Performance Assessment of Thermoplastic Road Markings on Kenyan Roads: Bridging Infrastructure Challenges through Retroreflectivity, Luminance, and Thickness Analysis

Abstract

Road markings are a vital, low-cost road safety intervention, yet their real-world performance in Kenya’s tropical environment remains poorly understood. This study evaluates thermoplastic road markings across nine sites with varying environmental, traffic, and surface conditions over 33 weeks. Using retroreflectivity, luminance, and thickness as key performance indicators, the study combines laboratory testing with field measurements and statistical analysis. Results show severe premature deterioration, with retroreflectivity declining by 79.3%, luminance by 56.1%, and thickness by 32.3%. All sites failed the minimum retroreflectivity standards within 23 weeks. No statistically significant differences were found across environmental or traffic conditions, though trends suggest a strong environmental influence. The findings reveal a mismatch between laboratory compliance and field performance. The study recommends performance-based standards, improved material specifications, and enhanced monitoring systems, while contributing new empirical evidence and an integrated evaluation framework for thermoplastic road marking performance in tropical conditions.