An on-board vehicle warning system includes a location detecting section, a regulation retrieving section, an incoming message receiving section and a potential violation alerting section. The location detecting section detects respective geographic locations of a vehicle and a forthcoming intersection. The regulation retrieving section retrieves, based on the intersection location, a jurisdiction including local intersection regulation information pertaining to a vehicle position with respect to an intersection boundary at the time of a particular phase transition of a traffic light. The incoming message receiving section receives intersection status information of the intersection containing a geographic location of the boundary and phase information including a current phase and a time to the phase transition of a traffic light of the intersection. The potential violation alerting section estimates a future position of the vehicle with respect to the boundary at the occurrence of the phase transition to determine a potential violation.