Perpetual pavements are a viable method for prolonging the life of asphalt pavements in the U.S these pavements combine a rut resistent surface layer with a fatigue resistent bottom layer to provide adequete capacity to ensure the pavements long life . In the 2003 test cycle at the National Center for Asphalt Technology (NACT) Test Track, a fatigue resistant bottom layer was used to investigate this approach; howover, this section soon showed signs of fatigue cracking. A forensic investigation using dynamic strain data collocted from embedded gauges and a trenching study were conducted to determine the couse of this early failure. Rations of strains from different depths in the pavement provided evidence of a possible bond problem, and the trenching also showed evidence of debonding. This debonding was the couse of the premature fatigue cracking in the section, and bond should be more carefully considered in the pavement design and construction process