Tunnel lights, as the name suggests, are lights used for lighting in highway tunnels. With the continuous progress of our social economy, the highway transportation network is becoming more and more developed, and there are more and more tunnels. The lighting in tunnels is also receiving increasing attention.

Many people assume that tunnel lighting should be similar to highway and street lighting. However, in reality, tunnels, as a semi enclosed tubular area, have some special characteristics. For example, when vehicles enter a tunnel during the day, due to a sudden drop in brightness and delayed human eye response, it is difficult to distinguish the situation ahead, forming the so-called "black hole effect"; On the contrary, when vehicles exit the tunnel, they will form the so-called "white hole effect" due to strong glare. Therefore, there are significant differences between tunnel lighting and general street lighting:

There are some special requirements for brightness. The lighting in tunnels is divided into adjacent sections, entrance sections, transition sections, middle sections, and exit sections, and different sections have different lighting requirements. Generally, it is required to gradually decrease the brightness, maintain stability in the middle, and then increase the brightness at the exit.
The second is that the lighting should be uniform, with no significant difference between the brightest and darkest, to avoid the continuous occurrence of the "zebra effect" of light and dark on the road surface. In addition, the installation spacing of the lamps should also be adjusted, especially to avoid the occurrence of light and dark changes between 2.5-15Hz, which can cause the so-called "flicker effect". Because both the "zebra effect" and the "flicker effect" can easily cause visual fatigue and psychological discomfort.

Thirdly, there are special requirements for lighting control. Unlike ordinary road lighting, tunnel lighting requires 24-hour uninterrupted operation, and the daylight intensity is stronger than at night, resulting in higher electricity consumption. In order to achieve energy conservation while ensuring effective and safe lighting, it is necessary to control the intensity of lighting in a targeted manner.

Before the emergence of LED tunnel lights, there were three main types of tunnel lights on the market: high-pressure sodium lamps, fluorescent lamps, and induction lamps. But these three types of lights each have some advantages, but also have some obvious disadvantages.

The advantage of high-pressure sodium lamps is that they have high light efficiency (up to 120ml/W) and are relatively energy-saving. The disadvantages are poor color rendering and limited selectable power range. Because it is often difficult to find a suitable power, high-power light bulbs have to be used, which not only consume electricity, but also easily cause glare and flicker effects under strong light.

Fluorescent lamps have good color rendering properties, and due to the general use of straight tube fluorescent lamps, they have a certain visual induction effect. However, the power of fluorescent lamps is relatively low, and the light intensity often cannot meet the requirements when used at the entrance or exit of tunnels. In addition, the service life of fluorescent lamps is relatively short, usually only 8000 hours, and they need to be replaced frequently, greatly increasing costs.

Infinite lamps have good color rendering, long service life, and higher power than fluorescent lamps. However, its luminous efficiency is not outstanding (80ml/W), and its large volume and emitting surface often limit the design of the lighting fixtures.
LED tunnel lights, on the other hand, combine all the advantages of the above three types of lights and eliminate their shortcomings. Therefore, it quickly became the most ideal light source for tunnel lighting. So far, tunnel lighting has basically been LED lit. Specifically, the advantages of LED tunnel lights mainly include the following aspects.

One is high luminous efficiency. Nowadays, the luminous efficiency of LED has generally surpassed that of high-pressure sodium lamps, and there is still a lot of room for improvement in the future. Therefore, the energy-saving effect is significant.

The second is longevity. The theoretical lifespan of LED lights is 100000 hours, and the actual product also exceeds 30000 hours, which can greatly reduce maintenance costs.

Thirdly, the design of lighting fixtures is flexible. LED is a point light source with small size, which can be designed according to the requirements of different tunnels or different sections of the same tunnel to achieve the best lighting effect.

The fourth is infinite dimming. As a semiconductor solid-state light source, the biggest feature of LED lights is their extremely flexible dimming. By combining the brightness of the tunnel entrance, the number of vehicles, or other parameters, the brightness of the lights inside the tunnel can be dynamically changed. With appropriate sensing and control systems, intelligent lighting can be achieved.
Of course, LED tunnel lights also encounter difficulties in application, and a typical problem is the light decay of LED lights. The light decay of LED lights is mainly related to the p-n junction temperature (junction temperature) of semiconductor diodes. As the junction temperature increases, the brightness of the lamp continuously decreases. LED tunnel lights, on the other hand, provide continuous lighting 24 hours a day and generate more heat, so they have higher requirements for heat dissipation. In addition, the environment in the tunnel is harsh, with poor air circulation and high humidity, which can accelerate the aging of the lighting fixtures.

To solve these problems, researchers in the industry have come up with many solutions. For example, Shanghai Sansi Optoelectronics has developed a ceramic LED tunnel light that directly welds LED beads onto an alumina ceramic heat sink, utilizing the high insulation and thermal conductivity of alumina ceramics to achieve rapid heat dissipation. At the same time, due to the excellent chemical stability of alumina ceramics, they are not sensitive to acids, alkalis, moisture, etc. in the air, and can be used for a long time in harsh environments. Coupled with appropriate structural design, it can effectively solve the problem of lamp aging. At present, this ceramic LED tunnel light has been applied in many important tunnels in China (such as the Hong Kong Zhuhai Macao Bridge underwater tunnel, Xiamen Haicang tunnel, Dalian Bay underwater tunnel, Jinan Yellow River tunnel, etc.), achieving good results.