Failure of several rock anchors on the north face of the rock cutting was discovered during routine inspection. For safety reasons the road was closed and traffic was diverted.
Cutting the north face back to a calculated stable angle, with some re-anchoring to the south face, was proposed.
The blasting work was carried out successfully, with 225,000 tonnes of rock and soil being removed from site.
The rock was utilised as recycled aggregate, while the soil helped restore part of the nearby Moel Y Faen quarry.
Once the rock had been removed, the existing carriageway was reconstructed.
It was reopened to the public on schedule.