London Underground infrastructure Tube Programme, investigating replacing the trains for the Bakerloo and Piccadilly lines, is looking for trains with better energy conservation and regenerative braking. The Underground serves 270 stations. 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. The longest distance between two stations is between Chalfont & Latimer and Chesham on the Metropolitan line. The shortest distance between adjacent stations is the between Leicester Square and Covent Garden on the Piccadilly line. The station furthest
Central line (London Underground) Crossrail 2 line, running from south-west to north-east London and due to open by 2030, was planned for a number of years to take over the Epping branch of the Central line between Leytonstone and Epping. As of 2013 the preferred route options for the line no longer include this proposal. The Central line runs directly below Shoreditch High Street station and an interchange has been desired locally since it opened in 2010. The station would lie between Liverpool Street and Bethnal Green, one of the longest gaps between stations in inner London. Although there would be benefits to this