This study examined the roughness and roughness progression of 21 test sections on the Long-Term Pavement Performance (LTPP) Specific Pavement Studies (SPS)-2 site in Arizona over the first 16 years of the experiment. The site included 12 test sections from the standard experiment and 9 supplemental test sections selected by the Arizona Department of Transportation.

Traditional profile analyses revealed roughness caused by transverse and longitudinal cracking on some test sections and some localized roughness caused by built-in defects. However, the analyses showed that curl and warp contributed to, and in some cases dominated, the roughness on many of the test sections. In addition, roughness did not increase steadily with time because of diurnal and seasonal changes in slab curl and warp.