Rapid transit

Large cities often have a metro system, also called underground, subway or tube. The trains are electrically powered, usually by third rail, and their railroads are separate from other traffic,

A Transperth B-series train

usually without level crossings. Usually they run in tunnels in the city center and sometimes on elevated structures in the outer parts of the city. They can accelerate and decelerate faster than heavier, long-distance trains.

The term rapid transit is used for public transport such as commuter trains, metro and light rail. However, in New York City, lines on the New York City Subway have been referred to as "trains"