Abstract

Modern traffic management systems increasingly depend on real-time Signal Phase and Timing (SPaT) data generated by Traffic Signal Controllers (TSCs) to support safety, mobility, and emerging connected-vehicle applications. The applications of SPaT outputs require timely and reliable access to such data from the traffic signal controllers. However, these controllers are safety-critical infrastructure and exposing them to external networks introduces significant cybersecurity and operational risks. Thus, there is a need for mechanisms that provide secure, low-latency access to SPaT data without compromising controller integrity. The information flow methods that are used traditionally for connected and automated vehicle (CAV) environments have several security weak points. There exists a need for new communication protocols through which new system implementation paradigms can be evaluated at higher levels of information security. Two previous CCAT projects addressed this need by developing and testing a hardware-enforced data diode architecture and device that enable strictly one-directional extraction of SPaT data from traffic signal cabinets. The system prevents any inbound communication to the controller while allowing real-time data dissemination over existing network paths, requiring no new communication infrastructure. The current study was motivated by the potential use of systems engineering and model-based design to reduce development complexity and cost. The Cubicon design methodology, a new graphical language that translates high-level system behavior into executable software, improving maintainability and architectural clarity, was adopted. The phase of the project implemented a lightweight communication protocol with differential SPaT updates to reduce bandwidth usage and improve scalability. Together, these contributions demonstrate a more secure, efficient, and cost-effective approach for extracting and disseminating SPaT data, supporting both current traffic operations and future connected transportation systems. The research product can have profound and far-reaching impacts. For the hundreds of thousands of signalized intersections that currently exist in the United States, the economical and secure acquisition of SPaT information facilitates critical traffic management functions including red-light violation warnings, signal priority, and trajectory planning.

Keywords

Data diode, Traffic signal controller, Signal phase & timing (SPaT), Smart Cities

DOI

10.5703/1288284318593

Date of this Version

12-2025

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