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 battery-electric locomotives ground. A number of the machines were fitted with Automatic Train Operation (ATO) equipment to enable them to work on the newly opened Victoria line. Subsequently, some have been fitted with Automatic Train Protection (ATP) equipment, compatible with the system used on the Central line, and some with ATP equipment which enables them to work with the replacement Distance-to-Go Radio (DTG-R) system on the upgraded Victoria line. The first two battery locomotives supplied for the London Underground were manufactured by Hurst Nelson and Co, who were based in Motherwell. They were delivered in August 1905, and were used during the