Circle route

When a circle route orbits a central business district in a large arc, it will often provide transverse (or lateral) links between suburbs or satellites, either on its own or in combination with other routes, such as Seoul Subway Line 2, the busiest line in the Seoul Metropolitan Subway network, and formerly the longest circle metro line in the world from 1984–2013.

The oldest circular rapid transit line was London's Inner Circle, today the Circle line of the London Underground, which was completed in 1884, operated by two separate companies.

[3] The route chosen forms the general border of what is today central London.

More recently, line 3 of the Copenhagen Metro opened in 2019, connecting the city centre to the northern and eastern suburbs.

Further examples are the Osaka Loop Line for the JR West Urban Network serving the Kyoto-Osaka-Kobe conurbation and the Yamanote Line for the JR East Greater Tokyo commuter rail network.

High Street Kensington station on the Inner Circle line in London, the world's first circle line.
Line 10 of the Beijing Subway , the world's second longest circular metro line