Several recent accidents involving aircraft punching through pavements prompted the Navy to address this problem. Initially, a successful void detection survey was completed at a Naval Air Station (NAS) where several voids were generated by leakage of large underground drainpipes. Various methods were used such as internal video taping of the pipes, heavy weight deflectometer (HWD) testing, ground penetrating radar (GPR), and dynamic cone penetrometer (DCP) testing. A state-of-the-art review was also completed to assess all existing technology applicable to void detection under pavements. However, the optimum technology determined (visual inspection, HWD, and DCP) still presented limitations in terms of availability and speed of data acquisition, requiring prioritization of the work. A risk analysis was then completed, establishing work prioritization within each airfield and providing a prioritization of all U.S. Navy and Marine Corps airfield pavements. An Interim Policy and Technical Guidance (IP&TG) was issued on 23 March 2000 to establish the developed void detection methodology. The void detection methodology has been successfully used at several airfields and Naval stations, detecting voids or loose layers, and providing repair recommendations.
