Impact Kinematics of Cyclist and Head Injury Mechanism in Car‐to‐Bicycle Collision

The number of cyclist fatalities is the third highest in traffic accidents in Japan, preceded by pedestrians and car occupants. The head is the most frequently injured body region in fatal cases. No injury assessment tests have been established for cyclist protection while impactor tests are regularly conducted for pedestrian protection. One of the reasons is that impact kinematics and injury mechanism of cyclists are not well understood. This study conducted car‐to‐bicycle collision simulations using finite element models for investigating head kinematics up to the contact with the car body. First, four collision cases were simulated with two car body types and two different impact locations. Impact kinematics of the cyclist was compared among the cases. The cyclist commonly showed an inclined trajectory against the car longitudinal line but the later direction changed in the sport utility vehicle (SUV) cases. Next, a parametric study was conducted assuming various car speed, bicycle speed, impact direction and impact position. The head reached the windshield glass and the A‐pillar in the sedan cases, while it impacted the rear end of the hood and the A‐pillar in the SUV cases. When the head impacted such windshield frames, the model indicated high risks of skull fracture and brain injury.