Still fit to drive? Effect of car sickness on takeover and driving performance – A test-track study

Abstract

In automated driving, car sickness may occur as a new driver state as drivers become passengers during automation. Given previous findings of cognitive impairments due to motion sickness, which could lead to safety critical behavior in takeover situations, the aim of this study was to understand if and how car sickness affects takeover and subsequent driving performance. In a wizard-of-Oz test-track study, N = 33 participants experienced a car sickness and a baseline condition without car sickness. Car sickness was induced by a dynamically simulated automated drive during which participants engaged in an NDRT. In both conditions, four takeover requests were triggered followed by four driving tasks: emergency braking, target braking, free speed slalom and a 25 km/h slalom. Driving with car sickness subjectively impaired the driving performance and was perceived as significantly more critical and demanding. Subjective fitness to drive decreased significantly with increasing car sickness (r = 0.601, p < 0.001). However, objective performance measures did not reflect these subjective impairments, showing no significant adverse effects on takeover times, emergency braking reaction times, distance to target position or slalom performance. Nevertheless, participants drove significantly faster with car sickness, contrary to participants’ report of reducing speed. To conclude, based on the objective data car sickness is unlikely to be a critical driver state, however subjectively it may be. Driving with car sickness appears to be more of a comfort issue than a safety issue. These results should be replicated with more realistic driving scenarios and with longer sustained driving performance.