3/17/2016
Reed Hollinshead
ITD Communication
208-334-8881
reed.hollinshead@itd.idaho.gov
REMINDER TO DRIVERS: Moisture in the air, rocks on the road
BOISE - The recent massive landslide near Elk City, and huge rocks that slid down to the road in southwest Idaho near Smiths Ferry and Council since the end of February, are a stark reminder of the dangers posed this time of year. These events demonstrate an increased likelihood of rocks and debris releasing from hillsides each spring, especially for highways bordered closely by steep hillsides or mountains.
Precipitation in the form of snow, rain or even fog with a high moisture content increase the chances of a slide. Moisture saturates these hillsides, loosening the soil.
“Many of Idaho’s highways cut through forests and along steep slopes," said ITD Emergency Program Supervisor Mel Coulter. "In the spring, when soils are saturated, the risk of falling debris is significantly higher. That is especially true in forests that have experienced recent fire or in mountainous terrain that is vulnerable to avalanches.”
The Idaho Transportation Department reminds drivers to plan ahead and check the 5-1-1 traveler advisory system (via phone or web) before heading out, especially to the mountains.
In the event of a slide or rocks on the road, drivers are asked pull onto the shoulder, turn emergency flashers on, and call local law enforcement, the local ITD office or nearest maintenance facility with a location description or milepost. Remain in the vehicle until help arrives.
The landslide west of Elk City carried about 100,000 cubic yards of material down to the highway. The biggest boulder near Smiths Ferry was estimated at 29 tons. While those are staggering numbers, even much smaller debris could derail a motorcyclist or bicyclist.
Last year’s spring was highlighted by a 50-ton boulder coming down the hill on Warm Springs in Boise, and a rockslide on Idaho 97 in northern Idaho that carried an estimated 450 tons of debris.