spain and the Porto Metro in Portugal.[34]

Notes and References

  1. Book: Transportation Research Board . 9th National Light Rail Transit Conference . 2003 . 16 February 2023 . 29 . By this time, there was considerable interest in reconfiguring the U.S. subway-surface streetcar systems to resemble northern European practice, and there was increasing recognition that modern tramways might be appropriate for urban regions that long since had given up streetcar operation..
  2. Web site: Pedestrian Observations . What is Light Rail, Anyway? . August 2019 . 16 February 2023.
  3. Book: Canadian Embassy. . Canada Today: Canada D'aujourd'hui, Volumes 13-15 . 1982 . 16 February 2023 . light rail subway/surface line.
  4. THE RAPID TRAMWAY: A FEASIBLE SOLUTION TO THE URBAN TRANSPORTATION PROBLEM . Traffic Quarterly . 1970 . 24 . 4 . 517 . 7 April 2024 . 0041-0713.
  5. John W. . Schumann . What's New in North American Light Rail Transit Projects? . TRB Special Report . 221 . Light Rail Transit: New System Successes at Affordable Prices . 31 . 24 July 2024.
  6. Web site: NACTO . Streetcar and Light Rail Characteristics . 16 February 2023 . National Association of City Transportation Officials. https://nacto.org/about/
  7. Book: Haring . Leonardus H. . 13th National Light Rail and Streetcar Conference: Transforming Urban Areas . 401 . 1 August 2023.
  8. Book: Organisation for Economic Co-operation and Development. . The Automobile and the Environment . 1973 . 9 February 2023 . descending into tunnels in the style of conventional underground mass transit.
  9. Book: Norley . Kym . Light rail: The semi-metro concept . 2010 . 4 . Semi-metro: Light rail on reserved right of way over congested parts of line typically in tunnel or viaduct for grade separation designed to Metro standards, with priority surface light rail in other sections.
  10. Book: Implementation of Transportation Controls: Hearing, Ninety-third congress . 1974 . Washington, D.C. . 492 . In essence, a semi-metro consists of light rail cars operating on exclusive tracks, generally on the surface but descending into tunnels in the style of conventional underground mass transit in city centres . 17 January 2023.
  11. Web site: U.S., Transportation Research Board . Transportation Research Board Special Report 179 . National Academy of Sciences . 17 January 2023.
  12. Orski . C.K. . New Transportation Service Concepts . Proceedings of the International Conference on Transportation Research . 1973 . 407 . 9 February 2023.
  13. Book: Light Rail Transit: A State of the Art Review . De Leuw, Cather & Company . 1976 . 8 February 2023.
  14. Book: George E. Gray, Lester A. Hoel . Public transportation . 1992 . Prentice Hall . Englewood Cliffs, N.J. . 9780137263813 . 131, 739 . 2nd . 8 February 2023.
  15. Book: White . Peter . Public transport : its planning, management and operation . 2016 . New York . 9781317383178 . Edition 6 . Types of urban rail system.
  16. Web site: van Lith . Joske . Geluidloos zoeven door Rennes . Verkeerskunde . 2 February 2023 . Dutch.
  17. Web site: Pedestrian Observations . What are the Strong Tramway Corridors? . 21 July 2016 . 16 February 2023.
  18. Book: Vuchic . Vukan R. . Urban Public Transportation Systems . 14 January 2002 . University of Pennsylvania . 4, 5 . en.
  19. Book: Vuchic . Vukan R. . Urban Transit Systems and Technology . 14 February 2007 . Wiley . 978-0-471-75823-5 . 579 . 15 August 2024 . en.
  20. The Boston Daily Globe, "First Car off the Earth: Allston Electric Goes into the subway on schedule time.", The Boston Daily Globe, September 1, 1897. Experiences of the first Subway Riders in Boston.
  21. Web site: The bigger dig. 26 January 2014. 8 February 2023. Most . Doug. Boston Globe.
  22. Web site: PREMETRO [1 record] ]. 8 October 2009 . TERMIUM Plus® . 9 February 2023.
  23. Book: Transportation Research Board National Research Council . Urban Public Transportation Glossary . 1989 . 16 February 2023 . pre-metro: a light rail transit system designed with provisions for easy conversion to rail rapid transit.
  24. Book: Harman . Reg . HIGH SPEED TRAINS AND THE DEVELOPMENT AND REGENERATION OF CITIES . 2006 . Greengauge 21 . London . 19 . Köln, like other major German cities served by ICE services over high-speed lines, has a regional rail system (Schnellbahn) and a substantial tramway system, part operated as Stadtbahn (semi metro)..
  25. Web site: Pedestrian Observations . Stadtbahn Systems . 29 October 2020 . 16 February 2023.
  26. Trams are coming back . Ian Yearsley . . Reed Business Information Ltd. . ... San Francisco and Boston, both with semi-metros and independent plans for new tramcars. . 21 December 1972 . 17 January 2023.
  27. Web site: Electric Light Rail Transit (LRT) (Interurban & Streetcar) . 17 January 2023.
  28. Landgraf . Robert J. . Cleveland's Light Rail System in the 1980s: The Ongoing Revolution . Transportation Research Record . 1992 . 1361 . 259 . 22 March 2023 . 0361-1981.
  29. Book: Cappelli . Agostino . Nocera . Silvio . Libardo . Alessandra . Environment, land use and transportation systems : selected papers . 2013 . 42 . 22 March 2024 . en . Rather soon attention was given to Light Rapid Transit modes such as pre-metro and semi-metro (Hannover) employing heavy trams instead of light trains to run on open-air independent or semi-independent tracks, and just and just seldom using short bypass tunnels or fly-evers to skip congestion in central areas..
  30. International Railway Journal: IRJ. . 1975 . 15 . 18 . Regional editors . 3 May 2024 . Simmons-Boardman Publishing Company . en . brake equipment to be fitted to 90 two-car articulated semi-metro trainsets, under construction by Duwag, for service in the municipal areas of Bonn, Cologne and Essen..
  31. The Highway Engineer . Tyne and Wear Metro . 1976 . 23 . 44 . 22 March 2023 . Institution of Highway Engineers. . en.
  32. The Modern Tramway . The Hague . 1967 . 30 . 118 . 22 March 2023 . en.
  33. Vogel . A. T. . The semi-metro plan for Den Haag . The Modern Tramway . December 1972 . 35 . 35 . 404 . 22 March 2023.
  34. Web site: Sistema de Metro Ligeiro do Porto . . 22 March 2024 .

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