Noboru HIRANUMA

Effects of snow removal on expressways in consideration of travel speed and traffic accident rate

Kazushi SANO

In this research, the benefit of snow removal was calculated from the benefit of speed recovery and the benefit of reducing traffic accidents. In order to estimate the benefit of speed recovery by snow removal, a model for estimating the speed from snow coverage and a model for estimating the accident rate from snow coverage were estimated. 
The snow coverage was simply estimated using snow coverage observed on the roadside and the time passed by the snowplow. Using the speed as the objective variable, multiple regression analysis was performed using snow coverage and snowfall, temperature, wind speed, and traffic volume explanatory variables, and a model was created that could reproduce the speed although it was not accurate. However, it was a model in which the temperature seemed to be related to the speed more than the snowfall.
The relationship between snow and accidents was analyzed using the amount of snow coverage estimated from the speed. The accident rate tended to increase as the amount of snow coverage increased, but the accuracy of the estimated amount of snow coverage was low and the estimated amount of snow coverage was less than the actual amount of snow coverage. It is considered that the rate became excessive when the snow coverage was small.
Using a model that estimates the speed based on the amount of snow coverage and a model that estimates the accident rate, the benefits when multiple snow removal criteria are set are estimated. By using the estimated amount of snow coverage, it was confirmed that the benefits of running time reduction and traffic accident reduction were generated by snow removal. Although the benefit of reducing traffic accidents is greater than the benefit of shortening the travel time, the estimated number of accidents in some sections is more than double that of the actual situation, which is considered to be far from the actual situation.