Location and Configuration of Passing Lanes

Kansas State University conducted a study of passing lanes on major two-lane highways in Kansas. Passing lane location and configuration are among the crucial design factors that may affect the operation and safety of two-lane highways containing passing lanes. The literature suggests that passing lanes should not be located where crossroad intersections exist. Yet a traffic conflict study of Kansas passing lane locations found that the mean traffic conflict level at crossroad intersections located within the passing lane was lower than it was at a similar intersection on a two-lane highway outside the passing lane sections. Crossroad intersections may be tolerated within passing lanes if they are not in the laneaddition and lane-drop areas of the passing lane and if turning volumes are relatively low. Based on traffic simulation, there was no evidence that tail-to-tail passing lane configurations are better than other configurations, as claimed in the literature. However, the difference in percent time delay between different passing lane configurations was found marginal from a practical point of view.