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
Central line (London Underground) Ilford carriage depot. The extension transferred to London Underground management in 1949, when Epping began to be served by Central line trains. The single line to Ongar was served by a steam autotrain operated by British Rail (BR) until 1957, when the line was electrified. BR trains accessed the line via a link from Temple Mills East to Leyton. The Central line stations east of Stratford kept their goods service for a time, being worked from Temple Mills, with the Hainault loop stations served via Woodford. The BR line south of Newbury Park closed in 1956 and Hainault loop stations