I am a doctor in the Children's Hospital in Manchester, United Kingdom.
Among other things, I deal with children who injure themselves falling
from heights on to indoor floors. Parents, lawyers and other doctors
often ask me whether injuries are more likely when children fall onto
hard floors such as concrete rather than softer ones such as carpeted
floors. I am trying to find someone who knows how to measure the
hardness of floors. Can anyone help me? Brennan
Common sense will tell you that someone falling onto a concrete floor will
more likely sustain an impact injury that some falling onto a heavily
If you insist on having test data, then I think that a local testing
laboratory might be able to devise some sort of impact test. Or you could
devise you own test. Perhaps you could use hard boiled eggs dropped from
various heights onto various surface types. Of course, the eggs will crack
differently depending on whether or not they impact on the side or on the
ends. Eggs are stronger when dropped on their ends.
Obviously with children, the damage inflicted in a fall will depend on how
they land as well. Land on their bottom and almost no damage -- land on
their head and there is potential for serious damage.
Bob Morrison, PE, SE
R L Morrison Engineering Co
As Bob Morrison points out, the actual hardness of the floor is only
one variable, and probably not the most significant one at that in the
severity of injury.
It is not at all difficult to ascertain the actual hardness of a
flooring material itself such as wood, tile or concrete. That
measurement, however, isn't feasible for soft or resilient materials
such as carpet or even the cushioned vinyls, say.
What is really significant is more nearly described as the elasticity,
but again as Bob points out, it only is common sense that a poured
concrete floor has the ability to impart more damage for a specific
fall height, attitude, etc., than a carpeted one.
I really see little point in the question other than the obvious one --
litigation. Can you explain in more detail what your end result of the
question is intended to be? That might provide futher insight on how
one might investigate the issue. I would think the best data, however,
would be empirical observation of reported accidents supported by
decent forensic examination of the accident site and reconstruction of
the accident itself to generate the parameters thereof. I would be
surprised if the medical literature doesn't have at least something
along these lines already.
Hardness is not the term you should be focussing on. Hardness typically
refers to the ability to resist scratching (e.g. diamond harder than
glass). You might look instead into shock absorption - flooring. Or how
about keep it simple. Drop a basketball onto different surfaces ...
concrete, carpet with underpad, ... or ... "this is your head on
concrete, this is your head on carpet." ... and leave it at that :-)
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