Bailey Bridge - Lecture notes 1 PDF

Preview

Summary

ponti...

Description

UK Military Bridging – Equipment (The Bailey Bridge) Posted by Think Defence Date: January 08, 2012 in: News (11) Comments

The Bailey bridge was described by General Eisenhower as one of the three most important engineering and technological of WWII, along with radar and the heavy bomber. …one of the three pieces of equipment that most contributed to our victory in Festung Europa Churchill was equally effusive and Montgomery wrote after the war. 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 Northwest Europe, I could never have maintained the speed and tempo of forward movement without large supplies of Bailey bridging. Without the Bailey Bridge, we should not have won the war. It was the best thing in that line that we ever had. There is no doubt that the Bailey bridge was a world beating design but it would be unfair to characterise it as the work of some lone genius. Sir Donald Bailey was inspirational, the driving force behind the design but he headed a team and many of the features that were found in the Bailey bridge were refinements or development of previous designs. The Bailey bridge design has endured and is likely to do so for many years. Although I have covered bridging operations that used the Bailey bridge in previous posts the image below provides a good example of just how many were constructed in North West Europe alone, Italy, Africa and the Far East also made extensive use of the Bailey.

Bailey Bridge in NW Europe

Donald Bailey Reflecting on the Bailey bridge after the war, Donald Bailey said I was always fascinated by the mastery of water. Water is a damnably difficult thing to tamper with Donald Bailey was born in Rotherham on 18th September 1901. He was a pupil at Rotherham Grammar School until he went to The Leys School, Cambridge, at age 15. After Leys School he attended Sheffield University gaining a Bachelor of Engineering

degree. His first job was with Rowntree in York, followed by work in the old L.M.S. Railway and then in Sheffield City Engineering Department. In 1928 he took a job as Civilian Engineer in the Experimental Bridging Establishment (EBE) in Christchurch on less than £400 per year. Donald Bailey with a dimensionally accurate model

DC Bailey, pipe in mouth, sits in his office and examines the model of a Bailey bridge which is resting on his desk. Donald was the first Director of the successor to the EBE, the Military Engineering Experimental Establishment or MEXE, of MEXEFLOTE fame.

In 1943 Bailey was awarded the O.B.E. and was knighted in 1946 for his valuable contribution to the Allied victory. The same year he also received an Honorary Degree of Doctor of Engineering (Sheffield University). In 1947, he was made a Commander of the Order of Orange Nassau in recognition of the part Bailey bridges played in the reconstruction of Holland. Bailey retired from the Military Engineering Experimental Establishment (MEXE), Christchurch in 1962 and was appointed Dean of the Royal Military College of Science, Shrivenham. After four successful years in this post, he suffered his first stroke and retired. He returned to the Christchurch area in 1966 where he lived with his wife, Phyllis, until his death on 4 September 1985 in Bournemouth.

No TD post on the subject would be complete without a British Pathe clip, click here to view.

Design History It all came down to weight and a tank named after a certain Mr Churchill. In the early stages of the war and just before it was realised that the existing British tanks were simply too poorly armoured. Subsequent design work resulted in the A22 Infantry Tank Mark IV, or Churchill. The first production models were produced in 1941 and weighed 39 tons. The need for a Class 40 bridge had been foreseen for some time and the Inglis Mark III (see the earlier post) was the first contender but even though it eventually came into service it was not really suitable. At a meeting in Christchurch in early 1941 the Structural Engineering Committee raised their concerns and decided that an alternative should be sought. That alternative was the Bailey Bridge, a design that Donald Bailey had been working on since late 1940 although it is reported that the EBE instructed him to do this on his own time and outside of the EBE offices! Donald Bailey said of this; I had worked out a scheme for a bridge about 1936 but it didn’t receive any great favour as the War Office had decided on another During the return journey from initial and problematical loading trails of the Inglis Mk III Donald Bailey produced his legendary envelope and sketched out a design concept that he had been thinking about for some time. Present were Major Stewart (Superintendent of the the Experimental Bridging Establishment) an Colonel Fowle MC of the Royal Engineer and Signal Board and the following day, further discussions and detailed design work commenced. After some calculations carried out by Captain Jarrett-Kerr, the now familiar K bracing configuration was chosen. There were 5 basic considerations that informed the design; One, flexibility was to be built in with the ability to create variable length spans, floating configurations and be able to be strengthened in situ if needed.

