82 formance data. The Standard Data Release (SDR) 23 made available in January 2009 was used in this study. LTPP pavement sections were constructed by using highway agency specifications and have been subjected to actual traffic for approximately 20 years. The Specific Pavement Studies Experi- ment 5 (SPS-5) was designed to study the effects of overlay reha- bilitation. Eighteen projects within the United States and Canada were constructed for the SPS-5 program as shown in Table 1. Most of the projects were built before implementation of Superpave ® specifications. As shown in Table 2, each project included eight test sections and one control section, and each was 152 m in length. The eight sections were used to compare asphalt mixtures with and without reclaimed asphalt pavement (RAP), overlay thicknesses of 50 mm and 125 mm, and rehabilitation with and without milling of the existing surface before the overlays. The recycled asphalt mixtures contained approximately 30% RAP material. PURPOSE The primary objective of this study was to compare pavement per- formance data for the sections with and without RAP. The study also examined the impact of location, age, overlay thickness, and milling of the existing pavement on the performance of the over- lays. Although several previous studies examined the performance of the pavements in SPS-5, most were conducted in the early lives of the test sections (1–8). METHODOLOGY Extracting Data from the LTPP Database For this study, the SPS-5 pavement performance data were extracted from the SDR 23 database. Information in the monitoring module includes distress records for international roughness index (IRI), mean rut depths, fatigue cracking, transverse cracking, longitudi- nal cracking, block cracking, and raveling. Each cracking category had three subcategories of data for low, medium, and high sever- ity. The values used for this analysis were the sum of the three severities. Use of Data from Specific Pavement Studies Experiment 5 in the Long-Term Pavement Performance Program to Compare Virgin and Recycled Asphalt Pavements Randy West, Jenna Michael, Rod Turochy, and Saeed Maghsoodloo The Specific Pavement Studies Experiment 5 (SPS-5) in the Long-Term Pavement Performance program was designed to study the effects of overlay rehabilitation type on typical distress measures. The rehabilita- tion treatments compared overlay thickness, overlay type, and surface preparation before rehabilitation. The thicknesses used were 50- and 125-mm overlays. The overlay types were virgin asphalt mix and recy- cled asphalt that contained approximately 30% reclaimed asphalt pave- ment (RAP). Surface preparation consisted of either milling or not milling the existing pavement before rehabilitation. Eighteen states and provinces in North America built SPS-5 projects between 1989 and 1998. Seven distress parameters from these test pavements were ana- lyzed, including international roughness index (IRI), rutting, fatigue cracking, longitudinal cracking, transverse cracking, block cracking, and raveling. Analyses were conducted to determine which factors affected overlay performance as measured with the above parameters. Further statistical testing compared the performance of the virgin mix sections directly with equivalent sections that contained 30% RAP. Over- lays with mixes that contained 30% RAP were found to perform as well as overlays with virgin mixes in terms of IRI, rutting, block cracking, and raveling. Thicker overlays improved pavement performance, except for rutting. Milling before rehabilitation decreased IRI, fatigue cracking, and transverse cracking but increased rutting. The Long-Term Pavement Performance (LTPP) program was estab- lished to study how pavement performance is affected by various design features, environmental effects, traffic loads, materials, con- struction quality, and maintenance practices. To collect and analyze data over a long period, the LTPP program developed a publicly accessible database that contains annually updated pavement per- R. West, National Center for Asphalt Technology, 277 Technology Parkway, Auburn, AL 36830. J. Michael, MeadWestvaco Corporation, 5255 Virginia Avenue, North Charleston, SC 29406. R. Turochy, Department of Civil Engineering, 238 Harbert Engineering Center, and S. Maghsoodloo, Department of Industrial and Systems Engineering, 3301H Shelby Center, Auburn University, Auburn, AL 36849. Corresponding author: R. West, westran@auburn.edu. Transportation Research Record: Journal of the Transportation Research Board, No. 2208, Transportation Research Board of the National Academies, Washington, D.C., 2011, pp. 82–89. DOI: 10.3141/2208-11