The JV is believed to have fought off fierce competition from Balfour Beatty/Morgan Sindall/Vinci, Bam Nuttall/Kier, Carillion and Laing O’Rourke/Strabag.
Work will start immediately on construction of two station box structures at the Western Ticket Hall and Eastern Ticket Hall to provide surface access at either end to twin mined platform tunnels.
The contract is due for completion in 2012.
Andrew Wyllie, Chief Executive of Costain, said: “We are delighted to have been awarded additional work on Crossrail which again demonstrates our broad range of capabilities in the rail sector.”