Research On Methods Of Delay-based Transit Signal Priority Control At The Isolated Intersection

Traffic congestion is growing to a more and more important problem all over the world. Transit priority is a strategy which can embody the people priority in traffic management. Giving priority to bus movements has been taken as an efficient way to ease the traffic pressure, ameliorate the traffic conditions, improves level of service of bus system, attracts more passengers and promotes urban traffic Sustainable development. So, transit priority became a development trend of many national urban transport. In many megapolises, Bus network which is huge and complex and playing a very important role in transportation system of China play an important role in the city traffic transport. However, the current overall level of service and operational reliability of the bus system is still very low. As the blossoming of motor traffic and automobiles, the unappealing bus system may loss it's foregone and potential passengers dramatically. Lots of exclusive bus lanes have been built to ameliorate bus system, and give priority to transit has been adapted as a basical politics in many countries including China. Under this condition, the research of bus signal priority control at intersection theories, an efficient tool to improve travel speed and reliability of bus system is very important and significative.In the Paper, the single intersection which has signal control is adopted as the priority control object. The bus signal priority control methods which based on a portion of bus can be priority is proposed. The core concept of the methods is According to optimal control idea, take the overall operating efficiency of intersections into account. Transit and vehicles of all societies participate in optimize all together. The control objective is all vehicles of the intersection have the minimum overall delay. Design the logic of the system running processes. Conceived the function of efficiency indicators. This concept extend capability of the bus signal priority to adapt the traffic condition of non-complex bus network and low frequency routes. In the course of the study, the model established by the corresponding analysis. Each model was test to prove it's effectiveness.In order to make transit signal priority adapting to transit situation of China which has complex bus network and heavy bus traffic, the paper focus on the research of multiphase bus signal priority control. In the support of the advanced information detection system, at the end of the previous cycle we can get the data of the next cycle, such as the information of all buses and the traffic flow parameters of each import roadway. Using non-linear programming method to establish the model of minimum delay. This method incarnate transit priority by means of redistributing the green time of the intersection each cycle. Subsequently, the paper introduce another way which is an optimization method based on the decision tree to resolve the problem that multi-request of bus priority conflict at the signal intersection. The decision tree has its own advantages what include clarity, non-omission, high exactness probability. We can quantify the benefits which under the different sequence of multi-request of bus priority. The paper study on the discriminant methods of multi-request bus interior conflict. Analysis the generation process of decision tree. Establish the control process and the optimum objective. In the course of generating decision tree, the core is arranging the sequence of multi-request of bus. And then we can optimized the sequence according to a unified decision-making model The final choice of bus priority sequence which can minimize the risk of losses arising from the priorities. Finally, the paper give an example to prove the effectiveness of model.The final chapter of this paper consider the bus timetable to optimize the signal of bus priority. It's a solution to the low bus on-time-point rate. The study mainly applies to the signal priority of one-way intersection and single bus route. Based on the objective of minimizing average person-delay of the intersection and the bus stop, as well as minimizing the bus arrive time. According to the actual bus arrived, judging whether the bus will be late or not through green extension and early green when arrive the downstream bus stop. This method take non-priority traffic of intersection and the passengers at the downstream bus stop into account. The paper established the model of bus journey time prediction, the model of passengers delay at the bus stop, the two goals of optimal model. Taking upstream and downstream bus stop overall consideration, we can make bus priority at the intersections more reasonable.