The words "dark" and "grey" aptly describe the light on many of the world's road tunnels. So when you see a bright tunnel, with no shadows or black spots, you might wonder why all tunnels don't have such good lighting conditions. In fact, new tunnels in many parts of the world have shown that well-designed LED tunnel lighting can help drivers adjust their vision easily and quickly, minimize maintenance, and save energy while improving light quality.

The total cost of ownership of public lighting depends on several factors such as illuminance, power consumption, equipment cost, installation cost, maintenance cost, luminaire form factor, and the expected lifetime of the luminaire. Although other quantifiable factors can be considered, it is primarily the decision of the administration.

Solid State Lighting Provides High Quality Lighting

As solid-state lighting technology matures, the quality of this lighting is very favorable for use in tunnels. Compared with commonly used outdoor lighting products, LED lighting has excellent color rendering.

Road users and pedestrians place high importance on light quality. Some cities and utilities have opted for LED lighting to improve commercial areas, making them more attractive and increasing a sense of safety and comfort.

In tunnel lighting, it can be said that both total cost of ownership and visual perception are factors to be considered. However, given the state of public funding, a lower total life cycle cost must be achieved. Fortunately, the development of LED technology has reduced the procurement and power costs of LED tunnel lighting systems. Compared to traditional high-voltage gas discharge light sources (HID), LEDs significantly reduce life cycle costs, while also providing other advantages of solid-state lighting systems. .

Comparison of LED and traditional lighting

At present, traditional high pressure gas discharge light sources (HID), such as high pressure sodium lamps (HPS) and metal halide lamps (MH), are still the main force of tunnel lighting. The tunnel lighting scheme requires a high minimum illuminance to provide a safe environment for users. The luminaire must be able to provide a high level of light at a considerable distance from the plane. Typical installation heights for road tunnels are 5-7 meters, providing clearance for high-side vehicles.

High pressure sodium and metal halide lamps are attractive to designers of tunnel lighting solutions, offering both low unit cost and high illuminance. Arrays of high pressure sodium and metal halide lamps, typically up to 400W per fixture, to meet illuminance requirements.

However, the disadvantages of high pressure sodium (HPS) and metal halide (MH) lamps are obvious. Both of these luminaires consume a lot of energy, often have low light quality, do not provide uniform lighting in the tunnel, and require expensive maintenance programs to remedy if they fail. Now, with the advancement of LED technology, tunnel operators have a new option that is increasingly attractive from a public and operational perspective.

The most obvious advantages of LED-based tunnel lights are their long life and high efficiency:

In typical tunnel lighting applications, high-quality LED lighting systems are capable of delivering >100 lumens/watt. Since LEDs are directional point light sources, their light output can be precisely delivered to the desired area, providing additional system efficacy compared to HID systems.