Craig Lyon
Published: 2016
Total Pages: 54
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The Federal Highway Administration organized a pooled fund study of 38 States to evaluate low-cost safety strategies as part of its strategic highway safety effort. One of the strategies selected for evaluation was the application of wet-reflective pavement markings. This strategy involves upgrading existing markings from standard marking materials to wet-reflective markings applied as a paint, tape, or thermoplastic material. The purpose was to provide an improved level of retroreflectivity in wet-road conditions. Geometric, traffic, and crash data were obtained for treated freeway sections in Minnesota, North Carolina, and Wisconsin; treated two-lane rural road locations in Minnesota; and treated multilane road sections in Wisconsin. To account for potential selection bias owing to regression-to-the-mean, an Empirical Bayes (EB) before-after analysis was conducted. The analysis also controlled for changes in traffic volumes over time and time trends in crash counts unrelated to the treatment. Intersection-related, snow/slush ice, and animal crashes were excluded from the analysis. For freeways, the combined results for all States indicated reductions in crashes that are statistically significant at the 95-percent confidence level for injury and wet-road crashes, with estimated crash modification factors (CMFs) of 0.881 and 0.861, respectively. For multilane roads, statistically significant reductions were estimated for total crashes (CMF = 0.825), injury crashes (CMF = 0.595), run-off-road crashes (CMF = 0.538), wet-road crashes (CMF = 0.751), and nighttime crashes (CMF = 0.696). For two-lane roads, the sample of crashes was too small to detect an effect with statistical significance for any of the crash types, but there were indications that the treatment had a safety benefit for wet-road crashes. Benefit-cost ratios estimated with conservative cost and service life assumptions were 1.45 for freeways and 5.44 for multilane roads. The results suggest that the treatment -- even with conservative assumptions on cost, service life, and value of a statistical life -- can be cost effective, especially for multilane roads.