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| (Top) Commonly used demining
tools—most of which are unsafe. (Bottom) Inappropriate tools that have featured in accidents. |
by Andy Smith, AVS Consultants
Introduction
A research and development program to design, develop, demonstrate and
test a wide range of Personal Protective Equipment (PPE) was initiated by
the U.S. Army Communication and Electronics Command (CECOM), Night Vision
and Electronics Sensors Directorate (NVESD), Humanitarian Demining Program
in 1999–2000. In a conceptual breakthrough, the PPE included safer
demining handtools as an integral component of the personal protection
scheme. The contractor, Andy Smith (AVS Consultants), conducted this
effort in Zimbabwe, a mine-affected developing country, with the side
effect of establishing an indigenous production capability and realistic
conditions in which to test and evaluate. The contractor and author of
this paper, AVS, retains no interest (commercial or otherwise) in
exploiting these results. The U.S. Army CECOM, NVESD point of contact for
this effort is Charles Chichester at charles.chichester@nvl.army.com. The
programme involved close collaboration with a company in the small
industrial sector of Harare, Zimbabwe. That company is currently producing
the tools.
Inappropriate Tools Maim and Kill
A study of recorded demining accidents revealed that deminers frequently
suffer severe injury when the tools they are using are unsafe. They fail
by being so short that the user’s hand is inside the most violently
disruptive part of the blast or by breaking up and becoming fragments
when a detonation occurs.
The picture to the right shows a range of tools commonly used in demining around the world. Many were designed for another purpose, and there is compelling evidence that almost all of them are unsafe for use in demining. Some of those that were designed for demining are also unsafe.
It is not only the users’ hands that suffer. At least five deminers
have died after part of their handtool struck them. Parts of tools have so
severely damaged the upper arm that amputation was needed. Parts of
brittle handles have pierced the user’s chest cavity. The head of a garden
trowel has sliced the user’s face in half—injuries from which he later
died. The mangled head of the yellow-handled garden trowel (shown on the
right) was discovered inside a deminer after he arrived in hospital.
Design Rules
The following design criteria were adopted for making appropriate
excavation tools. Tools used during other demining activities may not have
the same requirements.
- The user’s hand should be at least 30cm from the point of any tool. Some argue that this is too long for the user to control. I suggest they try because this is not the case.
- The materials used must be sufficiently malleable for the tool to distort in any AP blast mine detonation.
- The tool must be constructed so that it does not readily separate into component parts in any AP blast mine detonation—this usually means that the shaft must be taken right through the handle.
- The tool should be designed so that it is easiest to use at a low angle to the ground by a kneeling or squatting deminer, so encouraging the user to keep his hand beneath the fragment cone associated with many detonations.
- Whenever possible, the tool should include a blast-guard for the
hand using it.
It is not specified that tools should be designed for one-handed use, but this is recommended in order to expose only one hand to risk. Also, prodders designed for two-handed use put the “guide-hand” too close to the blast and invite the use of excessive force.
The excavation tools that were developed during the programme meet the above requirements but are not presented as the “answer.” There is no doubt that they could be improved upon ergonomically, and I challenge design engineers to do that now.
There is a “downside” for purchasers. I do not believe that it is possible to design tools with blast-resistant characteristics that are also very hard-wearing. If you use the tools shown here, you will have to budget to replace the blades regularly.
The materials I used were E304 stainless steel, Medium/High Density
polyethylene (MDP) and mild steel. These are all very inexpensive and
widely available. Mild steel parts were galvanised or chromed to inhibit
rust.
The Pick-Prod
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| The Pick-prod before (Top) and after (Bottom) blast tests. |
Made from a “T” section of mild steel, the Pick-prod blade is 31cm long. It can be used to pick at the ground with considerable force without the blade bending. In softer ground, a twisting movement breaks up the ground more efficiently than a bayonet. The blade extends through the handle.
Ground broken up with this tool should be removed using the Excavator or Mini-spade. The Pick-prod weighs around 0.5 kg (1.2 lbs). In tests pressed against PPM-2, MAI-75 and PMD-6 mines, the blades distorted as intended.
