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The definition of
‘barrier’
according to
the Oxford English Dictionary:
Barrier,
noun. An obstacle that prevents
movement or access.
Nowhere in that typically clear and
authoritative definition do you see the
words ‘sometimes’ or ‘occasionally’
or even ‘if you’re lucky’. No, a barrier
prevents movement and access. At all
times. That is its very purpose in life. If it
fails to do this, then literally by definition,
it shouldn’t be called a barrier.
I think that’s established. So why then, in
the great adventure of workplace Health
& Safety do some ‘barriers’ still take the
name, but clearly do not play the game?
It’s like this: In the industrial working
environment there are moving vehicles
and machines; forklift trucks, order
pickers, high rack stackers, hand pallets
– plenty more. Each one has its own
weight and load, each one has its own
speed and turning angles and, like all
moving objects, each one has its own
potential energy.
When these machines collide with
something – a piece of equipment,
a critical structure or, worse, a
pedestrian – it is this potential energy
that becomes impact energy when it is
transferred to whatever object is hit.
So take this impact energy and instead
transfer it to a barrier. It is now when
we see whether a barrier really lives
up to the name and purpose, which
is basically – with apologies to the
dictionary – stopping things from hitting
other things.
Let’s examine one typical impact
(and trust me on the calculations). A
lightweight counterbalance forklift
truck, traveling at a normal 12km/h with
a 1,000kg load hits a safety barrier at a
45 degree angle. This transfers 9,917
kilonewtons (kN) of energy to the barrier.
So, what happens next?
Those forces will travel into the barrier,
through the material and its internal build
and, dependent on the quality of the
barrier, either disperse with the design
dynamics or travel downwards to the
floor fixings. A rigid barrier, like steel, will
send almost 100% of the impact energy
into the fixings. In this case, the barrier
would be ripped out from the floor,
leaving behind a costly mess and putting
whatever the barrier was supposed to
be protecting in peril.
But a barrier that flexes, a barrier with
moveable parts, a barrier made from
an exclusive energy-absorbent material
(Memaplex
TM
) – now, that is different:
flex, dissipation, absorption, prevention
of forces traveling to the floor and,
finally, reformation characteristics all
combine. With them come costs savings:
to the vehicle, to the substrate, in
replacement barriers, to vital structures
and to a company’s reputation.
When is a Barrier
Not a Barrier?
By Matt Callard, A-Safe UK
But there is another important factor
about this barrier. It was in position
only because the company that
installed it knew – from research and
development, from exhaustive testing,
from independent verification – that
the barrier would withstand whatever
impacts occurred. Because what use
is a barrier, unless those who are
employing it are absolutely certain that
it will be fit-for-purpose?
Across the industrial environment
steel barriers are being replaced by
flexible, polymer-based barriers. They
offer strength, force absorption, cost
savings and the company that employs
them should have in-depth, up-to-date
scientific knowledge of the impact
forces, loads, angles, weights and
speeds of every workplace vehicle.
The answer to the question at the top
of this page is clear. A barrier is not
a barrier when it fails after impact or,
to use a technical term, is unable to
‘arrest’ its ‘striker’. So beware of things
calling themselves barriers when it is
clear they are not.
26
Logistics Business Magazine | September 2015
WAREHOUSE SAFETY