Speed Limit in City Area and Improvement of Vehicle Front Design for Pedestrian Impact Protection– a Computer Simulation Study

This paper presented a part of results from an ongoing project for pedestrian protection, which is carried out at Chalmers University of Technology in Sweden. A validated pedestrian mathematical model was used in this study to simulate vehicle-pedestrian impacts. A large number of simulations have been carried out with various parameters. The injury-related parameters concerning head, chest, pelvis and lower extremities were calculated to evaluate the effect of impact speed and vehicle front structure on the risk of pedestrian injuries. The effect of following vehicle parameters was studied: stiffness of bumper, hood edge, hood top, windscreen frame, and shape of vehicle front structures. A parameter study was conducted by modeling vehicle-pedestrian impacts with various sizes of cars, mini vans, and light trucks. This choice represents the trends of new vehicle fleet and their frequency of involvement in real world accidents. The mechanical properties of the vehicle front were based on the available data from EURO NCAP tests, and from published literature. Based on the results from the simulation study, possible benefits from speed control in urban area can be assessed. As the impact speed decreases from the 40 to 30 km/h, the probability of severe head injury will decrease from 50% to lower than 25%. The influences of the various compliance and geometric parameters of vehicle front are analyzed. The most significant parameters to pedestrian impact protection are clarified, especially for head and lower extremities. A procedure in new vehicle-front design is presented, which can lead to a design guideline of safer vehicles for pedestrians. Furthermore, gaps in pedestrian protection are identified, and the research priorities should be focused on the adult head and lower extremities and child head and thorax injuries.