Experimental Study On Lighting Condition And Driving Safety Of Highway Tunnel

With the continuous development of infrastructure construction in China,the number and mileage of highway tunnels are increasing.Highway tunnel has the advantages of shortening space distance,improving transportation efficiency and reducing accidents,but because of the special semi-closed structure of the tunnel,the driving safety problem in the highway tunnel is increasingly serious.The entrance of highway tunnel is the transition section of two different driving environments.The drastic change of brightness inside and outside the tunnel will lead to the phenomenon of dark adaptation and visual blind area of drivers.Besides,the tunnel is mostly in mountainous areas,and the road type and natural conditions before and after the tunnel are complex and changeable,so this section is prone to form a high-risk section with frequent accidents.Tunnel lighting is an important infrastructure to reduce the influence of dark adaptation and ensure the safety of tunnel operation,especially for the mountain road tunnel where the light source is mainly from natural light and tunnel lighting system,good lighting conditions are particularly important.Therefore,the study of tunnel entrance lighting brightness is of great significance to improve highway driving safety.In this paper,a representative tunnel entrance on wenma Expressway with a bridge/tunnel ratio of 86.5% is selected as the test section to study the relationship between tunnel lighting and driving safety.Firstly,the research on safety of highway tunnel lighting at home and abroad,the influence of external environment of highway tunnel on tunnel brightness and the adaptation time of tunnel lighting and darkness are described and their shortcomings are analyzed.Secondly,the light environment of tunnel entrance,the visual phenomena of drivers and their adaptation mechanism are analyzed.Then,the basic situation of the test tunnel in this paper is collected and sorted out,and the test equipment and test scheme of the three main tests in this paper are introduced: tunnel entrance brightness law measurement test,tunnel entrance outside brightness L20(S)measurement test and indoor dark adaptation time law research test.Then,on a clear and cloudless day,c M-10 luminance meter,tripod and other equipment were used to measure and analyze the luminance data of the section from 400 meters outside the target tunnel to 200 meters inside the tunnel for three consecutive days.At the same time,the luminance of all objects within 20° Angle of view was measured and divided at a stopping sight distance,and the percentage of all objects was calculated.The value of luminance L20(S)outside the tunnel is obtained,and the relationship between luminance of tunnel entrance section and human vision "adaptation curve" is studied.Then,based on the field measurement and analysis results,the indoor dark adaptation test was carried out to study the law of tunnel lighting brightness and dark adaptation duration under four different ambient brightness.According to the test results,the lighting brightness of the target tunnel entrance section was optimized,so as to optimize the lighting design of the whole tunnel and put forward suggestions for tunnel speed limit.Finally,according to the optimization scheme,DIALux software is used to model and analyze the brightness parameters in the tunnel after optimization.The simulation results show that the tunnel lighting after optimization conforms to the "adaptation curve" of human vision better.The above research proves the feasibility and effectiveness of tunnel lighting design optimization based on dark adaptation time.For tunnel with similar environment,tunnel lighting optimization can be carried out according to the research results of this paper.For tunnels in different regions,it is suggested to carry out targeted research based on local light climate conditions and vegetation distribution.