| In the context of the rapid development of the international economy,the number of automobiles in my country has also increased year by year,and the subsequent series of road traffic accidents have become a major social problem.According to statistics from the World Health Organization(WHO)in 2015,more than 1.25 million people died in road traffic accidents around the world,and about 20-50 million people suffered non-fatal injuries as a result,and the direct economic loss reached 518 billion US dollars.A collision between a small car and pedestrian is a relatively common type of accident among road traffic accidents and is also an important research topic in the field of vehicle safety development and first aid.However,there are few research reports on pedestrian injuries.Human injuries are the important trace of traffic accidents.Correct analysis of the characteristics of injury,injury mechanism and degree of injury play an indispensable role in restoring the accident process and correctly dividing responsibilities.This study focuses on the types of traffic accidents involving small cars and pedestrians with surveillance video,and studies the characteristics of pedestrian injuries,injury mechanisms,and injury conditions.The specific research content is as follows:1.The restoration of the accident scene and process.According to vehicle traces,road traces,human injuries and surveillance videos,combined with the registration of 3D scanned images and 2D and 3D information on the spot,the collision relationship and movement trajectory of the human body and the small car are clarified.Extract time information from the two-dimensional surveillance video,and then combine the human body structure model to calculate the speed,kinetic energy and other data of the human body and the vehicle at various stages.2.Autopsy,injury analysis and degree of injury.The assessment of the degree of damage in this subject uses the assessment of the degree of inj ury in this subject adopts the AIS-ISS injury degree scoring method,selects the 3 most severely injured parts of the body,takes the highest AIS score and calculates the square sum,and the result is the ISS value,namely ISS=∑(AIS12+AIS22+AIS32),quantify the degree of damage;head injury is the main cause of death in traffic accidents,for the score of which,this topic uses NISS score.3.Human injury occurrence process and injury conditions.Clarify vehicle damage,human body damage,etc.,use two-dimensional and three-dimensional registration techniques to determine the continuous process of one-time damage,secondary damage,and tertiary damage.Combine autopsy,damage inspection and clinical data to analyze injury mechanisms and injury condition.Two cases of small car-pedestrian collisions with surveillance video are selected,and the injury process is reproduced by the computer software PC-Crash to clarify the relationship between the morphological characteristics,location and severity of the human body and the speed,kinetic energy and other parameters of the accident vehicle.Studies have shown that with the increase of vehicle speed,the AIS-ISS score is getting higher and higher,and the degree of human damage is getting heavier.Using PC-Crash to reconstruct the accident process of typical cases,the collision process between small cars and pedestrians are reproduced,and the simulation results are consistent with the actual situation,showing the reliability of the accident reconstruction method.In general,when V<40 km/h,the vehicle does not cause severe injuries in pedestrians;when V>40 km/h,the collisions of the pedestrian’s head with the windshield lead to severe head injuries and the accident can cause severe pelvis and rib fractures;when V>60 km/h,the collisions of the pedestrian’s head with the windshield can cause cervical spine injuries in addition to head injuries.The occurrence of human injuries is related to not only the vehicle speed but also factors such as the height of the pedestrian,the height of the bonnet and the length of the bonnet. |
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