Light & Engineering Vol. 23, No. 4, pp. 30-32, 2015 Svetotekhnika No. 5, 2015, pp. 33-34 EXTENSION OF THE LUMINANCE CONCEPT IN ROAD AND TUNNEL LIGHTING* Axel Stockmar LCI Light Consult International, Celle, GERMANY E-mail: a.stockmar.lci@t-online.de ABSTRACT The visual impression of the luminance distribution of the road surface in front of a vehicle driver does not correspond necessarily well with the determined values of the lighting criteria obtained for the traditional angle of observation. <...> To overcome these discrepancies it is proposed to extend the current luminance concept and to apply an additional angle of observation. <...> This requires the knowledge of the refl ection characteristics of the pavements for different angles of observation. <...> For the determination of the expected uniformities at the design stage it is necessary to use a calculation grid which is about three times denser than the usual grid. <...> The assumption of a different angle of observation has also a decent impact on the estimated veiling luminance and the resulting threshold increments in road and tunnel lighting. 1 Keywords: reflection characteristics of road pavements, road and tunnel lighting, road surface luminance 1. <...> INTRODUCTION The controlling criteria for the lighting of roads and tunnels for motorized traffi c are the luminance level and uniformity of the carriageway and the limitation of disability glare. <...> The use of the luminance concept requires the knowledge of the refl ection * On basis of report published in Proceedings of the 28th CIE Session, 2015, Manchester 30 characteristics of the road surface. <...> Current pavements used on roads have refl ection characteristics, which are not only different from CIE standard refl ection tables [1] but are also dependent on the angle of observation. <...> At reduced speed during night time driving the drivers’ visual fi xations tend more to parts of the road in a distance of about 30 m in front of the vehicle, i.e. an angle of observation of 3° below the horizontal. <...> At a speed of 30 km/h the length of the area in front of a car lit by its own vehicle headlights is approximately equivalent to the stopping distance. <...> At such a distance the luminance distribution experienced could be quite different from the expected luminance distribution calculated under the usual assumption of an angle of observation of 1° below the horizontal. <...> To avoid these discrepancies between calculated results <...>