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 infrastructure All of the lines use fixed length trains with between six and eight cars, except for the Waterloo & City line, which uses four-car trains. New trains are designed for maximum number of standing passengers and for speed of access to the cars and have regenerative braking and public address systems. Since 1999, all new stock has had to comply with accessibility regulations that require such things as access and room for wheelchairs, and the size of location of door controls. All underground trains are required to comply with the Rail Vehicle Accessibility (Non Interoperable Rail System) Regulations 2010 (RVAR