testing environment and verification procedure for in-car tasks with ...

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4 International Driver Distraction and Inattention Conference, Sydney, New South Wales, November 2015

TESTING ENVIRONMENT AND VERIFICATION PROCEDURE FOR IN-CAR TASKS WITH DYNAMIC SELF-PACED DRIVING SCENARIOS Tuomo Kujala and Jakke Mäkelä, University of Jyväskylä, Department of Computer Science and Information Systems, Finland ABSTRACT The Visual-Manual NHTSA Driver Distraction Guidelines for In-Vehicle Electronic Devices were published in 2013. The NHTSA testing scenario comprises of driving with a steady speed on a straight highway while keeping a constant distance to a lead vehicle. However, the distraction effects of, for instance, navigation aids cannot be reliably tested within the scenario. Real-world driving scenarios with guidance include turns as well as lane selections with the associated deceleration and acceleration behaviors. In addition, the safety risk of a 2-second in-car glance (NHTSA criterion) is highly dependent on the driving speed. Consequently, we created an alternative test environment and in-car glance duration verification criteria for dynamic and selfpaced driving scenarios. By the means of visual occlusion, we collected the preferred occlusion distances of 97 drivers with varying backgrounds in a driving simulator simulating real Finnish suburban and highway roads. The results indicate that for each point of the road, it is possible to define occlusion distances that drivers are not willing to exceed while fully concentrating on the driving. We show that these dynamic verification limits and the generic method can be used for testing in-car tasks in dynamic driving scenarios where the drivers can freely adjust their speeds.

INTRODUCTION In 2013, National Highway Traffic Association (USA) published the Visual-Manual NHTSA Driver Distraction Guidelines for In-Vehicle Electronic Devices (NHTSA, 2013). The Alliance of Automobile Manufacturers (AAM) had published their own guidelines in 2006, on which the testing procedure and the verification criteria of NHTSA (2013) are partly based on. These kinds of guidelines are important for regulating in-car applications, of which user interfaces a driver cannot use in a safe manner in a moving vehicle without a significant risk of distraction. However, empirical studies have indicated several points of criticism towards the current NHTSA (2013) guidelines, in particular. The critical analyses have indicated that there can be simulator-specific variability in the visual demands of the NHTSA driving scenario, affecting the visual behaviors of the test participants (Kujala, Lasch, & Mäkelä, 2014), and that in-car tasks may fail to meet the proposed individual glance duration criteria simply because of normal variability in the driver population’s visual sampling skills or strategies rather than to poor in-car user interface design (Broström, Aust, Wahlberg, & Källgren, 2013). In addition, NHTSA (2013) testing scenario comprises of driving with a steady speed on a straight highway while keeping a constant distance to a lead vehicle. It can be argued that the distraction effects of, for instance, navigation aids cannot be reliably tested within the scenario. Real-world driving scenarios, in which the guidance is most typically used, include turns as well as road and lane selections with the associated deceleration and acceleration behaviors. AAM (2006) guidelines are much more imprecise than NHTSA’s (2013) on the suggested driving scenarios but it seems that similar highway scenarios with low or moderate traffic density are recommended. The NHTSA (2013) guidelines have three verification criteria for in-car tasks: 1. Individual off-road glance durations: “For at least 21/24 participants, no more than 15 percent of the total number of glances away from the forward road scene have duration of > 2.0 s.” 2. Mean off-road glance duration: “For at least 21/24 participants, the mean duration of all glances away from the forward road scene is