Assessment of the Accuracy and Classification of Weigh-in-Motion Systems: Part 2 European Specification

This is the second part of a two-part paper which addresses the issue of accuracy in weigh-in-motion (WIM) systems. The first part develops the statistical background necessary for any system of accuracy classification applied to a WIM system. This second part describes a draft European specification for the weigh-in-motion (WIM) of road vehicles, prepared by the COST 323 management committee. The philosophy behind the specification is outlined and the basic structure detailed. The specification gives an indication of what WIM accuracy might be achievable from sites with particular characteristics. There is a comprehensive review of methods of calibrating and testing WIM systems. Four types of calibration/test condition are described for tests using statically pre- or post-weighed vehicles. Accuracy classes are defined on the basis of the width of the confidence interval within which the measured results lie. Confidence interval widths arc specified for gross weights and weights of individual axles among other things. The percentage of test results which are required to fall within the confidence intervals is a function of the test conditions and the number of test runs. Examples using real WIM data illustrate the use of the specification.