Two, all parts were to be made from readily available materials and welded, certainly no aluminium alloys which were earmarked for Spitfires and the like! Three, all parts were to be able to be manufactured by standard engineering practices and companies which precluded extremely fine tolerances, although the tolerance and consistency must be sufficient to enable interoperability. Four, all parts were to fit in a standard 3 Tonne General Service lorry and be no more than 600 pounds in weight, or a six man lift. Five, launching and jacking down were paid particular attention and the design was to be simple to construct. Donald Bailey supervised the design effort although much of the detail work was carried out by Captain Charles Edward Jarrett-Kerr who would later be awarded the CBE for his contribution to the Bailey bridge and go on to be the last military director of the Military Engineering Experimental Establishment (MEXE). The expanded design team at the EBE also made a great contribution and interestingly, Mr Ralph Freeman Senior (designer of the Sydney Harbour Bridge) also contributed in his role of Chairman of the Structural Engineering Committee. Perhaps even more interestingly, Ralph Freeman Junior also served in the Royal Engineers posted to the EBE at Christchurch, ‘Junior’ would go on to build the Forth Road Bridge, Severn Bridgeand Humber Suspension Bridge. The Bailey bridge team, 1941

The Bailey Bridge Design Team. Back Row (left to right): R.S. Lane, Col P.K. Benner, Brig. F.E. Fowle MC, Col. S.G. Galpin, B.M. Furneaux, A.T. Bines Front Row (left to right) H.J. Taylor, S. Mountney, Lt.Col. S.A. Stewart, D.C. Bailey, Major H.A.T. Jarrett-Kerr RE, Maj H.W. Kenyon. (Image Credit – Red House Museum) After a number of designs were considered the final 120 foot long double truss double storey prototype was built by Braithwaite and Co of West Bromwich (more on Braithwaite later) and readied for loading trials in by May 1941. This was an extraordinary feat, from an envelope sketch to full scale prototype in less than 6 months. Testing represented an interesting problem because the EBE had never had a test load of the weight needed. The solution was to utilise a WWI vintage Mark V tank and drive two lighter tank (Whippet Class 5) onto its roof using an early prototype of the Tank Bridge Number 1.

Bailey Bridge Static Load Testing (Image Credit – Red House Museum) The heavy tank was then filled with pig iron! Extensive tests, some to destruction, were carried out at the EBE and National Physics Laboratory using full size and one third sized models. From these tests a full set of loading, span and construction tables were generated and in parallel, training and development was also carried out to determine optimum methods of construction, maintenance and strip out. These were combined in a single user handbook.

Final Design and Installation The Bailey bridge used the following basic components; Panel; the basic bridge member constructed of welded steel 10 foot by 5 foot 1 inch. Each panel top and bottom chord has interlocking male and female lugs into which the panel pins were inserted. The bottom chord has bottom chord has 4 transom seats. 570 pounds or 259kg

Cross Girder or Transom; 18 foot long, 10 inches high and 4 ½ inches wide clamped to the panels using transom clamps. Transoms had five sets of lugs on the top surface to locate the roadway stringers. There were holes drilled through the transom to allow the transom to be carried using lifting bars. 445 pounds or 202kg Transom Clamp, a screw lock clamp that secures the transom to the panel, 7 pounds or 3.2kg Sway Brace; fitted under the roadway and ran from one end of the lower run of the inner panel to the diagonally opposite end. 65 pounds or 30kg Stringers; form support for the roadway chesses, the stringer was 10 foot long, 1 foot 9 inches wide and 4 inches deep. The two outside stringers are called button stringers which have buttons along the outside edge to locate the roadway chesses. 133 pounds or 60kg Chesses; 12 foot long, 8 ¾ inches wide and 2 inches deep made of timber. These were laid across the stringers and located by the buttons on the button stringers. 50 pounds or 23kg Ribands; 6 inches by 6 inches, 10 foot long and chamfered on both sides, holds the chesses in place and acts as a roadway kerb. 95 pounds or 43 kg Rakers; fastened to the top run of the panel and a lug near the end of the transom. These kept the panel vertical. 18 pounds or 8kg Bracing Frame; used to connect multiple panels when doubling or tripling up and made of light mild steel. 40 pounds or 10 kg End Post; available in male and female form, each end of the bridge supported by end posts which sit on the base plate. 130 pounds or 60kg Panel Pin; used to connect panels together and secured using a safety pin. 6 pounds or 3kg Chord Bolt; mild steel bolt used to connect panels above or below to form multi storey bridges Bracing Bolt; used in a number of locations, for example, bracing frame and panel Base Plate; 4 foot 7 inches by 3 foot and spreads the load of the bearing. 400 pounds or 182kg

