Microscopic Modeling of Traffic Signal Operations

Abstract

Currently, there are three different methods to model traffic signal operations in microscopic simulation models: the simulation model's controller emulator, hardware-in-the-loop simulation, and software-in-the-loop simulation. Although all three methods can be based on the same industry standard code, their different implementations suggest potential operational differences. This study investigates operational differences of the three methods by examining how each method operates in five experimental scenarios. Each of the scenarios differs from the others in network size (one intersection to five intersections) and operational strategies (pretimed, actuated, actuated–coordinated, and two different signal transition logics). Ten 75-min simulation runs with 100-ms simulation resolution were executed for each experiment with the three signal control modeling alternatives. The results showed that for basic signal control operations, such as pretimed and isolated actuated operations, the three alternatives provided similar results as indicated by the average green time allocation and different operational measures of effectiveness. When advanced controller operations were used, such as signal transition logic, the simulation model emulator showed significantly different behavior than that observed in hardware-in-the-loop and software-in-the-loop simulations.