tunnel lighting

According to CIE 88 guidance, the lighting requirements of a tunnel are totally different by day and by night.

At night the problem is relatively simple and consists in providing luminance levels on lit routes inside the tunnel at least equal to those outside the tunnel.

The design of the lighting during daytime is particularly critical because of the human visual system. The driver outside the tunnel cannot simultaneously perceive details on the road under lighting levels existing in a highly illuminated exterior and a relatively dark interior.