Aggressive avalanche program reduces highway closures
ITD is taking an aggressive approach to prevent snow accumulations from cascading down steep hillsides and rolling across Idaho highways. Avalanche mitigation efforts last year significantly reduced the number of closure days on Idaho 21 and the Banks-Lowman highway.
Region 2 Engineer Tom Points summarized District 3’s efforts to reduce the avalanche threat for members of the Idaho Transportation Board when they met last week in Boise. Among the most vulnerable areas on Idaho 21 is the stretch near Canyon Creek.
The area, between Lowman and Stanley (from milepost 96 to 105), is considered to be one of the most active avalanche areas because of the 54 chutes that converge on the highway.
The transportation board approved an avalanche mitigation program for the area in 2005.
Safety is the highest priority, Points explained. Some of the safety measures ITD introduced include:
Locked gates for risk management
Employee training on winter survival and explosives use, transport, and storage; and
Restricted ITD employee access
Everyone working in the canyon is required to wear an avalanche beacon that helps searchers locate individuals if they are caught in an avalanche.
Last year, ITD received a permit to begin using explosives to trigger avalanches in a controlled manner. Initiating avalanches reduces road closures and improves highway safety.
A combination of forecasting and control work in the canyon resulted in the highway being closed 30 1/2 days last year, which is about half of the yearly average and is the goal of the avalanche program. This is especially significant because of the above-average snowfall in 2007-2008, which was responsible for more than 50 avalanches in the Canyon Creek area. With the decrease of road closures last season, the traffic volume increased on the highway by an average of 12.4 percent
Idaho 21 isn’t the only area to benefit from ITD’s growing expertise with avalanche control. ITD personnel and equipment were also used to assist in avalanche mitigation efforts in northern and eastern Idaho.
See Tom Points’ PowerPoint presentation