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 Rail Silverlink franchise in 2007. It has since taken on more services through a former London Underground line and over other network rail lines. London Rail lets a concession to operate the Overground. Operation is contracted to Arriva Rail London (owned by Arriva UK Trains) until 2024. London Trams is responsible only for the Croydon Tram known as Tramlink. Tramlink was set up in 2000 by a private finance initiative. It was bought by TfL in 2008 and is operated on its behalf by FirstGroup. London Trams has been working on proposals for other tram schemes in west and central