Improving Passing Lane Safety and Efficiency for Alaska's Rural Non-divided Highways

A series of experiments using a fixed-base driving simulator were conducted to examine the potential safety and operational benefits of several highway safety interventions for reducing collision risk. The approach sought to go beyond typical mitigations of collision risk that use explicit behavioral interventions, such as enforcing lower speed limits (regulation) and public education (safety warnings). Instead, the authors examined whether semi-permanent alterations to the visual appearance of the unsafe zones might implicitly reduce risky driver behaviors by slowing traffic and inducing better passing decisions without drivers being consciously aware that their behavior is being affected. Such implicit changes in behavior may be more efficient and long-lasting since they do not require conscious compliance from drivers nor engagement from law enforcement. Taken together, the results of the experiments clearly show that regulatory signs early in a passing zone that limit the speed of right-lane drivers relative to left-lane drivers offer the greatest opportunity for increasing the efficiency—and perhaps also the safety—of rural passing zones.