Publication

How do drivers change their behavior with increased experience of automated driving?

To explore driver behavior in highly automated vehicles, independent researchers are today mainly using driving simulators and conducting short experiments. This limits the ability to explore realistic driver behavior and how it changes over time.

This study focused on a method development experiment that combines subjective and objective data to capture effects of repeated interaction between drivers and highly automated vehicles. Each driver (n=8) participated in the experiment on two different occasions with one-week interval. On both occasions, the drivers traveled approximately 40 km on a rural road, and encountered various traffic situations. They could engage automation, or choose to drive manually. When engaged, the automation was able to handle all situations on the road without requiring the driver do any maneuvering or monitoring.

Examples of data collected include: vehicle state, driver biometrics, eye behavior, self-reported feeling of safety, as well as interviews and questionnaires capturing general impressions, trust and acceptance.

The study was conducted at the AstaZero proving grounds in Sweden by the Research Institutes of Sweden (RISE), Volvo Cars and Smart Eye.

The preliminary results show that the first encounter effects were attenuated over time. The drivers went from being exhilarated (”fun”, ”cool”, ”impressive”) on the first occasion, to a more neutral state (”positive”, ”safe”, ”good”, “relaxed”) on the second occasion. Furthermore, there were smaller variations in drivers’ self-assessed perceived safety on the second occasion, and drivers were faster to engage in non-driving related activities and become relaxed (e.g., they spent more time glancing off road and could focus more on non-driving related activities such as reading). These findings suggest that exposing drivers to automated driving on two successive occasions may give more informative and realistic insights into driver behavior and experience as compared to only one occasion.

The study identified a few different parameters that seem to indicate the shift in driver behavior from being tense to being relaxed including glance time off-road, perceived safety, and time to engage in non-driving related tasks. However, these insights are difficult to generalize due to the limited data sample. In the next step, the method will be refined and explored with a larger number of drivers, and in more dynamic traffic situations.

The study was funded by SAFER Open Research at AstaZero, the Strategic Vehicle Research and Innovation (FFI) and the Knowledge Foundation (KK-stiftelsen).