Abstract

Cost-effective ways to obtain and distribute traffic data, and thereby, to facilitate operations decisions. This includes a need to make Signal Phase and Timing (SPaT) and MAP data more useful to traffic data end-users. Existing data collection and delivery methods are time consuming and costly. Therefore, to facilitate traffic operations in the current era of human-driven vehicles (HDVs) and the prospective era of connected autonomous vehicles (CAVs), this research developed a device to acquire, process, and disseminate SPaT data from Traffic Signal Controller (TSC) cabinets in a manner that ensures system integrity and yet fosters accessibility of timing information for traffic data end-users. The device, referred to as a “Data Diode,” consists of two interconnected microcontrollers operating through simplex communication (one-directional data flow). The device connects the TSC cabinet and end-user devices (such as a userheld device (UHD)). The process begins with one microcontroller connectin g to the TSC’s Ethernet port. Then, using the Simple Network Management Protocol (SNMP) interface, the device securely acquires the SPaT data which then undergoes Cyclic Redundancy Check (CRC) encoding to ensure integrity protection and subsequently transmitted through a unidirectional UART interface to the second microcontroller. No SNMP commands can be passed back to the signal controller from the Internet. The interface cannot be used as an attack surface. The second microcontroller interfaces with a 4G Cell Modem to transmit the processed SPaT data to the NATS open-source messaging system, incorporating a unique identifier specific to each TSC. A battery of such TSC-Diode systems collect such data from various intersections, and the collected data are routed through their respective channels within the NATS system. A backend script acquires GPS coordinates from the UHD, pinpointing the nearest traffic intersection. Leveraging this information, the script retrieves relevant SPaT data from the database associated with the corresponding TSC. The user is granted access to this data through a user-friendly web app on their UHD . The app dynamically presents real-time information about the traffic signal status and precise timing of signal phase transitions for the lane of interest. Overall, the integration of this technology into human-driven or connected autonomous vehicle driver assistance systems can help smoothen arterial traffic flow and transform urban mobility.

Date

11-2023

DOI

10.5703/1288284317731

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