Many drivers are “multitasking” when their vehicles are set for partially automated driving, and some are even doing it while staying within the limits of the systems’ attention requirements. That’s according to a new report from the U.S. Insurance Institute for Highway Safety (IIHS) following a month-long study of driver behaviour conducted with the Massachusetts Institute of Technology’s AgeLab that built on three years of data collection.
The studies were done using Volvo’s Pilot Assist and Tesla’s Autopilot system. Both are partial automation systems — nothing currently available to consumers is fully automated. All current systems require drivers to pay attention and be ready to take the wheel at any time.
“The results are a good reminder of the way people learn,” said David Harkey, president of IIHS. “If you train them to think that paying attention means nudging the steering wheel every few seconds, then that’s exactly what they’ll do.”
Drivers using the Volvo system were “much more likely” to check their phones, eat a sandwich, or do other activities than they were when driving without the assist. The study noted that some drivers tended to increase their multitasking over time as they became more comfortable with the system, while others did so right away.
For the Tesla system, many drivers quickly grasped how soon the attention-reminder feature would activate, and they prevented the warnings from escalating into interventions. Some drivers remained distracted until they had to make quick moves to stop the system from alerting them. “This demonstrates why partial automation systems need more robust safeguards to prevent misuse,” Harkey said.
Over the course of the study, the Volvo sedan received two software updates which improved the attention reminders and the lane-centring feature. The volunteers were divided into three groups, with one driving before the updates; one after the lane-centring update; and a third with both the centring and attention updates. All three groups engaged in distracting behaviour, including eating, using electronics, and personal grooming. All also did this more often when using the Pilot Assist system, regardless of how often they drove with it activated.
The first two groups tended to become more distracted during the second half of the month, suggesting they “became bolder or more complacent as they got used to the system.” The third group, with both updates installed, tended to perform secondary tasks right from the start, and spent more than 30% of their time distracted while using the system.
Volunteers in the Tesla group had never used Autopilot or any other partial automation system. While the Volvo drivers were primarily studied for how comfortable they became with driving distracted, the Tesla study looked at how often the drivers triggered the Autopilot’s attention reminders, escalated warnings, and emergency slowdown and lockout features.
The study was done with a 2020 Tesla Model 3, which exclusively used a torque sensor in the steering wheel. It would issue a warning if it detected that the driver’s hands were not on the wheel. If the driver didn’t respond – by making a slight steering adjustment, toggling a dial on the wheel, or tapping the turn signal stalk – the system escalated with visual and audible alerts, and finally would bring the vehicle to a stop and lock out the Autopilot for the remainder of the trip.
The volunteers drove slightly more than 12,000 miles (19,312 km) with Autopilot on, and during that time, triggered 3,858 warnings. About half occurred when drivers had at least one hand on the wheel, but didn’t move it enough to register with the torque sensor. Most drivers responded within three seconds, usually by nudging the wheel, and most warnings did not escalate. Some did, though — 16 warnings went all the way to the driver being locked out, with 12 of these attributed to one driver.
Over the month, the rate of initial reminders increased by 26%, but the escalations fell by 64%. Meanwhile, the percentage of time drivers were distracted in the periods around the alerts increased, while the length of time the alert went on decreased. The researchers found that drivers looked away from the road, performed other activities, or had both hands off the wheel more often during the alerts and for ten seconds before and after them as they learned how the reminders worked. The longer they drove with Autopilot, the less time it took for them to take their hands off the wheel once they had touched it to turn off the alert.
While the IIHS said the safety impact of that behaviour change is hard to measure, it pointed to other research that shows the odds of being involved in a crash increase the longer a driver’s attention wanders; and it’s possible that at some point, even “short lapses of attention become so frequent that the periods of supposed engagement between them have little value.” In other words, if you’re constantly doing something other than paying attention while driving, it really doesn’t improve your safety if you occasionally look up to see what’s happening.
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