Purpose and Benefits of Tunnel Lighting

Abstract

Although the accident risk per vehicle km in tunnels is smaller than on open roads, the human and economic consequences are more severe. Just as with open roads, tunnels require good lighting in order to keep the visual performance good enough. Compared with the night-time requirements of tunnel lighting, the visual performance requirements that must be satisfied during the hours of daylight are considerably more demanding. The lighting in a tunnel must be such that the adaptation problem caused by the difference in high daytime brightnesses outside the tunnel and the low luminances inside the tunnel, is minimized. Even with visual performance aspects satisfied, the tunnel entrance may still appear somewhat as a black hole which may have a negative effect on the sense of confidence of the motorist approaching and driving through the tunnel leading to a hesitant driving behavior. As will be described in more detail in this chapter, the basic purpose of tunnel lighting for motorised traffic is to enhance the motorist’s visual performance and to maintain his sense of confidence.

Where cyclists and pedestrians in short tunnels and underpasses are concerned, the lighting should also help to promote personal security and discourage violence and vandalism.