The scope of this paper is to advance the use of the on-board computer in preventing accidents when the driver falls asleep. This paper proposes the setup of an interface, which constantly monitors the movement of the eye corners and eyelids, in sequences of eye region images. An iterative algorithm is used to estimate the threshold value of the driver?s eye width interactively. When the gauged value reaches a value lower than the threshold, the driver?s drowsiness is confirmed. The automated crash control system then activates the brakes and cuts off fuel supply, bringing the vehicle to a gradual halt.