Abstract
In tunnel lighting practice, only the scatter in the eye, in the windscreen of the car, and in the atmosphere need to be taken into account. For all practical day- time conditions, the required luminance in any portion of the tunnel can be assessed as being a constant fraction of this sum- luminance; the fraction being determined by the traffic situation. This system is applied in several new and renovated tunnels in the Netherlands. The high values of the luminance in the threshold zone are arrived at by applying louvres that are not sun- tight, and by artificial light. New design principles of the louvres are introduced.