Winter Maintenance Virtual Clearinghouse: Technical Briefs
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Snow and Ice Control
More Efficient Winter Operations
Snow, sleet, and freezing rain can create treacherous driving conditions. To keep roads clear and safe for travel, highway agencies spend more than $2 billion every year on winter maintenance. Conventional winter maintenance operations involve deicing techniques—that is, sending plows and trucks loaded with salt and other materials to clear the roadways after a storm has begun. Although effective, this strategy is costly and labor intensive, and can cause unnecessary harm to the environment.
Now there is a better way. The Strategic Highway Research Program (SHRP) found that by switching from traditional deicing techniques to an anti-icing strategy coupled with a road weather information system (RWIS), highway agencies can
- Slash their winter maintenance costs.
- Improve travel conditions.
- Help protect the environment.
SHRP also evaluated the snow fence, a simple technique more than 100 years old, and found it effective at preventing blowing and drifting snow from closing roads and reducing visibility.
Timing is Everything
An anti-icing strategy involves applying salt or other chemicals that lower the freezing point of water to the pavement before a storm hits. When sleet, freezing rain, or snow begins to fall, the freezing-point depressant will prevent ice from forming on the pavement. Instead of freezing over, the pavement stays wet or slushy—which means travel is safer and clean-up is easier.
Anti-icing technologies have been around for a while, but they have not been extensively used because highway agencies lacked the means to collect and analyze information telling them precisely when and where chemicals should be applied. That’s where the RWIS comes in.
An RWIS consists of a network of monitoring stations located along primary roads and at potential trouble spots, such as bridges. At each RWIS station, sensors collect data on
- pavement and atmospheric conditions, including temperature;
- the rate of falling snow, rain, or sleet; and
- the amount of chemicals remaining on the pavement from previous applications.
These measurements are transmitted to a central computer, where they are combined with meteorological information from the National Weather Service and with other, more localized forecasts. The information is then used to predict when and where precipitation is likely to freeze to the pavement and when and where crews should be sent.
An RWIS allows highway agencies to make more informed decisions about where and when to deploy materials, crews, and equipment. Not only does this help the highway agency stay ahead of the storm, but it also means less unnecessary crew standby time, which cuts overtime costs. Salt and other chemicals are more judiciously applied, which means less chemical runoff into streams and wetlands and onto farmland.
Many States are already using anti-icing strategies. Nevada, for example, has found that maintenance efforts are more effective and staff and equipment requirements are reduced with RWIS and anti-icing strategies. Nevada expects its expanding RWIS system to
- Provide motorists and shippers with safer, more reliable travel conditions.
- Save $7 million in labor, materials, and other costs over the next 25 years.
- Protect the environment by reducing the amount of chemicals and abrasives used.
In Colorado, an anti-icing/RWIS strategy is helping to improve air quality. Sand and other abrasives applied to pavements are responsible for about 20 percent of Denver’s persistent winter air quality problems. Anti-icing strategies are reducing sand use without sacrificing safe travel conditions.
Keeping the Snow at Bay
Snow fences work by trapping blowing snow, keeping it from piling up or drifting across roadways. In southeastern Idaho, for example, snow fences strategically placed along Highway 37 keep the road open even in severe winds. "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," says Brian Mansfield of the Idaho Transportation Department. Before the highway agency placed snow fences along the roadway, blowing snow forced the road to be closed several times every winter, and each closure required 8 to 10 hours of labor and equipment time to clear.
Saving Money, Time, and Materials
A recent economic study by the Texas Transportation Institute (TTI)* found that the SHRP winter maintenance technologies could save millions of dollars. According to TTI, if highway agencies adopt anti-icing strategies and RWIS, they could cut winter maintenance costs by $55 million to $108 million annually, depending on how quickly they implement the technologies. Because travel conditions would be safer, motorists could save $229 million to $447 million annually in user costs.
* Created in 1950 as the research arm of the Texas Department of Transportation, the Texas Transportation Institute (TTI) has since become the largest university-based transportation research organization in the United States.