A Longitudinal Simulator Study to Explore Drivers' Behaviour in Level 3 Automated Vehicles

In a longitudinal study, 49 drivers undertook a commute-style journey, with part of the route supporting level-3 automation, over five consecutive days. Bespoke HMIs were provided to keep drivers in-the-loop during automation, and help them regain situational-awareness (SA) during handovers, in a 2×2 between-subjects design. Drivers demonstrated high levels of trust from the outset, delegating control to the vehicle (when available) and directing attention to their own activities/devices. Ratings of trust and technology acceptance increased during the week -- even following an unexpected, emergency handover on day four -- with the highest ratings recorded on day five. High levels of lateral instability were observed immediately following takeovers, although improvements were noted during the week and following the provision of SA-enhancing hand-over advice. Results demonstrate benefits associated with novel HMI designs to keep drivers in-the-loop and improve takeover performance, as well as the necessity of multiple exposures during the evaluation of future, immersive technologies.