RELIABILITY OF THE FLEXIBLE PAVEMENT DESIGN MODEL

The design of flexible pavements by the U.S. Army Corps of Engineers is currently based on the California bearing ratio (CBR) curve. The CBR curve is empirical, and the current design approach is deterministic. A probabilistic approach, providing more reliable designs at potentially lower costs, can be developed from the current design procedure if the reliability of the CBR curve is known. This study was undertaken to establish the reliability of the current CBR-based flexible pavement design model using existing data from accelerated traffic tests. The reliability of the design model was found to be about 50 percent, excluding the effects of conservative estimates of the design parameters.