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
M25 motorway opened in 1986 traffic levels exceeded the maximum design capacity and in 1990 the Secretary of State for Transport announced plans to widen the whole of the M25 to four lanes. By 1993 the motorway, which was designed for a maximum of 88,000 vehicles per day, was carrying 200,000 vehicles per day. 15% of UK motorway traffic volume was on the M25 and there were plans to add six lanes to the section from Junctions 12 to 15 as well as widening the rest of the motorway to four lanes. In parts, particularly the western third this plan went ahead,