Glandyfi Junction on the A487 coastal trunk road runs through one of Wales’ most scenic areas, but its narrow bends made it a notorious bottleneck and accident blackspot. This improvement scheme involved widening and straightening a 1.3km stretch of the road beside the Afon Dyfi estuary, close to the Snowdonia National Park.
Location
The A487 is a major trunk road in west Wales, linking north Wales at Bangor to Haverfordwest in south Wales.
Challenges
This 1.3km stretch of trunk road was generally less than 5m wide with poor alignment and suffered from flooding. It was so narrow that large vehicles had difficulties passing each other. In addition, the confined project area presented technical challenges with the River Dyfi and Cambrian Railway on one side and the mountainside to the other, plus residential properties close by.
The scheme
The widening was generally on line. Widening to the east involved two separate 450m and 250m-long rock cuttings in rock faces up to 15m high. To the west, widening was on retaining walls adjacent to the railway and residential properties.
The scheme included new carriageway construction with associated drainage, earthworks, traffic signs, carriageway markings, safety barriers, retaining structures, and hard and soft landscaping together with statutory undertakers’ diversions.
Ramboll’s involvement
Ramboll provided technical expertise to the Welsh Government and supervision of the works for highways, structures, geotechnical and environmental aspects of the project.
Environmental considerations
The area is environmentally sensitive and is part of a Special Area of Conservation, a Special Protection Area, a National Nature Reserve, and a Site of Special Scientific Interest. Key environmental mitigations catered for bats and dormice and also included new hard and soft landscaping and provision for woodland management.
Zero waste to landfill
Nearly 300kt of excavated rock was re-used on the project as fill and masonry facing stone for the walls. The remaining 130kt of surplus rock was put to use within a 2.7 mile radius of the contract. With zero waste to landfill, the project avoided over 500,000 lorry miles on the local road network.
