ABSTRACT
Monitoring pavement structural condition on network level has become possible since Traffic Speed Deflectometer (TSD) was introduced. TSD data have been deeply investigated over the past years and many studies have shown relatively strong correlation with Falling Weight Deflectometer (FWD) results. Furthermore, the agreed vison, formulated by road authorities and research institutions, is represented by utilizing the TSD data directly for back-calculation of the modulus of the pavement layers. To accomplish this vision, layer thicknesses and temperature of the asphalt layer must be available. While the second can be calculated by the help of BELLS (BALTZER, ERTMAN-LARSEN, LUKANEN and STUBSTAD) or similar models, layer thicknesses are not always available on network level. Based on this aspect, the Danish Road Directorate (DRD) and the German Federal Highway Research Institute (BASt) have been working on a project with the aim to develop simplified models that could rank the remaining lifetime of a pavement structure using Surface Curvature Index (SCI) data. This paper presents the models developed by using two approaches based i) on historical FWD data processed with a standard back-calculation software and ii) on simulated FWD loads, applied on different standard pavement sections analyzed with a multilayer linear elastic (MLE) based computer program. Comparing the results obtained by the two approaches, a power type function which correlates SCI and remaining life (in ESALs) was found where its coefficients are different from country to country. Effects of relevant variables such as damage development rate of the asphaltic layer and the effect of different countries fatigue transfer functions have also been considered.
