Simulation Study of Passing Drivers’ Responses to the Autonomous Truck-Mounted Attenuator System in Road Maintenance

The autonomous truck-mounted attenuator (ATMA) system is a lead–follower vehicle system based on autonomous driving and connected vehicle technologies. The lead truck performs maintenance tasks on the road, and the unmanned follower truck alerts passing vehicles about the moving work zone and protects workers and the equipment. While the ATMA has been under testing by transportation maintenance and operations agencies recently, a simulator-based testing capability is a supplement, especially if human subjects are involved. This paper aims to discover how passing drivers perceive, understand, and react to the ATMA system in road maintenance. With the driving simulator developed for this ATMA study, the paper performed a simulation study wherein a screen-based eye tracker collected 16 subjects’ gaze points and pupil diameters. Data analysis evidenced the change in subjects’ visual attention patterns while passing the ATMA. On average, the ATMA starts to attract subjects’ attention from 500 ft behind the follower truck. Most (87.50%) understood the follower truck’s protection purpose, and many (60%) reasoned the association between the two trucks. Nevertheless, nearly half of the participants (43.75%) did not recognize that the ATMA is a connected autonomous vehicle system. While all subjects safely changed lanes and attempted to pass the slow-moving ATMA, their inadequate understanding of the ATMA is a potential risk, for issues such as cutting into the ATMA. The results implied that transportation maintenance and operations agencies should consider this in establishing the deployment guidance.