The Transportation Research Board (TRB) Expert Task Group (ETG) on Long-Term Pavement Performance (LTPP) Traffic Data Collection and Analysis (or Traffic Expert Task Group (Traffic ETG)) identified the inconsistencies in the classification data as problematic. Therefore, under the LTPP Specific Pavement Study (SPS) Traffic Data Collection Pooled Fund Study, TPF-5(004), the Traffic ETG developed a prototype classification scheme to be used in an effort to bring uniformity to the SPS traffic data collection. It was developed based on the experience of three States. The appropriateness of the application of the LTPP Classification Scheme needs to be done while the SPS data collection is still underway. This is very important research because binned class data cannot be reprocessed into different results. Implementing this national class scheme forms a basis for better data sharing among States. A better understanding of the classification scheme variability will allow pavement designers to account for this in their use of the data. Improved vehicle classification will result in better roadway designs as many States are using classification data in lieu of weight data at many locations. The Mechanistic-Empirical Pavement Design Guide (MEPDG) depends upon accurate vehicle classification data. Studies that use traffic data will be impacted by these findings. Software is available at no charge from LTPP Customer Support Service Center (phone: 2024933035; email: LTPPinfo@dot.gov).
The primary objective of this project is to develop an improved Long-Term Pavement Performance (LTPP) Classification Scheme that can be implemented nationwide, regardless of the type of weigh-in-motion system installed at a location to collect weight and classification data.