A safety system determines a correspondence between a vehicle and an upcoming traffic signal, and predicts a state of the traffic signal when the vehicle is expected to reach the signal's location. Based on proximity to the signal and speed of the vehicle, the system provides a warning if it determines that the vehicle is likely to proceed contrary to the signal (e.g., a driver is likely to run a red light). The warning is issued to the vehicle about to illegally enter the intersection, to other nearby vehicles and pedestrians, and to the traffic signal itself.