Traffic Controlling And Optimizing At An Intersection Based On The Cell Transmission Model

With the development of economy and acceleration of urbanization, whether the traffic system is smooth or not becomes an important criterion of a healthy, harmonious, and rapid developed city. Therefore, congestion alleviation and prevention have become plans ahead. In urban traffic engineering, Intersection design and control optimization affect the efficiency of urban traffic network. It is meaningful to promote the efficiency of the intersection. However, due to the influences of geometric conditions, traffic demand distribution and network framework nearby, travelers'behavior and so on, the traffic state is complicated at the intersection. Though the literatures have done a lot of research on this subject, there is still a lot of work remain to do.Based on problems mentioned above, some effective method and strategies of intersection channelization design and signal timing are investigated in this dissertation with the aid of dynamic network traffic flow theory. In addition, these methods are applied into real cases and some further studies are carried out. In detail, the contents of this dissertation are as follows:(1) An intersection channelization method is proposed. Based on the cell transmission model (CTM), a dynamic traffic flow propagation method is given under different channelization schemes. As the criterion, the method of average delay time calculation is also given in this dissertation. Simulation results show that the proposed method can improve the intersection efficiency.(2) Based on the dynamic user optimal conditions, an intersection signal timing method is presented. Different from the existing literatures, balancing the travel times of the travelers from different directions is taken as the objective. The model is meant to optimize the signal design from the view of the travelers, embodied fair among all the travelers, and avoided dissatisfaction in travelers'minds. Therefore, the probability of conflict or accidents can be decreased. Simulation results show that the proposed model and methodology can achieve the optimal signal timing results. Compared to the model with the objective of minimizing the delay time, the model presented in this dissertation has its own advantages.(3) The intersection channelization method and signal timing model proposed are applied into real cases and some further studies are performed. Firstly, the intersection data are collected. The optimal channelization scheme and signal timing result are got under the peak hour traffic demand. Secondly, the influence of traffic demand disturbance on the optimal channelization scheme, traffic under optimal signal and so on is investigated. In addition, traffic under optimal fixed-time signal and that under optimal dynamic signal are compared. The results show that the optimal channelization scheme can decrease the average delay. And optimal signal can balancing the travel times. When traffic demands fluctuate in a range, the optimal channelization scheme has a good stability. The dynamic signal is better than fixed-time signal on real-time equilibrium. When the demand is increasing and in a range of fluctuation, the delay change and the total delay under dynamic signal are smaller than that of the fixed-time signal. The stability is better, too.