The Research Of Freeway Theoretical Traffic Safety Degree

With the rapid development of national economy,the freeway mileage opened to traffic increase year by year,people’s work and life is becoming more and more close to the freeway.The problem of traffic safety in freeway is also attracting more and more attention.In the past,people studied the problem of freeway traffic safety mostly integrated the human,vehicle,road and environment,and analyzed and evaluated the traffic safety level of the freeway in all.In fact,people and cars are subjective and uncontrollable factors,but the road and environment are the objective factors,and can to be measured and predicted easily.The properties of two kinds factors are different,using the same method,is easy to deviate from the actual situation.It is easy to deviate from the actual situation by using the same method for analysis.In this paper,the road conditions and environment in freeway that two objective factors are separated to evaluate the level of the objective freeway traffic safety which are defined as freeway theoretical traffic safety degree.The mechanism of influencing factors of freeway traffic safety is analyzed,and the indexes of evaluating the theory traffic safety degree are determined and the evaluation index system is established.The traffic accidents data of freeway over the years is collected,and to analyze the importance sequence of each index to freeway theory traffic safety degree by using grey correlation analysis method.Calculating the weights of the influence of each index on the highway theory by the hierarchy analysis according to the sorting results.In this paper,the basis of establishing the model of freeway theoretical traffic safety degree evaluation is the satisfaction degree of each evaluation index relative to the relevant standards.And the relation between freeway theoretical traffic safety degree and the allowable safety speed is established.In order to establish relation between freeway theoretical traffic safety degree and the allowable safety speed,the main influencing factors of safety allowable velocity are analyzed,and the prediction model of allowable safety speed which including horizontal curve,superelevation,longitudinal slope grade,visibility and friction coefficient of pavement is established.Combined with the actual situation that the parameter indexs of the freeway are varied and erratic,the range of each index was set up and many groups of freeway random numbers were generated,to achieve the object that get a large number of data.Using the model of freeway theoretical traffic safety degree evaluation and the prediction model of allowable safety speed to calculate the safety degree and allowable safety speed of random data.Matlab is used to carry out the linear fitting of the multiple groups of the freeway theoretical traffic safety degree and the safe allowable speed,and through example calculation to verify.The evaluation indicators of the model in this paper is easy to obtain and relatively stable.The evaluation process can set aside the influence of subjective factors is fast and convenient,It has important guiding significance for freeway operation management and freeway speed limit.