An a posteriori control of weighbridges in self-certification schemes: a round-robin approach

The cost of legal metrological surveillance of weighbridges is constantly increasing because of the need for large standard weights and other facilities such as trucks, and also the need for qualified personnel – all of which are not always available to Local Metrology Authorities. In order to deter fraudulent actions by users, manufacturers and certified laboratories, Legal Metrology Authorities must plan alternative surveillance schemes that are at the same time both metrologically effective and cost effective. In this paper the authors describe a surveillance procedure for weighbridge self-certification tested at the Local Metrology Authority of Naples (Ufficio Metrico della Camera di Commercio, Industria, Artigianato e Agricoltura, Napoli). In this scheme large standard weights and other facilities of the manufacturer are used under the control of the legal metrology officer. With the Round Robin (RR) approach described below several weighbridges (up to 4–5 in a day over a small geographical area) can be verified in just a few hours and at a relatively low cost.