Two for the road: an exploratory study investigating driver and co-passenger interactions during automation and the transition of control in a level 3 automated vehicle

To explore the impact of a front-seat passenger during SAE level 3 (L3) automation, eighteen established driver-passenger pairings undertook three 30-minute journeys framed as ‘days-out’ in a L3 driving simulator. Participants were reminded of their responsibilities at L3 (as per SAE lexicon), and were given agency to decide what behaviour was acceptable, but were otherwise free to behave as they wished with the only stipulation that they should resume manual control and exit the motorway at the correct junction to reach a specified destination. Distracting behaviours emerged, in the form of participatory activities, that engaged both vehicle occupants in cooperative tasks, such as watching shared content or playing competitive games on a smartphone, and these delayed or disrupted the resumption of the driving task. Supportive behaviours were also evident amongst more loquacious passengers, who assisted with route-finding and keeping the driver awake/alert. Findings provide empirical evidence regarding permissible activities at L3 and can inform in-vehicle design to promote appropriate behaviour.