The lighting systems ensure that lighting is as balanced as possible in normal operation and should be similar to the outside brightness. That is why the lighting is also subdivided. On the one hand in entrance lighting and on the other hand in drive-through lighting. The entrance lighting helps the eyes to get used to the darker surroundings when entering the tunnel. This lighting is therefore regulated based on the currently prevailing brightness at the tunnel entrance and continuously decreases in the tunnel. At night it switches off completely.
The drive-through lighting, on the other hand, tends to be geared towards the volume of traffic rather than the external brightness. Because in the tunnel itself, you can’t see the outside world. But you can see – or rather – you have to see how many vehicles are in front of and next to you.
Like all other systems, the lighting must also react to special situations such as fire and accidents and ensure sufficient brightness at the scene of the accident
Furthermore, the optical guidance devices on the tunnel floor are used more and more. The function of this type of lighting is to help the fleeing person to find the correct escape direction in the event of a fire, if there is heavy smoke in the tunnel.