Use of seismic pavement analyzer in forensic studies

Seismic nondestructive testing technology as used for pavement evaluation has been incorporated in two devices: the Seismic Pavement Analyzer (SPA) and the Portable Seismic Pavement Analyzer (PSPA). A few short-term projects were conducted to learn when and where the use of seismic methods is feasible. The usefulness of the test methods involved in the SPA and PSPA has been to some extent evaluated. In their present states, the SPA and PSPA seem to be emerging as valuable tools in forensic studies and the day-to-day operations of state highway agencies. The devices have been useful in understanding some of the complex mechanisms encountered in a few projects. More experience is needed to fully understand the potential and weaknesses of the devices, and further development of their software is needed. This paper presents a summary of efforts put forth to improve the SPA and PSPA for their incorporation into the activities of the highway community in maintenance, rehabilitation and construction of pavements. Several case studies that demonstrate the usefulness and shortcomings of the two devices and the methodology involved in them are presented.