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Horticutral Lighting
For every stage of a tunnel lighting project, from the simplest to the most complex, there are certain requirements and standards that need to be followed to ensure comfortable lighting for drivers. A quite big difference between tunnel lighting and ordinary street lighting is that when drivers enter or exit a tunnel, visual brightness changes will take place. So it is necessary to adjust the illumination. In fact, lighting requirements in tunnel lighting projects may vary based on different zones of the tunnel.
Different lighting requirements for each zone of the tunnel lighting:
Tunnel lighting is divided into five zones according to different design brightness: access zone lighting, threshold zone lighting, transition zone lighting, interior zone lighting, exit zone lighting. the lighting requirements of each zone are different.
Tunnel lighting is divided into five zones according to different design brightness levels: access zone lighting, threshold zone lighting, transition zone lighting, interior zone lighting, and exit zone lighting. The lighting requirements of each zone are different.
Access Zone Lighting:
The approach section is designed to allow drivers to clearly see the conditions of the tunnel portal when preparing to enter the tunnel, and to adapt to the brightness of the tunnel entrance. In this zone of the tunnel, the brightness outside the tunnel is much higher than inside during the day. If the tunnel is long enough, what drivers see is a black hole, and if the tunnel is very short, a black frame will appear in front of drivers. When entering the tunnel, it is a process of moving from a brighter outside to a darker place. If adjustments are not applied to the lighting design, it will cause a visual contrast. Drivers will have to spend some time adapting to the new visual environment, that is to say, their vision will need a certain adaptation time, and then the conditions inside the tunnel can be seen. Although the adaptation time is probably very short, it is very dangerous for moving drivers. So in the access zone, it is generally recommended to use relatively bright tunnel lights to guide drivers to adapt to the conditions of the tunnel portal in advance.
Threshold Zone Lighting:
The threshold zone is the first section of officially entering the tunnel. Usually, the incidence of traffic accidents in this zone is much higher than other parts of the tunnel. The threshold zone is a sudden change section where drivers go from an ordinary driving environment into a special driving environment inside the tunnel. How to eliminate the adverse effects of this mutation section becomes the key point of lighting design in this threshold zone. What needs to start immediately is removing the vision phenomenon of a black hole, which occurs at the moment drivers enter the tunnel during the day. All illumination standards here are to keep the vision status of drivers unaffected.
Transition Zone Lighting:
The transition zone is between the threshold zone and the interior zone. As mentioned above, we solve the "black hole" problem by adjusting the brightness of the tunnel portal, but that causes another issue of luminance contrast here. The problem is high brightness in the threshold zone while low brightness in the interior zone. Drivers have the same problem of visual adaptation. So the lighting design for this zone is around measures to solve the view adaptation problem. It is merely a matter of extent, a smaller brightness contrast. When the driver drives into the transition zone from the entrance during the day, in order to reduce the visual difference for the driver, it is necessary to reasonably arrange and install different brightness level tunnel lights to improve the visual comfort of the driver. The brightness of the transition zone should decrease step by step.
Interior Zone Lighting:
The interior zone of the tunnel is somewhere far away from the influence area of natural illumination. The driver's vision is only affected by the tunnel lighting. After drivers drive through the threshold zone and transition zone, they have completed the adaptation process. The lighting goal of the interior zone is to ensure stability of the same visual conditions as before to improve security. So this zone only needs to provide an appropriate brightness level, it doesn't need to change.
Exit Zone Lighting:
When drivers exit the tunnel there are two cases. In the daytime, what they experience is transitioning from a darker section to a brighter section. While at night, the contrary is the case. At the exit zone of the tunnel, there will be a very bright exit during the day, which will produce strong glare for drivers, thus making it hard to see road conditions and prone to traffic accidents. On the contrary, when exiting at night, the exit of the tunnel becomes a black hole. It is not easy and convenient for drivers to see the route and obstacles. Therefore, the lighting design here can take dimming functions into account in order to automatically dim according to the different daylight environments outside the tunnel.
If you want to dive into more detail regarding tunnel lighting, please check our TN02 LED Tunnel Light.
