Driver/Vehicle Steering Response Latencies

Abstract

A steering maneuver was induced among unalerted drivers by the sudden opening of the door of a car parked near the path of travel. Lateral displacement of 1326 cars was measured unobtrusively. When plotted as a function of the time available for it, the averaged lateral displacement started at a latency of about 1.5 s, reached its halfway point at 2.5 s and its maximum at somewhat less than 4 s. This steering-response function was similar whether measured close to the parked car or 15 m in front of it, and it was independent of the cars' prior speed or lateral position. On the basis of these and consistent earlier results from related experiments, it was recommended that, for safe operation, at least 3 s should be reserved for drivers to respond, by steering, to changes in the road environment.