A 2.5 mile section of the A21 between Tonbridge and Pembury in Kent will be upgraded from single to dual carriageway, adding a lane in each direction, upgrading junctions and improving the road layout.
Balfour Beatty was awarded the main works contract in July 2014. Preparatory work on the scheme has been under way since winter 2014 and it is anticipated that the scheme will be fully complete by spring 2017.
Overall project cost is £70m.
Highways Agency project manager Graham Link said: “The A21 is a vital route linking the region to the M25 and London. The new section will provide much needed capacity to reduce congestion and will also improve safety with a better road layout and new junctions provided.”