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Local Calibration of the Mechanistic-Empirical Pavement Design Guide

Kevin D. Hall, Ph.D., P.E. University of Arkansas. Local Calibration of the Mechanistic-Empirical Pavement Design Guide. Previous AHTD MEPDG Research TRC 0302 Design Input Evaluation TRC 0304 ACHM Stiffness TRC 0402 Traffic Evaluation TRC-0708 PCC CTE/Poisson’s Ratio (K. Hall)

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Local Calibration of the Mechanistic-Empirical Pavement Design Guide

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  1. Kevin D. Hall, Ph.D., P.E. University of Arkansas Local Calibration of the Mechanistic-Empirical Pavement Design Guide • Previous AHTDMEPDG Research • TRC 0302Design Input Evaluation • TRC 0304ACHM Stiffness • TRC 0402Traffic Evaluation • TRC-0708PCC CTE/Poisson’s Ratio(K. Hall) • Subgrade / Base Materials(N. Dennis) • Portland Cement Concrete(J.Schemmel; M. Hale) • TRC-0602Master Plan for Calibration(K. Hall) • TRC-0702Database Support for MEPDG(K. Wang) • General MEPDGImplementation Activities • Sensitivity analysis • Materials/Traffic Inputs • Local Calibration • Performance Criteria AHTD has invested significant effort to implement the MEPDG; Local Calibration is the last MAJOR research effort prior to phased-in implementation

  2. NCHRP 1-40: Recommended Practice for Local Calibration of the Mechanistic-Empirical Pavement Design Guide “The calibration and validation of the performance prediction model is a mandatory step…to establish confidence in the design and analysis procedure and facilitate its acceptance and use.” Calibration: the mathematical process through which total (residual) error – the difference between observed and predicted values of distress – is minimized. Validation: the process to confirm that the calibrated model can produce robust and accurate predictions for cases other than those used for model calibration. 11-Step Process • Select Hierarchical Input Level for Each Input Parameter • Develop Experimental Design and Matrix • Estimate Sample Size for Each Distress Model • Select Roadway Segments • Extract and Evaluate Roadway Segment/Test Section Data • Conduct Field Investigations of Test Sections to Define Missing Data • Assess Bias for the Experimental Matrix • Determine Local Calibration Coefficient to Eliminate Bias of Transfer Function • Assess Standard Error for Transfer Function • Improve Precision of Model: modify coefficients and exponents of transfer functions • Interpretation of Results: decide on adequacy of calibration coefficients

  3. Calibration Effort “Snapshots” • Sample size (minimum) • Distortion (total rutting or faulting) 20 roadway segments • Load-related cracking 30 roadway segments • Non-load-related cracking 25 roadway segments • Reflection cracking (HMA only) 15 roadway segments • Roadway Segment / Condition Surveys • At least 3 condition surveys available for a roadway segment • Condition surveys cover at least 10 years • Increased number of surveys for higher levels of distress • Range of distress magnitudes – minor to “close to” design criteria • Distress definitions/measurements consistent with MEPDG(Data Collection Guide for Long Term Pavement Performance) • Use Existing Roadways IF POSSIBLE • If data unavailable, shift to new construction; begin monitoring plan Based on data availability, this could be a long-term effort !

  4. Tasks Envisioned for Proposed Effort(Based on NCHRP 1-40 Calibration Guide) • Select Hierarchical Input Level for Each Input Parameter • Develop Experimental Design and Matrix • Estimate Sample Size for Each Distress Model • Select Roadway Segments • Extract and Evaluate Roadway Segment/Test Section Data • Conduct Field Investigations of Test Sections to Define Missing Data • Assess Bias for the Experimental Matrix • Determine Local Calibration Coefficient to Eliminate Bias of Transfer Function • Assess Standard Error for Transfer Function • Improve Precision of Model: modify coefficients and exponents of transfer functions • Interpretation of Results: decide on adequacy of calibration coefficients TRC-0602 Proposed Calibration Project

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