Bearing; allows the bridge to be launched or recovered. 70 pounds or 32kg

Bailey Bridge Components

Bailey Bridge Components (Image Credit – Red House Museum)

US M2 Bailey Bridge Components In total, there were 28 standard and over 100 specialist parts. A completed bridge had two main girders, left and right. These were made of multiple panels, pinned together, the same concept as the Heavy Box Girder Bridge I looked at in the previous post. These panels were arranged in one, two or three trusses and one, two or three storeys high.

A Bailey Panel This is where terms like ‘double double’ come from. The first describes the number of trusses and the second, the number of storeys. A ‘double double’ Bailey bridge therefore has two trusses (panels) wide and two storeys high.

Bailey Bridge Configuration Example Chord bolts were used to connect multiple panels in storeys and bracing frames and bolts were used when connecting multiple panels in horizontal trusses. Two or four transoms could be fitted to each bay depending on the load to be carried and these connected the main panel longitudinal girders, secured using transom clips. The same transom could also be used as top bracing in the triple storey configuration. To provide extra stability and reduce twisting, sway bracing was connected in a diagonal configuration under the bridge deck to the corner of each panel. Stringers sat on the transom beams as a base for the timber decking or chesses and the ribands were bolted to the outer stringers to form a kerb. Specially strengthened ribands were used to create a ramp at the ends of the main bridge section. Footwalks could be attached to the overhanging transoms using footwalk bearers, this separated foot and vehicular traffic. Variations on panels, transoms and storeys would be used depending on the span and load carrying requirement.

For example, a 90 foot long single-single at Class 9, 240 foot long triple-triple at Class 9 or a 150 foot long triple-triple at Class 70. Class 70 was the design load of a Churchill tank on its transporter.

Building a Bailey Bridge The first part of a bridge build is a recce and using the design tables found in the manual, the requirements for the build are determined. Although a post War bridge the video below provides an excellent example of how a single span Bailey is built. Or this example;

Another good example here, although not in English The Bailey bridge was designed for construction and launching by hand and this would be deemed to be the normal method. The panels and transoms were joined together on a roller, a launching nose attached to the front and the whole assembly pushed or boomed over the gap, locked and jacked down off the rollers and onto the base plate, the rollers being removed as part of the process. The decking and other elements were then completed. The launching nose was the lightest section of the bridge, consisting of the side panels but without the roadbed and angled upward to compensate for the inevitable dropping downward of the bridge as it expanded across the gap, this was particularly ingenious and vital when a crane on the far bank was not available. The rest of the bridge provided a counterbalance to prevent it failing into the gap as it was pushed ‘towards the gap’

Bailey Bridge Launch Method Despite the hand construction and launch norm, powered equipment was also often used to either launch the bridge with a conventional launching nose or simply crane the bridge into position.

Materials and Mass Production Particular attention was paid to the materials used. A new high strength weldable steel was developed from BS 968 steel for use in the chord and web members and other parts used standard BS 15 mild steel except for the panel pins which were made of a manganese-molybdenum steel alloy. This alone could warrant a book. One of the key requirements of the Bailey Bridge was that it could be easily manufactured by a number of manufacturers, not necessarily specialists. 650 firms were to be involved in the production of Bailey bridge components, prior to the war some of them made greenhouses, window frames, bedsteads and even canoe paddles. Littlewoods of football pools fame even made pontoons and other components for Bailey Bridges. This mass production of Bailey bridge parts is an equally incredible story. Design work started in December 1940, testing started in May 1941, production in July 1941 and was with Royal Engineer units by December 1941.

