Extract
- AS/NZ 4422:1996 - "Forward" as 12 June
2007
In industrial safety, there is a recognized hierarchy
of hazard control measures, based on the principle
that hazards should be removed by `engineering out',
and that personal protective equipment is a last line
of defence. Playgrounds present a different situation.
Ideally, playgrounds should encourage development
of gross and fine motor skills, and also present a
stimulating play environment which presents children
with manageable challenges, through which children
can find and test their limits. In order to provide
these challenges, a balance must be found between
risk and safety.
A playground injury which leaves a child with a permanent
disability is not acceptable. Playground designers
must take every possible care to identify and eliminate
unacceptable playground risks and reduce hazards.
However it should also be understood that children
often lose interest in equipment which does not challenge
them, and that children will experience minor injuries
as they grow and learn, in playgrounds and away from
them. (Materials such as sand and water which a child
can manipulate and interact with maintain a child's
interest because they provide a continuing challenge.)
Although there continue to be differing interpretations
of the statistics on playground related injuries,
it is true to say that unless climbable items of play
equipment are entirely enclosed, children will continue
to fall from them. Over the last few years in Australia
and New Zealand there has been an increased interest
in the use of soft surfacing underneath and around
playground equipment. This surfacing is variously
known as soft fall, soft surfacing and undersurfacing.
The need for, and usefulness of, such undersurfacing
has been vigorously debated during that time and there
is now widespread agreement that adequate undersurfacing
is required underneath and around all playground equipment
from which a user might fall, in order to reduce the
effects of those falls. As equipment height increases,
additional protection is required, and should be provided
by increased use of other protective measures such
as platform guardrailing and infill, or even enclosure.
This Standard gives a method for determining a head
injury criteria (HIC) value, which is a calculation
of the severity of a deceleration impact on the brain.
In this Standard, acceptable materials and depths
for undersurfacing, and a guide to allowable fall
heights from equipment onto such undersurfacing, can
be determined by reference to HIC and gmax
values. The HIC and gmax values
set in this Standard are those which, if exceeded,
are likely to result in injury to the brain.
Possible brain injury has been used as the criteria
for several reasons. It is likely to be the worst-case
outcome for a fall, as the effect may be permanent,
and serious. A broken bone, however painful and distressing
it might be to the sufferer, is likely to heal without
long term ill-effect. Also, there are recognized methods
for calculating the effects 'of deceleration on the
brain, but not for predicting the likelihood of bone
breakage. Fall height and the impact energy attenuating
characteristics of the undersurfacing correlate with
the likelihood of brain injury, but they do not seem
to be the determining factors for long bone injuries.
A person can stand on the ground, trip and break a
bone, or fall from a great height and suffer no break.
For many, the possibility of a broken bone is an unacceptable
risk and it would certainly be preferable to eliminate
long bone injuries resulting from playground accidents.
Should a reliable means of predicting the likelihood
of long bone injuries become available, the requirements
of this Standard will be revised to take it into account.
Every effort should be made by playground designers
to ensure that the playground and the equipment in
it are as safe as possible, but it will not always
be possible to provide managed challenge and also
ensure that all injuries are prevented. However, adequate
undersurfacing will minimize the incidence and severity
of head injury, and will also reduce the occurrence
of long bone injury.
