The tunnel is a special section of the high – grade highway, when the vehicle enters, passes through and exits the tunnel, a series of visual problems will occur. In order to adapt to visual changes, additional electric lighting is required.
The tunnel lighting is generally installed on both sides of 5.5 meters to 6 meters, and the Angle is adjusted in the range of 25 degrees. Its installation requirements can usually be considered from the following aspects:
1.Brightness – The brightness of the tunnel entrance lighting during the day should be determined according to the brightness outside the tunnel, the speed, the field of view at the entrance and the length of the tunnel.The threshold segment is to eliminate the “black hole” phenomenon, and the lighting level of the transition segment further gradually decreases, thus providing the driver with time for visual dark adaptation.
2.Brightness uniformity – Good visual function not only requires a good average brightness, but also requires that the average brightness on the road and the minimum brightness can not be too different.
3.Dazzle – Tunnel lights should be truncated, take special technical measures to remove direct and reflective glare, form diffuse reflection, so that the light is very soft into the human eye.
4.Flickering – Generally speaking, the stroboscopic phenomenon is acceptable when the frequency of stroboscopic is less than 2.5 and greater than 15Hz.
5.Lighting control – As far as possible, the use of photosensitive devices, adjustable light electronic rectifier and other intelligent lighting system, so as to reduce the overall brightness of the lamps in the tunnel, reduce energy consumption; At the same time, the uniformity of tunnel brightness is guaranteed.
