Medium-capacity rail transport system

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In rail transport, a medium-capacity system (MCS) is a non-universal term coined to differentiate an intermediate system between light rail and heavy rail. It can be regarded as a medium-capacity rapid transit system. The concept is similar to Light Metro, found in European countries (see section Variants of the term). A medium-capacity system is proposed when an area requires a rapid transit service but the predicted ridership falls in the gap between the other two rail tiers. An MCS may also result when a rapid transit service fails to achieve the necessary train headways to achieve the requisite ridership due to network inadequacies (e.g. single-tracking).

In contrast with most light rail systems, an MCS usually runs on an exclusive right-of-way. In some cases, the distance between stations is much longer than is usual in heavy rail networks. An MCS may also be a branch connection to another mode of a heavy-capacity transportation system, such as an airport or the main route of a metro network.

Defining characteristics[edit]

A Docklands Light Railway train leaving Canary Wharf DLR station heading for Bank DLR station in central London

The definition of a medium-capacity system varies due to its non-standardization. This can exist even within a relatively small country. For example, the Taiwan Ministry of Transportation and Communications states that each MCS system can board around 6,000–20,000 passengers per hour per direction (p/h/d or PPHPD),[1] while the Taiwan Department of Rapid Transit Systems (TCG) suggests an MCS has a capability of boarding around 20,000–30,000 p/h/d.[2] For comparison, >30,000 p/h/d ridership capacity has been quoted as the standard for metro or "heavy rail" standards rapid transit systems,[3] while light rail systems have been quoted to have passenger capacity volumes of around 12,000-18,000 p/h/d.[3] However, passenger capacity volume is just one possible criterion used to define a medium-capacity rail transit system.

Another criterion that can be used to define a medium-capacity rail system is vehicle type. For example, the train in an MCS may have a shorter configuration than the standard metro system, usually three to six cars, allowing for shorter platforms to be built and used. Rather than using steel wheels, rubber-tyred metro technology, such as the VAL system used on the Taipei Metro, is sometimes recommended, due to its low running noise, as well as the ability to climb steeper grades and turn tighter curves, thus allowing more flexible alignments.

Fully heavy rail or metro systems generally have train headways of 10 minutes or better during peak hours.[4] Some systems that qualify as heavy rail/metro in every other way (e.g. are fully grade separated), but which have network inadequacies (e.g. a section of single track rail) can only achieve lesser headways (e.g. every 15 minutes) which result in lower passenger volume capacities, and thus would be more accurately defined as "light metro" or "medium-capacity" systems as a result.

Variants of the term[edit]

Train on the Copenhagen Metro

Usage of the term may vary in different countries. In Russia, the "Light Metro" (Лёгкое метро) 12 - Butovskaya Line has been built to serve residents of outer Moscow. This line connects passengers with the main routes of Moscow Metro. The French rubber-tyred fully automated metro system, VAL, also uses the term "Light Metro" to define its capacity (up to 30,000 p/h/d[5]), and thus can also be categorized in the medium-capacity rail systems family. In Hong Kong, MTR's Ma On Shan Line is classified as a MCS but can attain up to 32,000 p/h/d, which is comparable to the passenger capacity of some full metro transit networks.[6]

Advantages and disadvantages[edit]

The main reason to build a light metro instead of a regular metro is to reduce cost, mainly because of shorter vehicles and shorter stations.

Light metros may operate faster than heavy-rail rapid transit systems, due to shorter dwell times at stations, and the faster acceleration and deceleration of lighter trains. For example, express trains on the New York City Subway are about as fast as the Vancouver SkyTrain, but these express trains skip most stops on lines where they operate.

Medium-capacity systems have a limitation because as the service district's population increases, the increased transportation demand might create bottlenecks. It is difficult to extend the station platforms once in operation, since this must be done without interfering with traffic, especially for underground railway systems. Some railway systems like Hong Kong and Wuhan may make advance provisions such as longer platforms, so that they will be able to accommodate future trains with more or longer cars. Taipei Metro, for example, constructed extra space for two extra cars in all Wenshan Line and Neihu Line stations. The Ma On Shan Line in Hong Kong has even applied the railway standard (with less car configuration) for a possible link with the other existing heavy rail route without reconstructing the current system.[clarification needed]


