Trr No. 1355 Pavement Design, Management, And Performance, pp. 8-16
The results show that the range of bedrock depths over which dvnamic effects are important differs between the two nondestructive tests because Of the excitation frequencies and depends mainlv on the stiffness of the subgrade. The results also show that, when dvnarnic effects occur in the measurements but are not taken into account in the analvsis, the modulus of the subgrade is generallv undereatimated, sometimes by 50 percent or more, and the moduli crf the base and surface layer are overestimated. Finally. a simple rnethod is suggested for the FWD that makes it possible to c,timam the depth to bedrock by recording the free vibration of the panement system.