Research On Methods Of Transit Priority Signal Control Of Isolated Intersection

The development of urban public transit is attached importance widely with the increasing severity of urban traffic problems. Railway transit has many advantages,such as great capacity,rapid speed and little pollution,but is still limited by the disadvantages of high investment,long-building period and less flexible feature. Suffered from the personal car traffic,common bus performance has been increasingly slowed down and could not meet the multifarious requirement. Therefore,researchers found out a type of economic and efficient public transit between the railway and common bus ,that is bus rapid transit (BRT).It achieves higher performance with less invest and more flexible by modifying the traditional bus in planning,designing,operation and management. However, mixed traffic of BRT and common bus is still prevailing because of the large amount of existence of common bus and infrequent using of BRT. It is the key of solving the problem that how to control the two types and consider them simultaneously to realize the priority of the two.Generally speaking, the bus experience higher delay at intersections than at links, and the delay of buses can be greatly reduced by implementing Transit Signal Priority. So, it is the emphasis of the paper to study the methods of common bus priority signal control and BRT priority signal control of Isolated Intersection. Based on the theory of bus actuated, this paper studies the principle of actuated control, method of its parameter calculating and the types of bus priority. Study of these theories provides the basis. And we suggest a series of signal timing plan which is based on the tactic of bus priority. First, the strategy of common bus priority is analyzed in allusion to three aspects: control condition, principle and method. The study circumstance of the paper is defined, and the principle which serves the earlier bus firstly is suggested. The analysis of bus priority strategy leads the direction to the further research. Then, we study and describe the common bus priority control course of two conditions respectively: only one phase has bus and multi-direction collision according to the different number of the phase. The flow of common bus priority signal control is ascertained. Finally, we analyze the sub-module and compute the control parameter.Compared to the common bus, the level of BRT signal priority is higher. BRT priority can be achieved by inserting added phases in other phases if condition permitted in order to ensure the priority of BRT. So, based on the background above, under the premise that other phases wouldn't jam, this paper analyses BRT priority strategy, defines the research circumstance of BRT priority control, suggests the principle which serves the earlier bus firstly, confirms two levels of priority and studies priority principle. Later, the control flows of two conditions are suggested: only BRT and mixed of BRT and common bus to suit the current situation in China. Then we study high level and low level respectively as to only BRT priority control, and determine the control processes of two levels. At last, we compute and analyze the control parameters and sub-module—module of green compression, green expansion, added phase. The computation process of key parameters is also given.In conclusion, the paper studies the priority control of common bus, BRT and mixture of the two at an intersection in allusion to the phenomenon in our country. And according to the idea of bus priority signal control, the signal timing plan at intersections is modified. The study and analyses of bus priority above play a referenced role in the application and development of bus priority in China.