This research study addresses the collection, preparation, and use of traffic data required for pavement design by the Arizona Department of Transportation, focusing on data required as inputs for the American Association of State Highway and Transportation Officials "Mechanistic-Empirical Pavement Design Guide" design procedures. ADOT’s current traffic data collection and preparation processes are not adequate to meet the needs of the MEPDG procedure, and improvements are needed. These improvements include enhanced volume, classification, and weight data collection for vehicles, processing data and performing quality assurance checks, and the preparation/analysis of the data for use in the MEPDG. Use of the MEPDG in Arizona will require (1) an annual flow of updated key traffic data and (2) the ability to collect on-site (MEPDG Level 1) data in a timely manner for key projects.