1974 – A study for the government and London recommends a first scheme, known as Crossrail, and inspired by the Paris RER.
1989 – A second study, for British Rail, proposes fresh Crossrail plans for east-west trains under London.
1991-1994 – A private bill to build Crossrail is presented but ultimately rejected by the Conservative government.
2001 – Transport for London and the Department for Transport set up a joint body, Cross London Rail Links, to develop a new line.
2005-2008 – A Crossrail bill passes through parliament, and the government and TfL commit to build the scheme for £15.9bn.
2009 – The prime minister, Gordon Brown, and London mayor, Boris Johnson, launch the start of construction, the foundations of Canary Wharf station.
2010 – Crossrail’s budget is cut in the coalition government’s spending review to £14.8bn.
2012 – Tunnel boring machines start drilling 13 miles of tunnel under central London.
2014 – Renè Tkáčik, 43, is killed while spraying concrete in a tunnel – the only worker to die on Crossrail.
2015 – Tunnelling is completed.
2016 – The Queen visits, and announces that Crossrail will eventually be named the Elizabeth line.
2017 – Installation of track completed.
November 2017 – Electrical explosion in Pudding Mill substation, later described as first sign of major construction issues.
2018 – First of the new Bombardier trains start service on the overground lines, operating as TfL Rail.
August 2018 – Crossrail bosses admit delays for the first time, just three months before the 9 December opening date. The budget is also blown by £600m.
December 2018 – TfL bosses step in after Crossrail executives quit. Predicted budget rises to £17.6bn.
April 2019 – Target opening date revised from autumn 2019 to 2020-21.
July 2019 – Opening postponed “beyond 2021”.
November 2019 – Budget goes up to £18.25bn.
August 2020 – TfL takes over full control of the building and announces a new target of the first half of 2022.
May 2021 - Trains start test running under London.
24 May 2022 - Opening of the underground part of the line and nine new stations, with the Elizabeth line now officially spanning all three connecting sections.
September 2022 – First through trains to start running into central London.
May 2023 – The full shebang: east-west through-running trains, with up to 24 trains an hour in the centre at peak hours.
