Investigating the performance of as-built and overlaid pavements: a competing risks approach

Overlay has been a commonly used rehabilitation measure for flexible pavements. Properly designed and constructed overlays restore pavement service conditions and economically extended pavement service lives. In the light of different failure modes that could be experienced by a flexible pavement, such as cracking, rutting and roughness, and complex interactions among them, this paper considers these failure modes as competing risks and evaluates performance differences between overlaid pavements and as-built pavements in terms of hazard function, cause-specific cumulative incidence function and cause-specific conditional cumulative incidence function. A case study was undertaken using the pavement condition survey data in Florida. It was found that the overlaid pavements generally have a higher failure risk compared with the originally built pavements across all failure modes and exhibit three distinct phases of failure hazard change: increasing, stabilising and decreasing. For as-built pavements, the failure hazard increases dramatically after exceeding the design lives of pavements.