Subway train

Rapid transit is a type of high-capacity public transport generally found in urban areas. Unlike buses and trams, rapid transit systems operate on an exclusive right-of-way which is usually grade separated in tunnels or elevated railways. Modern services on rapid transit systems are provided on designated lines between stations typically using electric multiple units on rail tracks, although some systems use guided rubber tyres, magnetic levitation, or monorail. The stations typically have high platforms, without steps inside the trains, requiring custom-made trains in order to avoid gaps. They are typically integrated with other public transport and often operated by the same public transport authorities, but does not exclude a fully segregated light rail transit. It is unchallenged in its ability to transport large numbers of people quickly over short distances with little use of land. Variations of rapid transit include people movers, small-scale light metro, and the commuter rail hybrid S-Bahn. [Rapid transit. Wikipedia]