Crossrail 2 will be among major rail developments in the south east and north of England to get the green light in George Osborne's Wednesday Budget.
The Chancellor will confirm Government backing for the HS3 high-speed rail link between Manchester and Leeds, and the Crossrail 2 project to connect Surrey and Hertfordshire through new tunnels and existing lines, via stations in central London like King's Cross, Victoria, Chelsea and Clapham Junction.
The Chancellor will announce £80 million for Crossrail 2 to proceed to the next stage of planning and will ask Transport for London (TfL) to match that contribution with the aim of introducing legislation to Parliament before the 2020 election.
His announcement marks the first time that the Government has identified the project as its priority scheme for London. Mr Osborne said his decisions would drive forward the UK's largest investment in rail infrastructure since the Victorian era.
Proponents say the benefits of Crossrail 2 would be felt far beyond stations on the route between Wimbledon, Tottenham Hale and New Southgate, with towns and cities across the south east such as Cambridge, Portsmouth, Woking and Southampton getting faster or more frequent journeys into London.
Stations served could include Tottenham Hale, Dalston in the north of London and Clapham Junction, Wimbledon and Balham in the south west, with a potential new station at King's Road Chelsea.
Crossrail 1's Elizabeth Line will run from Reading and Heathrow in the west to Shenfield and Abbey Wood in the east via central London.
The first section of the Elizabeth Line between Liverpool Street and Shenfield has already opened, albeit under the branding of TFL Rail.
Crossrail's Elizabeth Line has also prompted change to the capital's iconic Tube map.
Transport for London's (TfL) newest version of the Underground map shows how the capital's transport will be look by 2019, with the Elizabeth Line appearing purple on the Tube Map.
May 2015: TfL Rail services opened between Liverpool Street Main Line and Shenfield.
May 2017: The first new train enters passenger service.
May 2018: TfL Rail service opens between Paddington (National Rail) and Heathrow Terminal 4, replacing the existing Heathrow Connect service and part of the Great Western inner suburban service.
December 2018: The Elizabeth line opens between Paddington and Abbey Wood.
May 2019: The Elizabeth line extends from Shenfield to Paddington.
December 2019: The Elizabeth line is fully open, extending to Reading and Heathrow Terminal 4.
In May next year a fleet of 66 Class 345 trains built by Bombardier in Derby will begin operating on the route.
