This manual was developed to provide a consistent, uniform basis for collecting distress data for the LTPP program. This manual provides a common language for describing cracks, potholes, rutting, spalling, and other pavement distresses being monitored by the LTPP program. In 1987, the Strategic Highway Research Program began the largest and most comprehensive pavement performance test in history—the Long-Term Pavement Performance (LTPP) program. During the program’s 20-year life, highway agencies in the United States and 15 other countries will have collected data on pavement
condition, climate, and traffic volumes and loads from more than 1,000 pavement test sections. That information will allow pavement engineers to design better, longer-lasting roads.