Thursday, January 4, 2001
Steamboat Springs State snowplow crews in Steamboat Springs are learning to put a new tool to use in the battle to keep U.S. 40 free of ice. And the city of Steamboat Springs is watching closely to see if it can adapt the new technique to the icy intersections of city streets.
Traditionally, the Colorado Department of Transportation has used a mixture of sand and salt to mitigate slippery highway surfaces on U.S. 40. The city's primary means of making its 63 miles of roads safe in winter, aside from plowing and scraping, is spreading a coarse volcanic gravel known as scoria.
Now, the crew at the Steamboat Springs shop near the intersection of U.S. 40 and County Road 129 is beginning to spread liquid magnesium chloride on U.S. 40, relying heavily on the knowledge gained through years of testing and experimentation by CDOT crews working in Glenwood Canyon on Interstate 70 east of Glenwood Springs.
CDOT's Larry Backes said Wednesday he is eager to work with Steamboat Street Superintendent Doug Marsh to help him determine if he wants to propose a shift to magnesium chloride for the city to the City Council.
"We all still work for the same person we work for you," Backes said.
Magnesium chloride, like sodium chloride (table salt), is technically a kind of salt. But diluted in water and spread as a liquid, it's more effective at anti-icing and de-icing pavement, said Paul McCollum of CDOT's Glenwood office. McCollum and Adam "Mr. Mag" Padilla were here on Wednesday to conduct a training session for local highway maintenance workers, both from CDOT and the city of Steamboat.
The term anti-icing refers to the practice of spreading magnesium chloride on essentially bare pavement in anticipation of an imminent storm, McCollum said. By doing so, highway workers can ensure the new layer of snow never forms a bond with the pavement. Even if traffic gets to the snow before snowplows do, it can easily be removed from the roadway, and ice will never form. De-icing is the term used when magnesium chloride is applied to already existing ice to melt and break it up.
Backes said the Steamboat crews have tested both types of applications.
"We have pre-melted (anti-iced) four times with huge success and de-iced twice with good success," Backes said.
Both techniques are used in Glenwood Canyon, where there are sections of road that never see sunlight during the winter months. Magnesium chloride also has proved beneficial on Glenwood Canyon's many bridges and viaducts, which are more prone to freezing than road sections installed on soil. In Glenwood Canyon, Padilla said his crew used 3,600 gallons of magnesium chloride to anti-ice 18 miles of four-lane highway. That compares to 7,000 tons of sand needed to do the job.
The key to effective use of magnesium chloride, Padilla said, is building up experience in driver/operators.
His crews use up-to-date data about temperature, wind, relative humidity and the dew-point that is fed either to a display in their truck or relayed through dispatchers. The weather information allows them to make informed decisions about the best dispersal rate for magnesium chloride on a given day.
"The dew point is very important," Padilla said. "Anytime the air temperature matches the dew point, you're going to have something falling from the sky rain, sleet or snow."
Crews in Steamboat will have to acquire their own experience on how best to apply the de-icer in town, where heavy snowfalls are more common than in Glenwood Canyon, 100 miles to the south.
CDOT's Steamboat maintenance shed houses a brand new plow truck fitted with twin tanks and a specialized spreader intended for use with magnesium chloride.
The truck is one of a fleet of four kept in the Steamboat shed. It is valued at $85,000. With the tanks and spreader rig added, the total cost is $130,000. Backes said the crews typically put 800,000 miles on the trucks before they are replaced.
Marsh emphasized that no decision has been made to use magnesium chloride on city streets.