A £3.1bn upgrade of four tube lines, including new, air-conditioned trains, was announced yesterday by London's transport commissioner, Peter Hendy. But London Underground passengers will have to wait until 2013 before all the new trains are in service. Lines to be upgraded are the Metropolitan, Circle, District and Hammersmith & City. The first of the new trains, which will be faster and longer, will enter service on the Metropolitan line in 2009. Circle and Hammersmith & City line passengers will get new trains in 2012, with the District the last, in 2013.