UK Military Bridging – Equipment (Assault Bridging)
In modern terminology this is called Close Support Bridging, designed to operate in the direct and indirect fire zone i.e. under fire. It is important to note that in many conflicts conventional equipment bridging equipment has and is used under fire but dedicated assault bridging equipment really came into being in response to the needs of the tank.
However, before the tank there were some equipment designs that supported rapid bridging under fire, or at least in the thick of it.
The Congreve Trough was a simple assault bridge or trestle invented by Sir William Congreve, best known for his rockets.
World War I and the Emergence of the Tank
It was the emergence of the tank in WWI that saw the birth of modern assault bridging. Major General Sir Ernest Dunlop Swinton RE, author of Duffers Drift and war correspondent was credited with proposing the first practical armed and armoured vehicle, mounted on tracks. These were first called land ships but were renamed tanks by Swinton in order to provide a measure of deception. Another Sapper officer, Brigadier H J Elles, went on to lead, in person, the Tank Corps on their first major success at Cambrai in November 1917.
Many of the stock spans of the time were simply unable to carry the weight of the new vehicles and were extensively redesigned. Tanks would thus have a major impact on bridge design but assault bridging was a completely new area of development.
The seeds of the bridgelaying tank were sown by a former Royal Navy officer, Admiral Bacon, who was then a manager at the Coventry Ordnance Works. The early tracked vehicles were unarmoured artillery tractors and the suggestion was that these could carry a small bridge section to enable them to traverse obstacles. Although the idea was not developed it was a concept that would come to fruition later as it was realised that the tank alone could not manage the extensive trench works in the area.
Early experiments involved bridges on sleds but the then Charles Inglis redesigned the Inglis Mk I bridge with the resultant Inglis Mk II bridge, the inspiration for the Bailey Bridge, able to carry the heavier loads. After a visit to France, Charles Inglis also designed a tank carried 21 foot bridge called the Lock Bridge, the first tank carried assault bridge, although it was too late to see service. Another image here
Despite the early promising designs it was the simple fascine that was to see most service in WWI.
A fascine is simply a bundle of brushwood lashed together to form a lightweight gap crossing. It can also be used to secure the banks of rivers or other construction uses but for the purposes of this post it is the former. They have been used since the early days of warfare, in the published work, a Treatise on Ancient Armour and Weapons by Francis Grose, published in 1786, he mentions their use a number of times.
Derived from the Roman word Fasci, its greatest advantage is that it can be constructed more or less on the spot, it is a simple device.
In 1917 the newly formed Tank Corps was started to look for the most effective terrain to test the new vehicles with as little shell holes and mud as possible. Cambrai was selected because of the terrain and after looking at the comparative cost of using artillery fire to destroy the barbed wire along the proposed attack route it was clear that the tank at least presented an economical alternative. GHQ, however, remained sceptical, pointing out that in some places the trenches were up to 18 feet wide, too wide for the tank to cross.
The answer was the ancient technology of the fascine.
Despite the Royal Tank Corp’s enthusiasm GHQ remained sceptical and concentrated on planning the Third Battle of Ypres, a battle where tanks were continually squandered in unsuitable ground. By mid-September it was clear that the Third Battle of Ypres had been a failure and so reluctantly the Tank Corps Cambrai plan was approved.
The attack started on the 20th November using a carefully planned combined arms approach and initial advances were rapid. After the inconclusive results of using tanks at Ypres and by the French at a number of locations it was thought to be make or break for the new machines.
Despite being ultimately inconclusive, the Battle of Cambrai showed that the humble fascine could be used to support tanks and tanks were here to stay.
Prior to the battle 400 fascines were constructed, 11 feet in diameter and 10 foot long. Whilst the construction work was the responsibility of the Tank Corps Central Workshop the majority were made by the 51st Chinese Labour Company who were attached to the Workshop. The timber for the fascines came from the Forest of Crecy and special techniques were used to compress them, two tanks driving in opposite directions!
18 tanks were specifically modified to carry the fascine bundles.
