Evaluating the Effectiveness of Winter Chemicals on Reducing Crashes in Idaho
Started: April, 2011 Ended: May, 2014 Project ID #4W3544 Status: Completed
Results & Findings
This research was performed for the Idaho Transportation Department (ITD) to investigate the safety issues involved with winter maintenance and to identify the most cost-effective and environmentally sound ways of using winter chemicals. The results are summarized in detail in the final report. Through lab testing, it was determined that the performance difference between salt brines and solid salts was insignificant, but brines posed less risk to vehicles, infrastructure and the natural environment. The use of sand without salt should be avoided in highway winter operations, especially in light of its low cost-effectiveness and risks to air quality and water quality. Brines, solid salts, and sand-salt mixtures are best suitable for different application scenarios. Different benefit-cost analysis was performed using the estimates of reduced crashes through chemical use. Based on this analysis, it was determined that in most cases, the use of chemicals produced greater benefits than costs. Comparisons of the annual costs per lane mile found that sand and sand-salt mixtures were the lowest cost materials available to ITD. The use of salt as a treatment material was comparable in terms of costs to sand and sand-salt, making that material an attractive option. Similarly, salt brines compared favorably in terms of costs, with only a slightly higher expense than granular salt. Magnesium chloride brines were the most expensive treatment material, which underscores the importance of using such a material in more specific applications and locations.
The goal of this research project is to evaluate winter chemicals and provide guidance on the most appropriate winter maintenance strategies to apply under specific roadway and climatic conditions within the Idaho Transportation Department districts. The research will evaluate the effectiveness of different winter chemicals on reducing crashes in Idaho.
Snow and ice control plays an important role in assuring the safety of winter driving. The United States spends $2.3 billion annually to keep roads clear of snow and ice; in Canada, more than $1 billion is spent annually on winter maintenance. Roadway maintenance agencies relied on abrasives (sanding material) in winter maintenance until the use of chemicals for deicing and, more recently, anti-icing strategies gained widespread acceptance. The Idaho Transportation Department (ITD) has been researching winter chemicals since the mid-1990s, and has supplemented traditional methods (snowplowing and sanding) with deicers and anti-icers based on the results of their work. The winter maintenance chemicals most commonly used by ITD are magnesium chloride, calcium chloride, and sodium chloride, sometimes coupled with a corrosion inhibitor additive. As noted by ITD, different chemicals have different performance levels, costs, and best conditions for use. Currently, there is little research regarding the effects of winter maintenance practices on roadway safety, partly because of the cross-cutting nature of the problem and the lack of abundant (or quality) data. Hence, it is essential for ITD to investigate the safety issues involved with winter maintenance practices and to identify the most cost-effective and environmentally sound ways of using winter chemicals.
Files & Documents
- Report by
Sponsors & Partners
- Idaho Transportation Department (IDT) Sponsor