The 2002 Mechanistic-Empirical Design Procedure for Flexible Pavements: How to Implement it in Italy Clara Celauro DIIV - Dipartimento di Ingegneria di Infrastrutture Viarie Universita’ degli Studi di Palermo, ITALY clara.celauro@ing.unipa.it Lev Khazanovich Associate Professor Department of Civil Engineering University of Minnesota khaza001@umn.edu Synopsis A new Mechanistic-Empirical Pavement Design Guide (MEPDG), also known as the 2002 Design Guide, has been recently proposed in the United States. The development of such a procedure was conducted by the National Cooperative Highway Research Program (NCHRP) under sponsorship by the AASHTO. The Design Guide represents a challenging innovation in the way pavement design is performed: design inputs include traffic (full load spectra for single, tandem, tridem, and quad axles), material and subgrade characterization, climatic factors, performance criteria and many others. One of the most interesting aspects of the design procedure is its hierarchical approach, i.e. the consideration of different levels of inputs. Level 1 requires the engineer to obtain the most accurate design inputs (e.g., direct testing of the materials, on-site WIM, etc.). Level 2 requires testing, but the use of correlations is allowed (for example, subgrade modulus estimated through correlation with another test), and Level 3 generally uses estimated values. Thus, Level 1 has the least possible error associated with inputs, Level 2 uses regional defaults or correlations, and Level 3 is based on the default values. A trial structure is then analyzed for adequacy through the prediction of key distresses and smoothness (as a measure of ride quality): if the design does not meet desired performance criteria, the structure must be revised and the evaluation process repeated. Although evaluation of this procedure is still underway, many State transportation agencies have already begun adaptation and local calibration of this procedure. This paper addresses the key aspects of the design procedure for flexible pavements and the way it can be transferred to Italy. To implement this procedure for Italian conditions, various issues should be addressed. This includes material evaluation, availability of traffic and climatic data, contracting methods and need of new specifications. In Italy, where pavement design is mostly based on the use of a Catalog, the implementation of the 2002 AASHTO Design Guide or any mechanistic-based design procedure will require a lot of effort, but it will provide a powerful tool accounting for changes in traffic, materials, construction, design concept, climate and so on.