The Royal Dutch Touring Club, ANWB, has been using the CAN interface from Beijer in its breakdown vehicles for years, for purposes such as tapping off the vehicle speed signal. At speeds above 50 km/h and if the vehicle has been standing still for longer than 2 minutes, the front flashing lights are turned off. The roof-set incorporating LED units can be controlled at your discretion, according to the requirements of a given situation. For example, the roadside patrol can warn traffic coming up from behind that a vehicle is parked on the hard shoulder, without traffic approaching on the other side of the road being affected.
