Road surface reflectivity The primary purpose of road lighting is to make people, vehicles and objects on the road visible by revealing them in silhouette against the road surface. As a result, road lighting standards are expressed in terms of three luminance metrics, average road surface luminance, overall luminance uniformity ratio and longitudinal luminance uniformity ratio. The luminance of any point on a road surface is a function of the illuminance on, and the reflection properties of, the pavement material. The reflection properties of the road surface will be determined by the pavement material used, whether it is wet or dry, and how much use the road has had. Despite the existence of these variables, the recommended design method for road lighting in the UK uses one set of data for characterizing the reflection properties of road surfaces, called the representative British road surface, although this is modified for concrete roads. However, there are now a number of new asphalt-based pavement materials available, such as porous asphalt, stone mastic asphalt and a number of proprietary thin surfacings. The objective of the report was to determine whether these new pavement materials can be accommodated within the representative British road surface road lighting design system. This research found that the representative British road surfaces overestimate the average road surface luminances produced for both new and established pavement materials. aims to improve our understanding of the interaction between lighting and road surfaces. It includes a desk-top review of applicable documentation; checking the validity of existing r-tables and their relevance to existing lighting design practice; determining, as necessary, r-tables for new road surfaces; determining the effect on existing lighting systems of a change of road surface following carriageway overlays or rebuilds; providing help and advice to highway authorities in determining the correct r-table to be used for road lighting design, and in designing economic and cost effective road lighting systems for traffic routes. This research was undertaken by Sheffield Hallam University
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