Study of Long-Term Pavement Performance (LTPP): Pavement Deflections

Chapter 8. Summary and Conclusions

This report presents the results of an indepth assessment of the pre-autumn 1998 LTPP load-deflection data. Several categories of errors and anomalies were identified, and the deflection data and associated parameters were recommended for flagging or correction, as appropriate.

The study resulted in an LTPP product called the transformed deflection basin procedure, also known as SLIC, that can identify sensor spacing errors or (potentially) erroneous sensor output. The SLIC procedure was also utilized in-house to facilitate the analysis of the deflection data as outlined in this report. This procedure has tremendous potential for routine use as one of the quality control checks by the FWD operator or the engineer reviewing the deflection data. It is recommended that the SLIC procedure be developed further as a user-friendly QC package that can be used in the LTPP program as well as by other highway agencies.