Abstract
This study examined a method for evaluating the risks caused by snowstorms on winter roads, based on visibility data. Visibility and other meteorological data, and driving speed and other driving behavior data are provided by mobile meteorological observation vehicles at times of blowing snow. The conditions that contribute to reductions in roadside visibility at the time of snowstorms were also analyzed.
It was found that driving tends to be affected by the change of average visibility and not affected by rapid deterioration of visibility. To be more specific, poor visibility causes reductions in driving speed because brakes tend to be applied more at average visibilities of less than 200 m and the standard deviation of steering angle tends to be greater at average visibilities of less than 100 m. It was also found that there are cases in which the average visibility deteriorates at the ends of bridges, at the ends of snow fences and at openings in snow fences. With respect to road structure, the average visibility tends to be lower at fills and flat land than at cuts.
