No abstract

Numerous measurements have shown that the standard R classes do not represent adequately many road surfaces used nowadays. Therefore, the construction of portable reflectometers intended for on-site measurements of road surface reflection properties has been given particular attention during the last decade. This paper presents a new procedure for the improvement of the accuracy of such a portable reflectometer. Optimally extrapolating the values of the 20 luminance coefficients (q), each measured by the portable reflectometer for a set of angles of observation (α = 5°–80°), the 20 q-values referring to α = 1° are calculated. This enables their comparison with the corresponding q elements from each of the 447 reduced q-tables derived from the available r-table database, obtained by using a precise laboratory reflectometer on a wide variety of road samples. Selecting the closest reduced q-table, the corresponding r-table and the actual average luminance coefficient can be determined. In order to validate the proposed procedure, which can also be applied to other similar portable reflectometers, measurements of the luminance and overall and longitudinal luminance uniformities were carried out on eleven road-lighting installations. They showed that the results obtained by this procedure deviate only slightly from those obtained using r-tables determined by the laboratory reflectometer.

One of the crucial street lighting design steps considerably influencing electricity consumption is the selection of an appropriate lighting class. Therefore, after a detailed analysis of the current CEN and CIE selection procedures for streets and roads with motor or mixed traffic, several modifications of the CIE 115-2010 procedure are proposed. This way not only is its simplicity maintained but also the agreement between the two procedures is increased by up to 50%. The modifications are related to the weighting values corresponding to the traffic composition and ambient luminance as well as the inclusion of a value linked to the complexity of the visual field. The necessity for further investigation regarding the selection of lower lighting classes during the late night hours and the determination of appropriate luminance levels is also discussed.