Bascule bridge

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.

Animation of a double-leaf Strauss fixed-trunnion bridge (based on engineering drawings from the Henry Ford Bridge)

There are three types of bascule bridge,[1] and the counterweights to the span may be located above or below the bridge deck.

The fixed-Trunnion (sometimes 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.[2]

Animation of a rolling lift bridge (such as the Pegasus Bridge)

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.[3]

The rarer Rall type combines rolling lift with longitudinal motion on trunnions when opening.[4] It was patented (1901) by Theodor Rall.[2][4][5] One of the few surviving examples is the Broadway Bridge (1913), in Portland, Oregon.[4][6]

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  Tower Bridge in London, opened, viewed from the northwest
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  Tower Bridge, closed, viewed from the southeast
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  Dimensional drawing of Tower Bridge
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  White Cart Bridge, Renfrew, Scotland
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  The Birkenhead Bridge in Port Adelaide, Australia, fully opened
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  Cherry Street Strauss Trunnion Bascule Bridge at Toronto Harbour Shipping Channel, Toronto
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  Cherry Street Bridge at Keating Channel in Toronto, Canada
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  Crook Point Bascule Bridge, Providence, Rhode Island, USA
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  Another Strauss design, the Lefty O'Doul Bridge adjacent to Oracle Park in San Francisco, California
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  Mystic River Bascule Bridge, Mystic, Connecticut
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  Palace Bridge in Saint Petersburg
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  Pamban Bridge over the Palk Strait in Rameswaram, India
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  Rolling lift Pegasus Bridge over the Caen Canal, Normandy, France
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  Bascule bridge in Montceau-les-Mines, France
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  The Patagones-Viedma Railway Bridge, Argentina. The longest rolling bridge in the world and the only with hydraulic counterweight.
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  Railway Rolling lift bridge in Oldenburg, Germany
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  Salmon Bay Bridge, a single-leaf through truss with overhead counterweight, Seattle, Washington, US
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  Kuala Terengganu Drawbridge in Terengganu, Malaysia
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  The Ashtabula lift bridge, a 1925 Strauss bascule built in Ohio, US
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  Wabash Avenue Bridge in Chicago, Illinois, US
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  Yeongdodaegyo in Busan, South Korea
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  Sturgeon Bay Bridge, Sturgeon Bay, Wisconsin
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  Via Rail Dayliner crossing the Johnson Street Bridge after completing a Victoria-Courtenay round trip, 13 May 2008
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  The Strauss design Johnson Street Bridge across Victoria Harbour, British Columbia, Canada, built in 1924
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  The new Johnson Street Bridge in Victoria, British Columbia, Canada
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  Lake Shore Lift Bridge, Toledo, Ohio