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[TowerTalk] Wind 3 Second Gust Speeds

Subject: [TowerTalk] Wind 3 Second Gust Speeds
Date: Wed, 20 Sep 2006 13:38:06 EDT
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I am sure this has been discussed before but I am a newbie to the TowerTalk 

In applying for a building permit with my city, they told me "it needs to be 
rated for 90 MPH with 1/2 inch radial ice".  I asked him what standard he was 
referring to and he referred me to the latest IBC Section 3108.4.  This spec , 
in turn, refers to EIA/TIA 222-E.  EIA/TIA 222 g has a windload map that that 
, indeed, confirms the 90 mph requirement.  However, if I am reading it 
correctly, it is referring to 3 second gust speed.  It, in turn, includes a 
for converting 3 second gust speed to  "Fastest-Mile (MPH) Speed.  The chart 
indicates that 90 mph (3 second gust) corresponds to 75 MPH "fastest-MPH speed".

Setting aside for a minute the radial ice issue, does this mean that that the 
70 MPH rating I get from a tower manufacturer like US Tower really 
corresponds the higher 3 second gust speed rating as required by the 

Or is this just wishful thinking?

Al, K0AD
Plymouth, MN

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