Editing Swing bridge (section)

{{Short description|Bridge that rotates horizontally around a vertical axis}}
{{About||New Zealand's wire tramping bridges referred to by the same name|simple suspension bridge|other uses|Swing Bridge (disambiguation)}}
{{More citations needed|date=August 2008}}
{{Use dmy dates|date=May 2019}}
{{EngvarB|date=June 2022}}
{{BridgeTypePix|type_name=Swing bridge|image=MovableBridge_swing.gif|image_title=|sibling_names=Other moving types: [[Bascule bridge]], [[drawbridge]], [[jetway]], [[vertical-lift bridge]], [[tilt bridge]]|ancestor_names=[[Truss bridge]], [[cantilever bridge]]|descendent_names=Gate-swing bridge – see [[Puente de la Mujer]]|carries=Automobile, truck, light rail, heavy rail|span_range=Short|material=Steel|movable=Yes|design=Medium|falsework=No}}

A '''swing bridge''' (or '''swing span bridge''') is a [[movable bridge]] that can be rotated horizontally around a vertical axis.  It has as its primary structural support a vertical locating pin and support ring, usually at or near to its center of gravity, about which the '''swing span''' (turning  span) can then pivot horizontally as shown in the animated illustration to the right. 

In its closed position, a swing bridge carrying a road or railway over a river or [[canal]], for example, allows traffic to cross. When a water vessel needs to pass the bridge, road traffic is stopped (usually by traffic signals and barriers), and then motors rotate the bridge horizontally about its pivot point. The typical swing bridge will rotate approximately 90 degrees, or one-quarter turn; however, a bridge which intersects the navigation channel at an oblique angle may be built to rotate only 45 degrees, or one-eighth turn, in order to clear the channel. Small swing bridges as found over narrow canals may be pivoted only at one end, opening as would a gate, but require substantial underground structure to support the pivot.