Protected by Snow Fences, Idaho Road Stays Open to Traffic
Snow fences ensure clear pavement and good visibility on State Highway 37.
The Challenge
When winter storms strike southeastern Idaho, they can cause road closures and dangerous travel conditions. Although snow accumulations rarely exceed 460 mm (18 in), the region of wide valleys, rolling hills, and farmland is whipped by winds of up to 97 km/h (60 mi/h) that can reduce visibility to zero in minutes and quickly form snow drifts across roads. This blowing, drifting snow forced the Idaho Transportation Department (ITD) to close State Highway 37 between American Falls and Rockland three or four times every winter.
The department knew that snow fences would solve the problems of drifting and blowing snow on Highway 37. But local farmers were concerned that the snow fences, which often must be placed on farmland, would interfere with planting and harvesting crops.
The solution was portable snow fences. These lightweight plastic snow fences, evaluated under the Strategic Highway Research Program (SHRP), keep blowing snow from drifting onto Highway 37 and are easy to remove before spring planting begins or previously planted fall grain could be damaged.
Putting the Snow Fences to the Test
Each winter since 1994, the ITD has deployed snow fences along a 6.5-km (4-mi) stretch of Highway 37 that is often closed by drifts. "There's a bad area where the highway curves up and around and down the hill and into a little valley," says Brian Mansfield, maintenance foreman with ITD. "In this area we place 3,000 ft [915 m] of snow fence at distances of between 100 and 250 ft [30 and 76 m] from the roadway." The 1.5-m and 1.8-m (5-ft and 6-ft) tall fences are installed in 30 m to 90 m (100 ft to 300 ft) sections to best capture the snow.
Setting up and removing the snow fences is quick and easy. It takes six crew members just 2 days to install the fences and 1.5 days to remove them.
The snow fences proved their value during the winter of 1995-1996. Mansfield says the snow that collected behind the fences would have closed the road several times. "Highway 37 is the only route between American Falls and Rockland, so a road closure is serious business, since this is a school bus, mail, and commercial route."
Keeping the road open saves time for ITD crews. It can take 8 to 10 hours to reopen the road. Mansfield estimates that the snow fences saved the ITD 40 to 60 hours of maintenance crew time during the winter of 1995-1996. He adds, "Most of that time is at overtime rates."
Because State Highway 37 is now rarely closed by drifts, ITD crews can focus their efforts on high-priority roads like the nearby Interstate 86. "Snow fences are a very economical way to buy us some time when we get a bad storm or high winds," says Dee Greene, maintenance engineer for the ITD.
The snow fences also improve safety. "An important benefit of the fences is that they make visibility a lot better by actually helping to break the ground blizzards," Greene says. "The increased visibility creates much safer driving conditions."
The highway agency is eager to use more snow fences in the future. Says Mansfield, "I've got another 3,000 ft [915 m] of portable fence that I'm anxious to use in another area as soon as we get permission from local farmers."
The Benefits
Snow fences offer several important benefits. The fences
- Keep roads clear.
- Improve visibility.
- Save money on overtime for plow crews.
- Allow crews to spend more time keeping high-traffic roads open.
