Urban Traffic Accident Risk Analysis Methud Based On Dynamic Fault Tree

Urban traffic system has the characteristics of complex roads of different levels,diverse types of traffic participants and vehicles,and poor consistency of traffic speed,which lead to higher traffic accident frequency and different severity of safety hazards.For urban traffic accidents,in-depth analysis of its mechanism,causes and consequences of the accident analysis,can provide a theoretical basis for traffic control.Therefore,based on the dynamic fault tree theory,this paper studies the risk analysis of urban road traffic accidents.According to the location,type and form of the accident,the research object,main accident type and main accident form are determined.At the same time,the direct causes recorded in the accident identification book are counted,and the basic probability is given.According to the binomial distribution statistical test,the potential factors with weak correlation are removed from the four aspects of people,vehicles,roads and environment,and the prominent potential influencing factors with significant influence are identified.The main influencing factors and prominent potential influencing factors obtained are regarded as the risk factors of urban road traffic accidents,which lays the foundation for the establishment of the follow-up model.It is necessary to build an effective risk analysis model for accident risk analysis.Firstly,the advantages,disadvantages and application scope of conventional risk analysis methods are compared,and the dynamic fault tree method is selected.Then,according to the accident mechanism,the dynamic fault tree model of urban road traffic accident is constructed.Firstly,the model is preprocessed and simplified,and then the simplified model is decomposed into modules to identify all the module subtrees.According to the static subtree,the corresponding ite structure expression is written by recursion method,and the subtree is transformed into binary decision graph to determine the minimum cut set and occurrence probability.For dynamic subtree,based on Markov process,it is transformed into Markov chain,and then the fault mode is judged,and the probability importance is calculated.Finally,the main accident cause chain is obtained by modular synthesis of each subtree.In addition to the cause of the accident,the severity is also an influencing factor of the accident risk.Therefore,the bow tie model is introduced to describe the whole process from the cause of the accident,to the occurrence of the accident,and then to the consequences of the accident.Firstly,the event tree model is constructed by analyzing the process of accident consequence.The fuzzy probability of each event chain is determined by expert scoring method combined with triangular fuzzy number.Combined with the risk matrix,the high-risk event chain is obtained.The main accident cause chain in the fault tree and the high-risk event chain in the event tree are connected,and the bow tie model is constructed.On the left side of the model,the corresponding prevention and solutions are proposed for five main accident cause chains,and on the right side of the model,the corresponding accident consequence response scheme is proposed based on two high-risk event chains.