Braithwaite, of Braithwaite water tank fame, was the first manufacturer, still in existence, click here for their website. The contribution of Braithwaite should not be underestimated, not only did they contribute to the design and prototype of the Bailey bridge they also freely shared their knowledge and experience with others engaged in production. Thos Storey were also instrumental in the initial stages of mass production. It was foreseen that maintaining quality and consistency would be a challenge and an absolute requirement. The UK decided to use different firms to manufacture different components rather than complete bridge sets, a sensible decision, this meant some means of consistent quality checking was needed to compensate for variations in skill and experience. Two types of jig were used, a welding jig and drilling jig, this contributed enormously to maintaining the interoperability of Bailey parts, drilling jigs for example were only used when 48 hours had elapsed from any welding to ensure shrinkage was taken into account. All panels were initially proof loaded but as production ramped up these was reduce dto 10% sample testing. A number of test centres were established that could test up to 500 panels were week, a more compact testing jig was designed and built which enabled higher sample testing. Over 70% of panels were tested and considering that 700,000 panels were made, only a couple of hundred were rejected due to material or workmanship defects. 490,000 tons of Bailey bridge were manufactured representing over 200 miles of fixed and 40 miles of floating bridge or from Christchurch to St Petersburg as John Joiner described in his book. Crucially, as the US were to learn, the fabrication and master gauges used in manufacture were crucial to interoperability.

The American Bailey Bridge The United States Army had for some time used the Small and Large Box Girder Bridges, designated the H-10 and H-20 bridges but realised at the same time as British engineers that these were rapidly becoming obsolete with increasing tank weights, in the US case, it was not the Churchill tank but the M3 Grant and M4 Sherman. Despite a number of modifications, the Civil War era pontoon bridges in service were also increasingly inadequate. Although the US created the M1 Treadway Bridge (based on a German

design) and the M2 Treadway bridge, probably the best floating assault bridge of the era, it was still not as flexible as the Bailey and for dry bridging, not relevant. In 1941 the Chief of Engineers directed the Engineer Board to investigate heavier bridging, both fixed and floating. The result of this research was a directive from the Chief of Engineers to Investigate modification of the British Bailey Panel Bridge to fit standard U.S. sections. In the summer of 1941 the UK sent a full set of construction drawings to the US. The project was called SP 341, Portable Steel Bridges for Heavy Loads and because of staff shortages a civilian engineering company was assigned to lead, Sverdrup and Parcel of St. Louis, Missouri. They were to modify the Bailey design to compensate for the differences in British and American steel production techniques, thread sizes and other standards but keep design changes to a minimum. The Commercial Shearing and Stamping Company of Youngstown, Ohio, provided the first test bridge. The CarnegieIllinois Steel Company of Pittsburgh, Pennsylvania, also became involved with construction. After some trial and error, discussion and modifications the initial manufacturing problems were eliminated. Another three firms were selected for volume production, Ceco Steel Products Company of Chicago, the International Steel Company of Evansville and the Virginia Bridge Company of Roanoke. A set of gauges were borrowed from Canada as part of this process. On the 5th of December the test results confirmed the brilliance of the Bailey design and it was accepted for service despite some reservations about the manufacturing issues. The US then built and sent 25 gauges back to the UK as part of the Lend Lease Agreement and more made for us in the USA. During later tests a serious problem was discovered when the U.S. 31st Engineering Regiment found that several panels would not fit together. This discovery came late, after hundreds of American-built Bailey kits had already been sent to Europe. Some 850 of them had to be tracked down and marked as stand-alone types, not to be intermingled with any others. What went wrong?

The first thing to say is that it was somewhat surprising to all concerned; there had been a great deal of willing cooperation between the UK and US forces, experimental establishment and manufacturers, for example, at the request of the US, a British liaison officer was posted to Fort Belvoir. After the problem was discovered it was decided to check the gauges being used against the Canadian master, it was found that many of them had been damaged and others were simply poorly made. The system of mass production and quality control applied to making the Bailey in the United States failed although it was quickly rectified. Subsequent...