Are standard tables r still representative of the properties of road surfaces in france?

摘要

The reflection properties of the pavement must be taken into account when designing a road lighting installation, to ensure luminance level and uniformity. In France, the standard r-tables of the CIE system R are used for that purpose. These tables are characteristic of pavement materials which were used decades ago. In the '90s, a first study on porous asphalt showed that they might no longer be relevant to deal with modem road surfaces. In 1999, the study was pursued on very thin asphalt concrete (VTAC) and surface dressing (SD). Different formulas, with different aggregate gradations and colors, were laid on two road sections with similar traffic. Samples were taken over a period of three years, to have their r-tables measured with a CIE compliant goniophotometer. The photometric data was analyzed in terms of lightness and specularity to estimate the influence of time and formula. VTACs start with a very high specular value which decreases rapidly during the first few months, and end up fairly or slightly specular after three years. On the opposite, SDs are diffuse at first, and end up more or less specular. Discrepancies were also found between the measured and the corresponding standard r-tables, even after reseating the latter to match the average luminance coefficient values.