Preface

The Origins of Mechanistic Empirical Design

Many highway agencies use the American Association for State Highway and Transportation Officials (AASHTO) Guide for the Design of Pavement Structures for design and analysis of new and rehabilitated pavement structures. From the early 1960s until recently, all versions of the AASHTO Pavement Design Guide were based on empirical performance equations developed at the AASHO Road Test in the late 1950s using limited data. In the late 1980’s, the need for and benefits of a mechanistically based pavement design procedure were recognized. To meet that need, the AASHTO Joint Task Force on Pavements (now called the Joint Technical Committee on Pavements), in cooperation with the National Cooperative Highway Research Program (NCHRP) and the Federal Highway Administration (FHWA), sponsored the development of an mechanistic-empirical (M-E) pavement design procedure and a manual of practice.

Mechanistic-Empirical Pavement Design Guide (MEPDG): A Manual of Practice (MOP), 3rd Edition describes a pavement design methodology, termed mechanistic-empirical (M-E) pavement design that represents a major change from the empirical based (AASHTO 72, AASHTO 93) pavement design methods. Based on engineering mechanics that have been validated through extensive road test performance data, the manual presents information necessary for pavement design engineers to begin using use the MEPDG design and analysis method.

AASHTOWare Pavement ME Design™ is the commercially available M-E pavement design software accompanying the MOP. The original MOP and research grade software tool were developed over many years by a large team of nationally recognized engineers from Applied Research Associates (ARA), Inc. and Arizona State University (ASU) along with several expert consultants. Most of the developmental work was completed under the following National Cooperative Highway Research Program (NCHRP) Projects:

  • NCHRP 01-37A: Development of the 2002 Guide for the Design of New and Rehabilitated Pavement Structures: Phase II.
  • NCHRP 01-40: Facilitating the Implementation of the Guide for the Design of New and Rehabilitated Pavement Structures.
  • NCHRP 01-40A: Independent Review of the Recommended Mechanistic-Empirical Design Guide and Software.
  • NCHRP 01-40B: User Manual and Local Calibration Guide for the Mechanistic-Empirical Pavement Design Guide and Software.
  • NCHRP 01-40D(01): Technical Assistance to NCHRP and NCHRP Project 1-40A: Versions 0.9 and 1.0 of the M-E Pavement Design Software.
  • NCHRP 01-40D(02): Technical Assistance to NCHRP and NCHRP Project 1-40A: Versions 0.9 and 1.0 of the M-E Pavement Design Software.

Subsequent enhancements to the research grade software tool and development of AASHTOWare Pavement ME Design™ Software 1.0 through 3.0 has been completed by AASHTO under the guidance of the AASHTO’s PMED Task Force.

To date, the models from the following NCHRP studies have been integrated into the AASHTOWare Pavement ME Design™ Software.

  • NCHRP 1-52 - Top-down cracking
  • NCHRP 1-XX - Reflection cracking
  • NCHRP Rigid Recalibration (CTE)
  • NCHRP 1-51

Disclaimer

This manual is intended to provide readers with in-depth guidance on the operation and application of the PMED software. It is not intended to provide instruction for pavement design. Users are directed to the AASHTO MEPDG Manual of Practice for design guidance.

PMED software greatly simplifies the pavement design and analysis methodology described in the AASHTO MEPDG Manual of Practice. Throughout this manual it is assumed that the user is reasonably familiar with the AASHTO MEPDG Manual of Practice and general principles of the pavement design and analysis. Neither this manual’s contents nor the routines that are programmed in the software can take precedence over AASHTO’s MEPDG Manual of Practice or the place of the professional judgment of a qualified pavement design engineer.

Abbreviations and Citation

The official AASHTOWare approved abbreviations are summarized below.

  • AASHTOWare™ Pavement ME Design: PMED
  • AASHTO MEPDG - A Manual of Practice: MOP

Citation:

AASHTOWare Pavement ME Design™ Software, Version #, June 2020, American Association of State Highway and Transportation Officials