Case study Dawlish Sea Defences

DAWLISH SEA DEFENCES

The winter storms took a heavy toll on the Dawlish coastline, breaching 90m of seawall and severing a key rail link to the south west, with a huge impact on the local infrastructure and economy.

Bison Precast’s specialists at Somercotes were called upon to design, manufacture and supply nearly 100 three-metre-high, heavy-duty bespoke precast concrete retaining walls, plus more than 150 precast seawall units, each weighing around 15 tonnes, as part of urgent works to get Dawlish back on track.

Phase 1 of the works relied heavily on the rapid production of the 96 precast L-shaped concrete retaining wall panels, which were used both behind the parapet seawall and the retaining wall for the roadway behind. This formed a U-shaped channel, which would support the railway line.

Phase 2 of the works required 152 profiled precast seawall units to replace 19 steel shipping containers, which had been installed as a temporary breakwater following the initial breach.

These precast components were shipped from Teignmouth docks to two enormous barge platforms, the largest of which featured a 160-tonne crawler crane used to lift the precast units into place. The units were placed into position between the sea and the railway line on an in-situ slab of fibre reinforced concrete, forming a plinth along the length of the works. Production began on these vital units just four days after Bison Precast’s representatives took part in an initial emergency meeting at the site with contractors AMCO. The rapid reaction time helped the damaged railway line re-open ahead of schedule.

This success was influenced by the design of a solution that involved the adaptation of existing concrete moulds at the Somercotes facility to be adapted, enabling rapid progression to the manufacturing stage.

Andy Crowley, Contracts Manager at AMCO Rail West, commented: “Following the successful completion of the works at Dawlish, and with the train line opened ahead of schedule by David Cameron, I would like to say a big thank you to Bison Precast – especially to the operational staff at the plants and the hauliers who worked around the clock to make things happen.

“Working against extreme weather conditions and tides meant that we were not able to predict with any sort of certainty the type and numbers of units that would be needed and when. Bison Precast’s approach in managing this situation in a positive and proactive manner is one of the key reasons AMCO selected them as the key supplier for the project.

“We also acknowledge the huge effort that went on behind the scenes to ensure the design and fabrication of the units to our demanding programme – working together, we got the job done.”