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
East Rail line branches in the north at Sheung Shui to terminate at Lo Wu or Lok Ma Chau stations. Both are boundary crossing points into Shenzhen. All of the stations are at- grade or elevated before the opening of Shatin to Central Link which will provide underground track. The distance between Hung Hom and Lo Wu stations is . The total distance of the line (including the Lok Ma Chau Spur line) is approximately , making it the longest line in total distance within the system network. The line is coloured light blue on the MTR map. The same railway is used