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 requiring smaller letters and arrows. Harry Beck had the idea of expanding this central area, distorting geography, and simplifying the map so that the railways appeared as straight lines with equally spaced stations. He presented his original draft in 1931, and after initial rejection it was first printed in 1933. Today's tube map is an evolution of that original design, and the ideas are used by many metro systems around the world. The current standard tube map shows the Docklands Light Railway, London Overground, Emirates Air Line, London Tramlink and the London Underground; a more detailed map covering a larger