Tunnel lighting practice world-wide

Abstract

From a world-wide examination of tunnel lighting practice one has to conclude that many tunnel lighting installations differ on fundamental points of design: for example, in the lighting levels employed, in the lengths of the various lighting zones, and in the type of light sources used. Some of these differences are due to the fact that the lighting designs were based on specifications originating from different codes or based on different investigations, or both. These codes and investigations will be briefly evaluated. It will be argued that in some cases the differences are justifiably caused by differences in the practical conditions prevailing: such as, for example, in local outside adaptation luminances, differences in tunnel constructions and differences in speed limits.