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.
6-675: The Mystic River Bascule Bridge is a bascule bridge spanning the Mystic River in Mystic , Connecticut in the United States . It carries vehicle and foot traffic directly into the tourist district of town via 33 ft-wide (10 m) Main Street ( U.S. Route 1 ). The counterweighted four bar linkage type bascule bridge was designed by former Otis Elevator Company Chief Engineer Thomas Ellis Brown of New York and built in 1922 by
12-571: 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
18-479: Is operated by the Connecticut Department of Transportation and opens for approximately five minutes around 2,200 times per year, carrying an average daily traffic of 11,800. It is driven by two 1,400 pounds (640 kg ) 40 horsepower (30 kW ) direct current motors, and its span is greased and inspected every one hundred openings or two weeks during the winter. From May 1 to October 31,
24-480: The J. E. FitzGerald Construction Company of New London, Connecticut , according to its historical marker. Its movable span is 85 ft (26 m) wide, 218 ft (66 m) long, weighs 660 short tons (589 long tons ; 599 t ), and employs two 230 short tons (205 long tons; 209 t) concrete-filled counterweights. Until 1928, the bridge carried streetcars of the Groton and Stonington Street Railway . It
30-462: The bridge opens hourly during daylight at 40 minutes past the hour and on demand. It usually raises to let sailboats and yachts pass under. 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
36-425: 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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