Review on factors influencing the light reflection properties of road surfaces – Part 1: Internal factors

To limit energy costs and environmental impacts related to road lighting, luminance-based designing is the best solution to provide the right amount of light on the surfaces to be lit. However, this exercise requires knowledge of the reflection properties of the road surface, which are generally unknown. Therefore, the design is often done in terms of illuminance, and luminance is estimated using the standard r -tables provided by the CIE 50 years ago. This review article presents the state of knowledge on the reflection properties of road surfaces and the internal factors (family and nature of road surface, composition, type of aggregates, binders used, surface treatments) that may influence them for road lighting applications. Although some trends emerge based on the family of road surface, the wide variety of these factors, their interactions, or the extent to which they have been studied make it difficult to establish generalisable rules. The main international consensus is the need to revise the CIE standard r -tables. This article also identifies the need for further research, and the descriptive summary of the characteristics of road surfaces and their field of use that we propose is a solid basis for carrying this out in a unified manner.