Research Of Vehicle-pedestrian Accidents Based On The Uncertainty Of On-scene Information

With the development of economy and the increase of car ownership,traffic accidents bring huge loss to China each year.Among all types of accidents,pedestrian have become the most vulnerable group due to lack of protection.When an accident happens,numerical simulation and accident investigation will be launched based on onscene information.The investigation results can be greatly affected by the accuracy of on-scene information.Aimed at this issue,the on-scene information is classified into measurable information and unmeasurable information.Uncertainty problems in these two kinds of information are discussed in this thesis:(1)Measurement reliability model of measurable information is built.Aiming at the most common measurable information in vehicle-pedestrian accidents—pedestrian projection distance,bloodstain positioning error model and distance measurement error model are built based on four positioning methods introduced in industry standard.With these two error models,limit state equations under different positioning methods are given based on First-order Reliability Method.Meanwhile,calculation of measurement safety factors corresponding to different positioning methods is also introduced.(2)A vehicle-pedestrian accident scene is established and influencing factors of measurement reliability are analyzed.In the accident scene that has been built,by setting different vehicle-pedestrian impact velocity,positioning methods and positions of datum points,influence of these factors on reliability safety factors is analyzed.Meanwhile,values of distance measurement error and bloodstain positioning error are estimated.With conclusions of this research,some suggestion about on-scene measurement is given.(3)An estimation method of unmeasurable information is introduced based on the combination of orthogonal tests and polynomial regression analysis.By postprocessing of orthogonal test results,unknown information in a real-world vehicle-pedestrian accident is reconstructed.The accuracy of reconstruction with this new method improves significantly compared with traditional orthogonal tests.Furthermore,influencing factors of reconstruction accuracy are discussed.Parameter selection methods are given in order to improve the accuracy of simulation optimization.