Evaluating the Impacts of Workmanship and Chemical Composition on Pavement Marking Retroreflectivity Degradation

Abstract

Pavement markings must exhibit adequate retroreflectivity and durability to ensure they enhance traffic safety. Several previous studies investigated factors that influenced marking retroreflectivity and durability. Yet, a significant knowledge gap exists in the literature with respect to the effects of workmanship and chemical composition on pavement marking performance. This is because controls were implemented in previous studies to ensure that markings were applied correctly, which represented ideal conditions that are not present in real-world scenarios. Therefore, the objective of this paper was to quantify the impacts of workmanship and marking chemical composition on the retroreflectivity and durability of water-borne paints and thermoplastic pavement markings. To achieve this objective, six field experiments were conducted in Pennsylvania to understand how the performance of pavement markings was affected by the marking film thickness, glass bead drop rate, glass bead application method, pigment volume concentration (PVC) of paints, and paint binder type. In the field experiments, the durability, edge retroreflectivity, and wheel-track retroreflectivity (R_W) were monitored at four different intervals. Key results indicated that the R_W of water-borne paints can significantly change, by up to 100%, because of variations in binder type, film thickness, PVC, and/or bead application method. These findings highlight the importance for state departments of transportation to include specifications for key factors such as paint binder type, paint PVC, film thickness, and bead application methods in their standards. The findings also emphasize the necessity of implementing data-logging practices to help road authorities verify that contractors apply pavement markings while ensuring adherence to specified standards.