Two rapid transit systems operate in Tokyo: Tokyo Metro and the Toei Subway. Most of the network is located in the 23 special wards, with portions extending into Chiba and Saitama Prefectures. The subways are one part of Greater Tokyo's passenger rail network, with through service further connecting the subway to suburban railways in Western Tokyo and Kanagawa Prefecture.
Toei 6300 series (left) and Tokyo Metro 9000 series (right) trains at Tamagawa Station
Rapid transit or mass rapid transit (MRT), also known as metro, is a type of high-capacity public transport that is generally built in urban areas. A rapid transit system that primarily or traditionally runs below the surface may be called a subway, tube, or underground. Unlike buses or trams, rapid transit systems are railways, usually electric, that operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles. They are often grade-separated in tunnels or on elevated railways.
The London Underground is the world's first and oldest rapid transit system.
The New York City Subway is the world's largest single-operator rapid transit system by number of metro stations, at 472.
A crowded Paris Métro average station platform in 2007
A station of the Guangzhou Metro in 2005
