Disengagement from driving when using automation during a 4-week field trial

Reagan, Ian J. / Teoh, Eric R. / Cicchino, Jessica B. / Reimer, Bryan / Mehler, Bruce / Gershon, Pnina / Seppelt, Bobbie D.
Insurance Institute for Highway Safety
November 2020

Introduction: A small body of research on the real-world use of commercially available partial driving automation suggests that drivers may struggle with or otherwise lapse in adequately monitoring the system and highway environment, and little is known about key issues such as how behavior associated with system use changes over time. The current study assessed how driver disengagement, defined as visual-manual interaction with electronics or removal of hands from the wheel, differed as drivers became more accustomed to partial automation over a 4-week trial.
Methods: Twenty volunteers drove a Land Rover Range Rover Evoque with adaptive cruise control (ACC), which automates speed and headway, or a Volvo S90 with ACC and Pilot Assist, which combines ACC and continuous lane centering. Instrumentation captured automation use, secondary task activity, hands-on-wheel status, vehicle speed, and GPS location during all trips.
Results: The longer drivers used partial automation, the more likely they were to become disengaged by taking their hands off the wheel, using a cellphone, or interacting with in-vehicle electronics. Results associated with use of the two ACC systems diverged, with drivers in the S90 exhibiting less disengagement with use of ACC compared with manual driving, and those in the Evoque exhibiting more.
Discussion: This study raises further concern about vehicle control and the degree to which drivers remain actively in the loop when using automation. Calls for implementing more robust driver monitoring with partial automation appear warranted — particularly those that track head or eye position.