Guide for Investigating and Remediating Distress in Flexible Pavements: California Department of Transportation's New Procedure

In 2001, the California Department of Transportation (Caltrans) initiated a 3-year, $7 million project with MACTEC, Inc. The project included on-call flexible pavement consulting services to Caltrans in the areas of new products, asphalt rubber, modified binders, moisture sensitivity, failure investigations, independent quality assurance, training, laboratory testing, pavement maintenance, pavement rehabilitation, and asphalt recycling. One of the key tasks of the project was to develop a comprehensive guide and a detailed procedure to investigate flexible pavement distresses and develop cost-effective remedies and repair strategies. The emphasis of the procedure is on addressing premature distress and certain problems that might arise during pavement construction. The guide contains two manuals: (a) an office manual that describes the types of flexible pavement distress, identifies the factors that affect distress and performance, and provides tools that can be used to characterize distress condition, determine likely causes, and generate a corrective solution and (b) a field manual for use in the field by experienced engineers familiar with the new tools and requiring little instruction on its application. The principles presented in the guide are based on modern pavement engineering technology and are applicable to the practices of many federal, state, and local agencies. The process presented in the guide is summarized, and several of the new tools that have applicability to other agencies are described.