The £11.3m scheme improves the existing substandard section of the Cardiff to Glan Conwy trunk road and enhances safety for users.
Combined with £56.7m works to improve the A477 St Clears to Red Roses that started mid-February and the £8.6m A470 Gelligemlyn works due to start in April the Welsh Government has pumped over £76m into improving the transport infrastructure across Wales over the last few weeks.
Minister with responsibility for Transport, Carl Sargeant, said: “Despite a very tough financial settlement we’re putting considerable investment into schemes that will deliver our vision of a modern and sustainable transport system for Wales.
“Transport is vital to our lives and getting our approach to transport right is critical for sustained economic growth in Wales.”
The new road will be constructed for the Welsh Government by Alun Griffiths (Contractors) Ltd.