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
Timeline of the London Underground of the network. Station names shown are current names; many stations have previously had different names. Timeline of the London Underground The transport system now known as the London Underground began in 1863 with the Metropolitan Railway, the world's first underground railway. Over the next forty years, the early sub-surface lines reached out from the urban centre of the capital into the surrounding rural margins, leading to the development of new commuter suburbs. At the turn of the nineteenth century, new technology—including electric locomotives and improvements to the tunnelling shield—enabled new companies to construct a series of "tube" lines deeper