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
Wimbledon station taking over the West Anglia Main Line north of there). This would provide another set of transport links for the area and direct services to and . There is also a proposal for an extension of the Tramlink services running from Wimbledon to Sutton via Morden, St. Helier and Rose Hill. The typical off-peak service (Monday to Saturday) frequency is: National Rail London Underground Wimbledon station Wimbledon is a National Rail, London Underground, and Tramlink station located on Wimbledon Bridge, Wimbledon in London, and is the only London station that provides an interchange between main line rail, Underground, and Tramlink.