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
Urban rail in the United Kingdom example Amersham and , but some stations much closer to the Greater London boundary, like and , are not in any zone. London has an integrated ticketing system via the Travelcard or Oyster Card for buses, Docklands Light Railway, suburban rail, tram, Underground and Overground. Unlike cities like Liverpool/Merseyside, Sydney and Paris, several operators provide suburban rail services. Most stations are served at least every 20 minutes, with many stations and routes having four, six or more trains per hour. c2c runs from London Fenchurch Street through east London via Basildon (or Grays and Tilbury) to Southend Central and Shoeburyness,