Road safety barrier assembly has a barrier and an electric circuit that can be supplied with direct current. The circuit includes an outward electric cable and a return electric cable, and sensors along the barrier for detecting impact of a vehicle against respective portions of the barrier, each sensor causing upon impact detection a switching of electric current from the outward electric cable towards the return electric cable at the respective portion of the barrier. A device is arranged so as to measure a voltage value between the outward electric cable and the return electric cable upstream of the sensors. A control unit is predisposed to receive a signal indicating the voltage value measured by the voltage measuring device and is configured to calculate the distance between the voltage measuring device and the location of impact against the road safety barrier, by applying Ohm's Law.