Through a National Cooperative Highway Research Program, AASHTO's Joint Technical Committee on Pavements is developing a new guide to pavement design.
The intent of the research is to produce a guide for designing flexible, rigid and composite pavements nationwide using a method which evaluates use factors such as traffic, weather and road materials. When completed, the guide can be used for new pavement or for reconstructed or rehabilitated pavements.
The $7 million first phase of the research project, NCHRP 1-37a, Development of the 2002 Guide for the Design of New and Rehabilitated Pavement Structures, was completed this summer.
The project produced a draft guide and accompanying software now available for testing by highway agencies. A series of six workshops introducing the guide were presented this year.
The new M-E Design Guide includes a white paper from Kentucky's Gary Sharpe, chair of the AASHTO Joint Technical Committee on Pavements. The paper emphasizes that the guide is still a research project and not yet ready for implementation.
The new guide uses a mechanistic-empirical approach that can improve the reliability of highway design by analyzing factors such as materials, climate and actual traffic data. This evaluation can assess probable pavement damage over a lifetime of use and predict pavement performance.
Additional evaluation is now necessary to prepare the guide for implementation by the year 2009. A second research project is now underway, NCHRP Project 1-40, Facilitating the Implementation of the Guide for the Design of New and Rehabilitated Pavement Structures. Under this project, researchers will:
* Conduct a thorough, independent review of the guide and software to objectively assess the material contained in the guide, identify deficiencies and recommend corrective measures, including short-term research activities;
* Develop step-by-step procedures for use by state DOTs to refine the performance models in the guide and software on the basis of local and regional conditions, materials and practices; and
* Identify and implement measures to reduce the run time of the software without compromising its technical competence.
The Federal Highway Administration also has launched efforts to promote this new approach to pavement design by establishing a Design Guide Implementation Team through FHWA's Office of Pavement Technology. For more information contact Jeremy Fissel at 202/624-3640; e-mail: jfissel@aashto.org.
