The dynamic response involved in car-roadside barrier impacts is studied.The risk of occupant injures in such accidents is investigated.An approach based on accident analysis and mathematical modeling is developed and described in three steps.Firstly a study of car-roadside barrier impact accidents is carried out with available data to define a system including car,road,roadside barrier,and occupant.Secondly a mathematical model to simulate car-to-barrier impact is developed by using multi-body program MADYMO.Finally,dynamic responses of the occupant during impact are simulated using a car compartment model with a HYBRID III occupant model and an input load pulse calculated in the second step.The dynamic responses of the car are analyzed by changing impact conditions such as impact angle and impact velocity.The injury risks of the occupants are discussed in terms of the occupant kinematics and calculated parameters:accelerations of the head,chest,and pelvis,as well as HIC value.Verification of model with experimental data is performed.Possible countermeasures for highway vehicle traffic safety and improvement of roadside barrier design are presented.Research prospects in this field are also proposed.