London Underground Fourteen Underground stations are outside Greater London, of which five (Amersham, Chalfont & Latimer, Chesham, and Chorleywood on the Metropolitan line, and Epping on the Central line), are beyond the M25 London Orbital motorway. Of the 32 London boroughs, six (Bexley, Bromley, Croydon, Kingston, Lewisham and Sutton) are not served by the Underground network, while Hackney has Old Street and Manor House only just inside its boundaries. Lewisham used to be served by the East London line (stations at New Cross and New Cross Gate). The line and the stations were transferred to the London Overground network in 2010. London
Central line (London Underground) Total track length is , of which is in tunnel; this track is electrified with a four-rail DC system: a central conductor rail is energised at −210 V and a rail outside the running rail at +420 V, giving a potential difference of 630 V. The single-track line north of Epping, which closed in 1994, is now the Epping Ongar heritage railway. shuttle services operate on weekends between North Weald and Ongar and North Weald and Coopersale. These do not call at Blake Hall, as the station platform was removed by London Transport after the station closed, and the remaining