From: cohill@vtserf.cc.vt.edu (Andrew M. Cohill)
Newsgroups: comp.human-factors
Subject: Re: Very poor human interface on Kubota tractor
Date: 14 Apr 92 13:28:16 GMT
Organization: Fire in the Mountain

In article <167C8C211.JHARTLEY@cmsa.gmr.com> JHARTLEY@cmsa.gmr.com writes:
>In article <3746@vtserf.cc.vt.edu>
>cohill@vtserf.cc.vt.edu (Andrew M. Cohill) writes:
>>Tractors are dangerous pieces of equipment.  If this worries you, don't
>>use them.
>
>I'd like to nominate this statement for the "Let Them Eat Cake"
>Human Factors award.  Rather than solving the problem, let's
>just tell all users that "tractors are dangerous and all you
>panzies that can't hack that shouldn't be on a tractor!"


Perhaps I was a bit abrupt in my post, but I stand by the sentiment.  As
a user of tractors since my teens, I have lots of experience with them,
and know extremely well how dangerous they are.  Most of the danger
comes from the requirements of the *task*, not because the foot pedals
are in the wrong place or because the brake lever is hard to use.  If
you designed out the dangerous qualities of a tractor you would no
longer have a tractor, you'd have some other piece of equipment that
would not be nearly as useful.

At this point I am reminded of the gentleman who used a rotary mower as
a hedge trimmer, then sued the lawnmower company when his fingers were
severed.

Human factors is about designing a good interface between man and
machine;  if some machines are inherently dangerous, it may not be
possible for even the most highly gifted human factors engineer to
arrange the interface in such a way as to eliminate the possibility of
human error.  Training, in this case, is almost always a prerequisite.

The three or four wheel farm tractor is an excellent example of a system
where training is very important. It's possible to do foolish things on
a tractor when it is standing still, like trying to lift something above
the center of gravity with the front end loader (a very common operator
error).  

One might argue for a warning system that alerts the operator of this
unstable condition, but as most human factors people know (and almost
all farmers) the safety warning systems are often not able to
discriminate between a well-trained operator working at the limits of
the safety margin, and an untrained operator about to fling himself out
of the tractor seat.

In such cases, the alarm system is invariably disconnected because it's
value as a warning is, in the operator's view, worthless.  

Huamn factors work is often thankless, because HF people are often
expected to compensate for poor design--a no-win situation, and then get
blamed for poor system performance by users.  Or in the case of the
tractor, are expected to eliminate all risks associated with a
particular piece of equipment.  

The ordinary kitchen knife is a paradox in this context;  razor sharp,
it is a pleasure to use and actually *reduces* the likelihood of hurting
yourself.  Nonetheless, it is extremely dangerous.  Would it be safer to
use if it was dull?  If it had a retractable sheath that only exposed
the blade when you started to cut with it?  Would the blade-hiding
mechanism clog up with food, frustrating and annoying users?  I think
so.  It would also be unsanitary.

I could go in this vein for quite some time.  Indeed, books have been
written on the subject....

Andrew Cohill

An architect with a human factors background....


-- 
|          ...we have to look for routes of power our teachers never       
|              imagined, or were encouraged to avoid.   T. Pynchon          
|                    
|Andrew Cohill        cohill@vtserf.cc.vt.edu            VPI&SU                                                  
Newsgroups: comp.human-factors