Introduction. In road safety, one of the most challenging tasks is speed control. The critical road sections that incorporate with horizontal and vertical curves, providing speed limit information based solely on the posted speed limit is not sufficient to mitigate the risk of collision. In addition, temporary and permanent sight obstruction could represent a major problem for drivers to stop the vehicle before an unexpected obstacle. To address this problem, Intelligent Speed Adaptation for visibility (V-ISA) system has been introduced, which is an in-vehicle system, prevailing three variants (informative, warning and intervening), that supports the driver in adopting a safe speed based on prevailing sight conditions.