The data analysis results summarized in this TechBrief use test sections from an LTPP Specific Pavement Studies (SPS) experiment, Study of Environmental Effects in the Absence of Heavy Loads (SPS-8), matched with test sections from other LTPP experiments that have normal truck traffic to compare and show the proportion of total damage caused by environmental effects. This analysis, which looked at data collected over a 15-year period, also identified many practical design and materials effects, including some very informative results.