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A470 (T) Maes yr Helmau to Cross Foxes Improvement

Client:  Welsh Government
Contractor:  Alun Griffiths (Contractors) Ltd
Value:  £7.3 million
Completion:  October 2013

Project Information

Roads  

This scheme represents a step forward in the assessment of infrastructure projects’ effects on environmentally sensitive sites, and their successful mitigation. It was assessed as affecting the qualifying features of the Meirionnydd Oakwoods and Bat Sites Special Area of Conservation (SAC, designated under the European Union’s Habitats Directive) and therefore underwent ‘Appropriate Assessment’ to demonstrate ‘Imperative Reasons of Overriding Public Interest’ and consequent ‘Compensatory Measures’. It’s the first Welsh highway scheme to undergo this process since the implications of the European Court of Justice’s 2004 ‘Waddenzee Ruling’ were fully understood; this led the environmental statutory bodies to change their approach to Appropriate Assessments.

The scheme covers the A470 between a previously improved section to the north and the junction with the A487 to the south. The road was narrow (around 5.5m minimum) with no verges, tight bends and limited visibility. The scheme objectives were:

 

  • Reduce accidents and casualties
  • Improve journey times
  • Maximise reliability

The new road is 7.3m wide with 1.0m hard strip southbound and 0.6m northbound, and minimum 2.0m grass verge. For environmental reasons, there were also departures and relaxations in horizontal alignment and visibility.

Environment

To address the qualifying features of the SAC, retention of trees was maximised, including crown lifting or steepened embankment slopes where appropriate. Mitigation for bats included oversize (2.7m diameter) culverts and a combination of lights and bat bridge. Other environmental measures were:

 

  • Dormouse tube through a culvert;
  • Lichen translocation
  • Protection of lichens and host trees;
  • Otter ledges, ramps and fences around culverts;
  • Protection of birch tree hosting Welsh Clearwing moths;
  • Extensive silt fencing and measures to avoid contamination of the Afon Clywedog, anotherprotected site;
  • Masonry walls instead of safety barriers;
  • Careful treatment of exposed rock faces.