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.
5-847: The Franklin–Orleans Street Bridge , commonly known as the Franklin Street Bridge , is a bascule bridge over the Chicago River , in Chicago , Illinois , United States. It was built in October 1920, and is located directly southwest of the Merchandise Mart . Connecting the Near North Side with " The Loop ," is at the junction of the branches of the river, lying directly west of the Wells Street Bridge . It carries four lanes of traffic in
10-571: 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
15-479: Is extremely efficient to operate. The bridge provided a new connection to the southern banks of the river and aided in westward expansion along Wacker Drive . 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
20-500: The northbound direction, and sidewalks are available on both sides of the bridge. Great Lakes Dredge and Dock Company was the contractor for the substructure, and the Ketler–Elliot Company was the contractor for the superstructure. Original electrical equipment was installed by C. H. Norwood. The bridge is an example of a trunnion bascule bridge , with each half of the roadway is cantilevered out from shore abutments. The bridge
25-425: 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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