Collision warning systems (CWSs) use sensors or video cameras to detect whether a collision may be imminent. Passive systems then warn the driver of the collision, and prepare the vehicle’s passive safety systems for a collision (e.g. pre-tension seatbelts). Active systems will activate the vehicle’s braking in order to avoid a collision. These systems have been identified as being effective to avoid or reduce the severity of both head-on and run-off-road collisions (Austroads 2010d).