Aswing bridge (orswing 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.
As this type requires no counterweights, the complete weight is significantly reduced as compared to other moveable bridges.
Where the channel is wide enough for separate traffic directions on each side, the likelihood of vessel-to-vessel collisions is reduced.
The central support is often mounted upon a berm along the axis of the watercourse, intended to protect the bridge from watercraft collisions when it is opened. This artificial island forms an excellent construction area for building the moveable span, as the construction will not impede traffic.
Disadvantages
[edit]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.
In a symmetrical bridge, the central pier forms a hazard to navigation. Asymmetrical bridges may place the pivot near one side of the channel.
Where a wide channel is not available, a large portion of the bridge may be over an area that would be easily spanned by other means.
A wide channel will be reduced by the center pivot and foundation.
When open, the bridge will have to maintain its own weight as a balanced double cantilever, while when closed and in use for traffic, the live loads will be distributed as in a pair of conventional truss bridges, which may require additional stiffness in some members whose loading will be alternately in compression and tension.
If struck from the water near the edge of the span, it may rotate enough to cause safety problems (see Big Bayou Canot rail accident).
Belize City Swing Bridge, Belize City, Belize. Oldest such bridge in Central America and one of the few manually operated swing bridge in world still in operation. (Restored in the 2000s)
Was last opened for marine traffic on December 30, 2014 remaining open for marine traffic since that date, no longer swings, Rail Traffic cannot cross.
Abandoned CN railway swing bridge in the middle of Lachine Canal. Constructed in 1912 by the Dominion Bridge Company for the Grand Trunk Railway company.[2] The pivot system and the cockpit are still in place, but the bridge has not been operational since the late 1960s.[3]
Lille Langebro Pedestrian double swing bridge crossing the inner harbour at Copenhagen.[4]
Egypt
[edit]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.
The Admiral Bridge (Admiralisild) is a pedestrian bridge in Tallinn, Estonia, connecting two parts of the Old City Harbour. It allows access to the Admiralty Pool (Admiraliteedi bassein) for yachts. It became the first swing bridge in Estonia in 2021.
Le pont tournant rue Dieu, across the Canal Saint-Martin in Paris, is a distinctive location in the 1938 film Hôtel du Nord, and is featured in the opening shot of the film.
Ponte Girevole, Taranto (built in 1958, after an 1887 one of similar design but using different materials) – a very unusual type, with two spans that separate at the bridge's center and pivot sideways from the bridge's outer ends.[5][6]
Chain Bridge, Klaipeda. Built in 1855 and still working today, this is the only swing bridge in Lithuania. When the bridge is turned, boats and yachts can enter the Castle port. Rotation of the bridge is manual; two people can rotate the bridge.
The Netherlands
[edit]The "Abtswoudsebrug", a swing bridge for bikers and pedestrians built in 1979
A swing bridge at the Gatun Locks provides the only road passage over the Atlantic side of the Panama Canal. This is a small bridge that swings out from each side. Another larger swing bridge at the Miraflores Locks is on the Pacific side but is rarely used, having been supplanted by the Bridge of the Americas and the Centennial Bridge.
A swing bridge at the Giżycko is one of four bridges that cross over the Luczanski Channel. It is one of ten (four still in operation) swing bridges in Poland.
A swing bridge in Ustka, which crosses the Słupia River, and is walkable every 20 minutes.
South Africa
[edit]The Clocktower Bridge, in Cape Town, starting to close behind a small boat
The Clocktower Bridge is a pedestrian swing bridge at the Victoria and Alfred Waterfront in Cape Town.
Kincardine Bridge – crossing the Firth of Forth from Falkirk council area to Kincardine-on-Forth, Fife (now deactivated).
Leeds and Liverpool Canal Has a large number of swing bridges, especially between Bingley and Skipton and Burscough and Liverpool. Many are manually operated, carrying only farm tracks, but a significant number carry road traffic and are mechanised for boater operation.
Tyne swing bridgeatNewcastle Upon Tyne, which 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.
The largest double swing-span bridge in the United States is the 3,250 feet (990 m) long, 450 feet (140 m) navigable span, 60 feet (18 m) clearance George P. Coleman Memorial Bridge.[14]
Alanson Swing Bridge, billed as America's shortest swing bridge, crossing the Crooked RiverinAlanson, Michigan.[15] The world's shortest are located in the United Kingdom over some of the narrowest canals in the world, for example on the Stroudwater Navigation,[16] or, see Yar Swing Bridge above.
Bridge No. 4455, Central Avenue over Lewis Gut, Bridgeport, Connecticut (1924 steel swing bridge)
Boca Grande Causeway, Built in 1958, this bridge is used for passage between Placida, FL to the island of Boca Grande. The original swing bridge was replaced by the current swing bridge in late 2015.[17]
Gianella Bridge, near Hamilton City California, connecting Glenn and Butte Counties over the Sacramento River, It was built in 1937 and demolished in 1987.
North Landing Bridge, built in the 1950s, on the Atlantic Intracoastal Waterway where it forms part of the border between Chesapeake and Virginia Beach, Virginia,[32]
Songo Lock Bridge, Naples, Maine; carries Songo Lock Road over the Songo River just upstream of the lock. Powered by human operator turning gears using a removable crank. Not to be confused with a former swing bridge about two miles upstream which carried US 302 until replaced with a fixed span in May 2012.
South Bristol, Maine Asymmetric swing bridge connecting Rutherford Island to the mainland.
Southport, ME connects Southport Island to Boothbay Harbor on Route 27.
Omaha NE Turn Style Bridge is now a historical landmark. Located 86H674H5+98 Used for rail transport. Connecting Council Bluffs, Iowa to downtown Omaha, Nebraska
Uruguay
[edit]Carmelo Bridge, Uruguay, during its inauguration in 1912.
Carmelo Bridge. Built in 1912 is the oldest swing bridge in all of Latin America.
^Leaphart, David (2016). Walt Disney World Railroads Part 3: Yucatan Jewels (1st ed.). Steel Wheel on Steel Rail Studio. pp. 148–149. ISBN978-1-533-03707-7.
^"Google Maps". Google Maps. Retrieved 17 February 2016.
