Similar accident scenarios occur on the open road. A driver on a motorway or a dual carriageway might be distracted and fail to recognise that the traffic in front of him is coming to a stop. By the time he notices the danger, it is too late for him to apply the brakes and avoid the impact or he may misjudge the braking of the car infront and fail to apply sufficient braking force.
To work at higher speeds, Inter-Urban AEB systems use long-range radars to ‘look’ further ahead of the vehicle (typically 200m).. The radar data is analysed to determine whether or not the vehicle could potentially collide with any obstacles it sees. If so, the AEB system might typically operate as follows: a warning signal is given to the driver to try to alert him to the danger. If the driver does not respond, a second warning may be given (for example a brake jerk or seatbelt tug) and the brakes will be pre-armed for maximum braking. Again, if there is no reaction from the driver, the system will itself apply heavy braking. Some systems also prepare the restraint systems for optimum performance in the impact, for example by pre-tensioning the seatbelts.
Systems fall into this category if they do more than simply warn the driver and operate over the speed range 50-80km/h. Some systems designed to operate primarily at Inter-Urban speeds may also provide benefit in city driving. For example, they may not be able to avoid accidents at low speeds but will be able to warn the driver and provide some mitigation effect. These systems are designed to see other road traffic including, in some cases, motorcycles and trucks. A potential advantage of radar sensors is their ability to function in all weathers and lighting conditions.