Tunnel Lighting Guide

Date October 19, 2022
Categories Blogs , Knowledge

Tunnel lighting is classified into five zones: access, threshold, transition, inner, and exit--- and each zone is important to have proper lighting.

Good tunnel lighting is essential to ensure drivers can adjust well and quickly once they enter the tunnel and to guarantee a safe journey while they are inside the tunnel. The driver must enter the tunnel without causing any damage, pass through the tunnel, and exit the tunnel.

Due to the contrast between daytime brightness and the darkness inside the tunnel, illuminating tunnels has specific requirements. Drivers may experience temporary blindness as a result of the low levels of illumination inside the tunnel versus the high levels of sunlight outside. To prevent potential accidents, the lighting must gradually change for easier adaptation.

Tunnel lighting is classified into five zones: access, threshold, transition, inner, and exit.

Access Zone

The entrance of the tunnel is the most important area in tunnel lighting. It is the space between the road and the tunnel's entrance, and its length is equal to the safe braking distance. Lighting this area ensures that drivers can see the tunnel rather than being faced with a black hole.

Threshold Zone

The threshold zone is the distance from the brake to the safe distance, depending on the speed limit. The first half of the region has the same illumination as the outside environment, and is then reduced to 40% at the end of the region. This allows the driver time to adjust to the brightness level.

Transition Zone

After approximately 20 seconds, the driver reaches the transition zone, depending on the speed limit. The lighting level in this zone gradually decreases until it is equal to the interior illumination at the end of the zone.

Suggested lights for tunnels are Lawson Canopy Lights

Interior Zone

Between the transition zone and the exit zone is the interior. It is usually the longest and most desolate section of the tunnel. Lighting in this area should be determined by the speed limit and traffic intensity. The luminance level in the tunnel's interior must be between 1 and 10lx/m2.

Exit Zone

The exit area is the space between the end of the inner region and the tunnel's exit. This zone protects drivers from the low levels of illumination in the tunnel, allowing them to adjust to the high light outside.

At night, different lighting requirements arise in tunnels. In the evening, brightness levels ranging from 2.5 to 5lx/m2 are required throughout the tunnel.

It is advised to use energy-efficient lighting in tunnel lighting as system maintenance is both difficult and expensive. Lighting fixtures with long service lives and low maintenance requirements should be used whenever possible.

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