Wi-Fi Honk is a tool that can alert pedestrians and cars to an
impending collision using existing Wi-Fi signals. It’s been
designed to protect those who might be distracted while wearing
headphones and so may not be able to hear traditional audio
warnings such as car horn beeps.
The system works by tapping into existing Wi-Fi connectivity.
Smartphones with Wi-Fi enabled periodically send out short blasts
of information at regular intervals as they search for preferred
Other systems that have tried to do something similar have
relied on dedicated short-range wireless channels that have required
specialised equipment. Wi-Fi Honk relies on putting extra
information into the Wi-Fi beacons about the (Android) phone’s
position as determined by GPS, the speed from the phone’s
accelerometer and direction of travel (from its gyroscope). Phones
send out these beacons every 100 milliseconds by default. Wi-Fi
Honk picks up signals from other devices and then uses a collision
prediction algorithm to work out whether a user needs to be warned
about an approaching car or pedestrian. If a collision is expected,
the app automatically generates alerts that are sent to drivers and
pedestrians using vibrations, sound and on-screen messages.
The group has tested the Wi-Fi Honk system IRL and found that it
could warn drivers about pedestrians who were veering into the road
with sufficient time for them to stop, even at speeds of up to
At the moment, to activate Wi-Fi Honk the user selects within
the app whether they are a driver or pedestrian. However, the group
of computer scientists that developed it — at the University of Missouri, Kansas City
— predicts that it could work as a safety dongle for the
vulnerable — be they elderly or very young. It could also work as
a night-time bicycle safety feature, for example.