London Underground at +420 V, giving a potential difference of 630 V. On the sections of line shared with mainline trains, such as the District line from East Putney to Wimbledon and Gunnersbury to Richmond, and the Bakerloo line north of Queen's Park, the centre rail is bonded to the running rails. The average speed on the Underground is 20.5 mph. Outside the tunnels of central London, many lines' trains tend to travel at over 40 mph in the suburban and countryside areas. The Metropolitan line can reach speeds of 62 mph. The London Underground was used by 1.379 billion passengers in
London Underground GN&C Stock Heath. These plans were curtailed by World War II and the Northern City line (or "Highbury Branch") continued operating with 1938 Stock until 1975, when the line was transferred to British Rail. Since 1976 the line has been operated exclusively by British Rail Class 313 electric multiple units. London Underground GN&C Stock The GN & C Stock was operated on the Great Northern and City Railway, an underground railway line in London, England. It was opened between Moorgate and Finsbury Park on 14 February 1904. The original GN&C Stock operated on the line between 1904 and 1939. The line was