US study shows drivers let their focus slip as they get used to driver assistance systems

  • December 3, 2020

Drivers fidget with electronics and take both hands off the wheel more often as they develop trust in assistance systems, new research from the Insurance Institute for Highway Safety (IIHS) and the Massachusetts Institute of Technology’s AgeLab shows.

To investigate how experience with partial automation affects driver disengagement, the researchers studied the driving behaviour of 20 volunteers over a month’s time as they gained familiarity with advanced driver assistance features, examining how often they removed both hands from the steering wheel or took their attention away from the road to do things like use their mobile phone or adjust the controls on the vehicle’s console.

One group of ten drove a Land Rover Range Rover Evoque equipped with adaptive cruise control (ACC), which automatically keeps the vehicle traveling at a speed chosen by the driver while maintaining a pre-established following distance. Another 10 drove a Volvo S90 with both ACC and Pilot Assist, a partially automated system that combines ACC with lane-centring technology that keeps the vehicle positioned laterally in the travel lane – but requires the driver to keep their hands on the steering wheel.

Under the classification system developed by SAE International, the levels of automation range from 0 (no automation) to 5 (fully self-driving). Level 1 systems can assist the driver with one driving task; ACC fits into this category. Level 2 systems, such as Pilot Assist, can assist with two tasks. Level 2 is the highest level of automation available in production vehicles today in Europe.

When the drivers first received the vehicles, there was little or no difference in how frequently they showed signs of disengagement, whether they were driving manually, using ACC or using Pilot Assist. After a month, however, they were substantially more likely to let their focus slip or take their hands off the wheel when using automation, and the impact of Volvo’s Level 2 system was more dramatic than that of ACC alone, according to the study authors.

Earlier this year, IIHS issued a series of recommendations for improving how such systems monitor whether the driver is paying attention and how the systems react when that focus falters.

Based on the results of the research by IIHS, as well as the findings of the Dutch Safety Board investigation, ETSC reiterates its call on regulators to review the current human factors-related requirements for hands-on lane keeping assistance systems such as Pilot Assist, with a view to addressing driver overreliance and mode confusion.