A New Hardware-in-the-Loop Traffic Signal Simulation Framework to Bridge Traffic Signal Research and Practice

In this paper, we present a new hardware-in-the-loop traffic signal simulation framework, which is referred to as HILS-NG. With this proposed framework, pioneering traffic signal control strategies proposed by researchers can be separated from traffic simulation engine while interacting with simulations as independent applications via standard traffic control communication. The advantages of this new framework include the following. First, pioneering traffic signal logic only needs to be programmed once for simulation, and the same code can be deployed to the field with minimal porting efforts. Second, control algorithms are hosted in supplemental hardened single-board computers (SBCs) do not require replacing traffic signal controllers in the field; therefore, the proposed framework will not compromise the existing signal safety protections in signal cabinets, such as phase conflict monitor. We expect that this new framework will greatly facilitate the prototyping and field tests of new traffic signal control strategies for scholars and practitioners. To further demonstrate the potential of this new framework, in the second part of this paper, we utilize an industrial communication standard for traffic signal controllers in North America, i.e., the National Transportation Communications for ITS Protocol (NTCIP), to set up real-time communications with a full-scale traffic signal emulator in simulation and then develop and evaluate a set of innovative e signal control strategies. A set of new signal control strategies is also presented to demonstrate how to design control functions and the corresponding NTCIP communication stacks.