The two largest contracts for the civil framework of the early works on the UK’s £16bn ($22bn) Crossrail project have been awarded.

The Royal Oak Portal, considered the largest work on Crossrail’s enabling works framework, will be carried out by a joint venture of UK firm Costain and Swedish firm Skanska.

Work includes building a tunnel portal just west of Paddington in London, where the trains will arrive from Maidenhead and Heathrow to enter the tunnel system and travel beneath the centre of the capital.

The contract for the Paddington Integrated Project, which includes site facilities, piling and groundworks at the station, has been awarded to UK firm Carillion.

The Crossrail project, expected to be finished by 2017, will see 12-carriage trains travelling under central London linking Heathrow and Maidenhead in the west to Shenfield and Abbey Wood in the east.