The purpose of this TechBrief is to present key findings from the study. Truck volume estimates are important in the design of roadways. The calculation of appropriate pavement depths and the design of many geometric features require truck volume estimates as inputs. States, however, traditionally collect only a limited number of short-duration truck volume counts. To provide a better understanding of how short-duration truck volume counts can be used to accurately estimate the key variables needed for design, planning, and operational analyses, the Long-Term Pavement Performance (LTPP) program recently completed a study entitled “Vehicle Volume Distributions by Classification.”