The central tunnels run from a portal just west of Paddington to Whitechapel, with further tunnelling to Stratford and to Canary Wharf.There will be new stations at Paddington, Bond Street, Tottenham Court Road, Farringdon, Liverpool Street and Whitechapel, with interchanges with the London Underground and other National Rail services.
A feasibility study was recommended as a high priority so that the practicability and costs of the scheme could be determined.
Crossrail's central core section will use new east–west twin tunnels under central London, splitting into two branches at either end.
The tunnelled sections will be approximately 22 kilometres (14 mi) in length.
and joins the main route at Airport Junction, between West Drayton and Hayes and Harlington.
Construction of a flyover near Hayes & Harlington station began in 2014, and will allow Heathrow Express trains to pass over the track used by Crossrail, avoiding delays caused by crossings.