Study on Optimization of Optical Parameters of Dimming Shed outside Tunnel

In recent years, more and more urban tunnels and highway tunnels have installed light sheds at the entrance to reduce the "black hole effect" and the low-angle sunlight glare effect, so as to improve the safety of the tunnel entrance section. The existing light sheds have poor uniformity of the road surface, bright and dark streaks, uneven brightness of the road surface and other undesirable conditions, bringing a certain negative impact on driving. On the basis of the safety and comfort of tunnel light sheds, based on the multi-source effect of light diffusion panels, a technology to reduce the negative impact of light sheds was proposed, construct a numerical analysis model of direct sunlight on light sheds, and lay light diffusion panels on the top of light sheds to fully diffuse the sunlight and then irradiate it to the road surface under the sheds, so as to avoid the undesirable phenomena caused by direct sunlight on the road surface, and conduct an indoor test and numerical analysis method. The optical analysis study was conducted by indoor test and numerical analysis. The results show that: the brightness uniformity of the road surface under the action of light diffusion plate is 0.7 ~ 0.95, which meets the requirements of the design specification, avoid the appearance of bright and dark streaks and other undesirable phenomena, and ensure the safety and comfort of the traffic at the tunnel entrance; due to the natural light provides luminous flux, the brightness level of the road surface under the shed can be controlled by the area of light diffusion plate, which reduces the carbon emission of the tunnel lighting system and achieves safety, comfort and low carbon environmental protection unity.