Study on the artificial control od snow on roads

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The proper control and maintenance of traffic roads in winter seasons in snowy areas can be accomplished only on the base od enough knowledge of physical properties of snow and ice on roads. However, even the classification, structures and properties of snow and ice have not been investigated in detail. This study was aimed at measuring systematically the structures and physical properties and proposing a new classification of snow and ice on roads; the main items of investigation are structures, physical properties, disappearing process, and heat balance. Obtained results are as follows1)The structures and physical properties of snow and ice on roads are strongly affected not only by meteorolgical conditions but also by artificial effects such as passing vehicles and snow removal; therefore the structures and properties are variable as the time and local points2)Snow and ice on roads are classified into seven types: new-snow, compacted-snow, powder-snow, grain-snow, slush, ice-crust, and ice-film. Then each of the five types except the powder-snow and slush, is divided into two subtupes; dry and wet. In addition the dry compacted-snow was subdibided into soft and hard ones. In total snow and ice on roads are classified into 13 types3)Dry new snow on roads is quickly densified into compacted-snow, the maximum density of which is from 500 to 550 kg/m^34)Hard compacted-snow(600-800 kg/m^3) and ice-crusts are often formed when melt water of the surface of road snow penetrates and refreezes in it5)The heat balance on the surface of snow on roads is colsely related to the melt and ablation process. The present study showed that the net radiation and surface albedo are the most important components to determine the heat blance both the contamination by vehicles and reflectance change due to melting increase the ablation and melt of snow, which is the main cause of the formation of ruts.