A Research on Interrelation between Illuminance at Intersections and Reduction in Traffic Accidents.

One recently apparent trend in increasing traffic accidents in Japan is the increase in nighttime accidents. To address this problem, various traffic safety measures have been introduced aiming at safer road traffic environments. Among these measures, road lighting, in particular ‘local lighting’ has been introduced in an increasing number as a countermeasure against nighttime accidents. However, in terms of number of fatal accidents by road profile, the ‘at intersection’ accounts for the largest portion of the fatalities. Therefore, a more effective intersection lighting measure must be studied. This paper discusses the illuminance levels expected for intersection lighting from the viewpoint of traffic accident reduction effect and reports the review result. The means used in reviewing were accident data before and after introduction of accident countermeasure and statistical analysis. It was learned from the result of these review works that an average road surface illuminance at intersections maintained at 20 lx or higher, as a level expected for intersection lighting, can provide the effect of accident countermeasure, and that an average road surface illuminance of 30 lx can further positively develop a statistically significant result as to reduction in traffic accidents.