Bridge WIM temperature calibration
Environmental temperatures heavily affect behaviour of some types of bridges, thus making results of weighing very unstable. In order to provide stable and reliable results, the B-WIM systems must be temperature calibrated.
Dependence of weighing results on temperature can be clearly seen from the diagram below which displays the average 12-hour temperatures as a function of average gross weight of heavy vehicles. Furthermore, the uneven pavement, with bumps before the bridges induce dynamic oscillations of the bridge, which again has negative impact on accuracy of the weighing results. Shifts of the calibration factor are particularly apparent during long-term measurements.
Complexity of bridges reduces the efficiency of lab-based calibration procedures. Thus, the statistical methods have been applied to identify the variation of bridge stiffness as a function of temperature and of dynamic interaction of various types of freight vehicles. This allowed defining the correction factors as functions of temperature and velocity. The results demonstrated considerable improvement in accuracy and long-term stability of results. This is essential for success of the SiWIM® system and for achieving BridgeMon objectives.