HOCHTIEF delivered Poole Twin Sails Bridge to improve traffic flows and provide access to development sites. The 140m structure comprises 41 steel sections and is the world’s first triangular lifting bridge, with two 65t opening leaves designed to look like sails. In the first year of operation it carried 11,000 vehicles per day and opened 2,403 times.

Key features:

  • 140m, 5 span lifting bridge comprising 41 steel sections weighing up to 200t each
  • 265t opening leaves
  • 50 concrete piles driven 31m into tidal channel
  • Signalised junctions
  • Twin hydraulic rams

In response to concerns about disruption from the harbour community, we built the western spans and the lifting bridge first, handing them over for operation before building the eastern spans. This saved time and meant that we could keep a shipping channel open throughout the works. We prefabricated the bridge deck components off site and welded them together at the quayside to minimise time spent working over water.

As the bridge site was next to a Site of Special Scientific Interest (SSSI), Ramsar Site and a Special Protection Area (SSA), we implemented robust environmental mitigation measures to avoid damaging sensitive habitats. We agreed protection measures for birds and fish, remediated contaminated land and banned diesel powered plant over the water to prevent pollution from fuel spills. We also filtered water ingress from the cofferdams before releasing it and monitored water quality monthly to ensure that high standards were maintained to protect oyster beds.

We achieved a CEEQUAL Very Good rating thanks to our environmental initiatives and we secured local subcontract packages worth £5.5m, representing 25% of the overall project cost and exceeding the client’s target.

Our innovative approach led to the project winning a Structural Steel Design Award 2013.