Study On Access Requirements Of Different Types Based On The Influence Of Vechiles’ Speed

With the increase of land exploitation intensity of urban road, the number of road access is increasing. On one side, it improves the accessibility of the land area; on the other side, it brings negative impact for main road though traffic flow as vehicles entry and leave frequently. In order to coordinate the relationship between accessibility and mobility of urban road and maximize road service efficiency, this paper discusses the dynamic effects of different access types’ operational characteristics on the main road traffic, and the interaction between two accesses, based on which, access spacing and access optimization strategies are proposed.Firstly, this paper analyzes the current research on access. The results and shortcomings of previous studies are summarized. On this basis, the object of this paper is defined. Then traffic survey for the study is launched. The vehicles’ operating characteristics at accesses and basic characteristics of road segment are analyzed based on survey data. Vehicles’operating characteristics include the arrival and departure rate of turning vehicles, and time spent in motor vehicle lanes. Basic characteristics of road segment contain headway, volume, speed and lane changing. Based on arrival rate and departure rate, access types are divided. The different influence between two access types differed from the residence time on the motor vehicle lanes of turning vehicles.In the matter of single access impact, road initial speed models of different lanes are established for none-queue access and queue access. According to different impact of deceleration, lane changing and queuing, the speed impact models are established. Traffic survey data is used of model calibration and parameter sensitivity analysis. Then the concept of speed influence zone is raised. Based on wave theory and speed impact models, speed influence zone length models for each lane are established. Parameter sensitivity analysis is about the impact of leaving influence time, speed difference of lane-changing vehicles and queue length. The length of outside lane speed impact zone is longest for none-queue access. Queue length is the decisive factor of adjacent lane for queue access.Simulation software and before-after test method are used to find out the combined access impact. This paper mainly studies the influence of upstream access on traffic conditions of downstream access velocity area. Using travel time as the comparison index, influence regularities of test factors such as volume, turning ratio, queue length on the downstream impact zone is gotten. Lasso regression is used for formulating travel time of different combined accesses and ordering the influence degree of different test factors.Finally, the average speed is selected as the evaluation index. Based on the research above, using the weighted average method to calculate segment average speed, aiming at satisfying service level of road, access spacing and access optimization strategies are proposed.In this paper, through the description of vehicle characteristics and traffic flow characteristics at urban road access, influence mechanism of single access of different types on different lanes and interaction between upstream and downstream access are deeply understood. The concept of speed influence zone is raised. From the point of view of urban road efficiency, it provides the reference method and basis for determining the access spacing.