The open-air laboratory for road lighting constructed at the Philips factory at Turnhout (Belgium) consists of a road, 320 m long and 14 m wide, provided with ten lighting masts mounted on trolleys. The road comprises various surfaces, which are used in the dry and in the wet condition. The height of the arms of the masts is adjustable to a maximum of 1205 m above ground level, the fittings can be changed and are mounted on these arms. The laboratory serves a fourfold purpose, being employed for 1. fundamental research in the field of road lighting, 2. judging fittings and lamps in course of development, 3. judging designs of road lighting installations by means of experiments, 4. demonstrating fittings and lamps in their normal conditions of operation. Results of experiments carried out in the laboratory show that a change in the distribution of luminance on the road has but little effect on the visibility of Landolt rings placed on the road surface, provided that from considerations of a more or less aesthetic nature the distribution of luminance remains acceptable. The visibility of Landolt objects placed on the road has been found - in otherwise identical conditions - to be better where sodium light is employed than where use is made of colour corrected mercury light.
Abstract