Journal of Cold Regions Engineering

The aims of the presentation are to discuss the efficiency of the different methods for friction control of winter roads on the safety and accessibility due to climatic conditions, to show that the climate should be an important factor in selecting the strategies for winter maintenance and to establish climatic parameters that may be helpful in making those decisions. The analyses are based on Swedish data assembled by VTI on road accidents involving fatalities and severe injuries, road surface conditions and climate. The accident and the road condition recordings are compared to self-defined climatic parameters, which describe the severity, stability and instability of the winter climate in the regions investigated. The parameters are assumed to describe whether salting or sanding is favorable/unfavorable for friction control. The results of the analyses show that the effect of salting is substantial for improving accessibility. Generally the number of winter accidents resulting in fatalities and severe injuries is lower on the salted road network compared to the unsalted road network in the southern and central parts of Sweden. However, in the northern region, with very cold winters, the number of winter accidents is highest on the salted road network. The data also indicates that the highest accident numbers are found when the proportion of vehicle mileage on snow and ice in the winters varies within 30–40%. The paper recommends that salting should be avoided in areas and in periods when the frequency of road surface temperatures below $-8°\text{C}$ exceeds 20%. In such climates the warm-wetted sand method is probably more favorable for friction control. Warm-wetted sand is also favorable on roads with traffic less than average annual daily traffic 2,000 and in periods with stable winter conditions.

A field investigation involving snow coring, surveying, and melt water collection was undertaken at a city snow storage facility to characterize the snow and melt water in Edmonton, Alberta, Canada. The investigation revealed a high content of both salts and sediment within the snow, a pile volume of $\mathrm{500,000}{\text{m}}^3$ , a snow density of $0.63–0.83\text{g}/{\text{cm}}^3$ , and an average road salt content of 1.2 g/L within the melted snow. The salt within the Poundmaker snow pile, one of Edmonton’s five snow storage sites, represented approximately 1.5–2.0% of the total amount of salt that was used on the city roads during the 2006/2007 winter. Melt water fractionation took place on-site during the spring melt and salt concentrations in the March melt water (early spring) were often more than 10 times the concentration of the bulk snow. Some of the factors affecting the snow and melt water composition included the snow retention time on streets, snow source, weather/climate, sampling technique, and snow site characteristics/operations.