Determination of Pavement Marking Friction Levels and an Equivalent Wear Model Correlating Laboratory Polishing with Field Traffic Conditions

Abstract Pavement marking friction is a critical factor in roadway safety, especially for vulnerable users such as pedestrians, bicyclists, and motorcyclists. However, standardized testing procedures and performance criteria remain undeveloped in the United States. The absence of a laboratory-to-field polishing equivalency relationship further hinders this process. To address these gaps, this study correlates laboratory polishing with field traffic conditions by establishing a systematic friction-level classification and developing an equivalent wear model. Building upon prior research, this work examines the friction performance of 23 pavement marking-additive combinations, encompassing six marking materials, three glass bead sizes, ceramic particles, and three antiskid particle sizes. Friction is measured by the British Pendulum Tester (BPT) and the dynamic friction tester (DFT), with simulated wear applied using the three-wheel polishing device (TWPD). Based on the Fuzzy C-Means (FCM) clustering analysis and engineering interpretation, three British Pendulum Number (BPN) levels are defined: 35 ≤ BPN < 45 (Level 1), 45 ≤ BPN < 60 (Level 2), and BPN ≥ 60 (Level 3). Corresponding dynamic friction (DF40) thresholds are determined through spline-based interpolation to provide cross-reference values for agencies or studies that use DFT-based friction measurements. Marking systems were then classified accordingly, and practical application recommendations are proposed based on observed performance across different road types and usage scenarios. Also, by developing a first-of-its-kind equivalent wear model, this study enables the conversion of laboratory polishing cycles to real-world tire-induced frictional work, addressing the long-standing laboratory-field equivalency gap. These findings provide a technical basis for transportation agencies in making performance-based material selection and maintenance decisions aligned with roadway function and traffic demand, supporting more cost-effectiveness and safety-oriented pavement marking applications.