For each step of a tunnel lighting project, from the simplest to the most complex, certain criteria and standards must be followed to guarantee that drivers are given with a pleasant lighting effect. A significant distinction between tunnel illumination and conventional street lighting is that as cars enter or exit a tunnel, visual brightness levels shift. As a result, the lighting should be adjusted. Indeed, illumination needs for tunnel lighting projects might vary significantly depending on the tunnel’s various zones.

Diverse lighting needs exist for the tunnel’s several illumination zones:
Tunnel lighting is classified into five zones based on their relative brightness: entry zone lighting, threshold zone lighting, transition zone lighting, interior zone lighting, and exit zone lighting. Each zone has its own distinct illumination needs.

Lighting in the access zone

The approach segment is intended to provide drivers with a good view of the tunnel portal conditions as they prepare to enter the tunnel, as well as to acclimatize to the tunnel entrance’s brightness.
The brightness outside the tunnel is much greater than the light within during the day in this zone of the tunnel. If the tunnel is sufficiently lengthy, cars will encounter a black hole. Additionally, if the tunnel is really short, a black frame will emerge in front of the drivers. When you enter a tunnel, you are traveling from a brighter environment to a darker one. Without adjusting the lighting scheme, a visual contrast will result. Drivers may need to adjust to their new visual surroundings for a period of time. That is, the eyesight must adjust over a period of time before the tunnel’s circumstances can be perceived. While the adaption period is likely to be brief, it is very risky for driving motorists. so It is normally suggested to utilize a moderately strong tunnel light in the access zone to assist drivers in acclimating to the tunnel portal’s conditions in advance.

Zonal illumination at the threshold

The threshold zone is the tunnel’s initial portion. Generally, this zone has a substantially greater rate of traffic accidents than the rest of the tunnel. The threshold zone is a part of the tunnel when drivers transition from a normal driving environment to a tunnel-specific driving environment.
How to avoid the negative consequences of this mutation section becomes the focal subject of lighting design in this threshold zone. What must be done quickly is to eliminate the black hole vision phenomena that occurs when motorcyclists approach tunnels during the day. The purpose of this lighting standard is to maintain the drivers’ eyesight state.

Transition zone lighting

Between the threshold zone and the interior zone, there is a transition zone. As previously stated, we resolve the “black hole” issue by altering the brightness of the tunnel entrance, however this introduces another issue of luminance contrast. The issue is that the threshold zone has a high level of illumination while the inner zone has a low level of illumination. Drivers have the same visual adaption challenges as cyclists. As a result, the lighting design for this zone is centered on methods for resolving the perspective adaption issue. It’s just an issue of scale, a lower contrast between light and dark.
When the vehicle enters the transition zone from the entrance during the day, it is required to organize and install tunnel lights with varying brightness levels to enhance the driver’s visual comfort. The transition zone’s brightness should gradually diminish.

Zone lighting interior

The tunnel’s inner zone is located far from the natural illumination’s effect region. Only the tunnel illumination impairs the driver’s eyesight. Drivers have completed the adaption procedure after they have passed through the threshold zone and transition zone. The inner zone’s lighting objective is to maintain the stability of prior visual conditions in order to enhance security. As a result, this zone just needs to offer an adequate degree of illumination and does not need to be altered.

Lighting for exit areas

There are two scenarios that occur when cars exit the tunnel.
They are transitioning from a darker to a brighter part throughout the daylight. At night, though, the opposite is true. At the tunnel’s departure zone, there will be a bright exit zone during the day, creating a high glare for cars, impairing their ability to observe road conditions and increasing their risk of traffic accidents. On the other hand, if you escape the tunnel at night, the exit becomes a black hole. For motorcyclists, it is difficult and inconvenient to observe the path and any hazards. As a result, the lighting design for this tunnel may have a dimming feature to enable automated dimming in response to the changing daylight environment outside the tunnel.