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 Underground 1992 Stock London Underground 1992 Stock The London Underground 1992 Stock is a type of rolling stock used on the Central line and Waterloo & City line of the London Underground. The 1992 Stock was built by British Rail Engineering Limited (BREL) (under ABB, later Adtranz and now Bombardier Transportation) for the Central line following extensive testing of the three 1986 tube stock prototype trains. Even so, the introduction of this stock was far from trouble-free and there were many technical teething problems. Eighty-five trains were ordered from BREL, each formed of four two-car units (two units have driving cabs, the others