Recalibration of the Flexible Pavement Rutting Model in Utah

摘要

The Utah Department of Transportation (UDOT) completed a study in 2009 to implement and adopt the American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical Pavement Design Guide (MEPDG). Prior to 2009, UDOT used a van mounted 3-point laser profiler to obtain the transverse profile of the pavement at regular intervals (typically a tenth of a mile). Maximum rut depth was then computed using the three points obtained. These measurements were found to be different than the LTPP definition through a direct correlation of rut depth measurements and an adjustment was made to the rutting of the UDOT sections so that they would match the LTPP rutting measurements. UDOT pavement sections rut depth measurement changed in 2009 to include closely spaced laser measured full transverse profile and calculation of maximum rut depth in each wheel path. This definition is thus very similar to that in LTPP. The change in rut depth measurements prompted UDOT to recalibrate MEPDG rutting model. The recalibration of the MEPDG rutting model was conducted using a nonlinear model optimization tool, SAS. A revised calibration coefficients were developed for rutting prediction model using Utah-specific design inputs and performance data. Overall, the recalibration process helped remove the bias (consistent over- or under-prediction), reduce the prediction error, and improve the accuracy of rutting model. The improvement in these models was notable; thus, indicating that the Utah-calibrated rutting model would provide much more accurate, reliable, and cost-effective designs than previous UDOT rutting prediction model.