London-based Studio E Architects are set to build the first three 'cranked stress ribbon' bridges in the world. They are part of a consortium led by Will Williams of Williams Environmental Design, who designed a scheme linking Whatmas Field with the rest of a £4 million river park, funded by the Millennium Commission. The field is currently cut off between the railway line and the river.
Each of the two planned bridges is 170m long, with a main river span of 46m. The bridges and access ramps will be built using cast stone segments which will be glued and post-tensioned to create a bridge deck - a continuous structural ribbon. The design inspiration included the tail of a dragonfly.
The stress ribbon principle results in bridges which are slender, light and easy to build. Substantial horizontal forces need to be anchored at abutments. There are an estimated 19 such bridges, mostly in Japan and the Czech Republic, all straight in plan. Studio E, headed by Cezary Bednarski, won last year's Hadrian's Millennium Bridge competition in Carlisle.