Establishing best practices of removing snow and ice from California roadways
Rochelle, Tiffany Ann.
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The recent legislation requiring the reduction of salt usage in California prompted the California Department of Transportation to investigate the best practices for winter maintenance using alternative chemicals. The objective of this research was to develop guidelines for optimal snow and ice removal operations designed specifically for California's typical highway environments. In particular, the research effort 1) synthesized information regarding winter maintenance best practices, and 2) designed and constructed an apparatus based on current practices, to perform a load-controlled anti-icing test in a controlled laboratory environment. These experiments were used to determine best practices for applying anti-icing chemicals to roads for three precipitation scenarios. Of specific importance is the temperature at which the bond between the precipitation and the road surface can be easily broken by a snowplow. The pavement samples and snow were conditioned by subjecting them to temperatures associated with each storm scenario. Chemical and snow were then applied to the pavement samples using a highly calibrated spray nozzle. Samples were placed on the temperature-controlled plow table, loaded with transverse and normal forces, and subjected to a warming cycle. Pavement temperature at the moment the ice bond was broken from the pavement was recorded, as well as a relative friction value of the pavement surface. The data available from the experiments was studied in an effort to correlate changes in the chemical performance with the various pavement types, application rates and storm scenarios, and then further to evaluate the relative performance of the five chemical types. A review and analysis of the friction and temperature data was performed. The primary conclusion from the analysis was that the presence of chemical, regardless of chemical type, increased the friction of the pavement surface and reduced the shearing temperature as compared to non-chemically treated substrates for all pavement types, all application rates and all storm scenarios. A secondary conclusion is that less chemical is required to prevent a bond on asphalt than on concrete. Although the behavior of all five chemicals was similar in nearly all respects, a few nominal differences were observed between them.