  This study presents the outcomes of empirical investigations pertaining to
human-vehicle interactions involving an autonomous vehicle equipped with both
internal and external Human Machine Interfaces (HMIs) within a crosswalk
scenario. The internal and external HMIs were integrated with implicit
communication techniques, incorporating a combination of gentle and aggressive
braking maneuvers within the crosswalk. Data were collected through a
combination of questionnaires and quantifiable metrics, including pedestrian
decision to cross related to the vehicle distance and speed. The questionnaire
responses reveal that pedestrians experience enhanced safety perceptions when
the external HMI and gentle braking maneuvers are used in tandem. In contrast,
the measured variables demonstrate that the external HMI proves effective when
complemented by the gentle braking maneuver. Furthermore, the questionnaire
results highlight that the internal HMI enhances passenger confidence only when
paired with the aggressive braking maneuver.
