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 S7 and S8 Stock The DMIs show destination and line, and can display other messages such as safety notices. There are also DMIs on the exterior, with text alternating between destination and line, and on S8 stock the type of service, i.e. fast, semi-fast or all stations. Another new feature is that to prevent accidental pressing of emergency alarms there are flaps over the alarm buttons where the wheelchair spaces are. The air-conditioning system, the first on London Underground trains, is supplied by Mitsubishi and has two circuits so that if one fails there is still 50% capacity. Through gangways from car to car