ABSTRACT
Non-destructive testing of pavements has progressed, from widely spaced pseudo-static methods, namely Falling Weight Deflectometer (with typically 300 tests per day), to Traffic Speed Deflectometer (40-70 km/hr), and now Multi-Speed Deflectometer (5-65 km/hr) testing both wheelpaths at 1m centres with 300,000 tests per day on urban roads. Analysis methods have also advanced so that interpretation can now be a matter of hours at most or close to real time in some instances. The technology has advanced, but has the interpretation and prediction of pavement performance? Deflection test studies of “Hit Rate” (defined as the success of predicting whether a given treatment length would reach a terminal structural condition within a prescribed time period) have been attempted previously, but well documented case histories are rare. This article presents the establishment of a study involving sites where different deflection methods have been applied, including some for which data were collected many years ago, with a long record of subsequent performance under known traffic loading. As well as documenting the necessary data for determination of Hit Rate, alternative methods of analysis and interpretation are used to compare the old and newer technologies as well as the outcomes using both traditional analysis methods and more recent developments, so that network managers, designers and contractors can evaluate the reliability of different techniques now available for predicting the remaining structural life of pavements.
