The accuracy and reliability of traffic load estimates are key to determining a pavement’s life expectancy. To better understand the variability oftraffic loading rates and its effect on the accuracy of the Long Term Pavement Performance (LTPP) program’s loading estimates, LTPP recently completed an analysis studying the effect of varying truck load rates anddata-collection plans on Equivalent Single-Axle Load (ESAL) estimates at sample sites in the LTPP data base. Results of the analysis are documented in a report entitled , Results of the Empirical Analysis of Alternative Data Collection Sampling Plans for Estimating Annual Vehicle Loads at LTPP Test Sites. The purpose of this TechBrief is to present key findings and products that resulted from the report.