The National Cooperative Highway Research Program Report 500, Volume 7: A Guide for Reducing Collisions on Horizontal Curves identifies 13 strategies that potentially could reduce the likelihood of a vehicle leaving its lane and crossing the centerline/leaving the roadway, and/or minimize the adverse consequences of vehicles leaving the roadway at horizontal curves. This article describes how the Federal Highway Administration and state departments of transportation are evaluating a selection of these safety improvements for horizontal curves. The improvements include curve delineation signage, centerline and edgeline pavement markings, centerline and edgeline rumble strips or stripes, and friction treatments for pavement surfaces. The study is considering how these strategies can be applied both individually and in selected combinations to achieve varying degrees of safety effectiveness. Although research is ongoing, findings have shown that curve delineation appears to be a cost-effective strategy. An evaluation of strategies for improving night visibility of curves suggests that streaming light emitting diode delineators offer greater potential safety benefit than standard reflectorized post-mounted delineators. Multistrategy safety improvement evaluations in Iowa, Kansas, Kentucky and Missouri are highlighted. (Author/publisher)
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