Research On Arterial Road Signal Control Optimization Method Under Oversaturated State

Urban road traffic arteries construct the skeleton of urban transport network. Its operational conditions affect the normal operations of the network. Especially in urban central business district(CBD), land development intensity is so high that caused the traffic flow operated under the capacity of artery traffic network. In addition, the impact of pedestrian crossing and other uncertainties, further deteriate the signal coordination program of the arteries. Under such condition, the lower classes of road cannot effectively play their role for serving the traffic circulation in the roadway network, which eventually led to the regional traffic grid-lock. Applying traditional signal optimization methods aiming at balancing traffic flows from all directions can no longer solve the traffic congestion under with saturated flow. This paper focuses on signal optimization algorithm along urban artery to improve the saturated or over-saturated traffic flow under the influences of pedestrians or other friction factors.Firstly, this thesis conducted the literature review on traffic signal control methods under oversaturated condition. Through which, the advantages and disadvantages of various traffic signal control methods are summarized, and corresponding improvement are proposed to improve the signal control method.Secondly, this thesis combined the classic traffic signal control theorywith the real-world signal control experience to propose a practical signal optimization approach with its method and application procedures. It aims at solving the traffic control problems with an effective signal control strategy under oversaturated condition. The method is based on the queue length estimation model. By assessing the correlation between the upstream and downstream signal phases, this thesis proposes a signal timing optimization method to optimize the traffic flow operations along the artery of CBD.Finally, a microscopic traffic simulation model is developed utilizing a prevailing micro-simulation package, PARAMICS software since it provides a pedestrian module and allows customized program of signal control strategies. Thus, the proposed signal control optimization method is evaluated based on the simulation model.