Tunnel lighting is generally divided into five sections of lighting, such as the approach section, the entrance section, the transition section, the middle section, and the exit section. Each section has a different role:
(1) Close section: The approach section of the tunnel refers to a section of road close to the entrance to the tunnel. The starting point of the approach section is an illumination parking distance from the entrance hole, and the illumination parking distance is based on the design rules of the road tunnel lighting design. Incidentally, the approach section Located outside the tunnel hole, its brightness comes from the natural conditions outside the cave, and no artificial lighting is required. However, because the brightness of the near segment is closely related to the lighting inside the cave, it is customarily referred to as a lighting section.
(2) Inlet section: The entrance section is the first lighting section after entering the tunnel. Previously, the entrance section was called an adaptation section, and this section required artificial lighting.
(3) Transition section: The transition section is an illumination section between the entrance section and the middle section. This section is used to solve the driver’s vision adaptation problem from the high brightness of the entrance section to the low brightness of the middle section.
(4) Middle section: After the driver drives past the entrance section and the transition section, the driver’s vision completes the dark adaptation process. The task of led light tunnel in the middle section is to ensure the safety and stability in the tunnel.
(5) Exit section: In daylight, the driver can gradually adapt to the strong light at the exit and eliminate the phenomenon of “white hole”; at night, the driver can clearly see the line type of the external road and obstacles on the road in the hole. To eliminate the “black hole” phenomenon at the exit, it is common practice to use streetlights outside the cave as continuous lighting.
In daylight, the illumination of the exit section of the tunnel and the illumination of the entrance section should be higher than the value of the radical illumination of the tunnel; at night, on the contrary, it should be lower than the value of the radical illumination of the tunnel. When a street lamp is illuminated outside the tunnel, the road surface brightness value in the tunnel shall not be less than 2 times the open-air brightness value.