With the increasing number of tunnel projects, tunnel construction plays an increasingly important role in modern transportation. The tunnel is a closed space. In order to ensure the continuity of travel and the safety of the driver, even indoor lighting requires artificial lighting throughout the day. Tunnel lighting is an indispensable part of tunnel construction. The light source of tunnel illumination should meet the requirements of light efficiency, luminous flux, life, light color and color rendering in a specific environment of the tunnel, and at the same time ensure good visibility in the smoke formed by automobile emissions. The effect of tunnel lighting must be achieved by relying on a reliable light source.
Tunnel lighting is different from the usual road lighting, and it has its remarkable speciality. Its thinking about safety is especially important in the lighting system.
When describing the tunnel lighting plan, it is necessary to think about the human habits and dark habits, and pay attention to the lighting depiction of the transition and transition. In order to satisfy the habitual needs of the driver's eyes, a dark transitional illumination is required at the entrance of the tunnel to ensure a certain vision requirement. Due to the short habits at the exit of the tunnel, it is usually within 1 s, so no other disposal is possible.
There are usually several special visual problems in tunnels:
(1) Before entering the tunnel (daytime): Because the brightness inside and outside the tunnel is not so great, from the outside of the tunnel, the entrance of the tunnel with very poor illumination will see the appearance of "black hole".
(2) After entering the tunnel (daytime): The car enters the less-dark tunnel from the bright outside, and it is necessary to see the inside of the tunnel after a certain moment, which is called the “habitual lag” appearance.
(3) Exit of the tunnel: In the daytime, when the car passes through the long tunnel and approaches the exit, the external brightness seen through the exit is extremely high, and the exit looks like a “white hole”, which will show a strong glare. The staff will feel uncomfortable; at night, as opposed to the white day, the tunnel exit does not see a bright hole but a black hole, so that the driver can not see the line shape of the external road and the obstacles on the road.
The above special visual problems have put forward a high demand for tunnel lighting. It is useful to deal with these visual problems and can pass the following aspects.
First, the setting of tunnel lighting
Tunnel lighting is usually divided into five sections: the introduction section, the habit section, the transition section, the base section and the exit section. Each section has different effects:
(1) Introduction section: Eliminate the appearance of “black hole”, so that the driver can identify obstacles at the tunnel entrance; take the daytime as an example, assuming the ambient brightness of the tunnel opening is 4000 cd/m2 and the speed is 80KM/H, the introduction of the minimum demand is satisfactory. The length and brightness of the segments are 40 meters and 80 cd/m2, respectively.
(2) Customary section: After entering the tunnel, the driver can quickly get used to and eliminate the appearance of “black hole”; according to the above conditions, the length and brightness of the customary section are 40 meters and 80~46cd/m2 respectively.
(3) Transition section: The driver is gradually accustomed to the internal lighting of the tunnel; according to the above conditions, the length and brightness of the transition section are 40 meters and 40~4.5cd/m respectively.
(4) The fundamental section: normal lighting inside the tunnel.
(5) Export section: During the day, the driver can gradually get used to the glare at the exit and eliminate the appearance of “white hole”. At night, the driver can see the line of the external road and the obstacles on the road in the cave. To eliminate the "black hole" appearance at the exit, it is common practice to use street lights outside the cave as continuous illumination.
During the day, the illumination level of the exit section of the tunnel should be higher than that of the entrance section, and should be higher than the normal illumination level in the tunnel; at night, on the contrary, it should be lower than the normal illumination level in the tunnel. When the street lighting is used, the brightness of the road surface in the tunnel shall not be less than twice the brightness value of the open air.
As a professional supplier of LED tunnel lighting, OAK LEDs offer a complete set of free lighting designs that are 100% matched to OAK LED tunnel luminaires to meet the brightness requirements of tunnel lighting and to meet driver lighting requirements.