Atkins, formerly Bennett Associates, working with structural engineer Gifford and architect Wilkinson Eyre won a competition in 2002 to design a second crossing for Poole Harbour. The design brief was to provide a landmark structure that would alleviate congestion across the existing moving bridge and aid regeneration of the surrounding area. Atkins produced exemplar designs and detailed specifications for the mechanical, electrical and hydraulic elements of this unique twin triangular bascule bridge.
Work on the project included:
This unusual double bascule design required several novel details in order for it to operate efficiently and reliably in challenging conditions. The triangular twin bascule design, intended to resemble twin sails, required Atkins to design unique passive interlock assemblies that allow the bridge leaves to act compositely under vehicle loading, which improves structural efficiency. Also, the deck tip locks prevent differential movement at the bridge leaf tip that would otherwise occur due to the unique geometry of the bridge deck.
The bridge is intended to reliably operate 5000 times a year, which posed a challenge to us as mechanical designers. To overcome this there are a total of four hydraulic lift cylinders (two per side) and the bridge can safely operate using only two lift cylinders (one per side) as well as a float system that isolates the cylinders from traffic loading. During the construction phase Atkins provided support to the client and contractor to ensure this landmark project was delivered successfully. Poole Harbour Twin Sails Bridge Webcam View webcam showing the progress of the construction of the Poole Harbour Twin Sails Bridge - click here
