Studying Interactions of Motorists and Vulnerable Road Users: Empirical Comparison of Test Track and Simulator Experiments

Crashes involving vulnerable road users (VRUs) account for nearly 70% of all traffic fatalities in urban areas. To evaluate the effectiveness of measures to improve VRU safety, the causes of accidents attributable to human behavior require investigation, which remains a challenge to date. Experiments for this purpose are often conducted in a controlled environment, such as on test tracks or in driving simulators. In this work, we compared gaze behavior and subjective realism between a test track and two different driving simulators, one using a head-mounted display (HMD-Sim) and one using an LED wall and a full vehicle mockup (LED-Sim). Both on the test track and in the simulator a right turn maneuver was studied in which a motorist turns right and a cyclist goes straight ahead through an intersection. The relevant areas of interest (gaze data) and subjective questionnaires were matched. Results show that shoulder glances were observed significantly more often in the test track experiment, whereas mirror glances occurred more often in the simulators. No difference was observed with respect to the perceived responsibility for safeguarding behavior across the different environments. The simulator study was subjectively perceived more similar to real traffic than the test track based on questionnaire data. The findings presented may facilitate the selection of an appropriate test environment for particular research questions. However, given the differences in the two study designs, further research is needed to make more informed conclusions about the applicability of test track and simulator experiments.