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.
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.
[16] Omaha NE Turn Style Bridge is now a historical landmark.
Connecting Council Bluffs, Iowa to downtown Omaha, Nebraska
I Street swing Bridge span turned to allow a boat to pass Sacramento California
An example of how small swing bridges like this one may be pivoted only at one end, but that does require substantial underground structure to support the pivot.
Victoria & Alfred Waterfront
,
Cape Town
.
El Ferdan Railway Bridge in
Egypt
; the longest swing bridge in the world, runs from the east of the
Suez Canal
to the west into
Sinai
. It is left open most of the time to allow sailing ships to pass in the canal, only closing during the passage of trains.
