Terminology
Metro is the most common term for underground rapid transit systems. Rapid transit systems may be named after the medium through which their busier inner-city sections travel: use of tunnels inspires names such as subway, underground, Untergrundbahn (U-Bahn) in German, or Tunnelbana (T-bana) in Swedish; use of viaducts inspires names such as elevated (el or L), skytrain, overhead or overground. One of these terms may apply to an entire system, even if a large part of the network (for example, in outer suburbs) runs on ground level.
In most of Britain a subway is a pedestrian underpass; the expressions Underground and Tube are used for the London Underground, and the Tyne and Wear Metro, mostly overground, is known as the Metro. However in Scotland the Glasgow Subway underground rapid transit system is known as the Subway.
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