3/12/2008
Reed Hollinshead
ITD Communication
208-334-8881
reed.hollinshead@itd.idaho.gov
Expanded avalanche management program reduces closures of Idaho 21
BOISE - Avalanche-related closures on Idaho 21 have been significantly reduced this winter by using explosives to bring down unstable snow before it slides and blocks the highway, the Idaho Transportation Department (ITD) announced.
The route, one of Idaho's popular winter recreation routes and host to the vast majority of the state's avalanches, is typically closed 60 days per year, but has been closed just 28 days so far this winter through these pre-emptive measures.
"Given the heavy winter we have had this season, this is a positive sign that we will be able to reach our goal of reducing closure days by about half," said ITD lead avalanche forcaster Jon Barker.
Three different methods are primarily used in this first-year program to deliver explosives:
- an avalauncher (a cannon-type device) to deliver explosives into avalanche chutes
- "heliblasting" to drop explosives in avalanche-prone areas by helicopter
- when conditions warrant, ITD avalache mitigation crews ski into areas and set charges by hand
These triggers bring down the snow accumulating in the chutes, reducing avalanche hazards and allowing ITD crews to safely clear snow from the roadway.
ITD received a special-use permit from the U.S. Forest Service to use these measures to reduce the avalanche hazard on Idaho 21 between Grandjean Junction and Banner Summit. The 11-mile Canyon Creek section, part of the Boise National Forest, has 54 avalanche chutes and experiences about 90 percent of the state's avalanches affecting roadways.
The agencies worked together closely to ensure natural resources in this area are protected in the development of a long-term avalanche control program. The department also uses other tools to manage avalanche danger. Information is gathered using technology such as weather stations and snow-density testing to determine when avalanches are likely.
ITD recently purchased an additional weather station to provide the best possible weather-related information for avalanche forecasters.
"Our primary goal is to ensure safety," said ITD Regional Engineer Tom Points. "The expanded program also provides more reliable access to winter recreation areas along this highway and to the community of Stanley."
NOTE TO EDITORS: Video and still photos of avalauncher and heliblasting activities are available from the ITD Office of Communications. Access to the avalanche area is limited to persons who have undergone qualified avalanche safety training.