In-Vehicle Decision Support to Reduce Crashes at Rural Thru-Stop Intersections

Project summary:

More than 30% of all crashes occur at intersections, and a disproportionate number at rural intersections. The proposed project is examining the safety impact of in-vehicle decision support systems (DSS) at rural thru-stop intersections: intersections at which a highway crosses a minor road controlled by a stop sign. Many crashes occur at intersections because even cautious drivers sometimes make poor judgments about when to enter high-speed highway traffic. The DSSs evaluated leverage existing highway infrastructure in which radar installed at intersections measures gaps between approaching vehicles. This information can be relayed to DSSs at the intersection, or in the vehicle.

The researchers conducted a study comparing three different DSS for conveying warnings about oncoming traffic to drivers to help them decide when to pull into the intersection. Using the Human-First driving simulator, driver performance was compared for: 1) an intelligent sign located in the in the intersection; 2) a visual display located on the side-view mirrors; and 3) a haptic warning system consisting of vibrating pads in the driver's seat. The DSS that had the most positive impact on safety margins was the haptic interface, most likely because it got drivers' attention, without requiring them to take their eyes off the road. However, there is still room for improvement in the haptic display; there were instances where they were either surprised by the vibration, or confused about the meaning of warnings. Several focus groups were organized to provide qualitative comments and suggestions on both problems, and possible improvements for these interfaces. Results indicated that a visual display would be easier to comprehend than a vibrotactile display when no training or explanation is provided.