Construction has begun on a novel bascule road bridge that has a 19-meter-long, diagonally split opening span at Poole Harbour, England. Hochtief U.K. Ltd., Swindon, has some 20 months to complete the 140-m Twin Sails bridge under a $28-million contract. Rendering: Poole Council Unique design features overlapping box girders in lieu of a conventional bascule. The roughly 30-m-long opposing tapering steel-box-girder spans will pivot upward to allow boats to enter the harbor. When closed, the tip of each 1.5-m-deep span will cantilever over the opposite support by about 10 m. This arrangement overcomes the need for pins to connect a
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.