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
History of the London Underground the mainline railways was given priority over the maintenance of the Underground. In 1953 an unpainted aluminium train entered service on the District line, and this became the standard for new trains. In the early 1960s the Metropolitan line was electrified as far as Amersham, and steam locomotives no longer hauled passenger trains. The Victoria line, a new tube line across central London, opened in 1968–71 with trains driven automatically. In 1976 the isolated Northern City Line was taken over by British Rail and linked up with the mainline railway at Finsbury Park. In 1979 another new route, the Jubilee