Carillion has been awarded the latest phase of the Heads of the Valleys dualling by the Welsh Assembly Government.
The Early Contractor Involvement contract, worth £75m, covers Section 3 of the A465 dualling from Brynmawr to Tredegar in Gwent.
The route runs between the A465's junction with the A467 (Brynmawr Roundabout Junction) and its junction with the A4048 (Nant-y-Bwch Roundabout Junction).
An integrated team including Carillion, the client, and the Assembly's agent, will work in partnership to carry the project through the development, statutory procedures and construction phases.
Five contractors bid for the project.