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
Art on the Underground Kensington's museum subway, and at Charing Cross and Earl's Court tube stations among others. Many other stations on London Underground host temporary exhibitions, with past locations having included Canary Wharf, Piccadilly Circus, Charing Cross, Southwark and Westminster stations. Art on the Underground Art on the Underground, previously called "Platform for Art", is a visual arts showcase sponsored by London Underground, the rapid transit system for London, England. London Underground's associations with visual art began in 1908 when its then Publicity Officer Frank Pick began commissioning leading artists to work on poster campaigns for the rapidly expanding network. The company's distinctive