Continuous Flow Progression Theory And Methods

Traffic congestion in urban network is a severe and growing problem, which leads to a strong reduction in network reserve capacity. Appropriate traffic signal control strategy can relieve traffic congestion. Because of this, making research on traffic signal control seems important and meaningful. Considering the characters of traffic signal control, combing with the concept of continuous flow (CF), this dissertation has researched and discussed in the following areas, including continuous flow progression (CFP) for under-saturated conditions, CF for over-saturated conditions, and application and evaluation of CFP technology.For under-saturated conditions, problems existing in MAXBAND are improved or revised as follows:In order to avoid the problem of limitation in bandwidth optimization that caused by using the centerline to calculate the bandwidth with MULI-BAND method, An MILP model with a new green wave style is established which generates variable bandwidth scheme in which each directional road section is allocated an individual weighted band that can be adapted to the traffic flow on that link. Considering that MAXBAND cannot get a feasible solution when constraint sets are empty, bandwidth proration impact factor and bandwidth demand ratio are proposed for a better control effect in bandwidth maximization. With these two parameters, the proposed model guarantees to maximize the total bandwidths with priority given to the direction with higher bandwidth demand. According to the problem that an artery with a double cycle intersection cannot be designed with the traditional progression method, an algebraic method is presented for dissymmetry signal design model, and a model method is established for symmetry signal design model.For over-saturated conditions, this dissertation analyzes the significance of red wave control, three major cases of implementation, and principle of dispersing traffic pressure. Delay model for an intersection, and coordinated control model for network are established basing on arrival and departure diagram for under-saturated and over-saturated conditions.This dissertation proposes that traffic signal control should be designed basing on the concept of CF and different control strategies should be implemented in under-saturated and over-saturated conditions separately. It also points out the problems existing in MAXBAND model and gives its approach to them. Control policies under over-saturated conditions are red wave for external district and minimizing total delay for internal district. Apart from these, Area traffic control is implemented by dividing road network to arterials and then linking them together based on the idea of coordinated step by step and all-inclusive.