Experimental Research On Traffic Safety And Energy Saving Of Highway Tunnel Lighting Based On Visual Performance

Highway tunnel is a tubular semi-enclosed traffic area,the driving environment is special due to the big difference between the luminance of the inside and the outside of the tunnel in daytime lighting.With the construction and operation of highway tunnels,especially long tunnels,highway tunnel lighting is becoming more and more important to the development of China's transportation.This paper,as one of the research topic of the program of the National Natural Science Foundation "Research and Evaluation of Equivalent Lighting System for Highway Tunnel Based on the Concept of Energy Conservation"(Grant No.51678096),will focus on the problems caused by highway tunnel lighting and do some experimental research based on visual performance.Since the 1950s,the study of highway tunnel lighting was mainly focused on the topic of "visual adaptation","luminance perception" and "perceived contrast" and so on.The luminance of the thresold zone,the luminance evolution from the threshold zone to the interior zone,and the glare limition,et al were recommended based on the previous research.However,the current standard of tunnel lighting based on photopic photometry can not fully consider the driver's visual perception due to the complexity of the vision and color response mechanism of the human visual system and the effects of the photo-biological effect.Meanwhile,the incandescent lamps,the high pressure sodium lamps and the fluorescent lamps were replaced by light-emitting diode(LED)with the developed of "high brightness blue(LED)".The LED has the advantage of low energy consumption,long life,and it can be intelligent control.Therefore,it is an urgent task to do research on the driving safety and energy conservation of highway tunnel lighting which can combined with the advantage of LED technology,the respons mechanism of human visual system and the actual driving environment.The primary task of this study is the evaluation of the lighting environment of highway tunnel.How to evaluate the influence of the lighting environment parameters(such as the correalated color temperature(CCT),the spectral power distribution(SPD)and the spatial distribution of these parameters on visual environment)on the driver's driving state is a big question.The visual performance method based on reaction times and missed rates of the visual target is proposed in this paper.Based on the highway tunnel lighting environment simulation and evaluation experimental devices,the influence of the SPD of visual field and the CCT on test subjects visual performance was studied.The results can be a guidance for the design of highway tunnel lighting.Secondly,the influence of dynamic highway tunnel lighting environment on driver's visual performance is closely related to traffic safety and energy saving of highway tunnel lighting based on the previous research.Therefore,the process of the driver driving through an illuminated highway tunnel in 80 km/h was simulated in the laboratory by gradually decreasing the luminance of the visual environment.The reaction times and missed target rates were measured in the process of decreasing the luminance step by step.The influence of transient adaptation,SPD and the CCT on drivers' visual performance in highway tunnel lighting was studied in this paper.Finally,the optimization of highway tunnel lighting environment is carried out based on the experimental results of visual performance in these two kinds of visual environment.Meanwhile,the optimization of highway tunnel transition zone and interior zone and the implementation of luminance evolution curve of each tunnel zones are proposed based on the results.Further more,the paper proposed the safe and energy saving mode of highway tunnel lighting based on visual performance,and puts forward the idea of the contstruction of the equivalent lighting system of highway tunnel based on the concept of energy saving.Based on the results of the visual performance of the test subjects in different tunnel lighting environment,the innovation of this paper are as follows:1.The experimental devices of highway tunnel lighting environment simulation and evaluation is proposed based on the study of the influence of the lighting environment parameters on the driving state.2.The effects of lighting environment of each tunnel zones on driver's visual performance are revealed based on the indoor simulation and evaluation of the driver's visual environment.3.The safe and energy saving modes of highway tunnel lighting are proposed based on the experimental results of visual performance in static and dynamic visual environment.4.The reasonable evaluation indexes and optimization measures of the lighting environment of the highway tunnel are proposed from the perspective of the visual performance of the driver.The experimental basis for the construction of the equivalent lighting system of the highway tunnel based on the concept of energy saving are provided in this paper.