At 04:39 AM 6/27/2007, Bill Winkis wrote:
>This information is all well and good ... it rings with a bell of
>caution ... BUT , how do you know .. ????
>In this case the climber felt all was well until the tower came down
>with him on it .. but now how in the world do you test and determine
>all is OK before you climb.?? Or what steps do you use to protect
>your self ...
>Certainly the professional tower people who partake in this forum
>will have a degree of in site for us .. but it needs to be
>discussed.!!! We've got guys here with 5-10-20 plus years old towers
>....What is the answer??
Someone who climbs towers for a living and does it everyday will
probably have a lot of subconscious insight into the potential
problems or condition when they actually see and feel the tower.
(viz. the book "Blink"). However, they won't necessarily be able to
articulate why it's safe or not, or be able to give you a set of
objective measurements.
Pros also get hurt too. They just don't get hurt by the "stupid"
things, so their overall injury rate is lower (but still high enough
that I'll bet workmens comp costs a LOT.. and even so, most of the
injuries are going to be the common sort of stretch,strain, drop
sorts of things.. picking up something wrong, twisted ankles and the
like)(just looked it up... about $30 per $100 of payroll)
A pro is also more likely to go the bucket truck or crane route..
You're already paying a fairly hefty hourly wage, insurance, etc, so
it's easy to make the cost/benefit analysis in favor of the crane or
truck. A ham is less likely to do so, because their "time is free".
And, finally, all towers "can" collapse. The failure mode would
likely be buckling, and I'd venture that even if you had a lot of
vertical load on it normally, the activities involved in erecting or
dismantling put a lot of sideways or unusual loads on it. Hanging
things off a haul line out to the side, tramming things up and down
the guys, etc.. Something which has been corroded or weakened, but
not necessarily visibly, might take a substantial load along the
axis, and even the windloads from the antenna turned into downforce
by the guy action, but still fail when loaded in a different
way. And, there's always the "small dents and bends from stuff being
lowered" problem. It's like the party trick of standing on the empty
beer can and touching it to get it to collapse on itself. (See, there
*is* a good engineering education reason to drink beer at parties!)
Jim, W6RMK
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