Study On The Influence Of LED Light Color On The Visual And Photobiological Effects In The Interior Zone Of Tunnel

For tunnel driving behavior,artificial light is an important factor affecting driving safety.Research shows that light not only provides visual information,but also has an impact on many physiological and psychological behaviors,such as alertness,emotion,body temperature,visual fatigue,pupil contraction and circadian rhythm.The use of road lighting sources with different light colors will produce different visual effects and photobiological effects,which will have an impact on the driver’s visual efficacy and alertness.Reasonable selection of light source color can make these effects contribute to driving safety.With the wide application of LED(light emitting diode)in tunnel lighting in recent years,the diversity of its light color has attracted the attention of relevant researchers.Applying the influence of light color on photobiological effect to road lighting has become one of the research directions in recent years.At present,the research on Photobiological effects mainly focuses on bright vision,and the brightness of road lighting is within the scope of intermediate vision brightness.The particularity of intermediate vision makes the relevant conclusions obtained under bright vision not necessarily applicable to road lighting.At present,there is also a lack of guidance in the selection of light color for road lighting.For example,the tunnel lighting design guide only gives the recommended index of brightness,and there is no clear recommended index about light color.Based on this,this thesis evaluates the influence of light color on human visual effect and photobiological effect under intermediate visual light intensity.The results show that in theory,the spectrum with high correlation color temperature and high color rendering index can make the human eye obtain higher visual sensitivity and brightness in terms of visual effect;In terms of photobiological effect,it can make people obtain higher alertness,contribute to the contraction of human pupil,improve visual sensitivity and good visual effect.In this thesis,the visual effect detection experiment of driving in the inner area of the tunnel is simulated in the laboratory.The visual effect and photobiological effect are comprehensively considered.The recognition distance is used as the visual evaluation index,and the flash fusion frequency,pupil area and subjective emotion are used as the evaluation index.The results show that under the irradiation of high correlation color temperature and high color rendering index spectrum,the subjects have smaller recognition distance,better vision and higher visual sensitivity;The subjects’ flash critical fusion frequency decreased more slowly,indicating that the driver was less tired and more alert in this light environment;Subjects had smaller pupil area and better visual effect;Drivers get higher positive emotions.However,no similar conclusion was found in the influence of negative emotion.At the same time,the vast majority of subjects said that they felt "colder" at high relevant color temperatures,which made them more energetic and focused on driving.Therefore,the combination of visual effect and photobiological effect,the spectrum with high correlation color temperature and high color rendering index is more helpful to improve the driver’s visual effect and alertness in the middle section of the tunnel and improve driving safety.Therefore,it is suggested to use LED light source with high correlation color temperature and high color rendering index in the middle section of the tunnel,so as to improve the level of road traffic safety.