3
4
3
6
1
1
4
6
1
2
1
2
5
2
5
1
1
6
4
1
2
1
1
3
1
3
2
Tower Height
> 1000 ft.
-1
601 to 1000
-3
301 to 600
-9
< 301
Unknown Height
-1
Figure 3. Icing-related tower failures since 1959. The boldfaced numeral in each state refers to the number of individ-
ual storms that caused the failures in that state.
ness accounts of the collapse itself, such as the date
ties collapsed. The 14 failures that I have confirmed to
and time of day, how the tower fell, how long after fail-
date for that storm are separately identified on the map.
ure before personnel arrived to assess the damage, sus-
Many sources reported that these towers failed under
pected cause of failure or whether a more formal engi-
radial ice thicknesses ranging from 4 to 6 in. Even
neering analysis was done to pinpoint the cause, and
though there was nearly no wind associated with that
the maximum distance outward from the tower base
storm, the damage to trees, powerlines, and crops in
that debris landed.
Mississippi alone was estimated at more than bil-
Figure 4 indicates that there have been several years
lion. The damage to eight of those towers, ranging from
in which major ice storms caused many failures over
172 to 530 ft tall with an average height of 344 ft, to-
talled nearly
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.8 million.
Other geographic and topographic
30
information contained in this database
3