Assessment of the accuracy and classification of weigh-in-motion systems Part 1: Statistical background

Abstract

This is the first part of a two-part paper which addresses the issue of accuracy in weigh-in-motion (WIM) systems. This part describes, and where necessary develops, the background necessary for any system of accuracy classification applied to a WIM system. The second part describes a draft European specification for WIM of road vehicles, prepared by the COST 323 management committee. The system of accuracy classification used in the specification is based on the principles described in this part. The common metrological definitions of accuracy are not applicable to WIM systems because the measured quantities are not traceable. Moreover, many WIM sensors may not be used to weigh static loads and/or cannot be checked with calibration masses. The WIM operations are not fully repeatable. Therefore particular definitions, sound reference values and statistical tools of which users should be reminded, are presented. Relevant formulas and methodology are developed and illustrated with numerical examples.