  This paper presents the results of real-world testing of human-vehicle
interactions with an autonomous vehicle equipped with internal and external
Human Machine Interfaces (HMIs) in a crosswalk scenario. The internal and
external HMIs were combined with implicit communication techniques using gentle
and aggressive braking maneuvers in the crosswalk. Results have been collected
in the form of questionnaires and measurable variables such as distance or
speed when the pedestrian decides to cross. The questionnaires show that
pedestrians feel safer when the external HMI or the gentle braking maneuver is
used interchangeably, while the measured variables show that external HMI only
helps in combination with the gentle braking maneuver. The questionnaires also
show that internal HMI only improves passenger confidence in combination with
the aggressive braking maneuver.
