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
Romford–Upminster line the refurbishment work was transferred to Wakefield in Yorkshire and the transfer was done by road. The point-work which was half installed is still visible from the eastern end of platform five at Upminster. The line is entirely within Travelcard Zone 6. Services are currently operated by London Overground, which replaced the previous operator, Abellio Greater Anglia, in May 2015. Trains are typically formed by a Class 315 or Class 317. As of December 2015, the service pattern on the route is one train every 30 minutes between approximately 6:15 am and 10 pm Mondays to Saturdays, and approximately 8:30