Effects of a Change in Environment on the Minimum Time to Situation Awareness in Transfer of Control Scenarios

Abstract

From previous experiments, it is known that control must be transferred to the driver in a Level 3 vehicle at least 8 s before the driver passes a latent hazard for the driver to be as aware of the latent hazard as the driver is when glancing continuously on the forward roadway. In these experiments, the driving environment remained consistent throughout the time the automated driving suite (ADS) was engaged, and immediately after control was transferred to the driver. Considering that drivers expect different categories of hazards in different driving environments, a transition to a different environment while the ADS is engaged may impair a driver’s ability to both achieve situation awareness and successfully mitigate hazards. The current experiment examined if 8 s was enough time for drivers to achieve situation awareness and appropriately mitigate hazards when the roadway environment changes while the driver is engaged in a secondary activity that takes his or her eyes away from the forward roadway. Drivers’ eye movements and vehicle metrics were recorded as they completed one of three conditions in a driving simulator: an automation condition where the driving environment remained consistent throughout; an automation condition that contained some transitions to a new environment while the driver engaged the ADS; and a manual driving condition that also contained the same transitions as the latter automation condition. Results suggest that even 8 s is not enough time for drivers to achieve situation awareness and mitigate hazards when the hazards are unexpected.