Synthesis of Information on Anti-icing and Pre-wetting for Winter Highway Maintenance Practices in North America: Final Report
This report obtained information from literature reviews, agency surveys and phone interviews on the advantages and disadvantages of anti-icing and pre-wetting for winter highway maintenance. Anti-icing is considered a proactive approach in areas where liquid chemicals could be applied early enough (prior to precipitation) to prevent snow or ice from bonding on roadway surfaces. Pre-wetting is typically used as a reactive measure to improve conditions on roadways already covered in snow and ice. In these areas roadway surfaces were treated with pre-wet solid salts and abrasives to enhance ice melting, and reduced the tendency of dry materials to scatter and bounce off roadways.
The research reveals that compared to traditional winter weather maintenance strategies, anti-icing and pre-wetting techniques lead to improved pavement conditions, decreased use of chemical products and abrasives, decreased maintenance costs, lower accident rates. The goals for transportation agencies to utilize proactive winter maintenance solutions include maximizing traveler safety, improving levels of service, mitigating environmental concerns, improving public relations, and identifying cost savings.
The methodology consisted of literature searches and a questionnaire sent to maintenance professionals in 18 states and 2 Canadian provinces. Those that responded to the questionnaire received a follow up interview. The questionnaire explored the state-of-the-practice for winter highway maintenance and documented the advantages and disadvantages of anti-icing and pre-wetting strategies. Many maintenance managers surveyed indicated that the best approach to winter maintenance is to utilize a combination of all tools available. Results are based on the opinions of those interviewed and the statistics they provided.
Colorado DOT saw an overall reduction in costs of 52 percent for freezing rain events. They also reported a 55 percent decrease in use of sand and a reduction in costs of about 50 percent per lane mile for all winter operations.
Oregon saw a cost savings of 75 percent for freezing rain events.
On U.S. 12 in Idaho, in the years following the deployment of anti-icing strategies, the number of crashes was 83 percent lower than before implementation. In addition, labor costs were reduced by 62 percent.
In Montana, anti-icing the Plains section of State Route 200 resulted in a 37 percent reduction in costs per lane mile.