London Underground with smaller trains that run in two circular tunnels ("tubes") with a diameter about . These lines have the exclusive use of a pair of tracks, except for the Piccadilly line, which shares track with the District line between Acton Town and Hanger Lane Junction and with the Metropolitan line between Rayners Lane and Uxbridge; and the Bakerloo line, which shares track with London Overground services north of Queen's Park. Fifty-five per cent of the system runs on the surface. There are of cut-and-cover tunnel and of tube tunnel. Many of the central London underground stations on deep-level tube routes
London Borough of Croydon is linked into the national motorway network via the M23 and M25 orbital motorway. The M25 skirts the south of the borough, linking Croydon with other parts of London and the surrounding counties; the M23 branches from the M25 close to Coulsdon, linking the town with the south coast, Crawley, Reigate, and Gatwick Airport. The A23 connects the borough with the motorways. The A23 is the major trunk road through Croydon, linking it with central London, East Sussex, Horsham, and Littlehaven. The old London to Brighton road, passes through the west of the borough on Purley Way, bypassing the commercial