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 Outer Orbital Path London Outer Orbital Path The London Outer Orbital Path — more usually the "London LOOP" — is a 150-mile (242 km) signed walk along public footpaths, and through parks, woods and fields around the edge of Outer London, England, described as "the M25 for walkers". The walk begins at Erith on the south bank of the River Thames and passes clockwise through Crayford, Petts Wood, Coulsdon, Banstead, Ewell, Kingston upon Thames, Uxbridge, Elstree, Cockfosters, Chingford, Chigwell, Grange Hill and Upminster Bridge before ending at Purfleet, almost directly across the Thames from its starting point. Between these settlements the route passes