Analysis Of Visual Illusion In Highway High Fill Horizontal Curve Section And Study On Its Improvement Measures

Road visual illusion is an important factor affecting traffic safety.Drivers in the process of driving,affected by road alignment,surrounding environment and other factors,will create a phenomenon of visual illusion on the driver in special sections,leading to errors in judgment and operation,and then forming hidden traffic hazards,even traffic accidents.In the Highway Route Design Code(JTD D20-2017),it is pointed out that "the circular curve with larger radius should be adopted in the section of highway high filling horizontal curve,and the traffic setting with guidance function should be set up in order to prevent the driver from misjudging curvature".Therefore,it is necessary to study the influencing factors,degree of influence and improvement measures of driver's visual illusion in high fill level curve section of highway.Firstly,on the basis of summarizing the mechanism of visual illusion,the causes and influencing factors of visual illusion in high fill level curve section of highway are analyzed from the perspectives of visual angle,surrounding environment and section design parameters.Secondly,by analyzing drivers' driving behavior of speed,trajectory and acceleration control on flat curve section,the relationship between different driving behavior is obtained.A comprehensive evaluation index of visual illusion based on maximum deviation and maximum acceleration of vehicle is proposed,and the relationship between the degree of visual illusion influence and comprehensive evaluation index is analyzed.Then,the experimental design is carried out from the aspects of alignment parameters,drivers and driving time of highway high filling horizontal curve section.The visual errors of drivers under different influencing factors are simulated by using Uc-win/Road software.The influence factors such as radius of circular curve,turning angle,slope,filling height,driving speed and number of lanes of highway high filling horizontal curve section are obtained.The relationship between factors and the degree of driver's visual illusion was analyzed,and the inflection point of the influence degree curve was analyzed.The results show that there is a negative correlation between the radius of circular curve and the degree of driver's visual illusion,a positive correlation between turning angle,filling height and driving speed and the degree of driver's visual illusion,and a weak correlation between the length of mitigation curve and the number of lanes.Finally,the corresponding visual error improvement measures are proposed for thedesign and operation stages of highway.In the stage of highway design,the reasonable setting range of design parameters such as circle curve radius,filling height and turning angle of high filling level curve section is put forward;in the stage of operation,direct measures such as setting deceleration and speed limit,and indirect measures such as planting trees and combining tree irrigation to change roadside reference materials are put forward,and simulation verification is carried out.The research results have certain theoretical significance for the further study of the visual impact of road errors,and can also provide certain reference and reference for highway designers and operation management units.