Effect of overlay thickness, overlay material, and pre-overlay treatment on evolution of asphalt concrete overlay roughness in LTPP SPS-5 experiment: A multilevel model approach

The objective of this study is to investigate the effect of overlay thickness, overlay material and pre-overlay treatment on roughness evolution of asphalt overlay in the Long-term Pavement Performance (LTPP) SPS-5 experiment. Roughness data collected from SPS-5 experimental sites has a clustered longitudinal structure. A multilevel model is established to simultaneously account for measurement correlation within the same test section and roughness evolution correlation within the same experimental site. It was discovery that while as-built roughness depends on overlay material and overlay thickness, roughness growth rate only depends on overlay thickness.