Implementation of Head Injury Criteria in Bicycle-Car Accidents

Several head injury criteria, some of which are generally accepted whereas others are newly proposed, are implemented and applied to multibody accident simulations of typical bicycle-car accidents. The main goal is to establish the importance of car - and bicycle speed and relative car-bicycle trajectory for accident reconstruction studies. For this purpose, Madymo® cyclist and car models are used in a parametric sensitivity analysis study. Head injury criteria include the HIC, maximum change in rotational velocity of the head and peak rotational head acceleration. Injury parameters are investigated for 30 different cases of frontal and sideways collisions. For cyclist speeds ranging from 10 to 30 km/h and car speeds from 20 to 50 km/h, HIC values range from 200 up to 2500. Maximum change in head rotational velocity ranges from 20 to 60 rad/s and peak rotational acceleration from 4500 to 22000 rad/s². In general, sideways impacts lead to higher values for all head injury criteria. The influence of car speed on the head injury criteria values is larger in the sideways collision cases when compared to the frontal case. On the contrary, cyclist speed has a larger influence in the frontal case. It is concluded that car speed is the most critical factor and traffic expert input is needed to calculate car speed at time of impact based on objective information. Next to car speed, the relative car-bicycle position needs to be established iteratively by matching modelled impact positions with those reported in medical files, eyewitness reports, police- and traffic expert reports.