1. The presence of Falling Weight Deflectometer meets this need.

2. The deflectometer described in this paper is used to locate drilling and determine the dip angle of boreholes.

3. The falling weight deflectometer ( FWD ) is used to evaluate the effectiveness of the impact compactor.

4. The technology of pavement moduli back-calculation is developed along with the appearing of falling weight deflectometer (FWD).

5. Furthermore, The data of load time histories are measured by Falling Weight Deflectometer(FWD) in situ to calculate the response curves of layered viscoelastic foundation.

6. The discovery of the method of using portable falling weight deflectometer and Rayleigh wave satisfy our need.

7. The principle and application of some methods which are widely used at present to identifyi pavement void such as FWD (Falling weight deflectometer) and geological radar were discussed.

8. First, a rut prediction model, in which the moduli of different layers were inversely calculated by the FWD(Falling Weight Deflectometer) deflection basin, was introduced.