Fig. 1. An automated vehicle with an "walking person" external human-machine interface is approaching a zebra crossing in the single pedestrian (left) and group of three pedestrians (right) scenario. Implicit as well as explicit cues are means of communication in driver-pedestrian interaction. With the introduction of automated vehicles (AVs), drivers can engage in non-driving related activities which rise new challenges of communication between AVs and pedestrians. In this context, external human-machine interfaces (eHMIs) are seen as a key contribution in building pedestrians' trust towards AVs by enabling communication between them. However, a research gap exists regarding the communication of AVs and pedestrian groups. In an intercultural study we investigated the impact of the variables eHMI concept and group size on pedestrians' street crossing decisions regarding (1) willingness to cross and (2) trust in AVs. Therefore, German (N = 126) and Chinese (N = 79)participants took part in an online-based video study. The results showed that a "walking person" eHMI had more stable effects with respect to the dependent variables in comparison to a "smiling face" eHMI in both countries. No main effect of group size on a pedestrian's willingness to cross or trust in AVs was found. Nevertheless, qualitative data indicated an effect of group size in pedestrian-AV communication processes. Our results therefore contribute to the investigation of communication between AVs and pedestrian groups.CCS Concepts: • Human-centered computing → Empirical studies in HCI; User studies.

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A significant variable describing the pedestrians' behavior when interacting with vehicles is gap acceptance, which is the pedestrians' choice of temporal and spatial gaps when crossing in front of vehicles. After a review of relevant approaches to measure gap acceptance used in studies, this paper presents a novel approach, which is suitable for the usage in field experiments and allows a natural crossing behavior of subjects. In particular, following a detailed analysis of forces exerted during human gait, an algorithm was developed that is capable of identifying the accurate temporal point at which subjects start crossing as the basis for calculating gap acceptance. Pretest results show the system's stability and reliability as well as the gait algorithm's robustness in determining the correct gap acceptance value. The human gait oriented approach can serve as a basis for designing interaction processes between pedestrians and automated vehicles that are a focus of current research efforts.

This study investigates the impact of initial contact of drivers with an SAE Level 3 Automated Driving System (ADS) under real traffic conditions, focusing on the Mercedes-Benz Drive Pilot in the EQS. It examines Acceptance, Trust, Usability, and User Experience. Although previous studies in simulated environments provided insights into human-automation interaction, real-world experiences can differ significantly. The research was conducted on a segment of German interstate with 30 participants lacking familiarity with Level 3 ADS. Preand post-driving questionnaires were used to assess changes in acceptance and confidence. Supplementary metrics included post-driving ratings for usability and user experience. Findings reveal a significant increase in acceptance and trust following the first contact, confirming results from prior simulator studies. Factors such as Performance Expectancy, Effort Expectancy, Facilitating Condition, Self-Efficacy, and Behavioral Intention to use the vehicle were rated higher after initial contact with the ADS. However, inadequate communication from the ADS to the human driver was detected, highlighting the need for improved communication to prevent misuse or confusion about the operating mode. Contrary to prior research, we found no significant impact of general attitudes towards technological innovation on acceptance and trust. However, it's worth noting that most participants already had a high affinity for technology. Although overall reception was positive and showed an upward trend post first contact, the ADS was also perceived as demanding as manual driving. Future research should focus on a more diverse participant sample and include longer or multiple realtraffic trips to understand behavioral adaptations over time.

In order to create framework conditions for the introduction of highly or fully automated vehicles in Germany, the Federal Ministry of Transport and Digital Infrastructure has drafted a bill to amend the Road Traffic Act and the Compulsory Insurance Act. A key aspect of the bill on automated driving is the introduction of Technical Supervision. This serves as a fallback level and must be able to intervene from the Control Center if necessary. Since future Control Centers for automated vehicles will differ significantly from existing Control Centers in other contexts, an appropriate distribution of tasks between the Technical Supervision and the automated vehicle on the one hand, and between the personnel within the Control Center on the other hand, must first be found. Therefore, this paper describes the requirements for framework conditions, work contents and processes, the necessary tools and the qualification of the employees of future Control Centers, which were identified on the basis of an analysis of the context of use. Since an analysis of existing systems and the participation of actual Technical Supervisors is not possible due to not yet existing Control Centers for highly or fully automated vehicles, the analysis is based on a systematic literature review and an expert workshop.