CITROEN DS3 Handbook page 159

Active City Brake
Active City Brake is a driving assistance
system that aims to avoid a frontal collision
or reduce the speed of an impact if the driver
does not react sufficiently (inadequate brake
application).
This system is designed to improve
driving safety.
It remains the driver's responsibility to
continuously monitor the state of the
traffic and to assess the distances and
relative speeds of other vehicles.
Active City Brake can in no
circumstances replace the need for
vigilance on the part of the driver.
Never look at the laser sensor through
an optical instrument (magnifying glass,
microscope...) at a distance of less than
10 centimetres: risk of eye injury.
Principle
Using a laser sensor located at the top of the
windscreen, this system detects a vehicle
running in the same direction or stationary
ahead of your vehicle.
When necessary, the vehicle's braking system
is operated automatically to avoid a collision
with the vehicle ahead.
Automatic braking occurs later than if
done by the driver, so as to intervene
only when there is a high risk of
collision.
Conditions for activation
Active City Brake only operates if the following
conditions are met:
● ignition on,
● the vehicle is in a forward gear,
● speed is between about 3 and 18 mph
(5 and 30 km/h),
● the braking assistance systems (ABS,
EBFD, emergency braking assistance) are
not faulty,
● the trajectory control systems (ASR, DSC)
are not deactivated or faulty,
● the vehicle is not in a tight corner,
● the system has not been triggered during
the previous 10 seconds.
157
Safety