A study of Long Term Change of Traffic Safety Measures Effects in Urban Expressway

Abstract

Urban expressway is the aorta that supports the traffic of metropolitan area in Japan. But many accidents are still occurring due to complicated road linearity. So far various safety measures have been taken, but the effect is not necessarily permanent. Further it is assumed that there is a possibility of diminishing. Therefore, in this research, we aimed to grasp the long-term trend of the effect of traffic safety measures implemented in the past. We analyzed the anti-slip measure which is the longest implementation extension and is a representative countermeasure. Focusing on the planar linear shape of the countermeasure part, it was recognized that the countermeasure effect diminishes after a long period in the sharp curve section with a curved line radius of less than 200 m, and in other sections, it was suggested that the countermeasure effect will continue. Based on these findings, it is possible to apply additional measures before the effect is reduced in the future, and it is expected to contribute to the prevention of accidents.