Abstract
One characteristic of traffic accidents in Japan is the low bicyclist fatality rate, with bicyclist fatalities being only about one-third as numerous as pedestrian deaths, even though bicyclists sustain approximately twice as many minor injuries as pedestrians do. It is thought that elucidating the mechanism accounting for the lower bicyclist fatality rate and applying that knowledge to future systems for protecting vulnerable road users would be extremely important to the protection of all such users, including pedestrians. In this research, data on vehicle-bicyclist accidents in Japan were analyzed to identify the collision patterns involved and the resultant fatality and injury levels. In addition, an analysis of bicyclist collision behavior revealed the mechanism that reduces the head impact velocity of a bicyclist, which can lead to a lower fatality rate. This mechanism was applied in developing an airbag system to control bicyclist collision behavior.