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
London Underground infrastructure is proposed that the Northern line be extended to Nine Elms and Battersea. Construction started in 2015, and it is hoped the stations will open in 2020. There are suggestions that the Bakerloo line be extended to Lewisham, and then taking over services on the Hayes Line to relieve capacity on the suburban rail network. The London Borough of Hillingdon has proposed that the Central line be extended from West Ruislip to Uxbridge via Ickenham, claiming the extension would cut traffic on the A40 in the area. The signalling system on the Northern line is being replaced to increase capacity