The effect of fence luminance on the detection of potential intruders

Abstract

Using a simulated security lighting installation, the effect of fence luminance on the performance of observers detecting potential intruders when looking through the fence has been assessed. The experiments were carried out on 2in. and lin. mesh chain link fencing made from bronze coloured plastic coated wire. The ratio of fence luminance to the luminance of the background, against which the potential intruder is seen, was found to be important. The best performance was achieved when the fence luminance either matched or was less than the background luminance. When the fence luminance is about three times higher than that of the background performance deteriorates significantly, the deterioration being greater for smaller fence mesh sizes. These performance results are supported by the observers' ratings of task difficulty and their subjective assessments of the most and least difficult conditions. It is suggested that the easiest way of producing the necessary low fence luminances in practice is to use a low reflectance wire, e.g. black plastic-coated wire, to form the fence.