Reinforcing the old adage of train hard fight easy, fascine launch drills were relentlessly practiced, using a technique devised by none other than Colonel Fuller himself. The tanks worked in sections of three with the lead tank responsible for barbed wire clearance, stopping just short of the obstacle it would veer away to the side and provide covering fire for the two follow on vehicles that would be carrying the fascines. These would be dropped into the gap with the first tank following through. It was an effective drill and its elegant simplicity did much to restore the morale of the tank crews who had suffered in the mud of Ypres.
In a precursor to the great deceptions prior to D Day a wide variety of counter intelligence and deception activities were used to mask intentions and keep the massive build of forces secret. A little known aspect of the battle was the logistic preparations beforehand. Using a combination of light railways, trucks and of course horses, an enormous amount of material was moved forward with little knowledge of the German forces. The tanks themselves were moved from the Plateau rail head, located close to Central Workshops.
Operation Hush was the planned amphibious landing on the Belgian coast by the British 1st Division.
Although the operation was cancelled it is an interesting case study in armoured amphibious landings and the need for specialist combat engineering, a lesson that was to be learned again at great cost at Dieppe many years later.
The sea wall would need to be breached and testing on replicas confirmed that a suitable tank carried ramp as shown below would allow the tanks to traverse them.
The Inter War Years
Development of tank launched bridges continued after the Great War and saw the establishment of a permanent home for combat engineering and bridging established at The Barracks Christchurch in Dorset.
The tanks influence on other forms of bridging and military activity in general was firmly recognised. Shortly before the armistice three Royal Engineers Tank Bridging Battalions were formed but with the end of the war these were disbanded, the last of the three forming the Experimental Bridging Company, Royal Engineers in 1919. The EBC was eventually transformed into the predominantly civilian Experimental Bridging Establishment although command of the establishment was not to be civilian until Sir Donald Bailey became its first Director in 1957.
There were a number of committees formed that oversaw overall direction, A Committee, field engineer equipment, B Committee, air defence, C Committee Signals, D Committee, Radar and E Committee, camouflage.
Trials with modified the Heavy Tank Mark V** continued, especially with the 21 feet canal lock bridge that could carry a load of 35 tonnes.
The tank launched Inglis Mark II Assault Bridge was refined but as tanks, embodied by designs such as the Vickers Medium Mark I, became much lighter it became apparent that carrying tank launched bridges on the front of the tank would no longer be possible as the weight of the bridge would tip the tank forward.
Bridges would have to be carried on the top of tanks and launched from a static position, thus the Bateman Assault Bridge designed and trialled, the first tank launched bridge to carry its bridge on the roof, although the vehicle was a Dragon artillery tractor. The bridge was launched horizontally, it being winched forward. Although proven, the concept was not developed further due to cost constraint.
The Stepping Stone bridge was not actually a bridge but a series of reinforced timber trestles floated into position and secured using rope and pickets. Again, it was proven to be effective but unfortunately not developed further, at about 2 minutes in, this video clip shows it in action.
Although not initially used as a tank launched assault bridge the Small Box Girder bridge was a significant milestone in military engineering and widely copied by allies and enemies alike.
More assault bridge concepts were developed including the Batemans Assault Bridge, the Scissor Assault Bridge and the Wild Assault Bridge.
This rare video clip shows the Batemans Assault Bridge in action.
Significant in this trio were the Scissor Bridge and Wild Assault Bridge.
The Wild Assault Bridge was developed by Messrs M B Wild and Co Limited of Birmingham and was years ahead of its time, using a two piece bridge design that was launched horizontally and fixed in place using an elaborate system of steel wires and winches. Although not adopted the system was subsequently developed by the Germans in their Leopard Biber tank in the seventies.
The Scissor Bridge was the first of the now familiar design, suggested by Captain S Galpin in 1935 but not realised until 1938 by Captain S Stewart and Mr D Delaney at the Experimental Bridging Establishment. The first prototype used a Mark V Light Tank with its turret removed.
The bridge itself was hinged in the middle and instead of being a single flat deck, was a pair of trackways spaced and dimensioned for the tanks and wheeled vehicles of the time. Having a clear span or fresh air between the trackways allowed the weight of the bridge to be minimised. 30 feet in length it could clear spans of up to 26 feet and carry loads of up to 7 tonnes. Carried folded on the roof of the tank it was unfolded and launched using a supporting frame that was lowered to the ground, this stopped any further rotation and at this point the folded bridge was vertical, in front of the tank. Cables were then winched in that acted upon a cam and the bridge was both extended and lowered, finally, the mechanism was disengaged and the tank driven away.