The Pick-prod complies with the design rules in the following ways:
1. The user’s hand is at least 31 cm from the point of tool.
2. The materials distorted in AP blast mine tests.
3. The tool did not separate in AP blast mine tests.
4. The tool is easiest to use at a low angle to the ground by a kneeling or
squatting deminer.
The MIT Profile Needle-Probe
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| The MIT Profile Needle-Probe before (Top) and after (Bottom) blast tests. |
This tool is based on the common demining probe or “prodder.” With a 40 cm-long blade, the shaft is 8-mm stainless steel that extends through the handle and has been reduced to 5.5 mm in one plane. The tool blade is almost oval in cross-section, but actually has flat sides as shown on the right.
The tool is designed to be used with a forward thrust by one hand. The forward movement is followed by a rotating action to reduce friction, then a further forward thrust to move deeper into the ground. The “oval” concept was published by a demining research group led by David Levy at MIT.
The complete tool weighs around 0.4 kg (12 oz). In blast tests, pressed against PPM-2, MAI-75 and PMD-6 mines, the probes distorted as intended. The basic design has also performed well in more than a dozen actual demining accidents.
The MIT Profile Needle-Probe complies with the design rules in the
following ways:
1. The user’s hand is at least 40 cm from the point of tool.
2. The materials distorted in AP blast mine tests.
3. The tool did not separate in AP blast mine tests.
4. The tool is easiest to use at a low angle to the ground by a kneeling
or squatting deminer. The length of the tool obliges a kneeling/squatting
deminer to work with his/her hand at a low angle to the ground.
The “Excavator”
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| The “Excavator” before (Top) and after (Bottom) blast tests. |
Designed as an alternative to the pick-axe or hoe commonly used in demining, this unconventional tool is used with a forward thrust, followed by a sideways sweep to remove the loosened spoil. The sideways sweep puts strain on the user’s wrist. To avoid this, the tool is extended so that a sideways movement is supported against the forearm. Starting well back from the centre of the detector reading, the user digs a downward slope towards the reading. If a mine is present (and horizontal), the side of the mine will be exposed.
The “Excavator” folds in half for easy transportation and weighs 0.9 kg (2 lb). In blast tests, the blade was distorted as intended and the metal structure, welds and fixings survived without visible damage. The hand-guard needed to be revised (the one in the middle of the post-blast test picture is the final version).
The “Excavator” complies with the design rules in the following ways:
1. The user’s hand is 35 cm from the point of tool.
2. The materials used distorted in AP blast mine tests.
3. The tool did not separate in AP blast mine tests.
4. The tool is easiest to use at a low angle to the ground by a kneeling
or squatting deminer. It is virtually impossible for a deminer in that
position to use it to dig vertically.
The Mini-Spade
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| The Mini-spade after blast tests. |
The Mini-spade is a small excavation tool designed to remove spoil loosened with the Pick-prod or the MIT profile probe or to dig entire excavations in sand. It is designed so that it cannot be used vertically and is ineffective on hard soils that have not first been prodded. The shaft extends through the handle.
The tool is designed to flex when excess force is applied, making it difficult to use for excavation of spoil that has not already been loosened—a process that would involve the risk of digging beneath a mine and detonating it with upward pressure. The complete tool weighs around 0.7 kg (1.5 lbs). After blast tests with the blade beneath PPM-2 and PMD-6 mines, the tool distorted as designed.
The Mini-spade complies with the design rules in the following ways:
1. The user’s hand is 37 cm from the point of tool.
2. The materials distorted in AP blast mine tests.
3. The tool did not separate in the AP blast mine tests.
4. The unconventional shape of the tool obliges a kneeling/squatting
deminer to work with his/her hand at a low angle to the ground.
The Demining Brush
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| The Demining Brush after blast tests. |
There is no evidence that any accident has occurred while using the paint brushes commonly seen in demining tool sets. They are used to brush away the final soil sticking to the side of a mine or suspicious object. However, paint brushes are not designed for this purpose. They are far too short for safety, and the bristles are usually too soft to perform their function well.
