Hardware-in-the-Loop Simulation Evaluation of Adaptive Signal Control

Abstract

Increasingly, adaptive signal control and other nontraditional solutions are being implemented in an attempt to improve signal system efficiencies, reduce congestion, enhance signal control responsiveness to incidents, and reduce signal-retiming costs. However, neither field nor simulation studies alone have proven sufficient to evaluate such systems. To overcome the limitations of field data or simulation-only studies, hardware-in-the-loop simulation (HILS) or software-in-the-loop simulation (SILS) may be used. HILS and SILS provide a means for realistic testing, under controlled and repeatable conditions, of signal strategies not directly emulated in a simulation model. This paper presents the initial findings of a HILS evaluation of ACTRA [i.e., semiactuated, coordinated, time-of-day (TOD)] and adaptive signal control on an 11-intersection arterial section. The HILS test bed generally provides a reasonable representation of both TOD and adaptive signal control performance. However, the adaptive a.m. HILS results contain some unexpected behaviors not observed in the field. The initial findings of the signal control comparison indicate that during peak conditions both control strategies provide similar performance; however, during the hours bordering the peaks, adaptive control is likely able to provide control more tailored to the current conditions.