Exploring the effect of pavement reflection and photometric properties on road lighting performance

The reflection properties of pavement have an impact on the lit environment and thus upon drivers’ vision and comfort and the energy consumption of the lighting installation. The reflection properties combine diffuse and specular components. The specular reflection component changes with different materials: it also changes when the surface is wet, although this is sometimes ignored in lighting design. This study used simulation (DIALux 4.13) to investigate the effect on lighting parameters (luminance, overall uniformity, longitudinal uniformity and threshold increment (TI)) of changes in pavement reflection properties using different pavement materials and under dry and wet conditions. Furthermore, comparison of lighting parameters was made with different road lighting arrangements. The results show that an increase in the specular reflection component leads to an increase in luminance and a decrease in uniformity. Of the surfaces investigated, the porous pavement had the lower luminance but better uniformity. Arranging the lighting installation based on the extreme wettest condition could make luminance and uniformity rise but with an increase of 2–2.5 kWh/m2 annual energy consumption. When trying to control glare problems during design process, it is suggested that uniformity cannot be neglected except the TI.