Design Of Tunnel Entrance Sunshade Based On Driver’s Visual Adaptability

In recent years,with the frequent occurrence of traffic accidents in tunnels,the safety of tunnels has attracted the public’s attention.Based on the analysis of traffic accident data in tunnel,it is considered that the typical light environment in tunnel section,especially the "black hole effect" caused by severe illumination difference in tunnel entrance section,is one of the main reasons for the frequent accidents.It is considered to be a reasonable and effective choice to set up a sunshade at the tunnel entrance,but there is little research on the design of the sunshade at present,which is mainly based on experience design.Considering that the sunshade is designed to meet the driver’s visual adaptation characteristics,the research on the influence of light environment transition at the tunnel entrance on the driver’s dynamic vision is carried out,and then the design method of light transition of the sunshade is proposed,which is of positive significance to ensure the driving safety at the tunnel entrance.Based on the research of driver’s dynamic vision theory,the mechanism of human eye recognition is analyzed,and combining with the traffic environment characteristics of the tunnel entrance,the mechanism of the influence of visual adaptation on the formation of "black hole effect" at the tunnel entrance is revealed,and the influence scope is determined.Based on the driver’s visual response ability,the visual effect method is selected to design the indoor model experiment,in order to detect rate and response time based on the dynamic visual characteristics of the driver,the dimmable lamps and changing visual aids are designed to replace the environmental light transition and obstacle recognition,and the dynamic visual recognition test of the environmental light change at the tunnel entrance is simulated.According to the safety visual response time regulated by traffic engineering,the illuminance transition curve which accords with the driver’s visual adaptation characteristics under the corresponding speed is drawn.Based on Ecotect,the tunnel entrance light reduction facilities are compared and analyzed,and the sunshade is selected as the engineering scheme to improve the transition of tunnel entrance light environment.The model of tunnel entrance sunshade is built by analysis light environment simulation software,and the change of illumination along the line from the sunshade to the tunnel entrance under the condition of different external light environment illuminance and control speed is obtained through simulation analysis;according to the fitting illuminance transition formula under different vehicle speeds,combined with the theory of increasing the minimum visual stimulation time driving step length of the sunshade section,the component length is determined.For the sunshade under this length,the combination scheme of different material transmittance parameters is selected,and the simulation of the light environment in the whole range is carried out.Based on the illuminance change index meeting the driver’s visual adaptability,the sunshade penetration is explored Recommended value of optical parameter combination.Taking the solid engineering as the object of light environment design,the length of sunshade and the combination mode of light transmittance are determined by reference method,and the illumination simulation is carried out.The research results can provide theoretical guidance and method support for the actual design of light reducing structures,help to improve the "black hole effect" of tunnel entrance,alleviate the driver’s visual transition between light and dark,and promote the development of tunnel traffic safety.