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
London Underground electric locomotives London Underground electric locomotives Electric locomotives were first used on the London Underground when the first deep-level tube line, the City and South London Railway (C&SLR), was opened in 1890. The first underground railways in London, the Metropolitan Railway (MR) and the District Railway (DR), used specially built steam locomotives to haul their trains through shallow tunnels which had many ventilation openings to allow steam and smoke to clear from the tunnels. It was impractical to use steam locomotives in the small unvented tubular tunnels of the deep-level lines, and the only options were rope haulage (as on the Glasgow