MEASUREMENTS OF ROAD LIGHTING AND ACCIDENTS - THE RESULTS

While the figure of 30% accident reduction has been used to justify lighting unlit or poorly-lit roads, little or nothing is known regarding the lighting qualities which do most to bring about this reduction in accidents. Furthermore, the validity of the 30% figure to support improvements to existing lighting is open to some doubt. It may be that there is a limit to the extent to which certain of the lighting qualities need to be improved, whereupon any further improvement does nothing more to reduce accidents, or indeed may adversely affect the trend in casualties. The aim of this study has been to provide a more detailed insight into the way in which road lighting is related to accidents. The study is limited to dry road conditions, and this paper might be regarded as comprising four parts: sections 1 and 2 explain the choice of road sites to be studied; sections 3 and 4 describe the measurement and computation of lighting values; sections 5 and 6 explain the statistical analysis of accident data and correlation with lighting data; finally, section 7 discusses the results. (TRRL)