Safety Evaluation of Profiled Thermoplastic Pavement Markings

Chapter 8. Summary and Conclusions

The objective of this study was to undertake a rigorous before–after evaluation of the safety effectiveness of profiled thermoplastic pavement markings applied to edge lines as measured by crash frequency. The study used data from two-lane and multilane roads in two States—Florida and South Carolina—to examine the effects for specific crash types, including total, fatal plus injury, ROR, head-on, sideswipe-opposite-direction, sideswipe-same-direction, wet-road, nighttime, and nighttime wet-road crashes. Only nighttime wet-road crashes, the principal target crash type, exhibited a material change, yielding a CMF of 0.908, which was not unexpected because this was the primary target crash type. Although the estimated CMF was based on a small sample of crashes and was not statistically significant at the 95-percent confidence level, it was consistent between the two States, which suggests its use may be justifiable.

Based on the consistent reduction in nighttime wet-road crashes and estimated with conservative cost and service life assumptions, the B/C ratio relative to flat-line thermoplastic markings was 3.65:1. Applying the sensitivity analysis recommended by USDOT, this value could range from 2.01:1 to 5.04:1. These results suggest that the treatment—even with conservative assumptions on cost, service life, and the value of a statistical life—can be cost effective.

With additional data, future research may provide statistically significant results for those crash types for which a CMF could not be recommended or for which a CMF was insignificant where recommended, as well as more informative analyses to develop disaggregate CMFs that reflect different application circumstances.