Monday, 14 March 2016

The Twin Sails Bridge

The Twin Sails Bridge is a double leaved bascule bridge that spans the Backwater Channel in Holes Bay linking the town center of Poole, in Dorset, England, to Hamworthy. In the closed position, the bridge lays flat over its supporting pillars, nonetheless when the two spans of the bridge are lifted to permit boats to pass, the two triangular lifting leaves look like the sails of a yacht. However, the triangular shape is caused by the fact that the bridge isn’t dissected perpendicularly across its width, but at an angle, making two long, opposing triangles that lie side by side. Therefore, when the bridge is opened, they rise skyward, like a pair of masts opening their sails.

The two triangular leaves measure 23 meters each, and when lifted, they provide a clear channel 19 meters wide for boats to pass through. The lift spans are powered by two hydraulic rams which operate up to 15 times per day, and take two minutes to fully open. The bridge was built and opened to traffic in April 2012, after nearly three decades of deliberation, approvals and cancellations. The plan for the construction of a new bridge was initiated in the 1980s. The current bridge, which was built in 1927, was facing heavy congestion due to increasing traffic levels. Thus, at first a fixed bridge crossing Holes Bay and linking with the A31 was proposed but it got cancelled in 1998. Moreover the idea of the second lifting bridge was put forward in 2004, and got approval in 2006, however instantly went into hold due to issues between the council and the land owners. So, when everything was cleared and parties had agreed, construction of the bridge commenced in 2010.

The bridge was designed by architect Wilkinson Eyre and constructed by Hochtief (United Kingdom) Construction, at an expense of £18.5 million. Furthermore, the project acknowledged the outstanding achievement award for exterior lighting at the Architecture Lighting Design Awards 2012. Moreover it was also nominated among the top four final bridges selected at International Institute of Structural Engineers Awards 2012, as well as being nominated under the commendation category for its structural authenticity.