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 Rail to Enfield Town, Cheshunt and Chingford and Romford to Upminster Line services on 31 May 2015. London Rail London Rail is a directorate of Transport for London (TfL), involved in the relationship with the National Rail network within Greater London, UK which manages TfL's non-London Underground train services. London Rail manages the London Overground (LO), London Trams and Docklands Light Railway (DLR). It will also be responsible for Crossrail. As part of an internal restructure within TfL, it recently merged with the (previously separate) London Underground directorate, bringing all of Greater London local transport services on rails under one division.