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This paper describes a method of estimating and recording surface luminance using widely available types of digital cameras and photographic image processing software. The method involves recording the luminance of a 10-step grey scale placed within a scene at the time an image is captured. The relationship between luminosity (a value obtainable from the software) and luminance of the grey scale may then be used to determine the luminance of surfaces within the scene to an accuracy of within 10%. The technique has been successfully applied to interior and exterior scenes lit in a variety of ways and to a number of types of digital camera. The methodology, robustness and limitations of the technique are set out.

The paper outlines recent investigations concerning the Polished Stone Value (PSV) test method. Although the research is limited to greywacke aggregate from Northern Ireland the results indicate that the standard PSV test may not adequately predict the ultimate level of skid-resistance reached by the aggregates assessed. Extending the duration of polishing further decreases skid-resistance. Modifying the apparatus to simulate cornering situations using angled polishing produced significant reductions in skid-resistance. It was also shown that results may alter when the aggregate size is decreased. The paper concludes that further research is necessary in order to predict the in-service performance of aggregates in the laboratory.

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