The A470 Blaenau Ffestiniog to Cancoed Improvement

77.9%

Interim Client & Outline Design Award

Project Partners: Transport Wales, Welsh Assembly Government (client), Gwynedd Consultancy, White Young Green (designers)

The Project

The A470 Blaenau Ffestiniog to Cancoed Improvement involves improving a 4-km (2.5 miles) section of road, and is the third part in a programme of improvements to the A470 corridor between Blaenau Ffestiniog and Betws y Coed. The improvement involves widening the existing road and easing the sharper bends to provide a new single carriageway, generally 7.3m wide with grass verges.

The improvement passes through the slate waste tips and quarries on the northern edge of Blaenau Ffestiniog before climbing out of the valley and over the summit of the Crimea Pass, where it enters the boundaries of Snowdonia National Park. To the north of Crimea Pass summit the road continues across open moorland before dropping down into the Upper Lledr Valley at Cancoed. The confinement of the road corridor at the south of the scheme as well as the undulating terrain further north provided significant challenges to the project design team.

Main construction of this phase of improvement began in 2007, with the critical parts of the programme including a three-span bridge structure (and associated temporary diversion) at the Blaenau Ffestiniog end, and a considerable embankment which exceeds 10m in height for a length of approximately 150m to the south of the National Park boundary.

Some examples of the environmental issues covered during the assessment are given below.

Archaeology

Thorough archaeological surveys were undertaken prior to work commencing on site. A vast number of sites/features of archaeological importance from the industrial period exist along the route of the improvement including quarry sites, small buildings, old bridges and the historical remains of past agricultural activity.

The design of the improved road in the vicinity of listed structures was undertaken in consultation with Cadw. An archaeological watching brief was included in the design which would cover the extent of works including the temporary diversion.

Ecology and Biodiversity

Mitigation measures have been included in the design of the improvement to take account of and minimise the impact on protected species, which were recorded during the ecological and protected species surveys.

Mitigation measures include the provision of otter-proof fencing and dry otter pipes within the scheme based on the suitability of the habitat and some evidence of the use of the area by otters. Additionally, boundary/concrete walls incorporated refuges for reptiles, bats and birds.

Landscape Issues

Careful consideration was given to the effects of the scheme on the landscape of the area and its location partly within Snowdonia National Park. Concrete walls were faced with local masonry stone while the design of fencing takes into account the sensitive nature of the landscape. The careful stripping, segregation and replacement of agricultural soils was incorporated into the design of the improvement, similarly the new seeded/planting areas only use indigenous species from local provenance seed.

Water Issues

The highway drainage for the proposed improvement consists of gullies, filter drains and carrier drains. Surface water is discharged from the highway drainage system into existing watercourses while appropriately sized culverts maintain existing watercourses. All aspects of the drainage design were undertaken in consultation with Environment Agency Wales.

Conditions were placed on the contractor to take adequate precautions to ensure protection against pollution, silting and erosion in order to ensure that the construction phase did not have a detrimental effect on the surrounding watercourses and water bodies.