Snow and Ice Control: The New Generation
New methods to prevent snow and ice accumulation are making Iowa's roads safer for motorists.
The Challenge
Keeping Iowa's roadway surfaces safe in winter often depends on the proper use and application of chemicals to prevent ice from forming and bonding to the pavement. The Iowa Department of Transportation (DOT) sought guidance on how to use anti-icing techniques to achieve optimum performance with a minimum amount of chemicals.
Developing a Strategy
Iowa DOT decided to participate in an FHWA extension of a Strategic Highway Research Program (SHRP) anti-icing test designed to reduce snow and ice bonding by applying a sodium chloride brine to the roadway before it starts to snow.
Putting the Strategy to the Test
The anti-icing test was conducted on Interstate 35 near Des Moines during the winters of 1993-94 and 1994-95.
What They Learned
During bad weather the anti-icing technique allowed snow crews to maintain the test lanes of the highway in "reasonable" driving condition even when the control lanes became entirely covered with ice. Following storms, crews clearing the control lanes usually found the test lanes already clean and dry.
Based on the test results, "we are adding brine to our sand/salt mixtures this year on the interstate system," said Cy Quick, resident maintenance engineer for Iowa DOT. "If a favorable result is demonstrated and funding allows, the prewetting could be extended to primary highways."
Conventional sand and salt spinners are being fitted with prewetting equipment to allow the brine to be applied directly to the salt and sand mixture during discharge.
The Benefits
The anti-icing method improved safety for motorists because of better road conditions. It also provided Iowa DOT the following cost savings:
- Fewer snowplow trips were made. The anti-icing truck only had to make one trip for every three trips made by the larger conventional snow-removal truck.
- Crews experienced less wear on equipment due to fewer snowplow runs.
- Less time was spent clearing roads. Crews were able to complete snow removal on roads that received anti-icing treatment 3 hours sooner than on conventionally treated roads.
- Fewer chemicals were needed by applying the treatment prior to snowfall.
