Wednesday, March 14, 2007

Clearing up questions about clearing roads

Devin Rigby is district engineer for District 4 of the Idaho Transportation Department, located in Shoshone. District 4 covers south central Idaho, which consists of 10 counties. Winter maintenance crews are made up of 53 10-wheeler trucks and approximately seven smaller trucks.


As a district engineer for the Idaho Transportation Department, I answer a variety of questions from funding of projects to common road maintenance. Over the past few months, I have been asked numerous questions about the department's use of salt and chemical deicers as part of our winter maintenance in the Wood River Valley (on state Highway 75).

Many valley citizens have voiced their concern about what impacts the use of these safety tools have on the environment and their vehicles. I would like to talk about our current deicing program and then answer questions.

In the past, we used magnesium chloride along with salt and sand as our ice fighting tools. We currently use a mixture of salt and sand along with a calcium chloride liquid deicer.

One suggestion that we hear is: "Why not just use straight sand?" Sand provides maximum results when used in combination with salt and/or a liquid deicer. Sand can be crushed by traffic and easily blown off the road with out a chemical to adhere it to the ice or snow. Without chemicals, repeated applications are required and produce airborne dust contributing to pollution. Sand also commonly contains sizeable pieces of gravel that can crack windshields and chip vehicle paint.

We have found that a liquid deicer such as calcium chloride is one of the best weapons against icy roads and is used in three ways:

· Anti-icing: A light application of the liquid is made to a road before a storm to prevent a hard bond of ice, reduce snow buildup and speed snow and ice breakup after the storm.

· Deicing: The liquid is applied to remove a thin layer of snowpack or ice already on the road. It can be very effective in melting black ice and freezing rain.

· Pre-wetting: Wetting traditional sanding material with calcium chloride causes sand to stick to snowpack better.

One issue that has been raised is the possible impacts of a chemical deicer such as calcium chloride on the environment and a motorist's vehicle. Tests have shown that the proper application of chemical deicers produces no negative effects on groundwater, surface water or vegetation.

ITD continuously monitors and tests any possible effects and the department constantly looks for improved forms of chemical deicers. In the last few years, Idaho has worked with Montana, Washington, Oregon and British Columbia to develop better standards for deicers. The goal among these four regions is to use a deicer that is appropriate for our environment and less corrosive than other alternatives.

I encourage motorists who regularly drive state highways where calcium chloride has been used to regularly wash their cars, especially the undercarriage. Over time, deicers (along with slush and dirt from the roads) can splash onto your car and build up, leaving a filmy residue on your car. Make car-washing part of your regular maintenance routine.

I recently attended the monthly meeting of the Blaine County Transportation Committee, where several members expressed their support and appreciation with ITD's current methods in clearing the winter roads. They applaud our efforts in preventing accidents, maintaining the flow of traffic and providing essential mobility for all valley emergency services.

ITD is committed to providing timely and environmentally sensitive winter maintenance programs, keeping Wood River Valley motorists safe and insuring their mobility even in the worst of winter storms.

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