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Re: [TowerTalk] Mast wind loading

To: Doug Renwick <>,
Subject: Re: [TowerTalk] Mast wind loading
From: Jim Lux <>
Date: Wed, 29 Mar 2006 07:27:26 -0800
List-post: <>
At 03:20 PM 3/28/2006, Doug Renwick wrote:
>You are to be commended for sharing your experiences and I
>agree with your philosophy.  A lot don't share their
>experiences because they get chastised by people who throw
>around words like 'unsafe'.  Have these people ever heard of
>'risk analysis'? much will your tower
>withstand can only be determined by 'product testing to
>destruction'.  If your tower arrangement has survived for 25
>years then IMO you have a safe installation.  Great job!

Well.. there's really two aspects to these kinds of things..

The first is your personal risk acceptance posture.  If a tower or antenna 
failure affects only you,  you get to get decide how strong or rickety you 
want to make things.  In this context, all the manufacturers' 
recommendations, and various and sundry engineering discussions here and 
elsewhere, basically go to make you an "informed risk taker", but 
ultimately, you get to make the decision.

The second aspect, and one that is sadly becoming more important, is the 
increasing regulatory environment, and the assumption of the responsibility 
for failure by others (e.g. a city, your insurance company, etc.)  30 years 
ago, I'll bet nobody ever asked for wet stamped drawings for a amateur 
tower. You went out, dug the hole, put up the tower, and were done with it. 
Certainly, that's what my friends and family did.  These days, though, you 
have to get a building permit, and that might require engineering analyses, 
etc.  Granted, in some cases, this is an attempt to get rid of 
aesthetically offensive towers by burying them in paperwork and attached 
fees for officials to review and comment upon that paperwork.  However, the 
regulatory burden has increased in many, many other areas, aside from 
antennas(see below).   In this application, you're asking someone else to 
take responsibility (i.e. the city that issues the building permit, the 
engineer who signs the plans, the insurance company covering the 
installation).  This naturally leads to a bit more conservatism.  The 
question has changed from "will the antenna and tower probably stay up" to 
"Can you guarantee, with your life's savings, or the city's budget, that 
the antenna and tower will not fall down?"  Remember also, the cost of the 
increased regulation falls on YOU, the consumer, not on the insurance 
company who asks for more analysis (it actually reduces their exposure), 
not on the city (which is now "safer", and has even increased their budget 
with user review fees), so there's a HUGE incentive to ask for analysis and 
demand conservatism.

As a licensed engineer myself, I use a VERY different standard on what I do 
for myself than what I use professionally, and both are different than what 
I might advise my friends to do over the lunch table.  And, even in my 
professional life, the level of analysis and margins might depend on a risk 
analysis and an acceptance of potential failure consequences.

(on regulatory burden increases) It's not all due to "blood sucking, bottom 
feeding plaintiff lawyers", as much as some would like to believe it.  I 
think it's more due to a "tragedy of the commons" type situation, where the 
lack of regulation prompts a few people to really push the limits (in the 
interest of improving their financial bottom line), leading to an egregious 
event, followed by calls that "something MUST be done to prevent this 
horrible thing from ever happening again".  I'd say it's more a function of 
the emphasis on monetizing everything, and being a "good citizen" costs 
money, reducing the bottom line.  I'd (cynically) blame the B-schools for 
encouraging analysis in terms of cost/benefit with all aspects reduced to 
some dollar value, that can then be tradedoff. 


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