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APPENDIX A: BRIEF FOR REVIEW TEAMS Note: The detail given below was the brief for the SWPE team. The other teams had the same gen- eral terms of reference with differences of detail re- lating to their specific tasks. BACKGROUND At the request of the AASHTO Joint Task Force on Pavements (JTFP), NCHRP initiated Project 1-37A in 1996 to develop a guide for the design of new and rehabilitated pavement structures. In con- trast to the current AASHTO Guide for Design of Pavement Structures, the guide recommended in 2004 by the Project 1-37A research team is based on mechanistic-empirical (M-E) principles, provides a uniform basis for the design of flexible, rigid and composite (rehabilitated) pavements and employs common design parameters for traffic, subgrade, environment and reliability. A key component of the JTFPâs plan for im- plementation and adoption of the M-E pavement design guide and software is an independent, third- party review to test the design guideâs underlying assumptions, evaluate its engineering reasonable- ness and design reliability and identify opportunities for its implementation in day-to-day design produc- tion work. OBJECTIVE Conduct an independent engineering review of the mechanistic-empirical pavement design guide and software developed in NCHRP Project 1-37A. WORK PROGRAM Accomplishment of the project objective will re- quire the following tasks: Task 1. Plan and conduct an independent engi- neering review of the mechanistic-empirical pave- ment design guide developed in NCHRP Project 1-37A, with specific emphasis on (1) the methodol- ogy employed in the guide to estimate the reliability of pavement designs and (2) its use for the design of composite (rehabilitated) pavements. In the plan make use, insofar as possible, of existing data and results from completed or ongoing studies. This will be accomplished through the following sub-tasks: Task 1.1. Assess the reasonability, soundness and completeness of the guideâs supporting engineering concepts and its process and procedures. Task 1.2. Conduct an appraisal of the consistency and sensitivity of results for composite (rehabilitated) pavement designs. Task 1.3. Evaluate the design reliability method- ology used in the guide. Task 1.4. Conduct an analysis of whether the dis- tress models in the guide can be calibrated to match the predicted performance of select pavement struc- tures with their known historical performance. Task 1.5. Review the completeness with which the final design guide and software address the review comments of the NCHRP 1-37A panel and the JTFP. Task 1.6. Assess the availability, clarity, and com- pleteness of the necessary test protocols for materials. Task 1.7. Assess the opportunities for agency implementation of the design guide and software in routine, day-to-day design production work. Task 2. Assess the clarity, ease of use, capabil- ities, speed, and stability of the design software and identify opportunities in the conceptual operation and structure of the design process, including the use of the environmental model outputs, to decrease the overall runtime of the software. Task 3. Meet with the NCHRP project panel at the beginning of the review and at its midpoint to present an update on progress, key issues, principal findings, and recommendations. Task 4. Prepare a final report that presents key findings and recommendations, identifies specific deficiencies and errors in the design guide and soft- ware and suggests corrective actions, including short- term research activities. Task 5. Prepare a concise summary report of the key findings and recommendations of Projects 1-40A (01), 1-40A (02), and 1-40A (03). [Contract 1-40(04) was introduced after these terms of reference had been issued]. 31
