Comparative study of the use of FWD and LWD for flexible pavement evaluation

Falling Weight Deflectometer (FWD) is the standard equipment used for the analysis and evaluation of flexible pavement. The number of this equipment is very limited in Indonesia. For a country owned 48,000 kms of road it is quite important to have an alternate equipment of FWD. Institute of Road Engineering (IRE) has performed the Light Weight Deflectometer (LWD) for the use in low to medium traffic roads for both evaluation and design of overlay. The study has done to compare these two equipment focusing on three parameters i.e Effective Structural Number (SNeff), Surface Modulus (Sm) and prediction of Subgrade Modulus (Esg). There are 15 points tested using FWD and LWD nearly in the same time on the IRE campus that is classified as low traffic volume road. Each point is then analysed to calculate SNeff, Sm, and Esg using the deflections derived from both of FWD and LWD tests. The analysis is done by plotting the parameters calculated from deflections derived from each equipment and then plotting each other. It is found that the plotting fall around the line of equality. This finding goes to the conclusion that the use of LWD of IRE version is acceptable to be used for the analysis of the flexible pavement especially for low to medium traffic.