Abstract
Design procedures of illumination for long vehicular tunnels are considerably more complicated compared with roadway lighting. The visibility at the tunnel entrance is affected by many variable factors that are changing, not only because of annual and daily solar cycles, but also because of atmospheric conditions and seasons. For these reasons, "Book rules" are difficult to apply in the same manner as the guides used in roadway lighting design. Here, a method, rather than recipes, for the assessment of visibility requirements and the lighting design is described.