A bascule bridge (also referred to as a drawbridge or a lifting bridge ) is a moveable bridge with a counterweight that continuously balances a span , or leaf, throughout its upward swing to provide clearance for boat traffic. It may be single- or double-leafed.
4-567: The Cortez Bridge is a double-leaf bascule bridge that connects the barrier islands of Bradenton Beach , and the mainland of Cortez , Florida . It crosses the Sarasota Bay , carries Cortez Road , part of SR 684 , and was built in 1956, replacing a swing bridge built in 1921. The current bridge was designated by the 1965 Legislature of Florida. In 2017, the Florida Department of Transportation began plans to replace
8-571: A "Chicago" bascule) rotates around a large axle that raises the span(s). The Chicago bascule name derives from the location where it is widely used, and is a refinement by Joseph Strauss of the fixed-trunnion. The rolling lift trunnion (sometimes a "Scherzer" rolling lift), raises the span by rolling on a track resembling a rocking-chair base. The "Scherzer" rolling lift is a refinement patented in 1893 by American engineer William Donald Scherzer . The rarer Rall type combines rolling lift with longitudinal motion on trunnions when opening. It
12-581: The Cortez Bridge with a high-level bridge. Construction is expected to begin in the mid-2020's. The new bridge will be 65 feet above the surface, and it will allow 98% of boats to pass underneath. Bascule bridge The name comes from the French term for balance scale , which employs the same principle. Bascule bridges are the most common type of movable span because they open quickly and require relatively little energy to operate, while providing
16-425: The possibility for unlimited vertical clearance for marine traffic. Bascule bridges have been in use since ancient times, but until the adoption of steam power in the 1850s, very long, heavy spans could not be moved quickly enough for practical application. There are three types of bascule bridge and the counterweights to the span may be located above or below the bridge deck. The fixed- trunnion (sometimes
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