CALIBRATION AND ACCURACY TESTING OF WEIGH-IN-MOTION SYSTEMS

Examined in this paper are the problems of calibration and accuracy testing for weigh-in-motion systems, and several approaches are proposed that might improve the present situation. After the definition of terminology, recent calibration techniques are outlined and a different approach is advocated, based on random vehicles. A statistical appraisal of the approach concludes the first part of the paper. In subsequent sections, a new technique is described for self-calibration of weigh-in-motion systems, based on the fact that loads on certain axles of particular truck classes show relatively little variation. Self-calibration offers the prospect of improved weigh-in-motion accuracy in between conventional calibration exercises. In the final sections of the paper, the questions of weigh-in-motion accuracy appraisal and weigh-in-motion performance standards are addressed. An accuracy funnel for the assessment of weigh-in-motion performance is proposed. This provides for an absolute accuracy tolerance at low axle weights, with a percentage tolerance at higher loads.