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A swing bridge is a bridge that has its primary structural support at or near to its centre, about which it can then pivot horizontally.
In its closed position, a swing bridge carrying a road over a river or canal, for example, would allow road traffic to cross. When a vessel needed to pass the bridge, road traffic would be stopped (usually by traffic signals and barriers), and motors would then rotate the bridge approximately 90 degrees horizontally about its pivot point.
English examples include the Connaught Crossing in London Docklands, built as a low-rising swing bridge to allow marine traffic in the Royal Docks to pass at a place when the proximity of London City Airport meant a higher fixed bridge was not practicable. Other well known swing bridges include those over the Manchester Ship Canal at Warrington; and that over the River Tyne at Newcastle Upon Tyne. The Tyne swing bridge has an 85.7 metre cantilevered span with a central axis of rotation able to move through 90° to allow vessels to pass on either side of it.