Abstract
FWD tests have been carried out for these four years at the testpit, whose bearing capacity was designed for D traffic. The measured deflection basins were statically back-calculated and failure analysis was performed by Asphalt Institute's formula. From the measured deflection and the back-calculated layer moduli, and furthermore, the calculated cumulative traffic passes to the failure by fatigue crack and rutting, the following results were obtained, 1) the measured deflection becomes smaller year by year, 2) the back-calculated modulus of the asphalt layer is larger as the years go by, 3) the calculated cumulative traffic passes to the failure tend to be bigger and the fatigue crack is more critical, as the asphalt itself becomes harder due to ultra-violet and other aging factors.
