One of the key parameters for analytical design or evaluationof a pavement is the stiffness modulus appropriate to each layer.This paper discusses both the laboratory determination of stiffnessmodulus, by means of the Indirect Tensile Stiffness Modulus (ITSM)test, and in situ determination, by means of the Falling WeightDeflectometer (FWD). Their complimentary roles are highlightedby means of several examples. The role of ITSM testing in allowingproper temperature correction of FWD data is presented. A comparisonof laboratory and in situ moduli is seen to provide informationon crack severity, material variability and debonding.

Finally, these stiffness modulus tests are set in the contextof a full pavement evaluation and their role in providing vitalevidence on overall pavement condition is shown.