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
Sutton railway station (London) 25 minutes on the direct route via and . The four platforms at Sutton station are numbered 1 to 4 from north to south. Platforms 1 and 2 are on the lines to Wimbledon, Epsom, Leatherhead, Dorking, and Horsham. Platforms 3 and 4 are on the Epsom Downs Line, which becomes single-track about south of the station. Platforms 1 and 3 are used by services from outer termini to Central London. Trains from Central London use platforms 2 and 4. Terminating trains which return to central London generally use platform 4. Platforms 1 and 2 can accommodate 12-coach trains, and