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.
6-908: The Mianus River Railroad Bridge , also known as the Cos Cob Bridge , is a bascule drawbridge built in 1904 over the Mianus River , in Greenwich, Connecticut . It was listed on the National Register of Historic Places in 1987. The bridge carries the Northeast Corridor , the busiest rail line in the United States, both in terms of ridership and service frequency. It is operated by the Metro-North Railroad , successor to Conrail, Penn Central, and
12-606: The New York, New Haven and Hartford Railroad , which erected it, and is owned by the Connecticut Department of Transportation . It is a rolling lift type moveable bridge , and was prefabricated by the American Bridge Company , to replace a previous unsafe bridge on the site. It has a total length of 1,059 feet (323 m), divided into 11 spans. Seven of these are deck truss spans, while
18-404: 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 a "Chicago" bascule) rotates around a large axle that raises the span(s). The Chicago bascule name derives from
24-555: The bridge. [REDACTED] Media related to Mianus River Railroad Bridge at Wikimedia Commons 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 the possibility for unlimited vertical clearance for marine traffic. Bascule bridges have been in use since ancient times, but until
30-457: 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
36-529: The others are deck girder spans, all set on stone abutments. The main movable span is 107 feet (33 m) long; four of the truss spans are 120 feet (37 m) in length. It is one of eight moveable bridges on the Northeast Corridor through Connecticut surveyed in one multiple property study in 1986. In November 2024, the Connecticut Department of Transportation was awarded a $ 6.4 million federal grant to "explore options for replacement" of
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