Study On The Characteristics Of Traffic Flow And Countermeasure At Urban Road Under The Variations Environment Illumination Conditions

In the process of inadequate illumination environment,traffic accidents occurred frequently,which have an inportant influence on traffic operation and urban social and economic life.In urban traffic,the high traffic density would aggravate above problems.How to institute the corresponding management and control of the traffic flow by studying the characteristic of road traffic flow under inadequate illumination environment,it is great theoretical and practical significance for solving various traffic problems under inadequate illumination environment.The paper is based on the national natural science foundation of “The mechanism research of traffic flow running characteristics under environment illumination change and the influence on traffic safety(No.51308177)”,the characteristics of traffic flow under inadequate illumination environment is studied,including the road velocity characteristic,the road traffic flow characteristic,the traffic flow characteristic of signalized intersection and the corresponding management and control measures under inadequate illumination environment.Firstly,the function and orientation of urban road are analyzed,and confirm the object of this study is the urban expressway.Based on the Hefei typical expressway section traffic survey results,the speed for expressway section by average speed,different lanes speed and different models speed are analyzed and compared with normal illumination environment.The goodness-of-fit of the comprehensive speed prediction model reaches 80% approximately based on the classic traffic flow theory by Greenshield.Secondly,based on the results of previous studies and traffic survey results,the relationship of illumination environment and vehicle spacing,expected speed,lane changing rate and randomization probability are analyzed,and set the spacing factor?speed factor?lane changing rate and randomization probability.The traffic flow model and lane-changing rules considering illumination are established.By numerical simulation,the curve diagram is obtained between speed,flow,changing-lane frequency and density in different environment illumination.It analyzes the effects of different environment illumination on the traffic flow.Thirdly,Based on the intersection video data,continuous observation and analysis of the intersections traffic flow in different illumination conditions were conducted.The headway,saturation flow rate and start-up lost time were selected as the characteristic indexes,and the traffic characteristic parameter reductions at signalized intersections were obtained by significant difference analysis and the relationship fitting in low illumination conditions,obtaining the rule of traffic flow parameters of signalized intersections under different ambient illumination.Finally,specific advice to expressway speed management and optimal timing model for signal intersection were proposed based on the previous results.