Studies sponsored by the National Highway Traffic Safety Administration (NHTSA)

In two recent studies with NHTSA, NADS researchers have been examining various aspects of transition of control (TOC) between human drivers and periods of automated driving.

We asked: How does the timing and design of takeover warnings influence how drivers regain manual control? We first looked at the amount of time given to regain manual vehicle control after engaging in a secondary email task during automation. Edge case events (such as a pedestrian walking onto the road or a dead deer on the road) were used to test situational awareness 5 to 10 seconds after the request to intervene (RTI).

What we found: “When the window was 10 or 15 seconds, drivers were typically able to transition back to manual control, although some drivers chose to continue emailing,” said John Gaspar, PhD, director of human factors research. To follow up, in a similar study (Temporal Components of Warning), the team looked at shorter windows (4 to 8 seconds) and the minimum window necessary to successfully make the transition back to manual control.

Next, we wanted to see if we could change behavior to get subjects to detect and respond to those edge cases. We created a brake pulse as part of a request to intervene, which was effective at getting participants to look up earlier compared to a condition with no brake pulse. Earlier disengagement from emailing and looking toward the forward road may be effective in reducing crashes in some edge case situations.