Unlike usual road lighting, tunnel lighting has its unique particularity, especially in the presentation of the safety of tunnel lighting system. When making a lighting solution for tunnel light, the most important element to consider is the clear-dark conforming of human’s eye, special attention should be paid on the lighting design of changeover portion. In order to sacrifice the conforming requirement of human’s eyes; a changeover portion (from clear to dark) should be made in the entrance of tunnel, to make sure people can see things clear by light changing. For the exit of tunnel, the conforming period is very short, normally within 1 second, so no need to do other dispose.
 

Tunnel is an enclosed area, so natural light could not get into there. To confirm the connection of driving and life safety of people in the vehicle, tunnel lighting is an indispensible part of tunnel building because even daytime, the whole tunnel need electrical lighting inside. The discussion of energy-saving new lighting source have been focused on by the lighting industry, especially for LED tunnel light, which have been paused for a while. According to clear vision and intermediate visual theory, the relationship of CRI and LUX, LED has advanced advantage when applied in tunnel light. In this way, many important tunnel light project use LED light for light source in domestic market.
 

There are breakable pause when LED light apply for tunnel lighting project, yet there will be some problems. For example, if there is no specialize design and construction standard when use LED as lighting source for tunnel light, it will cause the variety range of quality from good to bad. In Europe, 60% tunnels are in Italy; this case is an application of a tunnel in Roma, Italy.
 

Bad environment, such as vehicle exhaust, noise, vibration, pure air, etchant gas, will cause the specialty of tunnel lighting. For a safe and warm lighting circumstance to passing vehicle and passengers, we will discuss the design thought and method with analysis.

What we offer:

LED we use now for tunnel light have reached 114-122lm/W,with the electrical voltage of 3.2V, we still apply 320hA for power supply, so the practical working power is 1.024W, the total power of 56pcs is 61.6W, Upon 86% of power efficiency, the total power is 72.6W. Within 736meters tunnel, there will be a need of 103 pcs tunnel light, which total power is 103*71.3=7374.8W. Calculated with 24hrs per day as working time, the total power consumption will be 215.3Kwh per day, annual power consumption will be 71950 Kwh.

Detail: to install light sensors to collect light data in the entrance and exit place of the tunnel, the light data can directly control a total of 40 units LED tunnel light in the entrance and exit place to adjust the brightness. It will work with full power and full brightness in the day time and work with half power and half brightness at night. The brightness will be adjusted by external environment change. The sensor does not cost energy. In the day time, outside the tunnel is of very bright light, LED tunnel lights will work with full power in the entrance, the brightness will reach 80, 50, 30 LUX. At night LED tunnel lights will work with half power, the brightness of tunnel is about 30 LUX while the whole brightness is about 40 LUX. If you do not demand changes in brightness with the change of environment, LED tunnel lights can be directly settled up a fixed time to change the brightness.
 

There are several special vision problems in the tunnel.
 

a. Before entering the tunnel (day time): the brightness difference is very big between the tunnel outside and inside, it will come out “black hole” in the entrance of the tunnel when the brightness is insufficient.
 

b. After entering the tunnel (day time): the car gets into the dark tunnel from very bright environment, it needs to take a time to view the situation clearly, and this is so-called”comfort retardation”.
 

c. The exit of tunnel (day time): it is very bright in the outside of the tunnel exit at day time when the car passes the long tunnel, the exit looks like “white whole” and the strong glare will emerge. The driver will feel very uncomfortable. Night time is opposite to day time, it looks like a black hole but not bright hole on the exit, the driver will not view the line and roadblock clearly on the road. Several specific vision problems above show the tunnel lighting a higher request, effectively dealing with these vision problems can follow the below aspects.

Tunnel lighting design. 
The tunnel lighting can divide into five sections: lead-in section, conforming section, transition section, basic section and exit section; each section has played a different role:
 

1. Lean-in section: Eliminate the "black hole" phenomenon, so the driver can identify obstacles at the exit of the hole; For example, assume at daytime that the brightness on the tunnel mouth environment at 4000cd/m2 and speed at 80KM/H, then the lead-in section meets the minimum request on the length at 40m and brightness at 80cd/m2.
 

2. Conforming section: After entering the tunnel, the driver can quickly adapt to the light in the tunnel and eliminate "black hole" phenomenon; according to the above conditions, the length and luminous intensity on confirming section is at 40m and 80 ~ 46cd/m2.
 

3. Transition section: the driver will gradually adapt to lighting inside the tunnel; according to the above conditions, the length and brightness on transition section is 40m and 40 ~ 4.5cd / m.
 

4. Basic section: it is the basic lighting inside the tunnel.
 

5. Exit section: In the daytime, it gradually makes the driver adaptable to the exit of the strong light to eliminate the "white hole" phenomenon; at night, it makes the driver in the tunnel to view clearly the linear path and road obstacles to eliminate exit " black hole "phenomenon. Common practice is outside to use the street lighting as a continuous lighting.
 

In the daytime, the luminous intensity at the exit and at the entrance should be higher than the basic section. At night, on the contrary, the luminous intensity should be lower than basic section. When the outside of the tunnels has the street light lighting, the brightness on inside tunnel surface should not be less than 2 times the outside tunnel’s ground.