Comparison of two independently developed bridge weigh-in-motion systems

An experiment is described in which two independently developed bridge weigh–in–motion (WIM) systems are tested and compared, both for accuracy and durability. The systems, an Irish prototype still under development, and a commercially available American system, were tested on a bridge in Slovenia. Eleven statically pre–weighed trucks were each driven over the bridge several times at a range of typical highway speeds. Accuracies for axle and gross vehicle weights are presented within the framework of the draft European WIM specification, and the bias which can be introduced by the selection of calibration truck is demonstrated. Performance factors relating to durability are also discussed with particular emphasis on axle detectors.