A470 Dolwyddelan to Pont-yr-Afanc Road Improvement Scheme

Project Team: Transport Wales, Welsh Assembly Government; Halcrow Group Ltd; Wyn Thomas GordonLewis Ltd; Laing O’Rourke Civil Engineering Ltd and Arup.

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The project

The A470 Dolwyddelan to Pont-yr-Afanc Improvement of 7.2km (4.5miles) lies to the south of Betws-y-Coed. The project was an online widening of the existing single carriageway which is part of the main trunk road between Cardiff and Llandudno.

The critical parts of the A470 construction programme were the steep and wooded valley sides of the nationally designated Snowdonia National Park and mitigating the environmental impact. The successful completion of the improvement has therefore been a major achievement.

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Crucial to this success has been the careful design and programming, innovation in construction, diligent application of the Environmental and Quality Management Systems, and the establishment of good relationships between the project partners, the local community and statutory bodies. It enabled the scheme to be substantially completed 5 months ahead of programme despite the environmental constraints, weather conditions and challenging terrain.

The A470 was scored by CEEQUAL for a ‘Whole Project Award’ which assesses the combined environmental performance of the Client, Designer and Contractor and achieved an ‘Excellent’ award. Some examples of the environmental issues covered during the assessment are given below.

Landscape Issues

Careful consideration was given to the effects of the scheme on the landscape of the area and its location within the Snowdonia National Park. Concrete walls were faced with local masonry stone and incorporated refuges for reptiles, bats and birds.

Agricultural and woodland soils stripped from the site area have been stockpiled separately and re-used in the areas of origin to retain the indigenous seed source. Similarly, new planting areas only use indigenous plant species from local provenance seed.

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Archaeology

Archaeological surveys were undertaken prior to the works commencing on site. There are twenty archaeological sites throughout the scheme with the main areas of interest being the listed structures at Pont Gethin and Pont ar Lledr. The design and construction of the improved road in the vicinity of listed structures was undertaken in consultation with Cadw (the historic environment agency within the Welsh Assembly Government). During construction, watching briefs were carried out on site by Gwynedd Archaeological Trust.

Ecology and Biodiversity

The Lledr Valley is important for a large number of protected species and habitats including bats, otters and the Fairy Glen Site of Special Scientific Interest. The completed scheme incorporates features to ensure the favourable conservation status of these species. They include an artificial bat hibernacula for Lesser Horseshoe bats, refuges in the walls to provide opportunities for reptiles, birds and bats to nest/roost, and dry culverts and ledges to enable otters to pass safely beneath the road.

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Waste Management

Reducing the production of waste throughout the construction phase was fundamental. 33,000 tonnes of recycled aggregate was utilised. Waste from adjacent quarries was processed and used throughout the works. Stone from existing walls was salvaged and reused. Other facing masonry was won from waste stone at local quarries in Blaenau Ffestiniog. Where it was necessary to remove existing pavement material this was removed and reused within the lower sub-base of the new road.