Information on the life expectancy of retroreflective sheeting for road signs, exposed to various types of environment and in different directions to incident sunlight may contribute to the refinement of financial aspects of planning of their replacement in order to maintain their role in traffic safety. Research in their behaviour in urban and rural conditions in NSW has been conducted. This report presents the results of thirteen years of exposure of retroreflective sheeting oriented to north, west, east and south, at three different sites, quoting the observed difference in their lifetimes. It has been found that the urban atmosphere shortens the lifetime by approximately 10 per cent in north per cent in north orientation. Accumulated dirt reduces the retroreflectivity as well, so the unwashed sheeting would appear to have reached the end point by 5-10 per cent earlier than the washed ones. Correlations have also been drawn between the duration of natural, accelerated natural and artificial weathering necessary to decrease the photometric properties of these materials to the specified minimum of the Australian Standard AS 1906 Part I (1976) (A).
Abstract