5 Important Aspects To Consider in Tunnel Lighting

Tunnel lighting is a crucial project which requires criteria that need to be followed. The major factor involves proper lighting to keep drivers safe upon entering and exiting the tunnel. That being said, illumination is essential for tunnels as it differs from the visibility of road lighting.

Here is a checklist of important factors in the field of tunnel lighting:

Tunnel Lighting Standards

To get started, know the local regulations of the country for tunnel application. The gathered information will show the right lighting design to implement. This is to avoid further issues with the local standards.

Tunnel Lighting Design

Tunnel lighting considers the eye adaptation of drivers from natural light. There must be a transition of luminance level from highest to lowest to give eyes time to adapt. Project engineers will follow the 40-meter length rule for more efficient lighting.

Tunnel Lighting Stages

Within the 40-meter length of standard tunnels are five tunnel zones. Each requires a different luminance level, as follows:

Access Zone

In this zone, visual contrast could happen for drivers’ eyes in adapting to a darker place. It has to be brighter than the outside tunnel to guide drivers in entering the tunnel. The eyes adaptation time is very short that can be dangerous for moving drivers.

Threshold Zone

The threshold zone is the first section of the tunnel where accidents mostly occur. It is a total black hole during the day which demands special lighting for better visibility. The outside luminance helps to see details inside the tunnel, as the driver’s eyes already adapt to its brightness.

Transition Zone

Since the eyes start adapting to tunnel lighting in the prior zones, eye adaptation here becomes easier. The black hole visibility has lessened in the transition zone, and yet vision comfort must still be a concern.

The brightness contrast for the transition zone should start decreasing gradually to prepare the eyes for lower luminance. This is also the longest zone in the tunnel going closer to the exit zone, thus luminance reduction is necessary.

Interior Zone

Near the exit is the interior zone where only the tunnel lighting influences the eye adaptation. The lighting level remains constant in this zone as it completes the adaptation process. It supports natural illumination for the driver’s proper visual condition.

Exit Zone

Getting out of the tunnel requires the eyes to adapt from low to high luminance level, a total opposite with the access zone. The lighting design will differ for daytime and nighttime, thus dimming function is a good option. It adapts to changing daylight environments to help drivers clearly see obstacles. During the night, road lighting within 300-meters from the tunnel’s exit helps to avoid accidents.

Tunnel Lighting Distribution

Proper lighting distribution for each tunnel zone is important to consider in tunnel designs. Natural lighting can enter up to 15-meters from the entrance of the tunnel. Tunnel structures are mostly 200-centimeter high which makes objects visible from a 100-meter viewing point. The remaining 25-meters will need a gradual lighting design for eye adaptation.

Tunnel Lighting Maintenance

A time comes when tunnel lights fail to operate well. Regular checkups for the lights are important to ensure safety for road takers. They operate both day and night which could be less functioning for the coming months. Also, lighting maintenance needs to close the tunnel for more efficient work.

Final Thoughts

In conclusion, tunnel lighting demands great responsibility to function very well. It aims to protect many road takers passing through a tunnel. Proper lighting requirements bring comfort for eye adaptation, different from road lighting. The lighting distribution is different from the access zone upon exiting the tunnel. Therefore, tunnel maintenance is essential for better visibility in and out of the tunnel.


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