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
Circle line (London Underground) open in 2018, is expected to reduce crowding on Circle line services between Paddington and Aldgate. "The line then continues to Edgware Road where trains terminate, then reverse to traverse the loop in an anticlockwise direction to Hammersmith." Owing to its traditionally circular nature, the line has generated many urban myths over the years, including a dead man travelling around undiscovered, a school or office using the service to save infrastructure costs and, as an April fool in the Independent, a new particle accelerator to coexist alongside passenger services. Circle line (London Underground) The Circle line is a London Underground