Prior research has shown that novel, perceptually-based delineation techniques (such as altered delineator height, distance from the roadway edge, and specialized road markings) can increase drivers perception of roadwaycurve sharpness. On the basis of such research as well as theories of visual perception, this research tested whether manipulating the size and position of roadway delineation signage could increase drivers perceptions of roadway curvature and positively impact drivers behavior (e.g., to reduce speeds when approaching and traversing curves). A driving experiment and image-based surveys were conducted to determine drivers perception of curvature and their driving behavior when approaching curves having variousdelineation treatments. Modifying the standard positions of delineators along a curve to resemble a sharper curve did not produce any measurable effects on sharpness ratings or behavior. The size of the delineators had a statistically significant effect on perceived sharpness, but not on driverbehavior. However, several statistically significant correlations betweenperceived sharpness and driver behavior were found. The image-based sharpness perception study further revealed that the apparent vertical distancebetween the upper visible edge of the road pavement and the bottom of thefurthest visible delineators was significantly correlated with perceived sharpness. Although changes in size appeared to provide small but measurable effects on sharpness perception, the relative sign height probably had a stronger effect on sharpness perception than size.
Abstract