Study On Operational Performance Of Two Unconventional Intersections

With the quick development of economy and a large increase in all kinds of traffic tools, urban traffic demand are increasing rapidly, more and more intersections are operated under oversaturated conditions. Because of its main benefit, the continuous flow intersection and the upstream signalized crossover are rapidly becoming prevalent worldwide. However, due to the uniqueness of the geometric layout, the analysis of capacity of these two intersections, including the optimization of lane assignment and signal timing, has not been well resolved. In order to reduce the influence of left-turn movements on the capacity of traditional intersections and provide a new way to solve the problem of low efficiency of the intersections, this thesis presents a comprehensive optimization model based on lane group with the maximization of capacity as the optimization objective, which considers the similarity between continuous flow intersection and upstream signalized crossover. Based on the optimization results and the measured data from real world, a comparative study of the delay and capacity of these two design schemes is also conducted. The main works of this thesis are as follows:Firstly, the dissertation made a detailed analysis of the operation mechanism and the conflict point of continuous flow intersection and upstream signalized crossover, as soon as a qualitative analysis of capacity for these two unconventional intersections and also an integrated optimization model with the capacity as the target. In order to make full use of the limited time and space resources of the intersection, maximize the utilization rate of the resources, the model considered not only the timing parameters associated with finite time resources at intersections but also the lane assignment with limited space resources of intersection. The dissertation also presented a detailed solution algorithm for solving the integrated optimization model.Secondly, the dissertation selected the intersection of Jinzhai road and Fanhua road in Hefei as the data collection point, and the correctness of the integrated optimization model is verified by the simulation results of the traffic data collected as soon as a quantitative analysis on the capacity of these two unconventional intersections. The various traffic conditions, effects of turning ratio and whether the traffic is balanced have been considered, and the detailed sensitivity analysis results have been shown.Finally, through VISSIM. a microscopic traffic simulation software. the average delay of vehicles in different traffic scenarios is analyzed and compared with the analysis results of capacity under different scenarios. The results showed that if the traffic demand is fixed, the increase of capacity and the reduction of delay is usually mutually promoting.