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
South Wimbledon tube station South Wimbledon tube station South Wimbledon is a London Underground station in South Wimbledon, a suburb of Wimbledon in south-west London. The station is on the Northern line, situated between Colliers Wood and Morden stations. It is located on the corner of Merton High Street (A238) and Morden Road (A219). South Wimbledon is on the boundary between Travelcard Zone 3 and Zone 4. The station was opened on 13 September 1926 as part of the Morden extension of the City & South London Railway south from Clapham Common. On the original plan it had the name "Merton Grove". For geographical