In 1998, the Federal Highway Administration (FHWA) sponsored a two-phase study to develop traffic load estimates for Long-Term Pavement Performance (LTPP) sites. This report describes the results of the Phase 2 study. The Phase 1 study resulted in the development of methodology for estimating axle load spectra for all years the LTPP sites were in service. Phase 2 used this methodology to estimate axle loads for all LTPP sites that had acceptable site-specific axle weight data. In total, traffic load estimates were made for 558 LTPP traffic sites.

This report will be of interest to engineers involved in pavement management, design, maintenance, and rehabilitation and in traffic data collection and analysis.