Study On Theory And Application Of Combining The Visual Guiding Information In Freeway Tunnels

Due to the semi closed structure of the tunnels,the violent transition between luminous environment and space,and the lack of visual reference,traffic accidents occurred frequently in tunnels and the severity of accidents was high.Simultaneously,the establishment of visual guiding facilities is chaotic,and the relevant specifications cannot fully meet the needs of application and evaluation of visual guiding technology.Furthermore,the consumption of lighting energy in freeway tunnels is also large.As a result,this paper takes solving the actual contradiction between energy-saving lighting and improvement on traffic safety in freeway tunnels as the starting point,and standardizes the setting method of visual guiding facilities based on drivers’ needs for safe driving,in order to improve traffic safety at low cost.The main research work of this paper is as follows: 1)The correlation between traffic accidents and luminous environment was analyzed.By measuring the illuminance and luminance of the tunnels,the correlation between the changing speed of illuminance,annual accidents per kilometer,and the length of zone was analyzed.2)The perceptual influence of visual guiding information with different shapes in freeway tunnels on drivers was explored.By introducing the control layer of the driving task hierarchy,taking the speed judgment,distance perception,and gaze centre-of-gravity as indicators,the indoor simulation tests on single visual guiding information of point,line,and ring were carried out.3)A method of combining the visual guiding information in freeway tunnels based on linear guiding was proposed.The definition of linear guiding system in tunnels and its guiding functions were expounded.Through the indoor simulation tests,the effectiveness of linear guiding schemes at entrance zones,middle zones with straight sections,and middle zones with curved sections were verified.4)An evaluation system for the combination of visual guiding information in freeway tunnels was constructed.Aiming at the confusion of setting visual guiding facilities,this paper put forward the system,standards,and methods for evaluating the combination of the visual guiding information in freeway tunnels based on spatial right of way,driving factors,and driving performance.5)The effectiveness of the linear guiding schemes in the actual tunnels were verified.Through the field vehicle tests,the effectiveness was compared before and after the improvement with the indexes of eye movement and driving performance in different time periods(day-time and night-time).Combined with the system for evaluating the combination of visual guiding information in freeway tunnels,the schemes before and after the improvement were verified.The results show that: 1)There is a linear positive correlation between illuminance and luminance at the entrance and exit zones of the tunnels,and a power function negative correlation between the logarithm of illuminatnce and the distance from the tunnel portal.The change rate of luminous environment at the entrance and exit zones is positively correlated with the number of annual accidents per kilometer.2)According to the shape,the visual guiding information can be divided into point,line,and ring.Among them,information of point can effectively improve drivers’ perception on speed and local direction,and information of long vertical line and ring can significantly improve drivers’ overall perception on direction and distance.3)The linear guiding system in tunnels mainly uses the linear visual guiding facilities with retroreflection technology,which can improve the local luminance and contrast of the tunnels,and outline the alignment and contour.It has the characteristics of remote visualization,various forms,and prominent contour.The linear guiding system in tunnels can make it easier for drivers to obtain external traffic information.In addition to providing sufficient perception on speed,distance,and direction,it can also alleviate the problems such as unclear orientation of tunnel portal,the violent transition of sight zone at the entrance and exit zones,the illusion of curvature,and so on.4)The spatial right of way is mainly evaluated by the setting method of visual guiding facilities,which is divided into horizontal,longitudinal,and vertical right of way.Driving factors is mainly evaluated by drivers’ visual performance and the setting method of visual guiding facilities,which is divided into sight distance,sight zone,and visual load.Driving performance is mainly evaluated by the operating characteristics of vehicles,which is divided into speed maintenance,distance maintenance,and lane maintenance.5)The improved linear guiding schemes in the actual tunnels have better performance on vision and driving than the traditional schemes.During the day-time and night-time,the evaluating grade of the test sections changes from poor before improvement to good after improvement.To sum up,based on the improvement of traffic safety level in freeway tunnels,this paper analyzed the correlation between traffic accidents and luminous environment,explored the perceptual impact of visual guiding information of point,line,and ring on drivers,put forward the method of combining the visual guiding information,and constructed the system for evaluating the combination of visual guiding information.The research results can provide a theoretical reference for the design of traffic engineering and evaluation of traffic safety in freeway tunnels.