The performance models introduced in the Mechanistic-Empirical Pavement Design Guide (MEPDG), developed under the National Cooperative Highway Research Program (NCHRP 1-37A and 1-40D), are calibrated using sections spreadthroughout the U.S. Hence it is necessary to calibrate these models for state and regional conditions because of the differences in terms of materials, environmental conditions and construction practices. A pavement design based on the nationally calibrated MEPDG will result in either an overestimate or an underestimate of the pavement layer thicknesses because of systematic errors due to differences in the design inputs between different regions. This deficiency calls for a local calibration of the performance models in the design guide so that it can be used to design pavements at aregional level. The calibration procedure described in this paper concentrates on finding two bias correction factors for the asphalt concrete (AC)rutting performance model, after some default values have been assumed for the subgrade rutting calibration factors. Pavement data from the Texas SPS-1 and SPS-3 experiments of the Long-Term Pavement Performance (LTPP) database was used to run the MEPDG and calibrate the same to Texan conditions. The regional calibration factors were obtained by minimizing the sum ofsquared errors between the observed and the predicted distresses. Finally, an average of the regional calibration coefficients for AC and subgrade rutting was computed to obtain the set of calibration coefficients for Texas in general.
Samenvatting