Statistical Analysis of Traffic Accident Rate at Dusk

At dusk, the change in brightness of peripheral vision is striking. Such a sudden change in the viewing environment could affect the vision of a driver, possibly leading to an accident. I investigated the occurrence of traffic accidents at dusk by statistical analysis to determine whether changes in the viewing environment at dusk affect the accident rate. Dusk is considered to be the time of civil twilight, which is about 30 minutes in Tokyo. The analysis was done under certain conditions; for example, the target area was limited so that the time period for dusk was basically the same. Furthermore, the effect of the day of the week on the occurrence rate was investigated. I found no tendency for traffic accidents to occur with higher frequency at dusk. Moreover, the analysis of the accident rate of the day of the week showed that the accident rate is rather related to the traffic volume.