this storm. There was little damage to high-voltage transmission lines and communication towers
in northern New England. However, lower-voltage transmission lines in narrow right-of-ways,
distribution lines, and service drops vulnerable to damage from broken branches and trees took a
beating. As has long been recognized, the level of damage to these structures from trees could be
reduced by expert and frequent tree trimming and the removal of danger trees adjacent to the
right-of ways.
Severe ice storms are not confined to this part of the country. A widespread ice storm in the
Southeast in February 1994 caused month-long power outages in Mississippi and brought down
more than 16 communication towers. Back-to-back storms in Iowa in 1990 and 1991, the second
followed by cold temperatures and high winds, caused cascade failures of hundreds of miles of
transmission lines. Although some utilities design their major transmission lines for a heavy ice
load, they are required to design only for the loads specified by NESC. The completion of the ice
load and concurrent wind speed map proposed for ASCE 7-98 would provide 50-year return-period
loads from freezing rain for the entire country to use in the design of ice-sensitive structures.
When ice-sensitive structures, including communication towers and power transmission
lines, fail in an ice storm, it is often assumed that the ice load on the structure was greater than
the load it was designed for. The obvious simplistic solution is then to design for a larger ice
load. However, the collapse may have been initiated by a single component failing, perhaps
because of previous damage or deterioration. When that component fails, the transfer of the load
it was carrying, including the ice load and the wind load on the ice-covered structure, may over-
load other parts of the structure, which then may fail under a load they were not designed for.
Attributing this kind of failure to the ice load, and then concluding that it is necessary to design
for more ice, does not address the real problem. For tower and transmission line engineers to
better design structures to withstand the loads imposed by these severe storms, they must not
only determine how much ice accreted on structures in a damaging ice storm, they must also
determine what initiated the failure in the structures that collapsed.
9. ACKNOWLEDGMENTS
We obtained information on the ice storm and ice-storm damage to trees and the power and
communications infrastructure from conversations with many people across all three states in the
Region 1 disaster declaration, as well as in New York and Canada. We thank David Duplissis
(CellularOne); David Klumb and Dusty Kelley (United States Cellular); Bob Picard (Atlantic
Cellular); Mark Osborne (WBFB-FM); George Crouse (Northern Communications); Scott Fybush
(North East Radio Watch); John Erichsen (PiRod); Verle Miller (Rohn); Bill Uphoff (World
Tower Co.); Robert Parker and Derek Chase (U.S. Coast Guard); Stan Manning and Andy Arm-
strong (WKZS-FM); Martha Dudman (WEZQ-FM); Russ Dumont (WCDQ-FM); James Corbin
(WWNY-TV); Don Darling (Maine Department of Environmental Protection); staff at the Mount
Washington Observatory; Bill Duffy (Geomantics); David Plante, Reggie Lang, Teri Beaulieu,
Kevin Cote, Douglas McDonald, and Karen Mackey (Public Service of New Hampshire); Betty
O'Neil, Tom McDermott, Stephen Jeffery, John Knott, and Bud Upmal (FEMA); Tom Bragg
(Central Maine Power); Larry Billings, Ken Miller, Dean Dennis, Jeff Fenn, and George Baker
(Bangor Hydro); John Jensenius and Steve Hogan (National Weather Service); Art DeGaetano
(Northeastern Regional Climate Center); MSgt. Shook and TSgt. Burke (Air Force Combat Cli-
matology Center); John Farr, Royce Benedict, and Wayne Paschal (Berlin Fish Hatchery); Jack
Crowther and Doug Best (Central Vermont Public Service); Richard Holmes (Granite State Elec-
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