Bailey bridge
The Bailey bridge is a portable pre-fabricated truss bridge, designed for use by military engineering units to bridge up to 60-metre gaps (200 ft). It requires no special tools or heavy equipment for construction, the bridge elements are small enough to be carried in trucks, and the bridge is strong enough to carry tanks. It is considered a great example of military engineering. Bailey Bridges are also extensively used in civil engineering construction projects to provide temporary access across canals. rivers, railway lines etc.
Contents
History
Donald Bailey was a civil servant in the British War Office who tinkered with model bridges as a hobby.[1][2] He presented one such model to his chiefs, who saw some merit in the design. The consequent Bailey Bridge was built at the Military Engineering Experimental Establishment (MEXE), situated in Barrack road Christchurch, Dorset. The prototype was used to span Mother Siller's Channel which cuts through the nearby Stanpit Marshes, an area of marshland at the confluence of the River Avon (Hampshire) and the River Stour, Dorset. It still remains there as a functioning bridge.[3] After successful development and testing, the bridge was taken into service by the Corps of Royal Engineers and first used in North Africa in 1942. A number of bridges were available by 1944 for D-Day, when production was accelerated. The US also licensed the design and started rapid construction for their own use. Bailey was later knighted for his invention, which continues to be widely produced and used today.[1]
The original design however, violated a patent on the Callender-Hamilton bridge. The designer of that bridge, A. M. Hamilton successfully applied to the Royal Commission on Awards to Inventors.[4] The Bailey bridge however had several advantages over Hamilton's design.
Design
A large part of what made Bailey bridges as successful and unique as they were is the modular design, and the fact that it could be assembled with minimal aid from heavy equipment. Most, if not all, previous designs for military bridges required cranes to lift up the preassembled bridge and lower it into place. The Bailey parts were made of standard steel alloys, and were simple enough that parts made at a number of different factories could be completely interchangeable. Each individual part could be carried by a small number of men, enabling army engineers to move more easily and more quickly than before, in preparing the way for troops and matériel advancing behind them. Finally, the modular design allowed engineers to build each bridge to be as long and as strong as needed, doubling or tripling up on the supportive side panels, or on the roadbed sections.
The basic bridge consists of three main parts. The "floor" of the bridge consists of a number of 19-foot-wide transoms (5.8 m) that run across the bridge, with 10-foot-long stringers (3.0 m) running between them on the bottom, forming a square. The bridge's strength is provided by the panels on the sides, which are 10-foot-long cross-braced rectangles. Transoms rest on the lower chord of the panels, and clamps hold them together. Stringers are placed on top of the completed structural frame, and wood planking is placed on top of the stringers to provide a roadbed. Ribands bolt the planking to the stringers. Later in the war, the wooden planking was covered by steel plates, which were more resistant to the damage caused by tank treads.
Each unit constructed in this fashion creates a single 10-foot-long (3.0 m) section of bridge, with a 12-foot-wide (3.7 m) roadbed. After one section is complete it is typically pushed forward over rollers on the bridgehead, and another section built behind it. The two are then connected together with pins pounded into holes in the corners of the panels.
For added strength several panels (and transoms) can be bolted on either side of the bridge, up to three. Another solution is to stack the panels vertically. With three panels across and two high, the Bailey Bridge can support tanks over a 200-foot span (61 m).
A useful feature of the Bailey bridge is its ability to be "launched" from one side of a gap.[5] In this system the frontmost portion of the bridge is angled up with wedges into a launching nose and most of the bridge is left without the roadbed and ribands. The bridge is placed on rollers and simply pushed across the gap, using manpower or a truck or tracked vehicle, at which point the roller is removed (with the help of jacks) and the ribands and roadbed installed, along with any additional panels and transoms that might be needed.
Stories of Bailey bridges being built and erected during the Second World War are legendary. The very first instance of a Bailey being erected under fire was at Leonforte by members of the 3rd Field Company, Royal Canadian Engineers.[6] In one instance a bridge was pushed over the Saar River while under artillery and tank fire. When the enemy was finally cleared out the panels had holes in them and would not carry the weight of a tank. Replacing the panels would require the bridge to be "broken" in the middle. Instead they simply bolted an entirely new set of panels onto the bridge on top of the original set, a technique that later became a standard feature.
