Minimum time to situation awareness in scenarios involving transfer of control from automated driving suite. Paper presented at the 95th annual meeting of the Transportation Research Board TRB, Washington, D.C., January 10-14, 2016.

The current effort was aimed at assessing the impact of vehicle automation on a drivers’ ability to anticipate latent threats and detect materialized hazards on the forward roadway. In particular, the authors were interested in determining the minimum transfer of control alerting time, i.e., the minimum time required after a driver has been out of the loop for an undetermined amount of time (i.e., the autonomous driving suite is in full control, Level 3) for the driver to reacquire the same level of situation awareness that he or she had when in full control of the vehicle. The study was run on a driving simulator. There were five treatment conditions: drivers were either always in complete control of their own vehicle (the control condition) or they were required to resume control (indicated by a tone) either 4, 6, 8 or 12 s before the appearance of a latent hazard (the transfer conditions). While the vehicle was in autonomous mode, the driver was told to perform an in-vehicle task for upwards of a minute and not look up at the forward roadway. The driver’s eye movements were recorded throughout. The simulator study showed that drivers detected nearly 40% more hazards when they were in the control condition as opposed to the 4 s transfer condition. Drivers had to be alerted at least 8 seconds before the location of a potential hazard in order for them to be able to anticipate the latent hazard as well as they would if they were always in control of the car. The results of the study indicate at a minimum how long before control is transferred from the autonomous driving suite to a driver that a driver should be told that a transfer will occur if the driver is going to have full situation awareness. Unlike previous studies, this study both assures that the driver is out of the loop while the automated driving suite is in control and uses a measure of situation awareness (hazard anticipation) that is more closely linked to the actual understanding a driver has of the threats present in a given scenario. (Author/publisher)