The system was later used on Covenanter and Valentine tanks but the single piece tank bridge was to see more use until the Number 4 and Number 8 tank bridges of the later forties and early seventies, described later.
Dieppe, D-Day and Armoured Engineering
The abortive raid by the brave Canadian forces on Dieppe in 1942 confirmed that the usual combat engineering capabilities of demolitions and obstacle crossing were going to be needed for any large scale invasion of mainland Europe but they would need to be carried out under armour.
Although this is not a post about the history of the 79th Armoured Division, Sir Percy Hobart or the non-bridging vehicles that were collectively known as Hobart’s Funnies it is almost impossible to do one without the other, however, I am going to concentrate mainly on the bridging vehicles.
Before the D Day landings there were 3 main assault bridges available and a vehicle called the ARK.
Scissors Bridge 30ft, Number 1
A direct descendant of the earlier Scissor Assault Bridge, the Number 1 was designed to carry heavier loads, Class 24 over a 30 foot gap.
Early prototypes used the Cruiser Tank Mark II (A10) but this was soon replaced with new Cruiser Tank Mark V or Covenanter.
Subsequent testing showed the bridge was capable of carrying Class 30 loads but the Covenanter was not a good design and was replaced with the successful Infantry Tank Mark III or Valentine.
The Number 1 equipped Valentine was used in Italy, North West Europe and Burma.
This amusing video clip from 1941 shows the No 1 tank Bridge on exercise.
Tank Bridge 30ft, Number 2
The Infantry Tank Mark IV, or more commonly known as the Churchill Tank, posed a problem for the Scissor Bridge Number 1, it was too heavy at 40 tonnes so in 1942 a new bridge was designed. The Number 2 was still to span a gap of 30 feet but instead of Class 30 it was capable of carrying a Class 60 tracked vehicle load and a Class 40 wheeled vehicle load.
The Number 1’s carrying capacity could not be improved so a completely new approach was needed. Two arched steel trackways were connected by a number of cross braces and launched using a hydraulic mechanism that kept the bridge horizontal throughout the launch and recovery process.
The bridge was carried on a modified Churchill tank and operated by the driver, the only other crew member was the commander, the whole launch process taking less than 2 minutes.
The Number 2 and Churchill saw extensive service in Italy and North West Europe.
Tank Bridge, Small Box Girder
The final of the trio of tank launched bridges was called the Tank Bridge Small Box Girder or SBG Assault Bridge. Introduced specifically for D Day and the 79th Armoured Division it was designed to support a Class 40 load over a 30 foot span, or more specifically a 12 foot high sea wall.
The bridge itself consisted of 4 Small Box Girder hornbeam sections connected together to form a twin trackway bridge, connected with crossbeams.
Unlike the Number 1 and Number 2, it was carried by a standard Armoured Vehicle Royal Engineers (AVRE), not a specialised bridgelayer and thus the carrying vehicle was able to be used in other engineering roles once the bridge had been detached.
The sequence of operation on a sea wall is shown below, including using a fascine to cushion the fall!
Am I the only one thinking that the tank missed the fascine and had a tough landing?
A Mark II variant introduced a more sophisticated launching mechanism that provided for a more controlled release.
The bridges were carried on a small bogey trailer towed behind the tank and attached to the front prior to use.
Armoured Ramp Carrier (ARK)
The Armoured Ramp Carrier or ARK was used for crossing small gaps and used in a number of variants. At its simplest, an ARK was a tank with its turret removed and ramps fitted to the top of the superstructure and at either end of the hull.
The vehicle would be driven into the gap, deploy its ramps and other vehicles simply driven over the top of it. The original ARK’s were designed to enable other tanks to climb sea walls on the beach defences on D Day although it is not certain if any were actually used.
ARK Mark I, used in the D Day landings primarily for traversing the sea walls and defences it had a 2 foot wide wooden trackway with short ramps and about 50 were manufactured.
ARK Mark II, after the initial D Day landings had taken place the surviving Mk I’s were remanufactured with longer ramps and a shorter distance between the ramps to enable smaller vehicles to use it.
