Tunnel lighting and ordinary road lighting is different because it must be lit 24 hours a day, lighting intensity than the nighttime lighting intensity is stronger, you can imagine the tunnel power costs become an important part of the operating costs; In addition to the tunnel lighting is different from the general road lighting, has its obvious particularity, including the person to the light and shade adaptability , light and shade transition space and lighting, etc. these are reflected in the design of tunnel lighting, but also to the user's safety is not a separate relationship. Tunnel lighting is usually divided into entrance lighting, interior lighting and outlet lighting. The requirements for entrance lighting are very stringent, requiring a gradual reduction in brightness similar to that of the outside world. In particular, the brightness of the tunnel entrance illumination during the day is determined by the brightness outside the tunnel, the speed, the field of view of the entrance and the length of the tunnel. The International Lighting Institute (CIE) divides tunnel entrance lighting into (starting from the tunnel port) threshold and transition segments. Threshold segment is to eliminate "black hole" phenomenon, so that the driver can clearly identify obstacles in the hole, tunnel transition section lighting is to avoid the threshold segment illumination and the internal basic illumination of the strong change between the set, and its lighting level further gradually decreased.
The tunnel lighting standard in Japan further divides the tunnel entrance illumination into the introduction section, the adaptation section and the transition section. The inner segment is the area of the tunnel that is unaffected by the external natural light, and the driver's vision is only affected by the lighting inside the tunnel. The inner segment is characterized by a uniform illumination level throughout the whole segment. Since the level of illumination does not need to change at all, it is necessary to provide the appropriate luminance level within the paragraph, which is determined by the traffic flow and the speed of the vehicle.
The distribution and luminance of the entrance, transition, inner and exit sections of the tunnel.