a new type of matrix signal is being considered to improve the effectiveness of the motorway signalling system. in addition to the advice given by the present signal, it would inform drivers of the nature and location of hazards. a prototype three-part signal has been built to display this information, and a number of pictograms have been designed for indicating the nature of the hazard. measurements were made of the recognition distance of the three parts of the signal. the effect of a normal accumulation of road dirt on matrix signal recognition was assessed at the same time. the pictograms were tested to find out how effective they were in conveying the desired meaning to drivers who had not seen them before. the tests showed that the top advisory panel and the 'distance ahead' panel could be recognised from distances adequate for motorway speeds. although some of the pictograms on the prototype signal were not recognised from a sufficient distance, modifications have been made to this part of the signal which allow a 60 per cent increase in the linear dimensions of the pictograms within the same overall signal size. the recognition distances of the enlarged pictograms expected to be obtained by the average driver are now adequate. pictograms which were similar to those currently used on some fixed traffic signs were well understood. new designs were understood by between 40 and 100 per cent of subjects, indicating that some publicity might be needed before they were used.(a)

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