Final offers from the two consortiums bidding to build the new crossing of the Forth are to be submitted tomorrow.
The deadline for bids comes after final legal approval was given for the plans to build the new bridge last week.
The Forth Crossing Bill was given Royal Assent on 21 January, officially granting Scottish ministers the power to begin construction of the project later this year.
Two consortiums are bidding to win the contract to build the landmark cable-stayed bridge, under a contract that is expected to cost between £900M and £1.2bn.
The Forth Crossing Constructors group comprises Dragados, Hochtief, American Bridge International and Morrison Construction. The Forthspan consortium is made up of Balfour Beatty, Bam Nuttall, Morgan Est and MT Hojgaard.Danish firm MT Hojgaard replaced Vinci, which pulled out in August last year.
The contract is expected to be awarded in April.
The new bridge will form the main part of the total cost of the Forth Replacement Crossing, which is expected to total between £1.7bnand £2.3bn. A 2.7km, motorway-standard two-lane carriageway with hard shoulders will be built.
Trunk road connections north and south of the bridge, including approximately 5.5km of new or improved two- or three-lane motorway-standard carriageways, will be constructed as part of the project. An intelligent transport system will also be installed on the bridge, which include gantry displays to inform drivers of variable speed limits.