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 1992 Stock London Underground 1992 Stock The London Underground 1992 Stock is a type of rolling stock used on the Central line and Waterloo & City line of the London Underground. The 1992 Stock was built by British Rail Engineering Limited (BREL) (under ABB, later Adtranz and now Bombardier Transportation) for the Central line following extensive testing of the three 1986 tube stock prototype trains. Even so, the introduction of this stock was far from trouble-free and there were many technical teething problems. Eighty-five trains were ordered from BREL, each formed of four two-car units (two units have driving cabs, the others