Incorporation of Probabilistic Concepts Into Fatigue Analysis of Ultrathin Whitetopping as Developed for the American Concrete Pavement Association

Fatigue analysis for the design of ultrathin whitetopping (UTW) pavements as used in the design procedures published by ACPA is based on fatigue models that have been in existence for pavement design for decades. The underlying assumptions in the fatigue models result in an unstated, conservative factor of safety in all UTW designs developed using the procedure. Checking the performance of UTW projects against the design calculations reflects this conservatism. Recent efforts in the revision of the existing fatigue models to incorporate probabilistic concepts are reviewed and approximate comparisons are made with several existing projects constructed in Illinois as a base of reference for the revised models. Possible extension of the models into thicker designs is also discussed.