NCHRP Report 683 provides a set of protocols and methodologies for using available recent truck traffic data to develop and calibrate vehicular loads for LRFD superstructure design, fatigue design, deck design, and design for overload permits. The protocols are geared to address the collection, processing, and use of national WIM data. The report also gives practical examples of implementing these protocols with recent national WIM data drawn from states/sites around the country with different traffic exposures, load spectra, and truck configurations. The material in this report will be of immediate interest to bridge engineers. This report replaces NCHRP Web-Only Document 135.
Under NCHRP Project 12-76 the research team had developed and demonstrated the application of protocols for collecting and processing traffic data to calibrate national bridge live-load models. Additionally, under NCHRP 12-76(01) the research team conducted sensitivity studies and developed key recommendations on sorting of trucks into Strength I and Strength II limit states.