The £25.3m project will improve the present road to modern highway standards, addressing poor visibility, bends that are too tight as well as narrow lanes.
This will be done by building an entirely new section of highway which ties in at either end of the existing Five Mile Lane between the roundabout at Weycock Cross and the new junction at Sycamore Cross.
When finished, the project will have improved access for HGV and development traffic to the St Athan and Cardiff Airport Enterprise Zones. It will make cycling and walking safer and give better access to the M4, offering more reliable journey times for customers, freight, regional and local businesses.
Attending the turf cutting ceremony, Economy and Transport Secretary Ken Skates said, “This vital piece of structural engineering will have many more wider-reaching benefits than simply an improvement to a road.
“The work will also provide employment across the area. It will also provide a safer route for non-motorised road users, supporting commitments we made in the Active Travel Bill. Alongside this, it will offer direct access to the St Athan and Cardiff Airport Enterprise Zone, again supporting our promises to increase job creation and employment opportunities.”