Pont Briwet Road and Rail Bridge Replacement
On the Pont Briwet scheme, HOCHTIEF replaced an ageing timber viaduct with a new concrete structure across the Dwyryd estuary in North Wales. The new viaduct provides a two-lane highway as well as a crossing for the railway line, which is carried on a separate deck capable of increased line speeds.
- 6 span, 18m wide, 130m long concrete viaduct
- 1.5km bi-directional railway track
- 2km 2 lane of highway
- Walkway and cycleway
- New 2 car station
- Environmental mitigation measures
The new bridge posed unique challenges due to its location in a tidal estuary in a Site of Special Scientific Interest (SSSI).
To reduce the amount of work carried out over the estuary, and minimise our environmental impact, we pre-cast concrete bridge sections off-site. This provided a consistent and high-quality finish, shortened the programme and minimised the health, safety and environmental risks of working over water. We also made design changes to simplify construction and minimise the amount of in situ concrete pouring required, reducing the build time over the estuary.
We implemented robust environmental mitigation measures to avoid damaging sensitive marine habitats. These included using a silt curtain to prevent sediment pollution, carrying out hydrological monitoring to identify scour that could affect sensitive sand bank systems, and reducing lighting over the water that could affect the behaviour of migrating fish or otters.
The scheme achieved CEEQUAL Very Good and our innovative use of precast concrete sections led it to win the ICE Wales Cymru Innovation Award 2016, as well asa Concrete Society Award 2016.