A487 Caernarfon & Bontnewydd Bypass

The Balfour Beatty Jones Bros Joint Venture designed and constructed a 9.8km highway.

It forms a western bypass to Llanwnda, Dinas, and Bontnewydd before crossing the existing A487 to pass south of Caernarfon Quarry.

It then crosses the River Seiont, passing south of Cibyn Industrial Estate to a junction with the A4086. After crossing the B4366, the route drops steeply to the Plas Menai roundabout.

Works included:

• 8km two plus one carriageway (two lanes one way, one the other, switching along the way between Goat roundabout to Plas Menai roundabout)
• More than 1million m³ of earthworks, including substantial rock cutting carried out by Jones Bros’ in house personnel and equipment
• Construction of 22 structures, including 15 culverts and seven bridges, which included a crossing over Welsh Highland Railway, 300m viaduct over Afon Seiont, 280m viaduct over Afon Gwyrfai and its flood plains, plus four bridges over existing roads under/over the new road