Evaluation of the Performance of a Road Surface Gonioreflectometer

Abstract

The reflection properties of the road pavement depend on the material and the texture of its surface. They can be specified with a set of luminance coefficients, which can be measured thanks to a gonioreflectometer. We presented in a previous paper a gonioreflectometer designed for in-lab measurements, especially suited for public lighting applications. We present in this paper a metrological evaluation of this instrument. First, we compare measurements from the gonioreflectometer with measurements taken with an illuminancemeter and a luminancemeter. Then we look at measurements in two analytically tractable cases. Finally, we perform uncertainty calculations on the luminance coefficients, and extend the results to the road lighting application by calculating uncertainties on the lightness and specularity parameters. We also evaluate the influence of uncertainties on the performance of a given lighting design for two types of road surfaces. Our results indicate that the achieved uncertainties have a limited influence.

Review of road surface photometry methods and devices – Proposal for new measurement geometries

“…These devices are expected to have relatively small measurement uncertainty, typically evaluated to be around 10%. 23,29,30 They are therefore used to make the reference measurements necessary to calibrate the portable devices. However, a uniform approach is currently lacking regarding the calibration methodology, the measurement procedure, the traceability, and the measurement uncertainty of these instruments.…”

Chapter 6 Wet Road Surfaces, a Challenge for Road Users… and for Measurement

“…5) which was specifically designed for BRDF measurements of road surfaces. Saint-Jacques et al [9,10] give a detailed description of the functioning of our gonioreflectometer and the evaluation of its performance. In an exploratory study, samples of road surface have been wetted with water from a sponge.…”