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Commuters board an underground train at King's Cross station in London April 29, 2014. Millions of commuters faced transport chaos on Tuesday after eleventh-hour talks failed to avert a two-day strike on the London Underground train network over plans to cut jobs and close ticket offices.

Neil Hall/Reuters

Commuters board an underground train at King’s Cross station in London. Millions of people faced transport chaos on Tuesday after talks failed to avert a two-day strike on the London Underground train network over plans to cut jobs and close ticket offices.

Commuters take a bus in central London, ...Commuters take a bus in central London, on February 5, 2014, on the first day of a strike by London Underground workers. Workers on London's Underground train system kicked off a 48-hour strike at 9:00 pm (2100 GMT) on Tuesday, threatening chaos for commuters on Wednesday and Thursday.   AFP PHOTO / BEN STANSALLBEN STANSALL/AFP/Getty Images

Ben Stansall/AFP

Commuters take a bus in central London, on the first day of a strike by London Underground workers. Workers on London’s Underground train system kicked off a 48-hour strike at 9pm on Tuesday. Read more

ames Apps, six, looks at the 2020 Tube map of the future, made entirely from LEGO Bricks, at Londonís King's Cross Station to celebrate 150 years of the London Underground.

Geoff Caddick/PA

A child examines the 2020 Tube map of the future, made entirely from Lego bricks, on display at London’s Kings Cross Station to celebrate 150 years of the London Underground.