Pre-normative guidelines for measurement methods and procedures, including spectral properties, effects of measurement uncertainty in tolerance calculations obtrusive light and light pollution of road lighting installations

The design of a road lighting system should be based on the knowledge of the actual luminance coefficient (in the direction of emission of road lighting luminaires and the direction of observation) for the actual road. Because the actual quantity of q is not known, nor is listed as reference values in the EN standard (it provides only the directions in which q should be known), designers use in the calculations as q reference values the ones given in CIE 144 scientific publication. These values have been established from measurements on several road surfaces made in the mid-1970s and are obviously not representative of current road surfaces nor have uncertainty values. The low reliability of the available q data is well known: to be sure to reach the luminance standard requirements and avoid controversy with the customers, designers introduce an heuristic over-dimensioning of the installed luminous flux which compensates for the supposed depreciation due to ageing.

This guideline first presents quantities and practices of road lighting with a focus on road photometry. available data and measuring devices among SURFACE project are done in accordance with the bibliography. In the second part, review and suggestions on measurement procedures for on- site and laboratory measurements are presented. The last part of the guideline is on additional aspect including impact of spectral behaviour.