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Safe at all costs? [Was: stainless steel cable]

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If a designer can make things safer they should do so; it may not cure
everything, but it can help. And if it can help even a little it's worth it.

This is a common point of discussion around our lunch table
here.  The discussion often comes to the following, obviously
extreme, example:

* Given that severe earthquakes are low annual likelihood

* Given that people can be seriously injured and/or killed in
  severe earthquakes;

* Assuming that we should provide incremental safety (if possible)
  at any cost;

* Therefore, we should design and construct housing to resist the
  largest conceivable earthquake -- using the best possible
  materials -- regardless of the cost.

This line of thinking emphasizes to me (at least) that there
has to be some reasonable limit on the marginal return for
increased design/fabrication/distribution costs.  If the house
becomes too expensive for people to live in, it really doesn't
matter how safe it is, does it?  It's empty, and so are all the
ones in the development.  Where is the tipping point?

Personally, I tend to favor balancing cost with benefit, and
I also favor distributed responsibility.  Yes, I agree that
needlessly dangerous equipment and knowingly underdesigned
structures are problems.  However, a combine harvester should
not be expected to be "kid safe", even to the same extent as an
outdoor playground; possibly not even to the same extent as a
busy street corner.

If there are exposed shafts on which loose clothing can catch,
they should either be enclosed (ideal, if practical), guarded
with partial obstructions like grillwork (if practical), or users
should be trained to avoid these areas and wear close-fitting
garments the way those of use using machine shops are.  However,
if someone permits their kid to walk around the business end of
an operating harvester, it is not surprising to me that the kid
is injured or killed by the cutter heads.

Is it reasonable or beneficial to hold the manufacturer/designer
responsible?  It is if the system was knowingly designed without
safety features that could have been added at a cost which would
not make the overall cost of the device prohibitive.  However, if
adding a kid-safe grate to the harvester increases the cost 100%,
is it worth it?

To some, it probably is.  If it was my kid getting yanked into the
cutters, you better believe it would be worth every penny and more
to me.  Is it my place to tell someone else how much safety to
provide for their kids?  I'm not really comfortable with that,
unless that's what they hired me to do (e.g. design engineer), and
even then I tend to offer alternatives that all meet or exceed a
"gut check" minimum safety level and let the customer pick and choose
according to their needs, risk aversion, etc.

My parents used a "kid leash" when we were out in public, which
I am sure has fallen out of fashion in the last 25 years (since
I was little).  I got into a lot of trouble despite that precaution.
I saw my dad cleaning window screens, leaned out and opened one to
"help", and dropped headfirst onto the ground.  Split my skull wide
open and made a real mess, but I haven't leaned out a window since
without a *good* handhold or a belt clip.

Potentially fatal?  More than likely.  I missed the concrete walk
by probably 3-4 inches when I hit.  However, I lived through it
and learned something.  I suspect, although it is an unpopular
opinion, that routine risk increases the likelihood of long-term
survival in humans.  I'm not advocating base jumping.  However,
I think that enclosing everyone in a bubble is unlikely to
provide desirable operating conditions.  Somewhere in between is
(probably) a good balance.  I'll probably use a kid leash (if I
can find one) for my kids.

Just my opinion, and worth every penny paid for it.  ;-)


Charles Hamilton, PhD EIT               PGR and Lecturer
Department of Civil and                 Phone: 949.824.3752
    Environmental Engineering           FAX:   949.824.2117
University of California, Irvine        Email: chamilto(--nospam--at)

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