Passenger Expectation to Autonomous Bus HMI in Different Scenarios: A Field Study

The rapid development of autonomous driving technology made it possible to implement autonomous buses (ABs) for public passenger transport. Previous work has shown that for passengers, different autonomous driving scenarios will produce different information expectations. Passengers will have more information needs for unexpected autonomous driving scenarios. And the provision of relevant information can mitigate these negative effects of unexpected behavior. Nevertheless, it remains unclear in which conditions are unexpected scenarios for passengers of ABs, and what information expectations are for different scenarios. Through a semi-structured field qualitative study of 10 passengers, we have obtained seven factors that affect the HMI experience of ABs. Three unexpected scenarios and four reasons why the unexpected scenarios affect the passenger experience are identified. And passengers' expectations of different HMI information for normal and unexpected autonomous driving scenarios. Based on the above results, we proposed HMI information design recommendations for ABs.