Development of Transfer Functions for Spectral Compatibility of Inertial Profilers Used in Long-Term Pavement Performance Program

Abstract

A quantification of the difference in the wavelength content produced by K. J. Law Engineers and International Cybernetics Corporation (ICC) profilers is presented. Transfer functions were developed to modify the power spectral density (PSD) of profiles recorded by the ICC profilers to produce a pseudo–K. J. Law PSD so that it is compatible with the spectral content of the profiles recorded by the K. J. Law profiler. Comparison of PSDs of the original K. J. Law and pseudo–K. J. Law profilers exhibited an excellent match in most pavements. Furthermore, a transfer function was developed and used to reconstruct a pseudo–K. J. Law pavement profile from the ICC profile, whose spectral content is similar to that of the K. J. Law profile, by using the inverse fast Fourier transform technique. The international roughness indexes (IRIs) of pseudo–K. J. Law profiles were in general closer to the IRIs of K. J. profiles than those of the ICC profiles. The technique presented here has the potential to be applied to inertial profile equipment types other than those considered in this study, therefore allowing comparisons of data sets.