Study On Travel Time Reliability Of Urban Road

With the acceleration of life pace and the enhancement of time concept,the reliability of travel time is more and more concerned by traveler,ensuring the convenience of each path travel at the same time to achieve safety and economic requirements.Based on the unbalanced distribution of urban road traffic flow,this paper chooses the road resistance function that is suitable for the traffic flow in road network and intersection of urban road network in China,and considers the traffic capacity of each path unit affected by such factors as lane width,traffic composition and Traffic flow and other factors of the interference,the use of least squares method to obtain the corresponding path of each road in the road function model parameter values.The increasing demand of road traffic,congestion and the impact of unexpected events on the normal operation of the traffic network have brought a series of problems to become more and more prominent.We analysis the path unit quantitatively affected by the traffic volume,the path unit length,the traffic accident rate and the time period studied,and which can get the expected value of traffic accident in any path unit.Assuming that the number of traffic accidents in the path unit obeys the Poisson distribution,the probability of a traffic accident occurring within a certain period of time is obtained,and the conditional probability of each traffic accident level under accident conditions is obtained.The conditional probability of traffic accident and the influence degree of each grade on traffic capacity are taken as the influencing factors of road traffic accident capacity by quantifying the influence of traffic accidents on the traffic capacity of each level.We analysis the mean and variance of travel time using the method of network reliability analysis and applying the corresponding road resistance function of path unit,assuming that the traffic flow arriving at road section obeys the corresponding probability distribution;The travel time reliability of the traffic flow through each path unit is calculated under the condition that the unit travel time is normal distribution.Traffic jam and traffic accident in any path unit will affect the running traffic of adjacent road sections or intersections to varying degrees.The mean and variance of the travel time of the traffic flow through the adjacent road sections and the intersections are obtained by using the traffic volume of adjacent road sections and intersections as the basis of the correlation analysis.The travel time reliability of the traffic flow through the path is calculated under the condition that the travel time of the vehicle passing path follows the normal distribution.