This report describes a project to improve understanding of how road lighting quality influences night-time crashes in higher speed limit areas on the urban fringe. The work complements previous urban work by the same authors. In this new study traffic conditions and crash types are different, as are the expected relationships between lighting and crashes. The study featured a before and after study, generalised linear modelling, a relational study and a corridor study. It considered three road types: motorways, median divided highways and single carriageway roads. The study concluded that the largest lighting-related crash reductions occur for motorways, followed by divided highways and single carriageway roads, and are generally lower than reductions for urban roads. There was no evidence that lighting motorways (or divided highways) to levels above the current .0.75 cd/m2 design level improved safety. Increasing the overall uniformity improved safety at least up to a value of 0.50, but no safety relationship was found for longitudinal uniformity. Single vehicle lost control crashes are little influenced by the presence of lighting and may even increase with lighting. Rear end crashes are strongly reduced by lighting. Crash reductions were generally greater for more serious crashes. (Author/publisher)
Abstract