Abstract: A device to induce vehicles passing a temporarily speed-reduced road section from passing said road section with high speed, including elongated flexible elements, preferably of rubber, placed on the road surface, said elements having beam members extending from the upper surface in a mainly crosswise direction in relation to the direction of the road and in a parallel relationship to each other, the distance between two adjacent beam members being arranged to create a high frequency of vibrations in a vehicle passing with high speed, said distance being larger for a first element passed by a vehicle, thus creating a lower frequency of vibration acting as a warning to the driver.