On Soft Ground
Continuing my quest to find the most obscure subjects to write about, the next in line is Trackway and Matting.
Soft ground obviously creates problems for all types of vehicles reducing mobility and access to key points or routes.
In the preparations for D Day and as a result of some very brave reconnaissance missions carried out by the Combined Operations Assault Pilotage Parties (COPPS) it was discovered that the intended landing beaches had large strips of very soft ‘blue clay’ that analysis showed would not support armoured vehicles and heavy trucks. Similar geology was to be found on Brancaster Bay in Norfolk so the team behind the 79th Armoured Division (Hobart’s funnies) set to work testing various solutions.
Out of this work came the Churchill Bobbin tank, a development of the crude device first deployed during the Dieppe raid.
The early bobbin mat was made from coir matting reinforced with scaffolding pipe and whilst not particularly durable allowed the initial assault to press home its attack.
This design was refined in time for D Day and used a canvas track and several variations were ultimately employed;
AVRE with Bobbin Mk I and Mk II; a single spindle and 9ft 11in wide canvas mat, the Mk1 had moveable arms and the Mk2 fixed
AVRE with log carpet device; not used as much, consisting of 100 6inch diameter logs bound together with wire, the mat was unfurled by firing an explosive bolt which released the coiled mat
AVRE with Twin Bobbins; experimental only, designed to offer a choice of matting types
TLC Laying Device; the early types used at Dieppe
After the initial assault they were replaced with Pierced Steel Plank (PSP) and Square Mesh Track (SMT)
The bobbin tanks were to prove invaluable on Gold Beach and within an hour of landing, they, and the other Hobart’s ‘funnies’ had created four safe transit lanes which allowed the assault and follow on forces to push on to their objectives.
After the war, most of these were taken out of service
In the early 1940,s Laird Anglesey manufactured a number of defence products including pontoons and trackway.
In 1960, MEXE in Dorset designed the modern trackway after extensive exercising in Germany showed that assault and logistics bridgeheads needed some form of ground stabilisation system to prevent vehicles getting bogged down. The ever fascinating British Pathe has a short clip here
Bridgeheads are obvious concentration points and in poor weather they would quickly be churned into impassible quagmires by tracked vehicles making use of the bridges. In conjunction with MEXE, Laird Anglesey developed the ubiquitous Class 30 Trackway and subsequently won manufacturing contract.
In 1968, Mexe also outlined a requirement for a heavier version of the Class 30 product and the Class 60 was developed, trialled and placed into production soon after.
Class 60 Trackway was also extensively used for airfield bomb damage repair purposes and the RAF and Royal Engineers deployed large quantities to the strategic airfields in Germany.
Faun acquired Laird Anglesey in 1996 and continue to develop and promote trackway products.
A waterproof and winterised Case 721 BXT wheeled loader is used to deploy Class 30 trackway in support of amphibious landings, a specialised dispenser from Ulrich is used, the UK had in service 8 modified Case vehicles and 29 trackway dispensers.
The Case 721’s are in the process of being replaced with JCB 436 eHT wheeled loading shovels to be designated the Medium Wheeled Tractor or medium wheelie under the ALC C Vehicle PFI.
Class 30 has now been renamed the Medium Ground Mobility System (MGMS) and Class 70, Heavy Ground Mobility System (HGMS). Heavier vehicles can use the trackway beyond its classification but this depends on the ground bearing capacity and number of passes before the trackway becomes unusable.
Continuous lengths can be joined using a joining strip, as below
From Faun’s website
MGMS is a military specification system that facilitates the launch and recovery of a temporary roadway. A standard MGMS provides one 32m length of roadway as standard, further spools containing additional 32m lengths can be stored and deployed by the same FASTRACK.
MGMS can be deployed by a trained two-man team in less than 6 minutes. The aluminium TRACKWAY will withstand repeated loads of up to 30 tonnes (rated to MLC 30).
MGMS is suitable for tracked and wheeled vehicles up to 30 ton, and is chassis mounted by crane, MGMS can also be deployed by tractor to create a solid beach landing area, utilising the BEACH DISPENSER system.
MGMS provides access for these vehicles into areas where there are no roads, or roads have been damaged. MGMS enables boggy or marshy terrain to become accessible to medium sized vehicles.
MGMS is best suited to adverse terrain conditions, including snow, marsh, mud and sand in a variety of climates. MGMS can also be used as shelter and tent flooring. MGMS is in use worldwide in a variety of military engineering applications, including humanitarian and disaster relief.
