Design of Multiple-Sensor Weigh-in-Motion Systems

Theory is derived for calculating the statistical accuracy of a weigh-in-motion (WIM) system with multiple, evenly spaced force transducers, subject to random dynamic tyre forces generated by heavy vehicles. A straightforward design procedure is developed for determining the best spacing between sensors, providing the speed of the heavy vehicle traffic is known. Simulated dynamic tyre forces of two generic heavy vehicle models are used to assess the accuracy of WIM systems for a variety of conditions and it is concluded that a good design choice is to use systems with three sensors spaced along the wheel path.