- Modern nondestructive testing (NDT) of pavements is associated with measuring surface deflection bowls under various types of loading. One of the most common items of equipment used in NDT is the falling weight deflectometer (FWD). The load is applied to the pavement surface through a steel plate or a composite steel-PVC plate with a ribbed rubber pad placed on the lower face of the plate. Sometimes the plate is made of four sectors, such as in the KUAB FWD. In other items of equipment, such as the Road Rater, the loading plate rests directly on the pavement surface without any rubber pad. ASCE.