Abstract
The development of automated vehicles (AVs) and their integration into traffic are seen by many vehicle manufacturers and stakeholders such as cities or transportation companies as a revolution in mobility. In future urban traffic, it is more likely that AVs will operate not in separated traffic spaces but in so-called mixed traffic environments where different types of traffic participants interact. Therefore, AVs must be able to communicate with other traffic participants, e.g., pedestrians as vulnerable road users (VRUs), to solve ambiguous traffic situations. To achieve well-working communication and thereby safe interaction between AVs and other traffic participants, the latest research discusses external human–machine interfaces (eHMIs) as promising communication tools. Therefore, this study examines the potential positive and negative effects of AVs equipped with static (only displaying the current vehicle automation status (VAS)) and dynamic (communicating an AV’s perception and intention) eHMIs on the interaction with pedestrians by taking subjective and objective measurements into account. In a Virtual Reality (VR) simulator study, 62 participants were instructed to cross a street while interacting with non-automated (without eHMI) and automated vehicles (equipped with static eHMI or dynamic eHMI). The results reveal that a static eHMI had no effect on pedestrians’ crossing decisions and behaviors compared to a non-automated vehicle without any eHMI. However, participants benefit from the additional information of a dynamic eHMI by making earlier decisions to cross the street and higher certainties regarding their decisions when interacting with an AV with a dynamic eHMI compared to an AV with a static eHMI or a non-automated vehicle. Implications for a holistic evaluation of eHMIs as AV communication tools and their safe introduction into traffic are discussed based on the results.
Highlights
With the introduction of automated vehicles (AVs), today’s mobility will undergo fundamental changes
Derived from this, we could not find any negative effects of the static external human–machine interfaces (eHMIs) or the dynamic eHMI variants compared to a non-automated vehicle without an eHMI
The present study looked at non-automated vehicles and AVs with different eHMI interaction designs, which exclusively used light signals, i.e., a LED light band and/or signal lamp
Summary
With the introduction of automated vehicles (AVs), today’s mobility will undergo fundamental changes. In future highly and fully AVs (SAE level 4 and 5), the human driver will be more or less decoupled from the vehicle control [1]. Along with this shift of control, the communication with other traffic participants (TPs), previously performed by the human driver, needs to be substituted by AVs [2,3]. Schieben et al [4] describe today’s dyad of interaction between human drivers and other TPs (e.g., cyclists and pedestrians) shifting to a triad of interaction Within this triad, the main actors are represented by the onboard user (i.e., the former driver), the AV, and other TPs in the driving environment of the AV. Regardless of the existence of a human driver, AVs need to communicate with other TPs in their surroundings in ambiguous traffic situations, enabling a cooperative interaction among all TPs [4]
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