The Bailey provided an excellent solution to the problem of German and Italian armies destroying bridges as they retreated. By the end of the war, the US Fifth Army and British 8th Army had built over 3,000 Bailey bridges in Sicily and Italy alone, totaling over 55 miles (89 km) of bridge, at an average length of 100 feet (30 m). One Bailey, built to replace the Sangro River bridge in Italy, spanned 1,126 feet (343 m). Another on the Chindwin River in Burma, spanned 1,154 feet (352 m).[7]
Field Marshal Bernard Montgomery wrote in 1947:
Bailey Bridging made an immense contribution towards ending World War II. As far as my own operations were concerned, with the eighth Army in Italy and with the 21 Army Group in North West Europe, I could never have maintained the speed and tempo of forward movement without large supplies of Bailey Bridging.[8][9]
Modern Bailey bridges
One of the original steel and concrete bridges on the Hana Highway in Maui, Hawaii, damaged by erosion, has been paralleled by a Bailey bridge erected by the Army Corps of Engineers.
A Bailey bridge was built on the grounds of the Royal Military College of Canada in 2004 to commemorate the 100th Anniversary of the Engineering Branch and close ties between Branch and the college.
Bnot Ya'akov Bridge is a Bailey bridge across the Jordan River on Highway 91 in northern Israel.
The Westbound bridge of the I-10 Twin Spans has prefabricated Bailey Bridge segmets.
The Baily Bridge between the River Dras and River Suru, in the Ladakh Valley in India is the highest bridge in the world. It was built in 1982 by the Indian Army.[citation needed]
Other uses
The Skylark launch tower at Woomera was built up of Bailey bridge components.
In the years immediately following WWII, the Ontario Hydro-Electric Power Commission purchased huge amounts of war-surplus Bailey bridging, and established a small design group to promote its use in novel applications; for example, the trestles required for an extensive gravel-classification set-up for the power plants then being built on the Ottawa River.
In the mid-1950s auto racing circuit Lime Rock Park in Lakeville, Connecticut purchased a war-surplus Bailey Bridge so vehicles could enter/exit the infield and paddock sections of the track while races were taking place. The bridge has been in continuous service since, and was relocated to new, raised pilings in the spring of 2008. The track believes this may be the sole-remaining WWII-era Bailey Bridge in regular daily public service in the USA.
The Lake Shore Boulevard Bailey Bridge in Toronto was erected to allow visitors to the Canadian National Exhibition to walk to the waterfront, and is still in use today.
See also
- Callender-Hamilton bridge
- Mabey Logistic Support Bridge- the modern day Bailey Bridge used by NATO countries
- Medium Girder Bridge - a modern functional equivalent of the Bailey bridge
- Military engineer
- Pontoon bridge for another bridge type with mobile military application.
References
- ↑ 1.0 1.1 Caney, Steven (2006). Steven Caney's Ultimate Building Book. Running Press. p. 188. ISBN 9780762404094. http://books.google.com/books?id=AkfBLZzcI2gC&pg=PA188. Retrieved 2010-01-11.
- ↑ Lance Day, Ian McNeil, ed (1996). Biographical Dictionary of the History of Technology. Routledge. ISBN 0-415-19399-0.
- ↑ http://www.hengistbury-head.co.uk/stanpit.htm
- ↑ "Bridge Claim By General "Used As Basis For Bailey Design"". The Times: p. 4 col E. 26 July 1955.
- ↑ http://www.lonesentry.com/articles/ttt07/bailey-bridge.html "Launching the Bailey Bridge" from Tactical and Technical Trends No. 35, October 7, 1943.
- ↑ canadiansoldiers.com article on Leonforte
- ↑ Slim, William (1956). Defeat Into Victory. Cassell. p. 359. ISBN 0-304-29114-5.
- ↑ Mabey Bridge and Shore, Inc.: Bailey Bridge
- ↑ Other Equipment Used By The 7th Armoured Division
External links
- Royal Engineers Museum Royal Engineers and Military Bridging
- Homepage about Bailey bridges (many photos, information, links, ...)
- Slide Show of Erecting a Bailey Bridge in Washington State, USA
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