A simple methodology for evaluating the robustness of decentralised traffic signal controllers

This is the authors' abstract. We don't add key points for this paper.

Given the computational cost of simulations, many studies test Traffic Signal Controllers (TSCs) in limited scenarios, raising concerns about their generalizability. In this study, robustness refers to a Decentralized TSC's (DTSC) ability to maintain performance across varying traffic levels. Some algorithms excel in free-flow conditions but struggle under high congestion. To address this, we propose a standardised testing platform based on the two-bin model–an abstraction of a grid network–to assess DTSC robustness systematically. We introduce two metrics to quantify robustness by measuring the gap between optimal network flow and actual TSC performance under diverse conditions. The known upper bound of the Macroscopic Fundamental Diagram (MFD) for the two-bin model enables these calculations. We evaluate DTSCs inspired by proportional and Back-Pressure (BP) policies and validate insights using microsimulation in PTV Vissim. This work lays the foundation for standardised TSC evaluations and advancing traffic signal control research.