Three tunnel lighting systems--symmetrical, counter-beam (cbl), and pro-beam (pbl)--were compared under the same geometrical and weather conditions to determine their advantages and disadvantages in terms of visibility. The pbl system was found to have no advantages over the other two systems, and it should be used in combination withlight, diffusing tunnel walls, and road surfaces. The symmetrical system was found to provide good guidance when used with luminaires mounted in a continuous line, and the cbl system was found to ensure good perception of contrast and an acceptable level of glare, provided that certain conditions are met. This paper appears in transportation research record no. 1316, Visibility for roadways, airways, and seaways 1991: proceedings of a conference, july 25-26, 1990, washington, d.C.
Abstract