| Since Webster developed the principle of traffic signal control optimization theory in late 1950, the field of traffic signal timing control has advanced dramatically for the past few decades. These include coordinated actuated control and adaptive control on the basis of advances in the detection and communication technologies. However, existing traffic signal timing optimization programs still focuses on the basic four parameters (i.e., cycle, green split, offset, and phase sequence). In addition, these optimization programs do not consider stochastic variability in drivers' behavior, vehicle entry headway, vehicle mix, and so forth. Even though a few research efforts focused on the use of stochastic simulation models, little research was done in the optimization of traffic signal controller settings (e.g., minimum green time, vehicle extension time, minimum vs. maximum recalls) and detector settings (e.g., location).; This dissertation presents a stochastic traffic signal optimization method that consists of a heuristic simulation model and the microscopic simulation model CORSIM. For the heuristic optimization method, three heuristic methods including a genetic algorithm (GA), simulated annealing (SA) and OptQuest Engine were investigated and finally the GA was selected. The main feature of the GA-based stochastic signal control settings optimization method is the ability to optimize not only Group 1 settings (i.e., cycle length, green splits, offsets, and phase sequences) but also Group 2 (i.e., controller and detector related settings) and Group 3 settings (i.e., volume-density control related settings) in the microscopic simulation environment represented by CORSIM. The performance of the proposed stochastic optimization method was compared with existing signal timing optimization programs including TRANSTY-7F and SYNCHRO under microscopic simulation environment. The results indicate that the proposed method outperformed existing programs in the optimization of the basic four parameters, and also showed that additional controller and detector related settings can further improve the operations of coordinated actuated signal control systems. |
