A signal aspect enforcement method for a rail vehicle includes determining if vehicle position is unknown. The system determines if rail vehicle speed is less than a line-of-sight threshold speed. The system determines the grade of the rail. A worst-case braking distance of rail vehicle is calculated. The signal aspect is determined using a camera system and a beacon system. The system determines if the signal aspect determined by camera system is same as signal aspect determined by beacon system and, if so, determines the route of rail vehicle and speed limit of rail vehicle.