The ARJUN Demining System relies on a combination of the ARJUN machine and manual excavation using the Rake Excavation and Detection System (REDS). Both are inherently safe. With no accidental initiations and no injuries in Sri Lanka, we know that this is true. If you want to know why, read on.
The safety of Arjun
Each Arjun is armoured to meet the risk assessment where it will operate. Armouring is kept to a minimum because it is the last line of defence. Avoiding a detonation is the first line of defence. The threats to Arjun are from an accidental initiation in front of it while using the ground-engaging tool, or of driving a track over a deeply buried anti-vehicle mine.
Avoiding risk. The system relies on the operator having a clear view of the tool, so armoured glass is installed at the front of the cab. Additional steel plate is added at the front to provide blast-resistance. Arjuns have raked out tens of thousands of mines, including anti-vehicle mines and IEDs, and have never caused a detonation. We believe that this is because the operator has a good view of what is being exposed and uses the tool with appropriate caution. To avoid the visual distortion associated with looking though multiple layers of different materials, the operator is not required to wear additional eye-protection inside the cab. The distance between the operator and a potential detonation, the barrier presented by the armoured glass and the fact that a blast at the tool would be able to vent easily, mean that we have decided that the risk to the operator from a detonation at the tool-head is acceptably low. Experience confirms that giving the operator clear vision avoids unintentional detonations and so is an effective risk-mitigation strategy.
When Anti-Tank (AT) mines are known to have been placed at a shallow depth, (as in Sri Lanka), the Arjun tool lifts them without detonations. The tool has even lifted IEDs and booby-trapped AT mines, breaking the det-cord linking them to AP mines. The Arjun tool has not even initiated an anti-personnel mine - which requires a far lower pressure to detonate than an AT mine. Of course, an AT mine could have been damaged and become more sensitive, but this has not happened. In Sri Lanka, our risk assessment relies on the fact that AT mines are placed at a shallow depth and that the Arjun tool does not apply enough pressure to initiate them, therefore they represent a minimal threat.
In other theatres, AT mines may have been placed deeply in the ground, or may have become deeply hidden by ground movements. When this is anticipated, our risk avoidance strategy is for Arjun to rake to a greater depth before driving forward into the ground it has raked. We generally rake to 20cm but can readily rake more deeply when required.
Residual risk. It is known to be unlikely that any mine would be initiated as Arjun works. Anti-personnel mines require low pressure to initiate and it may be expected that the Arjun tool will initiate one at some time. If that occurs, the tool is strong and mobile so we anticipate no significant damage to the tool or the boom arm. While proven to be "unlikely", it is possible that a large and sensitive device could be initiated by Arjun's ground-engaging tool. If that occurs at a distance of at least four metres where the tool first engages the ground (when some downward pressure is unavoidable) we know that even lightly armoured vehicles have survived AT sized blasts at that stand-off without significant damage. If a large blast were to occur in front of Arjun, the machine has a very low centre of gravity, so making it likely to remain upright as a blast wave passed. The ground-engaging tool is very robust and we believe it would stay in one piece, even if severely distorted. The linkage to Arjun's boom arm and the articulation along the boom itself might well be damaged, but we believe they are robust enough for the boom arm to stay in one piece. We do not anticipate that the integrity of the middleweight Arjun cab armour would be compromised.
Because the Arjun cab is often "open" to allow ventilation, the blast pressure wave can be expected to pass through the cab and could cause tympanum injury to the operator. However, the operator must be in voice communication with the rest of the team, so it is not practical for him/her to wear ear-protection. Because the risk of an initiation is very low, we consider the risk of ear-drum injury to be tolerably low. We also believe that allowing the blast wave to pass through the cab is far safer than any effort to keep it out (while will concentrate entry and has caused injury on recorded accidents).
AT mine under tracks. When there is an unknown threat that may include deeply buried AT mines, it is possible that a detonation could occur under a track as Arjun moved forward. If this occurred, the mine would (by definition) be deeply buried and the ground above it loose. We believe that the main risk would be that Arjun could lose a track and could be tipped onto its side. To mitigate the risk of injury to the operator in this scenario, the operator must be strapped into a firm seat using a three-point harness. All items in the cab must be held firmly in constraints that prevent them being thrown around. The Operator will always have minimal (IMAS compliant) PPE in the cab to facilitate his recovery by the rest of the team. The risk of blast forces entering through the floor of the cab is mitigated by placing heavy deflection plates outside the cab where necessary.
The safety of REDS
REDS is proven to be safer than other manual demining methods. The evidence is given below.
The Database of Demining Accidents (DDAS) holds several hundred records of demining accidents that have occurred since 2005. A pi-chart of the activity taking place at the time of these accident looks like this…
The most common activity at the time of an accident was "excavating" a metal-detector or a dog signal. This occurred in almost 64% of accidents. When excavating with conventional tools, the deminer is kneeling or squatting directly in front of the mine, and is frequently leaning over it. The injuries that result often leave the deminer severely disabled, with finger, hand and eye loss being common. This is not only a human tragedy for the victim. It is also devastating for their dependants and imposes additional strain on the health and social care systems in the post-conflict country. For example, of more than 80 excavation accidents in Afghanistan over this period, three quarters involved severely disabling injury or were fatal. Twenty involved amputations and/or eye loss.
In Jordan, the border with Syria has been cleared using metal detectors, dogs and machines since 2005. For the first time, the excavation of metal-detector indications was carried out using REDS rakes, so putting the deminer further away from any accidental detonation. Of 40 recorded accidental detonations while excavating with REDS in Jordan (recovering a hundred thousand mines from a dense border minefield) more than 50% involved no injury at all. Other injuries were minor (requiring no surgery). Only one accident involved a severe injury - when a deminer who was not wearing eye protection suffered a serious injury to one eye (but kept the eye).
There have been accidental detonations while raking with REDS in several other countries, but there have been no severe injuries as long as eye-protection is worn. This is because the deminer is at the end of a long-handled rake, at least 1.5 metres away from the point of initiation. So REDS is proven to be safer than other excavation methods when used without Arjun. When used with Arjun, it is safer again.
To date, many thousands of mines have been lifted using REDS behind Arjun in Sri Lanka and there have been no accidental detonations. This appears to be because the ground is already loose and there is no need to apply heavy pressure to rake effectively. Whatever the reason, it seems that the deminer working in the Arjun Demining System is safer than any other.
For an independent assessment of the Arjun Demining System (made in April 2011) see http://www.nolandmines.com/Arjun_Demining_System.htm