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 table below gives details of each junction, including the roads interchanged and the destinations that are signed from the motorway on the blue advance direction signs. Figures in kilometres are from the driver location signs; figures in miles are derived from them. !scope=col| miles !scope=col| km !scope=col| Clockwise exits (A carriageway) !scope=col| Junction !scope=col| Anti-clockwise exits (B carriageway) !scope=col| European Route Citations Sources M25 motorway The M25 or London Orbital Motorway is long encircling almost all of Greater London, England (with the exception of North Ockendon). An ambitious concept to build four concentric ring roads around London was first mooted