What is Rapid transit?
{{redirect2|Metro|Subway|the area consisting of a city and its suburbs|Metropolitan area|the restaurant chain|Subway (restaurant)}} [[File:Lancaster Gate tube.jpg|thumb|right|The [[London Underground]] is the world's oldest underground system.]] [[File:WMATA Metro Logo small.svg|thumb|upright|Logo of metro]] '''Rapid transit''' is the name for a type of [[railway]] which has [[train]]s that run very often and carry many [[passenger]]s at one time. It is usually in a [[city]] or [[urban area]] and takes people in and out of it. Unlike [[bus]]es or [[tram]]s, trains go between places very quickly because they do not mix with other [[traffic]]. Most rapid transit railways do not have [[level crossing]]s, but the [[railway track|tracks]] go over and under other roads, or run in [[tunnel]]s or over [[bridge]]s, so they do not meet. [[File:Metro in the World.svg|300px|thumb|Rapid transit [[Transport network|networks]] around the world:<ref>{{Cite web|title=urbanrail.net > metro - subway - light rail|url=http://www.urbanrail.net/|access-date=2021-07-26|website=www.urbanrail.net}}</ref> {{Legend|#000080|Rapid transit in one city}} {{Legend|#FF0000|Rapid transit in two or more cities}} {{Legend|#FF8040|Rapid transit under construction}} {{Legend|#804000|Planned rapid transit}} {{Legend|#CDC3CC|No rapid transit}} ]] Many places call their rapid transit system a '''metro'''. Other words for rapid transit, which vary around the world, are '''subway''', '''underground''', '''tube''', '''elevated''', or '''heavy rail'''. These words sometimes describe how the system is built: some systems are completely below or above ground, while others may have both below-ground and above-ground sections. A single rapid transit system can have many lines that go to different places and many [[train station|stations]] where people can get on and off trains. They often have stations where people can change from one line to another to go in a different direction, or change between other forms of [[public transport]]. These stations are call