The dynamic nature of a train in operation is caused by variables in rail condition, track smoothness, wheel defects, truck hunting and skewing, and coupler effects. These conditions can each cause perturbations that may affect the accuracy of the weight measured by a Weigh In Motion (WIM) system. China is the only country that has mandatory requirements to calibrate a WIM system dynamically after it is initially installed and every year after it’s in revenue service.
This paper talks about the importance of both static and dynamic calibrations to achieve the highest accuracy of a WIM system. This paper also describes the process of conducting a dynamic calibration, and the lessons learned in the past several years in the effort to improve the weight accuracy of a WIM system.