Italian ARK, these were designed and manufactured in Italy, did not use separate trackway on the superstructure but used longer front and rear ramps made from 15 foot long US M2 Treadway Pontoon Bridge components. The Italian ARK’s saw extensive service.
BURMARK, instead of using the Churchill the lighter Valentine tank was used for the Burma theatre.
Great Eastern Tank Ramp, although designed in 1944 the Great Eastern ARC was not available before 1945 and not in time for the D Day landings, still based on the Churchill it was fitted with two ramps, one 27ft long and the other 25ft long. This was to enable higher obstacles to be traversed than the normal ARK’s.
Sherman Twaby ARK, the basic ARK design was also deployed on the Sherman chassis.
Widely used in WWI the bundle of sticks called the fascine was also see extensive service in WWII, this time on the Churchill AVRE.
This video clip shows one in action, including a very good clip of a Churchill AVRE firing its 165mm spigot charge, the flying dustbin.
Later in the war, fascines were used extensively in the campaign in Italy, notably in the crossing of the River Senio by New Zealand forces. In this instance modified Sherman’s joined the Churchill’s and a new type of fascine called a bolster was used, combining the traditional bundle with a steel lattice crib.
Post War Assault Bridging
The immediate post war effort was concentrated in improving the load carrying capacity of existing bridges so the Number 3 Tank Bridge was essentially an evolution of the Number 2 and the Churchill ARK Mark III a similar improvement designed to accommodate the heavier tanks coming into service. The Number 4 was a scissor bridge tested on the Valentine tank, a successor to the Number 1.
With the development of the Centurion tank came the next evolution is assault bridging, the Number 6 Tank Bridge, Centurion ARK and Centurion ARK Mobile Pier (CAMP)
The Number 6 was single piece bridge mounted on the Centurion that departed from the launch method employed by the Churchill Bridgelayer and used an up and over deployment. The bridge itself was 52 feet long, significantly longer than its predecessors and 4 feet 8 inches wide, able to accommodate a load class of 80.
The bridge was dimensioned from extensive trials and was the largest single piece that offered a reasonable compromise on mobility. Although the folded or scissor bridge offered a lower visible footprint when deploying and recovering it is slower. Thus, the single piece Number 6 whilst presenting a conspicuous target when being deployed it was not for very long, less than 2 minutes.
The Centurion ARK (FV 4016) was introduced in 1965 and withdrawn in 1977. It was similar in design to the previous Churchill ARK’s but the ramps were articulated and launched in a scissor like manner. A screw mechanism allowed the track width to be varied to accommodate different vehicles and reduced in width for easier road and rail transport.
British Pathe, as dependable as ever, has a good video of the Centurion ARK in action here, at about a minute in, check out the hover stretcher as well!
Another interesting Centurion ARK derivative was the CAMP.
This was designed to provide a rapidly deployed pier for the Number 6 bridge when used in multiples or combination bridging to use the correct term.
The Centurion was in time replaced with the Chieftain tank and to coincide a new bridge and tank carrying engineer vehicle introduced. The Number 8 Armoured Vehicle Launched Bridge was 100 feet long and therefore had to be of the Class 60 scissor variety.
The FV4205 Chieftan AVLB was also able to carry a single piece tank bridge, called rather unsurprisingly, the Number 9. Both were launched by a combination of hydraulic and winch mechanisms, the hydraulic system supplied by AP Precision Hydraulics.
Deployed to BAOR in 1979 it was to see action in the 1991 Gulf War and the Balkans.
It is at this point that things become both simple and complex. Simple from an equipment perspective but more complex for anyone writing about the subject!
I will cover the general support bridging systems in a later post but the programme that delivered them also delivered a new set of bridge components that could be tank launched so there is inevitably some crossover.
Towards the end of the sixties British military bridging was in pretty good shape, the MGB, second to none and widely adopted, the M2 rigs for the wide wet gaps of Northwest Europe and the Chieftain AVLB with its No 8 and No 9 bridges were equally world leading.
But the world does not stand still and a multi-national project was initiated called Bridging for the Eighties or BR80, this programme ultimately failed but the considerable design work carried out at Christchurch was not wasted and the resultant national programme was called BR90 with the Close Support Bridging requirement defined under General Staff Requirement 3983.
