Traffic Signal Information Provision Technology for Infrastructure-Based Cooperative Automated Driving

<p>The following three points were identified as requirements for traffic signal information from the standpoints of improving the reliability and availability of automated driving: (1) a maximum margin of error of ±300 msec between the timing of the traffic signal information and the actual traffic signal color, (2) the detection of traffic signal information errors and notification to vehicles when errors occur, and (3) the realization of traffic signal information provision with various traffic signal controls. First, focusing on the vehicle-to-infrastructure (V2I) approach, this project verified the accuracy of traffic signal information and defined failsafe specifications for roadside devices, before then validating the feasibility of functions using prototype units. To improve availability, this project organized a proposal to review the operation of traffic signal controls and carried out validation experiments for traffic signal information with special traffic signal controls on proving grounds and the like. It then expanded the scope of information provision to include emergency vehicle priority (FAST) controls, which are difficult to adopt with traffic signal information provision and pedestrian-operated button controls. Based on these validation results, technical specifications for traffic signal information provision infrastructure using V2I systems were determined. In addition, this project has also begun examining the vehicle-to-network (V2N) approach using mobile circuits as a method of providing traffic signal information without using V2I systems From the 2021 fiscal year onward, validation experiments are planned for V2N systems, with the objective of defining the appropriate provision methods based on the experiment results.</p>