Comparison of Georgia Department of Transportation Design Procedure with Mechanistic-Empirical Pavement Design

This research had several objectives: measure the dynamic modulus of commonly used hot-mix asphalt mix types, two aggregate base courses, and two soils that represent high and low values; compare the results of using measured moduli with Mechanistic-Empirical Pavement Design Guide (MEPDG) Level 3 default moduli for the subgrade and aggregate base material; and compare design results using the AASHTO 1972 Interim Guide for Pavement Design currently being used by the Georgia Department of Transportation (GDOT) with the MEPDG results. The research showed that the MEPDG Level 3 default values for resilient modulus of both soil and aggregate materials are significantly higher than the actual values determined from laboratory test results. Use of actual material properties and load spectra resulted in significantly greater structures being recommended than when Level 3 default values were used for the MEPDG design program. On the basis of these results, GDOT is cautioned against using the default values built into the MEPDG software and should conduct a thorough calibration study using Georgia materials before implementing the MEPDG design procedure.