車輛前面形象과 多重因子를 고려한 步行者衝突事故해석 모델 개발

Abstract

Pedestrian involved accidents have a characteristic of high fatalities due to their exposure to vehicle impact. The fatalities of pedestrians account for about 40.0% of all traffic accident fatalities in Korea 2005. The social loss by pedestrian accidents is serious, and conflicts caused by pedestrian accidents increase annually. But there have been little studies on pedestrian accidents. In pedestrian involved accidents, the method to analysis the impact speed of vehicle is based on the position of pedestrian, vehicle, fragment of vehicle, road evidence. And the method by the deformation of the collision objects is not presented. Pedestrians involved in accidents generate a trajectory of the pedestrian. In pedestrian accidents, the most important data to inspect accident is throw distance of pedestrian. Previous studies on pedestrian accidents have been carried out for the trajectory of the pedestrian using simple formulae derived by elementary physics. Throw distance of pedestrians can be influenced by many variables classified into vehicular factors, pedestrian factors, and road factors. Previous studies on pedestrian accidents did not consider all factors. So, previous studies could not explain relationship between throw a distance of pedestrian and impact situation sufficiently. And the estimate value by previous studies did not coincide with real accidents. The frontal shape of vehicle is a rounded shape, and slipping caused by rounded frontal shape decrease throw distance of pedestrian. So, throw distance of pedestrian can be effected by the offset of vehicular impact point. About friction coefficient pedestrian to vehicle and pedestrian to road, the state of rain differ from the state of dry. In previous studies, the influence of rain and the offset of vehicular impact point were neglected. In this study, all factors concerned in the throw distance of pedestrian were taken into consideration to overcome the problem of previous studies. The aim of study is the deduction of formula that explains the real accident actually. The procedure of study is the following. Firstly, the analysis methods in previous studies and the difference among studies were examined Secondly, the theory about collision was examined to research the movement of pedestrian after collision. Thirdly, the study on the effect of variables that influence the trajectory of pedestrian was performed. On the ground of result about variables that influence trajectory of pedestrian, the important variables were vehicular frontal shape, vehicular impact speed, the offset of vehicular impact point, the height of pedestrians and the friction coefficients of the pedestrian. By the result about variables that influence trajectory of pedestrian, variables that should be worked in experiment by steps were determinated. Fourthly, the restitution coefficient of pedestrian was analysed by the simulation of real accident which could obtain the data of accident, impact speed, collision point, the height of pedestrians and the state of scene. Fifthly, the computer simulation tests considering variation of variables that influence trajectory of pedestrian were conducted to examine movement of pedestrian. The trajectory of pedestrian, dynamic characteristics of multi-body were analyzed by PC-CRASH, a kinetic analysis program for a traffic accident. PC-CRASH enables an analyst to investigate the effect of many variables. The vehicle and pedestrian are modeled with rigid bodies and joints. By vehicular frontal shape, the type of vehicles were classified into 4 types, such as sedan, box, SUV, and van. Simulations were performed for each type of vehicle considering all variables by steps, and the range of impact speed of vehicle was 20∼70 km/h. The offset of the vehicular impact point was divided into 3 states of 0, 40, 80% offset collision. The height of pedestrians was considered by 4 steps, 1.83, 1.65, 1.40, 1.20m model. The state of the road was divided into dry and wet by adjustment of friction coefficients of pedestrian. The number of simulation test is 800 times. Sixthly, by the simulations results, multi variate regressions were conducted. Based on the regression, regression formulas were derived. Regression formulas can explain the relationship between throw distance of a pedestrian and all other variables that influence the trajectory of a pedestrian sufficiently, and can be used in traffic accident investigation usefully.