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.

The effects of increased truck loads and higher tire pressures on performance of flexible pavements were investigated in this project. This Volume 1 report presents the research performed and the useful results obtained. Tire pressure studies were performed using both in field measurements and theoretical simulations of the effects of tire pressures on pavements. Volume 2, provides documentation for all of the computer programs developed on the project.