Traffic Safety Optimization Method Of Curve Section Of Highway Tunnel Based On Linear Guidance

This work was supported by nsfc-funded project(No.52072291).The interior environment of the tunnel is dim and single,and there is little visual information.The driver is prone to speed illusion and curvature illusion in the tunnel,and the side wall in the curve section will block the visual line,resulting in the limitation of the driver’s sight distance and visual area,which further increases the accident risk.At present,there are some problems about the setting requirements of visual guiding devices on curve section of highway tunnel are unclear and the improvement effect is poor.Therefore,this paper discusses the functions and setting methods of visual guiding devices on curve section of tunnel,and designs corresponding visual guiding schemes for different curve radii to optimize the driving environment on curve section of tunnel.The main research work and conclusions are as follows:(1)The curve radius division and traffic safety optimization direction of highway tunnel based on sight distance is proposed: the range of small,medium and large radius curve sections of tunnel are defined by whether the visual distance meets the stopping sight distance or the recognition sight distance.The visual environment,visual characteristics,driving behavior and visual demand of curve section of highway tunnel are analyzed.The optimization direction of traffic safety on curve section of tunnel is put forward: meeting the driver’s visual recognition of the road environment ahead,improving the perception ability,reducing discomfort and fatigue,and visual guiding devices should follow the principles of linear induction and contour induction.(2)The design idea and method of linear guidance are proposed: based on the analysis of the shape and function of visual guiding devices,and drawing lessons from the design idea of linear lighting,the design idea of "linear guidance" is proposed.It mainly uses a variety of line shape(including short line,medium line,long line and ring)of visual guiding devices to construct linear of visual induction system(hereinafter referred to as linear induction system),which can improve local brightness and contrast,outline the tunnel profile and road alignment.According to the setting of visual guiding devices on curve section of tunnel,the optimization of the driving environment on curve section of tunnel based on linear guidance is proposed: using the combination of visual guiding devices such as linear contour mark,chevron sign and reflective ring to build multi-layer linear induction and contour induction to clarify space right of way and reduce optical illusion.Therefore,according to the tunnel curve environment with small,medium and large radius,different combination schemes of visual guiding devices on curve section of tunnel are proposed.(3)Verification of optimization method of the driving environment on curve section of tunnel based on perception experiment: taking the stimulation of subjectively equal speed and curvature perception accuracy as indicators,the driver’s speed perception and curvature perception ability are quantified,and the semantic differential method is used to subjectively evaluate the visual guiding effect of each optimization scheme.The experimental results show that the speed perception effect and visual guiding effect are better,when the length of the linear contour mark is designed as 1m;The optimization effect of the combination scheme of visual guiding devices on curve section of highway tunnel is as follows: reflective ring + combined chevron sign >reflective ring + ordinary chevron sign > reflective ring > combined chevron sign >ordinary chevron sign.(4)Verification of optimization method of the driving environment on curve section of tunnel based on eye movement experiment: the changes of saccade angle and pupil area change rate are selected to analyze the influence of each optimization scheme on the driver’s information acquisition difficulty and visual load.The experimental results show that for small and medium radius curve sections of tunnel,the setting of chevron sign or reflective ring would increase the understanding of the surrounding information.The setting of chevron sign could effectively relieve the tension,while reflective rings would effectively stimulate the driver’s visual response,maintain a certain sense of tension,and keep the driver’s attention focused.For large radius tunnels,the setting of reflective ring can still enhance the understanding of the surrounding information,but will not increase the tension,and the optimization effect is good.