A487 Porthmadog bypass


Client: Welsh Government
Contract value:
Contract date:
2010 - 2011
Featured Highways Highways Surfacing & soil stabilisation Surfacing & Soil Stabilisation m

The 50:50 joint venture between Jones Bros and Balfour Beatty saw the construction of a 5.2km carriageway. The project was constructed through SSSIs and AONB, predominantly on green field land on a flood plain. The work required protective species design and mitigation works, as well as close liaison with the Environment Agency.

The Scheme passed through the busy holiday resort of Porthmadog and required extensive planning and the provision of traffic management to ensure minimum disruption to the community.

The route included 7.3m wide single carriageways, 1.0m hard shoulders and 2.5m grass verges, three roundabouts and junctions and eight bridges, including a landmark three-span viaduct over the environmentally sensitive Glaslyn Estuary.

Works included the placing of rock armour and geotextiles within the tidal estuary of the Afon Glaslyn, forming a temporary working platform within the river to assist with bridge construction.

The project was also delivered seven weeks early and below budget.

Major activities included:

  • 425,000m3 of earthworks
  • Installation of 14.2km of drainage systems
  • Surfacing work over 74,000m2
  • 18 km of statutory undertakers diversions
  • Construction of eight bridges and 22 culverts
  • Environmental mitigation work worth £1m