Study On The Difference Of Human Injury In Vehicle-Cycling/Pushing Bicycle Collision

In recent years,under the combined effect of factors such as the large number of cars and bike,the common phenomenon of mixed driving of motor vehicle and non-motor vehicle in traffic and the rapid development of bike-sharing industry,the incidence and the casualty rate of car-bike accidents have been increasing year by year in China,the form of bicycle road traffic safety is severe and complex.In addition,in order to prevent and reduce the bicycle accidents,the relevant laws and regulations stipulate that the controller should get off the bicycle when the bicycle crosses the motor vehicle lane.However,the existing research have not given a reasonable explanation for this regulation,resulting in the weak theoretical support of the laws and regulations.Therefore,it is very necessary to carry out the research of car-bicycle accidents under the current background.For this reason,this paper will combine with accident video and collision simulation technology to carry out research on the difference of human injury in cycling/pushing bicycles accidents.In order to explore the characteristics of bicycle accidents and the controller injury factors,184 videos of car-bicycle accidents were analyzed by descriptive statistics.Accident characteristic:the accidents involving cyclists often occur on sunny days,on dry pavement surface and at the crossroads with good visual and lighting conditions.85.4%of the involved vehicles were sedan and SUV,before the collision most of the cars an d the bicycles were going straight,and most of the car drivers took braking actions.The vehicle and bicycle speed were concentrated at 5～45 km/h and 5～20 km/h respectively.The main collision pattern was side right-angle collisions.Mostly the vehicle strikes the bicycle left or right body with its center of the front bumper.In the accident,the lower limbs were most common fist landing site and more than 1/3 of the controllers were severely injured.Injury factors:the causes of more severe rider injuries include the high collision speed,landing head first,being hit by the middle or right side of the front bumper,no emergency measures taken before the collision and the side impact or crushing.The high proportion of severe injuries at low speed was largely due to being crushed beneath the vehicle.When the first landing site was the head,the proportion of serious injury+was high,which was related to the high collision speed in this case.When the collision part was in the middle and right of the front bumper,the proportion of controllers’ serious injury+was high,which was related to the layout of the drivers’ cab and the collision form.In order to obtain the postures of three body size(5th,female,50th and 95th,male)controllers cycling/pushing typical bicycle,60 groups of physical experiments of cycling/pushing bicycle were designed and carried out with the type of bicycle,seat height and body size as variables,and the whole experiments process was recorded.According to the motion characteristics of cycling/pushing bicycles,8 cycling/pushing postures were defined(quantified by 5 kinds of angle parameters).Further using Simi Motion to extract the angle parameters of 8 cycling/pushing postures under different experiment conditions.The date show that:the type of bicycle,seat height and the controller body size have a significant impact on the cycling posture;the type of bicycle and the controller body size have a significant effect on the cyclist lean forward angle of back(back angle),the upper arm elevation angle and the elbow bending angle.However,it has little effect on the thigh elevation angle and knee bending angle of the pushing posture.In order to better carry out the simulation experiments,the multi-rigid body dynamics theory and the human body injury evaluation index were briefly introduced to clarify the theoretical basis of collision simulation.A complex multi-shape coupling collision accident was reconstructed to show the effectiveness of the multi-rigid body model in simulating the collision response of human body.Finally,a simulation platform of vehicle-human-bicycle-ground coupling collision was built based on MADYMO software,and the reconstruction of a real carbicycle accident was used to verified the reliability of the simulation platform.In order to obtain the influence rule of seat height on the controller’s head injury,firstly,the date of cycling back angle of physical experiments was analyzed by nonlinear regression method,and a nonlinear regression model with strong correlation between seat height and the controller’s cycling back angle of three body sizes was obtained;it was found that the cycling back angle of the small body size controllers first increase and then decrease with the increase of the seat height,while the cycling back angle of other-size controller continued to increase.Then,98 groups of simulation experiments were designed and carried out with vehicle type,bicycle type,seat height and controller body size as variables.The results showed that the seat height considering the back angle was significantly correlated with the controllers’ head injury.The change tendency of cyclist head injury with seat height was different under different combination of car type and controllers’ body size,with being a tolerance limit seat height of the head injury.However,the internal cause of the decrease in cyclist head injury under the tolerance seat height was the decrease of the relative collision velocity between the head and the vehicle.In order to obtain the difference of human injury in cycling/pushing bicycle accident,336 groups of simulation experiments were designed with vehicle type,bicycle type,controller body size and cycling/pushing posture as variables.It was found that there was a significant difference in the injury of the controllers’ main parts between cycling and pushing state in most of the simulations.The overall injury degree of the controller was the least in the right pushing state.The injury degree of each major part was different under different cycling/pushing posture.The injury degree of the controller was the most serious under cycling posture 4,which was dangerous posture,and the injury degree of the controller was the least under cycling posture 8,which was safe posture.The research results can provide a basis for the improvement and interpretation of relevant domestic laws and regulations in China,provide support for the design of bicycle seat height to reduce the damage of bicycle controllers,provide suggestions for the safe travel mode of bicycle controllers,and lay a foundation for further research on bicycle accidents in the future.