Study on Optimization of Night Illumination in Expressway Long Tunnels

Night illumination of expressway long tunnels in China was far from drivers’ demand and caused lots of traffic accidents and electricity wasting. In order to solve this problem, reasonable night luminosity in expressway long tunnels in China was studied. Based on a visual disturbance generation mechanism, the mistakes in night illumination of Chinese expressway long tunnels were analyzed. Real road experiments were conducted and fuzzy assessments were used to establish models. The results showed that night luminosity was too high and should be controlled below 9Lx. In the entrance segment, the luminosity should be gradually increased from 0Lx to 9 Lx. In the middle segment, the luminosity should be remained at 9 Lx. In the exit segment, the luminosity should be gradually decreased to 0 Lx. The optimized luminosity is highly consistent with the actual demand of drivers. Traffic safety was improved and electricity consumption was reduced.