rely on applying pressure to the ground, so detonating
pressure-sensitive devices. In practice, mined areas are
rarely level and large rollers fail to apply ab even pressure,
so missing pressure initiated hazards that would theoretically have been initiated
by the roller's weight.
attempted to get around that with segmented disc rollers,
accurately than long rollers.
order to achieve this, the undergrowth must first be
cleared AND removed. Even then, rocks,
tree stumps or large irregularities mean that the discs
do not always touch the ground.
shows a Soviet T55 bridge layer tank with KMT5
roller system mounted on the front. Tanks with the KMT5 were once used to 'clear' a defensive
belt of AT mines in Angola.
picture was taken when a T55 tank and KMT5 rollers failed to detonate a pressure initiated AT mine, then drove over it. The tank's armour was breached
and an occupant killed. The system missed mines, and was
even unsafe for its operators.
fundamental problem with rollers is that they can never
let off anything but a pressure-operated device that
is orientated correctly and in good working condition.
Mines on their side or damaged, mines that are not pressure
fuzed, and all manner of unexploded ordnance will always be
left behind - and may be left behind in a more damaged
state. If the ground is uneven, anything could be left
behind, even by heavy roller systems.
are ground processors - chewing or milling
the ground. Tillers are push-or-pull ploughs designed to
turn up and expose mines.
are designed so that AP mine detonations do not disrupt operations.
A few claim that even AT mine detonations cause only minimal
damage. See what happened to the tank in the previous section
- AT mines are designed to disrupt armoured vehicles so the
claim of AT immunity always relies on the device detonating
in a conveniently 'harmless' place.
The FMR-2000 is one of these 'miracle' machines.
is the optimistically named 'Mineguzzler'...
Tillers use tines or plough blades to break
up the soil and expose any shallow buried items that may
be there. In areas where there is friable soil without
dense tree roots, this can be effective - but the effect
may be to simply turn devices over, or to bury them more
deeply than they originally were.
protect the machines, some are designed to push rather than
pull the tiller. The machine above is the Mine Clearance Cultivator
(MCC). It weighs 32 tonnes (too heavy for the road bridges
in many countries) and pushes its tiller through the ground
with immense force. Needless to say the tiller blades tend
to be broken off by the pressure, especially when there any
large stones or roots for them to catch on. The only effective way
to use it is with a minimal cutting depth, so ignoring any
mines buried below 8cm. Given that its target is AT mines,
and it is normal for them to be buried more deeply, this is
a fairly significant design limitation.
the machine was backed by huge sums of US taxpayers
money and 'found' two AT mines in Angola.
It blew itself up with both.
cost of the repairs alone would have paid for many months
of real clearance by a real demining team.
millers and tillers are on a smaller scale - usually
as attachments to fit on a multi-purpose
As usual, multi-purpose machines rarely perform any action
as efficiently as a dedicated item, and some...
contrive to look absurdly amateur despite vast sums of
R&D money being spent.
machines could really locate and break up the range of unexploded
ordnance common in mined areas, (which includes ordnance with
an armour piercing capability) they would blow themselves
to bits in the process regularly. What happened with the MCC
illustrates what can happen with simple blast devices. If
they reliably exposed everything that must be found in HD,
commercial demining groups might find them commercially viable
to purchase, but they do not.
ground tends to look smooth despite the original irregularities
- so items can be missed and buried more deeply than they
were before. Bed-rock, fibrous tree roots and soft ground
all lead to failures of coverage that means the whole area
must be searched again using reliable procedures.
If the machine has disrupted mine patterns or left damaged
devices behind, this can be slower and more expensive than
it would have been without the machine being involved. In
any case, the cost of using the machine must be added to the
cost of manual search and clearance - so it can never be cheaper than
manual clearance would be.