Bailey bridge

The Bailey bridge is a type of portable, pre-fabricated, truss bridge. It was developed by the British during World War II for military use and saw extensive use by both British and the American military engineering units.

A Bailey bridge had the advantages of requiring no special tools or heavy equipment to construct. The wood and steel bridge elements were small and light enough to be carried in trucks and lifted into place by hand, without requiring the use of a crane. The bridges were strong enough to carry tanks. Bailey bridges continue to be extensively used in civil engineering construction projects and to provide temporary crossings for foot and vehicle traffic.

History




Donald Bailey was a civil servant in the British War Office who tinkered with model bridges as a hobby. He presented one such model to his chiefs, who saw some merit in the design. A team of Royal Engineer (RE) officers was assembled at the Military Engineering Experimental Establishment (MEXE), in Barrack Road Christchurch, Dorset, in 1941 and 1942; among them were Robin Foulkes, Darrell Herbert, John de Waele, and Bill Buckle, all R.E. subalterns at the time. In the course of development, the bridge was tested in several formats, e.g., as a suspension bridge, and as a "stepped arch" bridge, as well as the flat truss bridge which became the standard. The prototype of this 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 remains there (50.72528°N, -1.76215°W) as a functioning bridge. Bridges in the other formats were built, temporarily, to cross the Avon and Stour in the meadows nearby. 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.

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. The Bailey bridge however had several advantages over Hamilton's design. For example, damaged parts could not be replaced quickly on the Callender-Hamilton bridge, an essential requirement for military use. The Callender-Hamilton bridge was modified by the London County Council engineers' department in the design of three emergency bridges which were erected across the River Thames in 1940. Damaged parts of these could be quickly replaced. Experience gained in this work contributed to the development of the Bailey Bridge.

Hamilton was awarded £4,000 in 1936 by the War Office for the use of his early bridges and the Royal Commission on Awards to Inventors awarded him £10,000 in 1954 for the use, mainly in Asia, of his later bridges. Lieutenant General Sir Giffard Le Quesne Martel was awarded £500 for infringement on the design of his box girder bridge, the Martel bridge.

Design


The success of the Bailey bridge was due to its unique modular design, and the fact that one could be assembled with minimal aid from heavy equipment. Most, if not all, previous designs for military bridges required cranes to lift the pre-assembled 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 ft transoms that run across the bridge, with 10 ft stringers running between them on the bottom, forming a square. The bridge's strength is provided by the panels on the sides. The panels are 10 ft, 5 ft, cross-braced rectangles that each weigh 570 lb, and can be lifted by six men.

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 tracks.

Each unit constructed in this fashion creates a single 10 ft section of bridge, with a 12 ft 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 ft. Footways can be installed on the outside of the side-panels, the side-panels form an effective barrier between foot and vehicle traffic and allow pedestrians to safely use the bridge.

A useful feature of the Bailey bridge is its ability to be launched from one side of a gap. In this system the front-most 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.

During World War II, Bailey bridge parts were made by companies with little previous experience of this kind of engineering. Although the parts were simple, they had to be precisely manufactured if they were fit each other correctly, so they were assembled into a test bridge at the factory to make sure of this. To do this efficiently, newly manufactured parts would be continuously added to the test bridge, while at the same time the far end of the test bridge was continuously dismantled and the parts dispatched to the end-users.



Use in the Second World War
Stories of Bailey bridges being built and erected during the Second World War are legendary. The first operational Bailey Bridge was built by 237 Field Company R.E. over Medjerda River near Medjez el Bab in Tunisia on the night of 26 November 1942. The very first instance of a Bailey being erected under fire was at Leonforte by members of the 3rd Field Company, Royal Canadian Engineers. 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 mi of bridge, at an average length of 100 ft. One Bailey, built to replace the Sangro River bridge in Italy, spanned 1126 ft. Another on the Chindwin River in Burma, spanned 1154 ft. Such long bridges required support from either piers or pontoons.

Field Marshal Bernard Montgomery wrote in 1947:

Modern Bailey bridges
Bailey bridges are in regular use throughout the world in the 21st century.

Some exceptional examples include:


 * The longest Bailey bridge was put into service in October 1975. This 788 m, two-lane bridge crossed the Derwent River at Hobart, Australia. It was opened around a year after the Tasman Bridge disaster destroyed the only river crossing and effectively divided the city in two. The Bailey bridge was in use until the reconstruction of the Tasman Bridge was completed on 8 October 1977.
 * A Bailey bridge between the Suru River and Dras River in Ladakh, India is the highest bridge in the world at an altitude of 5,602 metres (18,379 ft) above sea level. It was built in 1982 by the Indian Army.
 * 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 U.S.
 * An under-construction footbridge at Jawaharlal Nehru Stadium, one of the main venues for 2010 Commonwealth Games collapsed on September 21, 2010, a few weeks before the opening ceremony, injuring 27 people. The Delhi Government requested the Indian Army to construct a Bailey bridge to replace it. The 3 Engineer Regiment of the Corps of Engineers of the Indian Army, finished the job in four days flat and at a fraction of the original cost.

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. After Hurricane Hazel in 1954, some of the bridging was used to construct replacement bridges in the Toronto area. The Old Finch Avenue Bailey Bridge is the last still in use.

Depiction in the media
The 1977 epic war film A Bridge Too Far, depicting the events of Operation Market Garden in September 1944, has a lengthy scene showing the construction of a Bailey bridge at Son in the Netherlands by units of both the American 101st Airborne Division and the British XXX Corps.