Vehicle Activated Speed Limit (VASL) signs, with a built in dopler radar, measure the speed of approaching vehicle and if speed is higher than certain pre-defined “triggering” speed, signs will be put in a certain working mode and will show different combinations of pictograms/speed limit/text messages. VASL signs are produced in compliance with European standard EN12966. For use on a city streets, regional roads and highways. Modular design ensures simple maintenance by simple replacements of the parts. LEDs with high luminous intensity and long life time. Special system to protect LEDs from temperature peeks that might happen during device operation. Possible brightness control: manual brightness control, brightness control according to actual day time using precise algorithm, brightness control according to external illumination measured by 1 or 2 light sensors and external brightness control. Communication interfaces: RS232, RS485, Ethernet, Wi-Fi, GSM/GPRS. The sign can also show additional text information or activate two or four flashers if the speed is higher than allowed.