drawbridge: see bridgebridge,
structure built over water or any obstacle or depression to allow the passage of pedestrians or vehicles. See also viaduct. Early Bridges
In ancient times and among primitive peoples a log was thrown across a stream, or two vines or woven fibrous ropes (the
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At the entrance to fortifications, a bridge over the moat or ditch, hinged and provided with a raising and lowering mechanism so as to hinder or permit passage. See also: Bridge
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
a bridge with a movable span to permit the passage of ships. Drawbridges are usually built across rivers traveled by large ships when conditions make it technically and economically inadvisable to construct a bridge on high piers and with long approaches. The movable span of a drawbridge can be of the vertical-lift, swing, bascule, balance-beam, or rolling-lift type; the choice of type depends on local conditions. Construction of a drawbridge span requires either massive piers or towers to house the mechanisms and engines required for moving the span. Electric and hydraulic drives are the most common, and drawbridges are often equipped with backup drives from internal-combustion engines. The movable span generally has light-duty structural members, with trusses or beams of steel or lightweight alloys.
REFERENCEKryzhanovskii, V. I. Razvodnye mosty. Moscow, 1967.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
Any bridge that can be raised, lowered, or drawn aside to provide clear passage for ships.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
At the entrance of fortifications, a bridge over the moat or ditch, hinged and provided with a raising and lowering mechanism so as to hinder or permit passage.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
a bridge that may be raised to prevent access or to enable vessels to pass
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005