History of the London Underground services reached Richmond, Ealing, Hounslow and Wimbledon. As part of the project that completed the Circle line in October 1884, the District began to serve Whitechapel. As a result of the expansion, by 1898, 550 trains operated daily. Services began running to Upminster in 1902, after a link to the London, Tilbury & Southend Railway had been built. In 1869, a passage was dug through the London Clay under the Thames from Great Tower Hill to Pickle Herring Stairs near Vine Street (now Vine Lane). A circular tunnel was dug , using a wrought iron shield, a method that had
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