Work is expected to begin later this year on the project after an announcement by Transport Scotland that the number of firms bidding for the £415 million contract is down to two.
The plan will result in the upgrading of the M8, M73 and M74 motorways. The firms battling for the work have been named as Connect Roads and Scottish Roads Partnership.
This is the first roads infrastructure scheme to be procured as part of a £2.5 billion Scottish Government plan. The project will complete the motorway between Glasgow and Edinburgh by upgrading the A8 from Baillieston to Newhouse, creating a three-lane motorway.
When it opens in 2017, the new section of road will take up to 18 minutes off peak-time journeys, Transport Scotland claims.
Deputy First Minister Nicola Sturgeon said: "On completion, the M8, M73, M74 Motorway Improvements Project will boost the nation's economy by improving connections between the commercial centres of Glasgow and Edinburgh and beyond. It will deliver lasting benefits."