Research On Modeling And Clearance Control Of Visible Range For Roadside Of Expressway Curve Based On Dynamic Vision Occlusion

The signs,exits,landscapes,etc.on the roadside of expressway curves are easy to occlusion by roadside plants,cutting slopes,sound barriers,etc.during the high-speed driving of vehicles,thus inducing curve traffic accidents.For this reason,according to the traffic accident investigation and statistics of Hunan sections in two expressways of Beijing-Hong Kong-Macao(G4)and Shanghai-Kunming(G60),the signs,exit ramps,landscapes,etc.on the roadside of expressway curves that are vulnerable to occlusion were selected as the research objects,and the research on modeling and clearance control of visible range for roadside of expressway curve based on dynamic vision occlusion were carried out,so as to provide a theoretical basis for the design,construction and maintenance of expressways and the improvement of traffic safety.(1)Through investigation,statistics and analysis of traffic accidents on the two expressways,it is found that the de-occlusion of visible range of roadside signs,exit ramps and roadside landscapes on curves is intrinsically related to traffic accidents in high-risk road sections.The factors of the occlusion of visible range on the roadside of expressway curves mainly include roadside plants,cutting slopes,sound barriers,signs,overpass bridges(pipelines),vehicles driving in the same direction,central divider,etc.Accordingly,the occlusion of visible range on the roadside of expressway curves can be divided into occlusion types such as signs,entrances and exits,roadside landscapes,etc.,so as to provide a basis for the modeling of visible range on the roadside of expressway curves.(2)According to the drivers’dynamic visual characteristics of high-speed driving,the visible range of roadside signs on curves was determined.Based on the drivers’ dynamic visual recognition law of signs,the dynamic geometric model was constructed for the visual process of roadside signs on curves,and the calculation equation to the visible range of roadside signs on curves was derived.According to the actual parameters of the G4 Hunan section,the occlusion law of the obstructions to the visible range of roadside signs on curves was analyzed by MATLAB,and the clearance control value and control content of the roadside signs on curves were proposed.The results show that the clearance control range is the distance from the starting point of the visible range,which is controlled at 210 m.The clear width of outer curve(outer left turn curve)is controlled at about 5 m in the roadside direction,and the clear width of inner curve(inner right turn curve)is controlled at about 3 m in the central divider direction.The clear height is controlled at 1.2～5.2 m.The results can provide a theoretical basis for the setting of roadside signs,clearance control,intelligent assistant driving system,traffic sign maintenance,etc.,and provide a technical path for effectively solving the problem of anti-occlusion in the visible range of roadside signs on expressway curves.(3)According to the design specifications and standards of expressway routes and exit ramps,as well as the driving characteristics and recognition process of vehicles on the exit ramps on curves,the visible range of curve exit ramp was determined.On the basis of determining the target area of the visible range of curve exit ramp,the dynamic geometric models of area and volume of the visible range were established for the exit ramp target area.The discrete expression equation was used to establish the judgment model for the de-occlusion of the target area of the visible range of exit ramp.Based on the actual parameters of G4 Hunan section,the occlusion laws were analyzed by MATLAB for different widths of obstructions as well as same widths of obstructions at different positions to the target area of the visible range of exit ramp,thus the clearance control value and control content of the exit ramp were proposed.The results show that the clearance control range is the recognition sight distance of exit ramp,which is about 330 m at the design speed of 120 km/h,285 m at 100 km/h and 246 m at 80 km/h.From the comprehension point to the action point of the visible range of exit ramp,the clear width of inner curve connecting with the exit ramp is controlled at 28 m outside the roadside boundary,and there is no clear width control for the outer curve connecting with the exit ramp.Therefore,the visible range and de-occlusion judgment model of exit ramp established from the perspective of three-dimensional dynamic vision can provide theoretical support for improving the recognition of roadside exit ramp on curves and reducing the accident rate of exit ramp.(4)According to the drivers’ visual depth and visual distance of high-speed driving,the visible range of roadside landscape on curves was determined.By constructing the dynamic geometric model of the visual process of roadside landscape on curves,the calculation equation of the visible range of roadside landscape was derived.The dynamic occlusion ratio was constructed by spatial coordinates,and the judgment model was proposed for the de-occlusion of the visible range of roadside landscape.According to the actual parameters of G4 Hunan section,the occlusion laws were analyzed by MATLAB for different widths and different heights of obstructions as well as same widths and heights of obstructions at different positions to the visible range of roadside landscape,thus the clearance control value and control content of the roadside landscape were proposed.The results show that the clearance control range of roadside landscape is 270 m at the design speed of 120 km/h,220 m at 100 km/h and 170 m at 80 km/h.The control value of clear width is 25 m,and the control value of clear height is recommended to be 20 m.Within the scope of expressway land expropriation,it is recommended to land expropriation 25 m wide from the road boundary.The results can provide model support for building the tightness and openness of roadside landscape of expressways.(5)Aiming at the visible range and occlusion laws of the factors such as signs,exits,landscapes,etc.on the roadside of expressway curves,one high-risk section of inner and outer curve of G4 Hunan section was selected respectively,and the real vehicle driving simulation was carried out based on the simulation model of dynamic visual occlusion for the visible range on the roadside of expressway curves.The analysis of one-way ANOVA of eye tracking data was conducted for the three simulation scenes such as current roadside occlusion,clearance control of signs and exit ramps on roadside as well as clearance control of signs,exit ramps and landscapes on roadside.The results show that the clearance control can effectively solve the problem of visible range occlusion on the roadside of expressway curves,which further verifies the scientificalness,applicability and innovation for the research on visible range control to signs,exit ramps and landscapes on the roadside of expressway curves.In summary,the innovation of this study is to research the problem of the visible range on the roadside of expressway curves from the perspective of dynamic vision occlusion.Aiming at the roadside signs,exit ramps,roadside landscapes and other target points of expressway curves,the dynamic geometric volume models of visible range and the dynamic occlusion judgment models were established,respectively.The driving simulation technology was used to verify the clearance control range,clear height control,clear width control,etc.for the visible range on the roadside of expressway curves.Thus,it provides a new method to explore the problem of occlusion of the visible range on roadside.Therefore,the visible range models and its clearance control factors on the roadside of expressway curves based on dynamic visual occlusion proposed in this study can provide theoretical basis and technical support for the design improvement,construction and maintenance decision-making on the roadside of curves and the traffic safety guarantee of curves.