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
History of the London Underground the City & South London and Central London Railway joined the company. That year the Great Northern & City was taken over by the Met. Suggestions of merger with the Underground Group were rejected by the Metropolitan, a press release of November 1912 noting its interests in areas outside London, its relationships with main line railways and its freight business. Further coordination in the form of a General Managers' Conference faltered after the Metropolitan withdrew in 1911 when the Central London Railway, without any reference to the conference, set its season ticket prices significantly lower than those on the Met's