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
Wimbledon and Sutton Railway any construction and so extensions to the earlier acts were granted each year from 1918 to 1922 to give a final date of 26 July 1924 for completion of the compulsory purchase. In November 1922, notices of new bills to be placed before Parliament were published by the W&SR, and by the UERL's subsidiaries the London Electric Railway (LER) and the City and South London Railway (C&SLR, now part of the London Underground's Northern line). Taken together, the bills brought significant changes to the plans for the Wimbledon to Sutton line. The C&SLR was an underground railway running in deep