SHRP 2 Project R23—Development of Guidelines for the Design and Construction of Long Life Pavements Using Existing Pavements

Guidelines are being developed to help State Highway Agencies (SHAs) in the selection and design of long life pavements using existing in-place pavements. There is currently very clear design guidance and procedures for designing new long life pavements in terms of new or reconstruction. Guidance that does consider the use of existing pavement is typically directed toward pavement rehabilitation with some determinate life expectancy (ARA, 2004). There is no clear and specific guidance for designing and building long life pavements using existing pavements in place. Using the existing pavement in the design and construction of long life pavements offers numerous advantages both in facilitating rapid renewal of the roadway and in the sustainability aspect of utilizing existing materials. Using the existing pavement significantly reduces the mass movement of materials in and out of the project, and in many cases can facilitate the staging of traffic during construction as part of a cost effective rapid renewal strategy. The approaches found for designing long life pavements using existing pavements presented in the R-23 guidelines are similar to what many agencies currently use, with a few additions from international practice. It was discovered that most agencies use one or more of the approaches contained in the guidelines but have abandoned or no longer consider several of the approaches because of past construction problems. It was found that the assessment of the existing pavement and use of the appropriate design and attention to construction details are critical features of the process. An overview of the form of the guidelines and the detailed information contained in those guidelines are presented, including project assessment, design guidance, critical construction aspects, and guide specifications.