Evaluating the Effectiveness of Winter Chemicals on Reducing Crashes in Idaho

US Transportation Collection2013PDFTech ReportYe, Zhirui (Jared)Shi, XianmingVeneziano, DavidFay, LauraWestern Transportation InstituteIdaho. Transportation Department. Research ProgramUnited States. Department of Transportation. Federal Highway AdministrationIdaho. Transportation DepartmentIdahoUnited StatesBenefit cost analysisDeicing chemicalsHighway safetyWinter maintenanceMaterialsChemicalsCrashesBenefitsCostsFHWA-ID-13-201RP 201Final Report 05/01/2011 - 06/30/2013Roadway maintenance agencies rely on a number of different materials and chemicals as part of their winter operations. Different chemicals have different performance levels, costs, and best conditions for use. Little research exists regarding the effects of winter maintenance practices on roadway safety, partly because of the cross-cutting nature of the problem and the lack of data. 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. 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.143