Driver Situation Awareness and Perceived Sleepiness during Truck Platoon Driving – Insights from Eye-tracking Data

ABSTRACT

Truck platoon driving technology uses vehicle-to-vehicle communication to allow one truck to follow another in an automated fashion. The first vehicle is operated manually, the second vehicle is driven semi-automatically once platoon-mode is activated. In this mode, the driver merely has to monitor traffic. Semi-automated driving in passenger cars has been shown to increase driver sleepiness and reduce situation awareness. The aim of the present study was to gain first insights whether this also applies to semi-automated platoon driving and whether platoon-specific situations pose special visual demands. In a first on-road experiment, ten professional truck drivers experienced a two-vehicle platooning system on a German highway as platoon follower or leader. In addition, all drivers conducted reference drives with a single truck. Driver situation awareness was measured with eye-tracking recordings, perceived sleepiness with subjective ratings. The results showed that the lead vehicle drivers kept their eyes less time on the road ahead as compared to normal truck driving. In particular in situations that required decoupling, drivers (in the lead vehicle as well as in the following vehicle) spent about 40% of fixations on the HMI. That is, situation awareness was reduced, amounting to potentially risky behavior, as the platoon goes blindfolded when both drivers attend to the display. Drivers did not report higher perceived sleepiness in semi-automated platoon drives than in the manual reference drives. Adequate solutions to reduce the time spent looking away from the road are required. Head-up displays should be investigated for this purpose, as they can simplify driver communication and present platoon-specific information while the eyes remain on the road.

Acknowledgments

We thank the research consortium consisting of MAN Truck & Bus AG, DB Schenker and Hochschule Fresenius for making the test drives on highway A9 possible. The experiments were part of the dissertation work by Sarah-Maria Castritius at the Department of Psychology, Mainz University, Germany.

Additional information

Funding

This research was conducted within the research project “Elektronische Deichsel – Digitale Innovation” (electronic drawbar – digital innovation) funded by the German Federal Ministry of Transport and Digital Infrastructure [funding code: 16AVF1031B].

Notes on contributors

Sarah-Maria Castritius

Sarah-Maria Castritius is an Applied Psychology researcher, who finished her PhD at Johannes Gutenberg-Universität, Mainz in 2020. Her research focuses on human-machine interactions (e.g. physiological effects of truck platoon driving, technology acceptance). She is now working as human factors engineer and user experience specialist at Robert Bosch GmbH.

Patric Schubert

Patric Schubert is a statistician and data scientist at the Hochschule Fresenius (Idstein, Germany). His main interest is based on complex system dynamics and algorithms. Research projects he is working on deal with human machine interactions in autonomous driving, applications of artificial intelligence and system behavior in logistics.

Christoph Dietz

Christoph Dietz is a physiotherapist with degrees from University of Applied Sciences Fresenius, Idstein (Bachelor of Science in Physiotherapy and Master of Science in Therapy Sciences). He is currently a PhD student in the mobility and logistics cluster and focusses on human-machine-interaction, human factors and neuromechanics.

Heiko Hecht

Heiko Hecht holds the chair of Experimental Psychology at the Johannes Gutenberg-Universität Mainz, Germany. His research focusses on picture perception and virtual reality, artificial gravity, time-to-contact estimation, and intuitive physics as well as on applied aspects of driving simulation and cybersickness.

Lynn Huestegge

Lynn Huestegge is a professor of “Psychological Research Methods” at Würzburg University. He completed his PhD at Bielefeld University and worked as a postdoc at RWTH Aachen. He works on attention (oculomotor control), cognition, and action control in basic and applied research fields (e.g., human-machine interaction and automation in traffic psychology).

Magnus Liebherr

Magnus Liebherr is a postdoctoral researcher at the University Duisburg-Essen. He holds a doctoral degree in psychology. His research mainly focuses on the topics of human-machine interactions (e.g., driver-assistance systems, autonomous driving, smartphone usage), cognitive functions (e.g., attention, inhibition, self-regulation), as well as cognitive trainings and mindfulness interventions.

Christian T. Haas

Christian T. Haas is Professor of quantitative research methods at Fresenius University and Director of the Institute of Complex System Research. His research topics are human-machine-interactions, neurophysiology of human behavior, digital-transformation and autonomous-systems. He is a member of the research board of the Association of German Transport Companies.