A real-time simulation environment for evaluating traffic signal systems

Features and operating modes of the current generation of actuated controllers have evolved to the point where there is a significant difference between the configuration parameters associated with an actuated controller and the information obtained from traffic signal system optimization packages such as TRANSYT 7F and PASSER II. As a result, TRANSYT 7F and PASSER II give no guidance on the impact or sensitivity of many actuated control parameters on a traffic signal system's performance. Furthermore, none of the current generation of microscopic simulation models is detailed enough to evaluate the effect particular features, such as cycle transition algorithms or return from preemption algorithms, have on overall system performance. To address this need, an enhancement made to the CORSIM package that allows physical controllers to be connected to CORSIM is described in this paper. In this arrangement, CORSIM provides the microscopic simulation and tabulation of measures of effectiveness (MOEs). However, instead of CORSIM emulating controller features, CORSIM sends detector information to the physical controllers and reads back phase indications. This type of simulation is often referred to as hardware-in-the-loop. Since CORSIM tabulates performance MOEs, qualitative before-and-after measurements can be obtained for any hardware conforming to the NEMA TS-1 electrical standard for phase outputs and detector inputs. To validate the performance of this hardware-in-the-loop approach, an evaluation is presented that shows there is no evidence of a significant statistical difference in MOEs between the internal control algorithm and the hardware-in-the-loop control algorithm for both a fixed time and actuated controller.