The Effects of Edgeline Presence on Performance in a Driving Simulator under Sober and Alcohol-Dosed Conditions

Abstract

Accident studies have identified nighttime conditions on rural roads as particular problems for alcohol-impaired drivers. Uneventful driving is hypothesized to result in progressive degradation of tracking performance and a reduced capability to handle the demands of hazardous locations, such as curves. To address these problems, simulations of continuous roadway treatments (i.e., wide edge lines) and spot treatments for curves (i.e., post delineators, chevron alignment signs, patterned pavement markings, and flashing displays) were evaluated experimentally. Twelve subjects drove a simulator under two conditions of task demand and three levels of BAC (0.0, 0.07, 0.12%). The objectives of the study were to determine the effects of alcohol and task demand on driving performance and to determine if providing enhanced visual information concerning roadway alignment would improve the performance of subjects when sober and/or alcohol-dosed. Alcohol effects were measured in terms of overall scenario performance, which included the number of accidents and speed exceedances, and performance on the approach and negotiation of horizontal curves of varying length and curvature. Curve approach and negotiation behavior were also used to evaluate the effects of the roadway treatments. Specific measures included spot measures of speed and lateral placement taken at eight 100-foot intervals along the curve approach and lateral acceleration and position taken continuously over the fixed portion of the curves. The results presented pertain to the effects of the presence of standard and wide edgelines. The discussion relates current findings to those from a previously conducted study.