The resultant seven modular panels are used to construct both close and general support bridges.
The close support bridges consist of three types
No 10 Tank Bridge
26m scissor bridge comprising two 8m ramp panels, two 4m standard panels and a 2m hinged panel. The 4m panel can be removed to create a smaller bridge if needed.
No 11 Tank Bridge
16m up and over bridge comprising two 8m ramp panels
No 12 Tank bridge
13.5m up and over bridge comprising a single specially designed ramp panel which is not interchangeable with other panels
All the bridges can be combined to form longer bridges using trestles, river beds or even floating pontoons.
The Pipe Fascine
As above, fascines were widely used in WWI and WWII but in the seventies an alternative to the Chespale bundle was sought. One of the problems was weight, the traditional fascine bundle could be between 6 and 10 tonnes and would of course create a significant visibility hazard.
Inflatable fascines had been trialled in the sixties as shown towards the end of this video from Pathe but they were not adopted.
The Pipe Fascine was developed in 1981/82 from an idea in the mid seventies by Major J M Allen Royal Engineers using modern polythene pipes. The area of operations of the British Army of the Rhine (BAOR) had numerous small gaps (streams, ditches etc) that would hamper the free movement of military vehicles and to counter weight limitations of brushwood and reduce the carried weight the new system was proven to be a great success. In addition, wooden fascines have a tendency to float which makes them difficult to use in water filled obstacles, the pipe system allowed water to flow normally.
Plastic water pipes had seen rapid introduction in civil works and they were seen as a promising alternative. After much testing and refinement by the Experimental Bridging Establishment the development continued with significant further testing in the likely area of operations by Lt Chris Roebuck and 5 Troop, 31 Armoured Engineer Squadron, 32 Armoured Engineer Regiment. The development took over 6 months using a variety of exhaustive testing on a multitude of critical elements, eg steel rope tensions, release timings, methods and positions, launch techniques on gap types, sizes during both during the day and at night and rapid recovery and re-use procedures. This testing used the Royal Engineers a version of the Centurion AVRE was introduced in conjunction with modified bundles of plastic pipe. The launch technique was to approach the target gap at speed, brake sharply at a marked point, aligned to the line of the desired drop, and fire the explosive bolts holding the travel hawsers so that the fascine, through inertia, rolled off the AVRE directly into the middle of the gap. When in position the AVRE would then travel over it to level the road surface for other vehicles to cross.
The development team, through constant practice, was able to accurately launch two and even 3 fascines to fill larger gaps. In the acceptance into service recommendations and user manuals the launch of any more than single fascines for non Armoured Royal Engineer units was restricted for safety reasons. Triple fascine launches were only very rarely practised even on the development trails to test the limits of possibilities and only then by the most experienced crews. Even with these it was concluded by all involved that they were such a potential for significant risk to the tank crew that they should not be used unless in the most extreme emergency.
The image below shows one of a handful of rare triple bundle being used by a Centurion AVRE during development trials by 5 Troop 31 Armd Engr Sqn Hannover 1981.
The Maxi Fascine consists of 30 pipes connected in a continuous length that are wrapped around an inner core of 45 loose pipes, the whole thing is secured by a net, supplied by Tulmar.
The fascine systems themselves are supplied by Pearson Engineering.
As might be imagined, the Mini Pipe Fascine is a smaller version designed for smaller vehicles than main battle tanks.
The fascine continues to be used on the Trojan armoured vehicle Royal Engineers.
Pipe fascines are still very much in use today and in Afghanistan they are used to provide quick crossings for many of the small irrigation ditches with sheets of AM2 runway matting acting as a footway.
Modern Assault Bridging
The latest assault bridging equipment to enter service with the Royal Engineers is the BAE Systems Titan, a total of 33 were ordered in 2001, together with another 33 Trojan armoured engineering vehicles under a £250 million contract . The Titan is based on the Challenger 2 and can launch and recover the Number 10 and Number 12 bridges, already in service.
The Tank Bridge Transporter was part of the BR90 project and forms an integral part of the Close Support Bridging capability.
At the time of contract award Baroness Symons, the Defence Procurement Minister, said;
Under MOD’s Smart Acquisition programme this contract is being awarded early. The vehicles will enter service one year earlier than if traditional procurement methods had been used and they will be equipped for immediate deployment worldwide
The prototype was unveiled on February the 20th 2003.
