Driver Response to Roadside Obstacles

Abstract

It is often contended in court cases that a prudent driver when encountering obstacles adjacent to the side of a roadway (e.g., a stopped vehicle or pedestrian) will decrease their speed of travel and/or shift their lane position in order to allow greater margin of safety. A search of the available literature, however, has not produced any validation that this assertion is in fact true, or a quantification of the level of such avoidance maneuvers. This study examined the behavior of drivers in response to four different scenarios involving obstacles adjacent to the roadway: 1) a vehicle parked on the shoulder of the road, 2) a parked vehicle and a visible pedestrian adjacent to it, 3) a pedestrian alone, and 4) a baseline condition with no obstacle present on the roadside. Dependent measures included change in passing vehicle velocity and the displacement of the passing vehicle from the edge of the roadway. The results indicated statistically significant changes in both the speed and lane position of the passing vehicle.