Intelligent Control Algorithms For Bus Signal Priority At Intersection

Faced with the serious situation of urban transportation, improving public transportation system to maximize the utilization of public road resources has become a consensus; and bus signal priority as an important part of the advanced public transportation system has become the effective way to solve the urban transportation problem, what’s more, how to carry the bus priority strategy and make the multi-mode traffic flow cooperate with each other on premise of taking the time and energy consumption into account, has become an urgent problem. Under comprehensive considering the impacts of bus signal priority on other social vehicles such as the delays, speed, emissions, the improvement research of bus signal priority is promoted with good results by realizing time priority access for buses based on rough set algorithm and delay area model, with using strategies of green time extension and advance.The paper presents main research contents as follows:1.The strategy of bus signal priority research is studied, especially the green time extension and advance strategies which belong to the active priority control strategy.2. A rough control system is established with rough control parameters such as red light vehicle eager degree, green phase jam degree and bus priority degree.The intersection of zhongguancun south street and south college road is selected as an case, then the rough decision table is set up with rough control parameters as the condition attributes, and green time extended as the decision attribute, later which is reducted by rough set theory to make the rough decision regulations as the control tactics. At last applying the delay model as the estimation function, the comparison between timing control mode and bus signal priority control algorithm is done according to intersection application of rough set theory. The result indicates that this algorithm could decrease the average intersection waiting time of passengers by6.86%and the right of bus transport priority at the intersection is protected.3. With the relationship analysis between public transport rate and intersection delay, a intersection benefit model is established with parameters such as total delay of passengers per car, delay per car, exhaust emission per car, which are constructed combined with delay area model. The intersection of zhongguancun south street and south college road is selected as an case. The extend time is distributed reasonably for each phase in fixed and dynamic green time modes. Using dynamic time control mode is better than the fixed time control mode by22.618%on the transit benefit value. Thus the buses would take the priority right under maximizing traffic benefit at intersections.