Location Country System Lines Year
Ottawa  Canada O-Train 1 2001 Single-tracked for most of at-grade route, limiting headways to 15 minutes. Uses DMU trains, so system is not electrified like most "Light Metros".
Toronto  Canada Scarborough RT
(part of Toronto subway and RT)
1 1985 Categorized by APTA as being "intermediate rail"[7] (i.e. between "heavy rail" and "light rail")
Hong Kong  China Ma On Shan Line (MTR),
South Island Line
Ma On Shan LineTrains: 4-car config.
South Island Line – Under construction: Rubber-tire system.
Shanghai  China Shanghai Metro: Line 5 and Line 6 2 2003,
Wuhan  China Wuhan Metro: Line 1 1 2004 Trains: 4-car config.
Copenhagen   Denmark Copenhagen Metro 1 2002 Driverless vehicle system. Trains: 3-car config., 39 metres length.
Rennes  France Rennes Metro 1 2013 VAL people mover system - while trains have 80 second headways, they can only carry 158 people per train.
Brescia  Italy Brescia Metro 1 2013 Light Metro. Trains: 3-car config, 39 metres length
Catania  Italy Catania Metro 1 1999 Light Metro. Single-tracked at-grade section limits headways to 15 minutes.
Milan  Italy Milan Metro: Line 5 1 2013 Portions still under construction. Driverless vehicle system.
Naples  Italy Naples Metro 1 1993 Line 6 is categorized as Light Metro, with only 16 minute headways. Line 1 has a single-tracked tunnel section.
Rome  Italy Rome Metro: Line C 1 (2014) Under construction. Driverless vehicle system.
Kuala Lumpur  Malaysia Kelana Jaya Line 1 1998 Light Metro. Trains: Mixed 2-car, 4-car config. fleet.
Manila  Philippines Manila Light Rail Transit System Line 1,
Manila Metro Rail Transit System
Manila Light Rail Transit System Line 1Trains: began with 2-car configuration, changed to 3-car in 2004, and added 4-car config. in 2007.[citation needed]
Moscow  Russia Moscow Metro: Line 12 – Butovskaya Line 1 2003 Can carry 6.7k pph. Trains: 3–4-car config.
Singapore  Singapore Singapore MRT: Circle MRT Line 1 2009 Trains: 3-car config.
Busan  South Korea Busan–Gimhae Light Rail Transit 1 2011 Busan–Gimhae Light Rail TransitTrains: 2-car config.
Uijeongbu  South Korea U Line 1 2012 Trains: 2-car config.
Barcelona  Spain Barcelona Metro: Line 11 1 2003
Taipei  Taiwan Taipei Metro: Brown (Wenhu) Line:
Wenshan Line & Neihu Line
2 1996 Wenshan LineTrains: Rubber-tire system; 4-car config.
Neihu Line – Extension of the Wenshan line.
Bangkok  Thailand BTS Skytrain 2 1999
Ankara  Turkey Ankaray Light Metro (A1 Line) 1 1996 Light Metro. Trains: 3-car config, 77 metres length.
Istanbul  Turkey Istanbul Hafif Metro (M1 Metro Line) 1 1989 Light Metro. "Hafif Metro" literally translates as "Light Metro". Trains: 4-car config.
Glasgow  United Kingdom Glasgow Subway 1 1896 Gauge: 4 ft (1,219 mm). Trains: 3-car config.
London  United Kingdom Docklands Light Railway 7 1987 Driverless vehicle system.
Philadelphia  United States Norristown High Speed Line
(part of the SEPTA rail system)
1 1907 Has been categorized by APTA as being "Light rapid rail transit"[8] (i.e. between "rapid transit (heavy rail)" and "light rail")

Former examples[edit]

  • Guangzhou -
    • Line 3 (began with 3-car configuration, changed to 6-car in 2010)


  1. ^ "Transportation term definition" (in Chinese). Ministry of Transportation and Communications (MOTC). Retrieved 2008-06-30. 
  2. ^ "Comparison between high capacity and medium capacity systems" (in Chinese). Taiwan Department of Rapid Transit Systems, TCG. Retrieved 2008-06-30. [dead link]
  3. ^ a b Great Britain: Parliament: House of Commons: Transport Committee, ed. (2005). Integrated Transport: The Future of Light Rail and Modern Trams in the United Kingdom. The Stationery Office. p. 216. Retrieved 2014-02-22. 
  4. ^ Schwandl, Robert (2007). "What is a metro?". UrbanRail.Net. Retrieved 2014-02-22. 
  5. ^ "VAL and NeoVAL". Siemens TS. Archived from the original on 2008-06-26. Retrieved 2008-06-30. 
  6. ^
  7. ^ "APTA Ridership Report - Q2 2013 Report" (pdf). American Public Transportation Association (APTA) (via: ). August 2013. p. 32. Retrieved 2013-09-26. 
  8. ^ "American Public Transportation Association - A MULTIMODAL TOUR OF THE DELAWARE VALLEY". American Public Transportation Association (APTA). June 1, 2013. Retrieved 2013-11-10. 

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