In order to evaluate the role of edge lines in curve driving we examined steering behaviour in the face of unexpected gradual changes in road geometry. Experienced drivers (N = 13) operating a fixed-base driving simulatorsteered a car along a single-lane (3.80 m or 7.60 m wide) winding road. The experimental track consisted of eight 90_ curves with radii of curvature varying between 75 m and 500 m, separated by 500-m long straight line segments. The model-based nature of the simulator was used to create unexpected online changes in road geometry, implemented through a gradual displacement of one or both edge lines while drivers steered around the delineated bend. Although they regulated their speed as a function of road curvature, drivers were found to consistently cut into and out of the curves. Whenthe edge lines did not move, drivers stabilized their lane position during the 20_û70_ curve segments, adopting a position closer to the interior edge line for the narrower lane width and smaller radii of curvature. Motion of the interior edge line, whether inward or outward, gave rise to systematic changes in lane position, while motion of the exterior edge line didnot affect driving behaviour. Overall, the results point to a visuo-motorstrategy of steering based on zeroing-out changes in the rate of change of angular bearing of the tangent point. (A) Reprinted with permission fromElsevier.
Abstract