Engaging with Highly Automated Driving: To be or Not to be in the Loop?

This desktop driving simulator study investigated the effect of engagement in a reading task during vehicle automation on drivers’ ability to resume manual control and successfully avoid an impending collision with a stationary vehicle. To avoid collision, drivers were required to regain control of the automated vehicle and change lane. The decision-making element of this lane change was manipulated by asking drivers to move into the lane they saw fit (left or right) or to use the colour of the stationary vehicle as a rule (blue – left, red – right). Drivers’ reaction to the stationary vehicle in manual control was compared to two automation conditions: (i) when drivers were engaged and observing the road during automation, and (ii) when they were reading a piece of text on an iPad during automation. Overall, findings suggest that drivers experiencing automation were slower to identify the potential collision scenario, but once identified, the collision was evaded more erratically and at a faster pace than when drivers were in manual control of the vehicle. Short (1-minute) periods of automation used in this study did not appear to impede drivers’ ability to complete simple operational and tactical-level driving tasks, following a system initiated take-over request. Results suggest that until there is an effective strategy to help drivers regain situation awareness during the resumption of control from Highly Automated Driving, they should be encouraged to remain in the driving loop.