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 and Sutton Railway any construction and so extensions to the earlier acts were granted each year from 1918 to 1922 to give a final date of 26 July 1924 for completion of the compulsory purchase. In November 1922, notices of new bills to be placed before Parliament were published by the W&SR, and by the UERL's subsidiaries the London Electric Railway (LER) and the City and South London Railway (C&SLR, now part of the London Underground's Northern line). Taken together, the bills brought significant changes to the plans for the Wimbledon to Sutton line. The C&SLR was an underground railway running in deep