Research On The Duration Of Traffic Congestion On The Second Ring Road In Xi’an

The rapid development of cities has brought tremendous pressure to the operation of urban road traffic.As one of the important functions of the city,traffic is closely related to people’s daily life.However,the increasingly serious traffic congestion problem restricts the development and construction of the city and the efficiency of traffic operation.People’s daily life brings great inconvenience and trouble.In the past,the research on traffic congestion was mainly based on the analysis and evaluation of flow parameters,but there were few studies on the duration of congestion.In actual travel,travelers are not only concerned about whether the traffic state is in congestion,but also when the congestion state ends,how long the congestion will last,and factors affecting the duration of the congestion.The congestion duration itself can be used as an important parameter for studying the law of congestion and the temporal and spatial distribution,so it is meaningful to study the duration of traffic congestion.Based on the above problems,this paper takes the real-time traffic data of the Second Ring Road in Xi’an City as the basis,regards the duration of congestion events as medical individual survival time,and uses survival analysis methods to explore the temporal and spatial distribution of congestion duration and find out Influencing factors of congestion duration,analyze and compare the difference of the influence of each factor on congestion duration.First,the non-parametric method of survival analysis is used to estimate the congestion duration.Starting from the survival function and the hazard function,the overall distribution law of the congestion duration is analyzed.Secondly,the non-parametric regression model is used to compare and analyze the congestion duration under different time and space factors,and analyze the difference in the distribution of congestion duration under different time and space factors.Finally,an accelerated failure time model was established,the survival analysis parameter method was used to fit the optimal model of the congestion duration,and the significant influencing factors were analyzed based on the estimated coefficients of the model.The research of the paper mainly draws the following conclusions:(1)By analyzing the overall distribution of congestion duration,it is found that as the congestion duration increases,the survival rate curve continues to decline,and most congestion ends within 6minutes,accounting for congestion.69.7% of the total number of samples,the number of congestion that ended within 8 minutes accounted for 76.4%.The risk rate reaches the highest at 6 minutes,and the duration is flat in the interval [12,22],indicating that the probability of congestion lasting for a certain period of time in this interval is almost the same at the next moment.(2)By analyzing the temporal and spatial distribution of traffic congestion duration,it is found that there are significant differences in the distribution of traffic congestion duration in the four directions of the second ring road,southeast,and northwest during peak and rush hours,and there is no significant difference.The difference between weekdays and weekends.The morning peak congestion lasts shorter than the evening peak congestion.The morning peak congestion is more likely to end at the next moment,and the congestion is easier to end;on the contrary,once the evening peak congestion occurs,the congestion lasts longer and the congestion is more difficult to dissipate.South Second Ring Road and West Second Ring Road last longer than East Second Ring Road and North Second Ring Road,and the congestion is more difficult to end.By comparing the mean and median,the severity of congestion is ranked as: South Second Ring Road>West Second Ring Road>East Second Ring Road>North Second Ring Road.(3)The weibull distribution is obtained as the optimal model for the congestion duration,and the Cox-Shell residual test is used to determine the optimal model;by analyzing the influencing factors of the congestion duration,the effects of morning and evening peaks,inner loops,and exit ramps on congestion are obtained.Duration is a dangerous factor and will accelerate the end of congestion.Pingfeng,outer ring,entrance ramp,and main line opening are protective factors that will delay the end of congestion.Viaducts,working days and weekends have no significant impact on the congestion duration;The duration of congestion has a significant impact.The duration of congestion in the west and south directions of the Second Ring Road is longer than that in the east and north directions of the Second Ring Road,and the congestion in the west and south directions is more difficult to end.