SNOW CONTROL/ITD adds chemical treatments to anti-icing work
The Idaho Transportation Department (ITD) sees all kinds of winter weather, from blizzards to mild frost to solid black ice. From November to March each year, the temperature rarely climbs above 34 degrees Fahrenheit, leaving little opportunity for ice to melt on its own.
The department has approximately 70 employees who perform snow control work on 605 miles of roadway. Their efforts keep safe travel possible, according to Bob Ewing, district maintenance engineer for ITD. “I’ve lived here for 28 years, and we’ve never closed a road for weather,” he says.
Years ago, during snow and ice events, crews often had to work 24 hours a day, seven days a week to plow roads and dispense gravel. “There are some roads where trucks just went back and forth all day,” Ewing says.
In the last few years, ITD has reorganized its snow and ice control methods to minimize problems in winter weather. Ewing characterizes the department’s methods as preventive anti-icing rather than de-icing.
Ewing starts by monitoring the weather. Crews subscribe to several weather services to get predictions and current weather data. When ice and snow accumulation seem likely, crews hit the streets to apply FreezGard, a liquid magnesium chloride product manufactured by IMC Salt, Bannockburn, Ill. Like sodium chloride (salt), the magnesium chloride melts ice quickly.
ITD applies the chemical prior to an ice storm so that ice melts as it lands, rather than spreading the chemical on top of accumulated snow and ice. Magnesium chloride freezes at about -25 degrees Fahrenheit, so putting the liquid magnesium chloride on top of ice makes the liquid likely to freeze instead of melting the existing ice. “There were a few times we applied it when we shouldn’t have,” Ewing says. “It created a real skating rink.”
Crews combine the chemical application with gravel spreading to further enhance the roads’ drivability. Magnesium chloride typically will last for a few days before re-application is necessary, Ewing says.
As traffic has increased on several routes, ITD’s efficiency has kept roads safe, even in the worst weather. By adding new techniques and more organization to its snow control work, Idaho is able to survive each winter with minimal disruption to residents.