£25 million will be spent on improving the A55 at Abergwyngregyn.
The Welsh Government has given the go ahead for an 18-month project aimed at reducing the flood risk between junctions 12 and 13 and resurfacing the road to reduce traffic noise following complaints from local residents.
Work is due to start this Autumn, but the route will remain fully open with speed restrictions in place from 6am-7pm.
A new walking and cycling route near the eastbound carriageway will also be built as part of the upgrade to the 2.2km stretch between Talybont and Abergwyngregyn.
Transport Secretary, Ken Skates, said: ”The scheme will be vital in ensuring a safer route for local and through traffic, reducing flood risk, building better pedestrian and cycling connections with communities and enhancing biodiversity.”
”The next stage is to appoint a contractor with works planned to begin towards the end of this year. This construction phase will also result in local employment and workforce training opportunities providing a real boost to the area’s economy.”
The project – backed by almost £15 million of EU funding – is due to be completed by the end of 2020.
The announcement comes weeks after the Transport Secretary gave the go-ahead for the long-delayed Caernarfon and Bontnewydd bypass – work on the £135 million relief road could begin as soon as November.
Meanwhile, a decision is expected by the end of the summer on the Government’s preferred plan for a third crossing over the Menai Strait.