Abstract
Head injuries of pedestrians and bicyclists in collisions with four-wheeled vehicles were analyzed using the Japan Traffic Accidents In-Depth Database, J-TAD (micro) which is maintained by Institute for Traffic Accident Research and Data Analysis (ITARDA). From the micro data, pedestrian and bicycle accidents in 2016~2018 were extracted. There were 116 pedestrian accidents and 60 bicycle accidents. We analyzed the relationship between the impacting part against the head and the impact speed in pedestrian accidents that resulted in brain injury. The results showed that the average impact speed exceeded 40 km/h in the case of windshield and pillar/hood collisions. In the case where the road surface was the impacting part, the impact speed was less than 30 km/h. This may be because collisions with a truck or a cab-over vehicle with a flat frontal profile pushed the pedestrian forward and caused collisions between the head and the road surface even at a relatively low speed. On the other hand, the average impact speed exceeded 40 km/h in the case of windshield, pillar/hood, and road surface in bicyclist accidents that resulted in brain injury. This is because there was only one pedestrian sustained a brain injury caused by contact with a cab-over vehicle and pushing down against a road surface. For both pedestrian and bicycle accidents, it was confirmed that brain injuries of AIS 3+ can occur even i n c ollisions w ith w indshields, w hich a re c onsidered t o h ave h igh p edestrian h ead p rotection performance when the impact speed is high. In the case of both pedestrians and bicyclists, various AIS 3+ injuries such as cerebral contusions, subdural hematomas, subarachnoid hemorrhages, and diffuse axonal injuries occurred in road surface collisions and windshield collisions. No relationship was found between the impacting part and the injury description.
