Design and Evaluation of a Differential Speedometer

Abstract

Differential speedometers are gauges that continually display real-time over/under vehicle speed relative to the current speed limit. Use of these gauges may increase situation awareness and reduce driver workload. The design of such a gauge, however, is critical to its usability and its effect on driver performance. Thirty differential speedometer designs were brainstormed and subsequently down-selected to nine gauges using a heuristic assessment. The selected gauges were then tested for usability in a desktop study. Participants answered questions regarding vehicle speed with respect to the current speed limit using information presented on the gauges. Understanding was assessed by measuring the response time and accuracy of the participants’ response. Subjective ratings of usability and overall gauge preference were also obtained. Results were used to select three gauge designs for future study in a vehicle simulator for the purpose of selecting an optimal design of a differential speedometer.