The Demining Brush uses a 40-cm section of malleable stainless steel pipe with bristles set into it at both ends. A simple reversible tool, the Demining Brush has stiff “yard-broom” bristles at one end and softer hand-brush bristles at the other. In blast tests, the bristles of the brush were placed on top of a mine. The bristles were burnt off.
The Demining Brush complies with the design rules in the following
ways:
1. The user’s hand can be at least 30 cm from the point of tool.
2. The materials burnt or distorted in AP blast mine tests.
3. The tool did not separate in AP blast mine tests.
4. The tool’s length makes it easiest to use at a low angle to the ground
by a kneeling or squatting deminer.
While the tool performed as designed, it would be possible to add a
central disk as a hand-guard (providing protection to whichever end was
held).
The Demining Trowel
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The Demining Trowel is a variant on the gardening trowel that often features in a deminer’s toolkit. It is used to remove loose spoil and to excavate in soft ground. The shaft of the tool extends through the handle and keeps the user’s hand at least 30 cm (12 in) from the tip of the tool. The demining trowel is in widespread use but has not been blast tested.
The Demining Trowel complies with the design rules in the following
ways:
1. The user’s hand can be at least 30 cm from the point of tool.
2. The tool is made using the same materials and methods as those that
were blast tested, so it is expected to stay in one piece during AP blast
mine detonations.
3. The tool’s length makes it easiest to use at a low angle to the ground
by a kneeling or squatting deminer. The complete tool weighs around 0.6 kg
(16 oz).
The Mine-Grab
During the programme, the team was asked to develop a means of picking up
mines that had been deposited on the ground surface by a machine. The
mines were to be moved to demolition pits for destruction The Mine-grab
was the result.
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The Mine-grab is a two-handed tool with the weight supported by the forearm. The left hand holds the steadying handle; the right hand rests in the support and pulls the trigger to grip the mine. The grabbing head is angled so that the mine can be approached from the side while the user stands upright.
The tool turns over, positions and picks up mines with relative ease and keeps them over a meter away from the man doing so. Assuming he has frontal protection and a visor, he should survive an AP blast detonation without serious injury. I recommend long rubber knee-pads to extend a frontal apron to the ground when working while standing.
In tests, we detonated a mine in the jaws of the grab. The polycarbonate
jaws burnt up, but the shaft and the handle were unmarked.
The Complete Tool Bag
To make the tools more attractive to the manufacturer to advertise and sell, we designed a bag and filled it with everything that a deminer might need. The bag itself is made from waterproof canvas reinforced with polycarbonate. The lining has pockets for all the tools, held in place with Velcro straps. The bag can be used as a “suitcase” or a backpack. Several demining groups are now using the excavation tools.
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Acknowledgements
The following workshop technicians and tailors contributed greatly to this programme: Colin Jombo, Field Butizha, Fanny Chaitezvi, Christopher Marizani, Fordson Gwatidzo, Cosmos Mutema, Matthew Chambers, Washington Mbundire, Jonah Mahanisi, Matthew Smith and Jonathon Gwaze.
The following individuals provided invaluable assistance during the testing and evaluation stages of this programme. My personal and professional thanks to all of them. Hendrik Ehlers, Ken O’Connell, Herman van der Vorm, John Kirby, Temba Kananga, Fredrik Pallson, Noel Spencer, John Morrissey, Steve Priestley, Filipe Mazuma, Havard Bach and Gier Bjorsvik.
Most thanks are due to all at U.S. Army CECOM NVESD, in particular
Charles Chichester, the late Beverly Briggs and retired Colonel George
Zahaczewsky.
Contact Information
Andy Smith, AVS Consultants
E-mail:
avs@landmines.demon.co.uk
Manufacturer
T. Thomsen, Security Devices Pvt
14 George Avenue, Msasa, Harare
PO Box AY 125, Amby, Harare, Zimbabwe
Tel: (263) 4 487064/5
Fax: (263) 4 486885
E-mail: secdev@samara.co.zw
  Publisher: MAIC Contact: MAIC@jmu.edu |
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