Causes and spatial distribution characteristics of urban traffic accidents among vulnerable groups

On the basis of the data from the city of Beijing and the accident tree analysis,through researching and analyzing the causes leading to the crashes of the vulnerable road user,and considering the characteristics of the vulnerable road user,the concept of the movable obstacle in the line of sight is used and it is proved to be one of the main causes leading to crashes of the traffic vulnerable road user.From microcosmic analysis to macroscopical sum-up,through researching the relation of the number or severity of crashes of traffic vulnerable and traffic volume or speed of vehicles,the main characteristics of crashes of traffic vulnerable road user can be found out,and it will be helpful to improve the situation of the traffic safety of the vulnerable road user.