Mixed-Effects Analysis of Pavement Roughness and Rutting Performance of Preventive Maintenance Treatments Across Climatic Regions Using the LTPP Database

Abstract Preventive treatment selection should be based on the right climatic and environmental conditions to achieve maximum pavement performance. This is possible if treatment performance and the factors that influence it are investigated. Unlike previous studies that emphasized pavement characteristics that influenced the effectiveness of treatments, the linear mixed model used in this study includes fixed effects that consider treatment types, climates, and pavement characteristics; and random intercepts for section-level performance (nested within states). This accounts for repeated observations on the same pavement sections as treatments aged, while adjusting for unobserved section- and state-level differences. The aim was to evaluate the long-term effectiveness of asphalt thin overlay, slurry seal, chip seal, and crack sealing on pavements across the four climatic regions of US and Canada using longitudinal distress data from the Long-Term Pavement Performance program. From the results, the random effects explained a significant portion of the variability in pavement distress. Pavement roughness and rutting differences were greater at the section level than across states. States like Nebraska and Montana had higher rutting values than the national average. There was also an increasing post-treatment trend of pavement deterioration in all four climates. Asphalt thin overlay outperformed all other treatments and the control in the wet-freeze regions. Chip seal remains a viable alternative for treating pavement rutting, aside from asphalt thin overlay. Pavements with higher pretreatment roughness significantly led to higher posttreatment roughness and rutting. These insights provide transport agencies with a better understanding of the performance of treatments in different climates.