Research On Guidance Facilities Optimization Of Highway Tunnel Based On Sight Distance And Sight Zone

Highway tunnel traffic accidents are frequent and the main types are collision accidents.In addition,one of the main causes is drivers’ lacking reaction and operation time,which are caused by insufficient sight distance for the driver to recognize the obstacle or overspeed.The condition of the driver’s sight distance and zone has significant impact on recognizing the obstacles in time,judging the correct driving direction,and controlling the driving speed.Therefore,this paper studies the driver’s sight distance and sight zone in highway tunnels.Based on the analysis of characteristics of highway tunnel accidents and the problem of drivers’ sight distance and zone,this paper proposes the idea of constructing an ideal sight distance and zone,combining with the theory of visual reference frame,right of way,driving task and so on.At the same time,aiming at the deficiencies in the setting of guidance facilities in tunnels,this paper puts forward the types and ranges of optimization indexes of guidance facilities in consideration of driving sight distance,edge rate and angle of view,and presents the method of combinatorial design of guidance facilities in different tunnel sections.On this basis,using the simulation video produced by 3ds Max to carry out the eye tracker experiment and psychophysical experiment,and selecting the area of visual sensitive area,attention distribution of interest area and sight distance as the evaluation indexes of the optimization effect of guidance facilities.Through the experiments,the recommended distance of each guidance facility is obtained and the visual distance enhancement effect is verified.The results show that:(1)The reflective ring in the middle section of the tunnel can enlarge the driver’s visual sensitive area and draw the driver’s attention to the central area,sidewalls and the top of tunnels.Moreover,with the standard of drivers’ visual sensitive area increase greatest and the distribution of drivers’ attention to be reasonable,the spacing of reflective ring is recommended to be 400 m.(2)When the spacing of reflective rings is 400 m,the recommended spacing of the reflective strips is 80~100m.The reflective strips can expand the visual sensitive area by a small margin and improve the driver’s attention to the sidewalls,and resolve the problem of drivers’ spending inordinate amount of time on the top of tunnel caused by reflective ring.(3)During the daytime,the chevron alignment signs in the entrance area of the tunnel can reduce the driver’s attention to the interference information such as roadside scenery in distance.The combined design of the chevron alignment signs and the reflective rings can relieve drastic transit of visual sensitive area when the driver enters the tunnel,and the mitigation effect is best when the spacing of alignment signs is 30~60m.During the night,the chevron alignment signs can simultaneously expand the driver’s visual range and driver’s visual sensitive area.In summary,the spacing of chevron alignment signs is suggested to be 30 m.In the tunnel exit area,this guidance system can also reduce the driver’s attention to the useless information on the roadside during the daytime and improve the driver’s perception of the range of roadside at night.(4)The guidance system can effectively increase the driver’s perception distance to the tunnel entrance that meet the requirement of decision sight distance.It can slightly improve the driver’s perception distance to front car when they are driving in the entrance or middle of tunnels that meet the requirement of stopping sight distance.(5)The guidance system can reduce the tunnel lighting requirements.When the lighting rate of the tunnel is 50%,it is recommended to use a combination of high-pressure sodium lamp and guidance system.