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.

In the mid‐1990s, the Arizona Department of Transportation initiated the Maintenance Cost Effectiveness study (SPR 371) with the development of plans and an experiment design to evaluate the effectiveness of a variety of asphalt pavement maintenance treatments. During 1999 and 2001, ADOT oversaw the construction of hundreds of experimental sections throughout the state under the Phase I, Wearing Course Experiment (nine treatments and 82 sections at three sites), and the Phase II, Preventive Maintenance Experiment (24 treatments and 137 sections at four sites). Work continued in 2006 and 2007 under the Evaluation of Maintenance Strategies study (SPR 628) for ADOT with a yearlong program of pavement performance monitoring involving manual pavement distress surveys and automated skid, friction, and surface texture measurements at all the experimental sites. The project culminated with a detailed analysis of key pavement performance data to compare the performance of the individual treatments and determine their overall effectiveness. This report documents the independent findings of both the Phase I and II experiments.