Understanding the Impact of Bead Type on Paint and Thermoplastic Pavement Markings

Each year the United States spends approximately two billion dollars maintaining pavement markings. In addition, an impending Federal policy establishing a minimum retro-reflectivity value for pavement markings has driven asset managers to develop performance models to effectively and efficiently manage these high quantity, low cost assets. Research over the past decade has sought to identify and understand the many factors influencing pavement marking degradation. Despite the fact that reflective glass beads are foundational to pavement marking retro-reflectivity, little research has specifically considered the impacts of bead type. The purpose of this study is to quantify the impact that bead type has on the degradation rate of waterborne paint and thermoplastic pavement markings in North Carolina. The results of an average value analysis and Wilcoxon rank sum test support the inclusion of bead type as a significant variable in future degradation models and the following two key findings. First, there is a statistically significant difference in the rate of retro-reflectivity degradation between standard beads and large beads for both thermoplastic and waterborne paint pavement markings. Second, thermoplastic pavement markings with standard beads are more economical than those with large beads in areas that experience snow plow operations