First deliveries commenced in 2006, five years after the order was placed and a year late, demonstrating the development difficulties that had plagued the £4 million vehicle with initial operating capability in 2011.
The final outturn for the project was £336 million, for 66 vehicles plus associated support, just over £5m per vehicle on a programme basis, final vehicles at Batch 5 design.
From the BAE Systems Titan product page;
TITAN can launch the 26 metres No 10 bridge – also made by Land Systems – in two minutes and using integral trestles and wedges can lay multiple combination bridges in depths of 5 metres, and overbridge oil pipelines and bridges. TITAN can carry two 13.5 metres No 12 bridges, which are laid in only 90 seconds.
23 Titan systems will be in service with the Royal Engineers and the remaining 10 assigned to training units although what impact the recent SDSR has on these plans is not certain.
The USMC also uses the Titan launch and recovery mechanism on their M1A1 bridging vehicles.
The Army has long had a vision for a Medium Weight Capability as defined by the Future Rapid Effects System or FRES but with the various problems with that programme and demands of ongoing operations this has yet to come to fruition. The latest SDSR and Planning Round 11 deleted the Manoeuvre Capability (thought to be about 30 vehicles) from the FRES Specialist Vehicles programme and although details are a little vague it seems that a Warrior conversion may be used instead.
BAE Systems demonstrated a Warrior REME variant at the 2011 DSEi trade show fitted with a Pearson Engineering Bridge Launch Mechanism (BLM) and carrying a single BAE Systems Number 12 bridge. The BLM is an interesting piece of equipment because it is designed to be fitted to a wide variety of wheeled and tracked vehicles and is available in a number of weight categories in addition to a variant that can be used with demountable load carrying equipment such as the Foden DROPS vehicle or MAN SV EPLS. Using the Pearson Engineering Common Interface System (CIS) it can be rapidly re-rolled, to a bulldozer blade for example. Although unable to deploy the large Number 10 bridge the Warrior bridgelayer might be able to carry two No 12’s.
The description from Pearson is;
The Bridge Launch Mechanism is a lightweight system which allows Medium Gap Width bridges to be launched from a range of vehicles.
Typically fitted to medium or heavy class tracked or wheeled platforms; the Bridge Launch Mechanism is installed onto the host vehicle using a Pearson Engineering Fitting Kit, a system which facilitates the attachment/detachment of the front end equipment and allows different equipment to be used on the same vehicle.
Whilst retrieving and launching a bridge the foot of the Bridge Launch Mechanism maintains contact with the ground, thus reducing load transfer onto the host vehicle and ensuring a stable launch platform.
In the transport configuration the bridge is stowed longitudinally above the vehicle.
When not in use, the launch mechanism is raised and stowed close to the host vehicle hull, thus minimising its effect on vehicle manoeuvrability and mobility.
With the Terrier vehicle coming in to service in support of the Medium Weight Capability it may be possible to fit the same role kit, thus allowing the Terrier to provide the same bridging support. There are 60 Terriers planned to enter service soon but are not as well protected as Warrior and therefore less able to operate in the direct fire zone.
The choice of Warrior would be interesting because as we have seen above, front engine vehicles have sometimes been problematical when laying bridges but if the demonstrator has shown that a Number 12 bridge can be successfully launched and recovered then that would not seem to be an insurmountable problem. It might also be a recognition of the need for a manoeuvre support element for FRES SV Scout given its threefold increase in weight over CVR(T)
The recent introduction of a small number of General Dynamics Rapidly Emplaced Bridge System (REBS) on the Man Support Vehicle truck may also provide a long term solution to the medium weight bridging requirement given that it was developed for the US Stryker Brigade Combat Team although being truck based it is not comparable to either Warrior or Terrier in protection or mobility terms. At MLC50 REBS will support the proposed FRES vehicle family but only at 13.8m or 45 feet, MLC50 being the same requirement as for the cancelled FRES Manoeuvre Support variant.
So, beyond Titan, there is obviously a great deal of uncertainty regarding the future medium weight bridging requirement but whichever vehicle is chosen it will provide a valuable addition to the Corps bridging capability.
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