Simulating Deflection of a Jointed Rigid Pavement Under Rolling Wheel Deflectometer (RAPTOR) Loading

The falling weight deflectometer (FWD) has been the principal equipment used for accurate assessment of pavement structural condition for well over 30 years and back-calculation techniques are well established. In recent years however different types of rolling wheel deflectometer have been developed and they have the potential to allow the collection of structural information on a routine basis. The challenge is to interpret the data from these devices in the most meaningful way, since it is necessary that the deflections take place in different locations compared to the FWD. This paper describes an analytical approach that allows prediction of deflections in a jointed rigid pavement on a line offset from the wheel path. It outlines the assumptions that have to be made and the refinements that are potentially possible. Comparisons with both real measurements and finite element analysis are presented and it is found that the proposed approach is adequate in terms of accuracy and sufficiently rapid for practical back-calculation. The issues of vibration and noise in the deflection measurements are discussed and possible ways of handling these are put forward. Additionally, the sensitivity to model parameters of the rolling wheel deflectometer passing a joint are assessed, which can lead to strategies on back-calculation of load transfer. The conclusion reached is that the technique outlined in this paper opens the door to effective use of rolling wheel deflectometer (RWD) equipment for evaluation of load transfer efficiency in joints.