Sample Rigid Pavement Design Tables Based on Version 0.8 of the Mechanistic Empirical Pavement Design Guide
This Technical Memorandum describes a design of a sample catalog for rigid pavement as requested by the Caltrans Division of Design in 2005. This task is part of a larger project, begun in 1999, to help Caltrans implement mechanistic empirical (ME) procedures. Before implementing the Mechanistic Empirical Pavement Design Guide (MEPDG) software from the NCHRP 1-37a project, Caltrans has adopted a three-step process for evaluating it including: sensitivity analysis or bench testing, validation using data from accelerated pavement testing, and validation (and possibly recalibration) using field data. Upon Caltrans request, the University of California Pavement Research Center (UCPRC) has done a sensitivity study to check the reasonableness of the model predictions. Limited work was done to evaluate the models using APT data due to the closed architecture of the software. Evaluation using field data is underway. For reasons described in this Memorandum, Caltrans has decided to use simple design tables developed from the software for routine use and to use the actual software will be used only for special projects. Simple design tools based on the software, such as the catalog for jointed plain concrete pavement (JPCP), produce some of the benefits of ME design procedures and serve as a starting point to understand the needs for full scale implementation of ME procedures in the future. In addition to describing development of the design catalog, this Memorandum presents limitations about the catalog and observations about version 0.8 of the MEPDG software. Key variables to be included in the catalog were selected based on results from sensitivity analyses. A factorial produced 2,160 cases that were loaded into a database. For each combination of inputs (climate, traffic volume, load transfer efficiency, base type, subgrade type, spectra), the least thickness resulting in distresses that fall within the failure criteria is designated as the design thickness. Results were then compiled into the design tables that are contained in this Memorandum.