Study On The Analysis Of Low-angle Solarblinding Effect At The Exit Of East-west Tunneland Its Improvement Application

The height angle of the sun is small in the morning and evening.For the drivers who have just driven out of the east-west tunnel,especially the long tunnel,the low-altitude sunlight will suddenly direct their eyes and lead to strong glare,causing transient blindness.For a moment,the driver cannot obtain the information of the dashboard and the safety of the road ahead,which leads to traffic accidents such as rear-end collision,wall collision and rollover.From the perspective of traffic safety,the main line of this paper is’measurement of solar irradiance-quantification of blinding effect-improvement of prevention and control application’.Combined with visual experiment and numerical simulation,the influence of blinding sunlight with solar altitude angle of 15°-30°on vision is analyzed.The main research work includes:introducing the causes and mechanism of glare,explaining and analyzing the characteristics of solar glare and accident correlation;The vertical illumination of human eyes and horizontal illumination of ground at 15°–30°solar altitude angle were collected as data reference;Combined with the visual criterion of small target obstacle,the subjective evaluation experiment was carried out.In the experiment,the solar elevation angle of 15°–30°was equivalent to the glare angle of 15°–30°with the precondition of horizontal forward line of sight and straight road without longitudinal slope.The glare light source with the same illumination level as sunlight was used to irradiate the human eye,and the small target obstacle of 40 m-80 m ahead was observed and the subjective evaluation was given.A small target recognition clarity index is proposed.The mathematical model is used to fit the functional relationship between the index and the glare angle under different visual distances,and the influence of blinding effect on vision is quantified.Using the unified glare value UGR evaluation standard,the psychological comfort rating of subjects facing this level of glare was obtained.A dynamic protection system is deduced according to the deficiency of anti-glare facilities abroad,and the protection effect of the dynamic system is verified by numerical simulation.The conclusions are as follows:（1）When the solar elevation angle in Chongqing in summer is 15°–30°,the vertical illumination range of human eyes is between 49.46 klx and 84.71 klx,and the horizontal illumination range of ground is between 18.98 klx and 53.79 klx;（2）When the visual distance is 80 m,15°–25°is the glare angle with the most serious blinding effect;When the visual distance is 60 m,15°is the most serious blinding angle;When the visual distance is 40 m,the blinding effect rarely occurs,and the visual recognition is good.（3）When the visual recognition distance is constant,the relationship between the small target identification clarity rate and the glare angle is logarithmic function.The fitting results show that R²is greater than 0.9,and the correlation is strong.The relationship between the clarity of small target identification N and the equivalent light curtain luminance L_seqis derived under the experimental conditions.（4）When the subjects were faced with the same magnitude of sunlight and the glare angle of 15°–30°,the UGR values were all greater than 30,and the rating was‘Intolerable’;（5）Based on the structure form of anti-glare facilities at the exit of foreign tunnels,the layout method of dynamic protection system under the ideal condition（the sun light is injected from the east）is deduced;（6）The general applicability of the derived ideal situation is realized by means of numerical simulation,and the debugged dynamic system can ensure the formation of a protective area covering the lane throughout the year（vernal equinox-summer solstice-autumnal equinox-winter solstice）,eliminate the’blinding effect’and suppress the’white hole effect’.