The difference in the kinematic and injury risk of cyclists between normal and emergency avoidance postures in vehicle collisions

Abstract

To investigate the global kinematic differences between normal and emergency avoidance postures of cyclists at different crash speeds and the risk of head and lower extremity injuries during vehicle crashes. Seven postures (three normal and four emergency avoidance postures) were selected based on video information from 200 bicycle accidents in the VRU-Traffic Accident Video (VRU-TRAVi) database. Fourteen simulations were performed using the Total Human Safety Model (THUMS) 4.0 occupant model considering the seven postures and two-vehicle impact speeds (20 and 40 km/h). The global kinematics of the cyclists, as well as head injury parameters such as peak linear acceleration, head injury criterion (HIC), peak angular acceleration, brain injury criterion (BRIC), maximum principal strain (MPS), cumulative strain damage measure (CSDM), and lower extremity injury parameters such as von Mises stress and bending moment were calculated to assess the risk of head and lower extremity injury. The results showed that the moment of head contact with the vehicle was earlier and the slip distance of the pelvis was shorter in the emergency avoidance postures compared to the normal posture at vehicle speeds of 20 km/h and 40 km/h, which reduced the head wrap-around distance (WAD) and increased the head impact velocity. In addition, the emergency avoidance postures did not significantly reduce the risk of head injury compared to the normal posture; instead, they increased the risk of injury to the lower extremities.