Metrication in the weighbridges

When the National Coal Board converts from the Imperial system to the Metric system of measurement, one of the major problems will be the conversion of bulk weights from tons, hundredweights and quarter hundredweights to either tonnes and kilogrammes, or to kilogrammes alone.This conversion can be made in two ways; either, the existing weighbridges can be left to read in Imperial units and a conversion applied to enable advising and invoicing to be done in Metric units, or the weighbridges themselves can be converted to read in Metric Units, The decision as to which method to adopt has not yet beon taken, but in any case the question of providing instantaneous conversion tables would arise, whichever method is used.If it were decided to adopt the latter system it would be advisable to set the date for conversion before the alteration of any weighbridges takes place; by doing this, it would avoid the existence of a dual conversion system within the N.C.B., i.e. those bridges converted before the date set, would have to convert from Metric to Imperial; those bridges still not converted after the changeover date would have to convert from Imperial to Metric. Under these conditions two sets of conversion tables would be required, one for each system.A number of N.C.B. weighbridges were visited to observe and analyse the weighing/weighing and recording system. To avoid overlooking any differences within the Board, weighbridges were selected in four different areas (S. Midlands, North Westerns South Yorkshire and West Wales) in order to study the problem in a little more detail. Individual differences exist in ticket format, size, the amount of numerical information recorded, the use of draftage (moisture content) and the recording of quarter hundredweights. These differences exist more in the landsale offices than the railway offices.It was found that the only figures which require conversion are those for the gross and tare weights since, irrespective of the differences in the system, this particular requirement remains constant in all Areas, Therefore, any increase in time and error probability in the uso of conversion tables can be regarded as being equal throughout all the K.C.B. weighbridges.Four conversion table formats were designed and tested experimentally. Significant differences were shown in the amounts of errors produced by each table. A suitably presented book-form table is recommended. “”