Evaluation of WIM Data Consistency based on Temporal Axle Load Spectra

The test truck data collected immediately before and after calibration are used to assess the WIM measurement errors. An alternative approach is needed to characterize temporal variations in WIM data consistency. Therefore, it is crucial to evaluate the relative consistency in WIM loading over time for different sensor types and quantify the relative accuracy of axle loads based on axle load spectra data for various sensors. Analysis of ALS data over time shows that for single ALS, there is a significant difference in peak loads between the bending plate and quartz piezo sensor measurements. The results show that calibration frequencies longer than one year may be acceptable for the bending plate sensors; however, at least one year for quartz piezo, and less than a year for piezo cable sensors, are recommended.