HGMS or Class 70 (was reclassified from Class 60) is the heavy duty version.
From the Faun website
HGMS is a military specification system that facilitates the launch and recovery of a temporary roadway. A standard HGMS provides one 50m length as standard, with the option of further 50m lengths to be carried by trailer.
HGMS is suitable for very heavy tracked and wheeled vehicles, including tanks and bridge transporters.
HGMS provides access for these vehicles into areas where there are no roads, or roads have been damaged. HGMS enables boggy or marshy terrain to become accessible to large, heavy vehicles.
HGMS can be deployed very quickly and efficiently. A trained two-man team can deploy 50m of roadway in less than 10 minutes over the toughest of terrain. The aluminium TRACKWAY will withstand repeated loads of up to 70 tonnes (rated to MLC 70).
HGMS features a unique ‘spool to spool’ transfer system that allows multiple 50m lengths of roadway to be laid quickly and easily. HGMS can be easily mounted to chassis with a PLS/DROPS hook lift system.
HGMS is best suited to adverse terrain conditions, including snow, marsh, mud and sand in a variety of climates. HGMS also provides rapid access to bridgeheads. HGMS is in use worldwide in a variety of military engineering applications, including humanitarian and disaster relief.
One of the ingenious features of the Faun trackway system is its ability to utilise any DROPS vehicle. Both the Trackrack (launch and recovery) and Spoolrack (additional lengths) can be carried and operated from any number of military trucks, the MGMS needs a 4×4 or 6×6 with a 4 tonne payload and the HGMS needs an 8×8 vehicle with a 13 tonne payload.
Class 30 and 70 trackway has achieved excellent export success and it has had a great deal of operational deployment spanning many years, a good example is Operation CHIKARA in 1980 in which trackway was used to recover an RAF Phantom that had overshot the runway at RAF Coningsby (Images from 60 Company Royal Engineers)
Class 30 Trackway also enjoyed considerable export success
Class 30 and Class 70 Trackway remains in service with the British Army
British design, innovation and the operational art at its best
A lighter duty woven textile mat commonly called ‘mammoth mat’ from Robusta of Holland is often used to supplement the heavier duty aluminium sectional trackway for non heavy tracked vehicles and recovery applications.
Robusta have a selection of videos here and the fast deployment dispenser is below
Although the challenge is somewhat similar, expedient surface reinforcement for aircraft is sufficiently different to have created a range of unique solutions.
Rapid airfield construction in support of manoeuvres forces was essential and as aircraft grew heavier the need evolved, in addition, the enemy would seek to disrupt air operations by destroying your airfields. This also created a range of rapid repair needs and solutions.
Somerfeld Matting (patent details here) was used in the early stages WWII but was soon replaced with Square Mesh Tracking for use in Normandy and beyond. The French also created an innovative chevron pattern steel planking used for runway construction, pictured here and the US created the Pierced/Perforated Steel Planking (PSP) that is still in widespread use today. PSP is often called Marston Matting and during the war years over 800 million square feet was produced.
When the invasion plans for Normandy started to crystalise it was clear than a rapid expansion in the number of airfields would be needed, Operation Hadrian created 26 so called Advanced Landing Grounds on the south coast of England, all constructed to a common design and making extensive use of temporary matting and trackway.
PSP was suited to heavier loads but suffered from poorer drainage than some of the ‘chicken wire’ mesh type products like SMT and the US Rod and Bar Tracking
Much of this development was carried out in the UK and USA, particularly MEXE and the US Army Waterways Experiment Station at Vicksburg Mississippi. WES is still there today and have published a detailed account of landing mat developments here
A development of PSP was PAP, or pierced aluminium plank, this was used where logistic constraints meant a lighter version was needed but it was not as durable.
A good PSP gallery is here
It should also be noted that PSP was used well beyond aircraft applications as shown below
After the war, runway repair and expedient airfield construction was not neglected because it was widely assumed that airfields in western Europe would be very quickly attacked by Warsaw Pact air forces and of course, this is where the Harrier came from.
Since the cold war a bewildering number of solutions have evolved, everything from matting to soil stabilisation binding agents.
This is a huge subject and I will be covering it in a separate post in the future but here are a few videos that demonstrate the range of products for both landing site construction and runway repair
An interesting project called JRAC from the US and Australia
More on this in a follow on post and don’t forget to click the links!