It was also suggested that the alignment of the tunnels should be safeguarded while a final decision was taken.
The Central London Rail Study of 1989 proposed tunnels linking the existing rail network as the "East–West Crossrail", "City Crossrail", and "North–South Crossrail" schemes.
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.
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.
Positioning a new station at Paddington presented structural design challenges due to its positioning just below Eastbourne Terrace and the station's taxi rank, and within 3 metres of Isambard Kingdom Brunel's 150 year old mainline station.One branch runs to Heathrow Central (for Terminals 2 and 3), Heathrow Terminal 4 and Heathrow Terminal 5, The main western section runs on the surface from Reading to Acton Main Line.Upgrades are being made to stations at Maidenhead, Taplow, Burnham, Slough, Langley, Iver, West Drayton, Hayes & Harlington, Southall, Hanwell, West Ealing, Ealing Broadway and Acton Main Line.The project that became Crossrail has origins in the 1943 County of London Plan and 1944 Greater London Plan by Patrick Abercrombie.These led to a specialist investigation by the Railway (London Plan) Committee, appointed in 1944 and reporting in 19.
Part of the eastern section, between Liverpool Street and Shenfield in Essex, was transferred to a precursor service called Tf L Rail in 2015; this section will be connected to the core route through central London to Paddington from May 2019.