Research On Effect Of Combination Of Stereo Chevron Alignment Signs And Deceleration Markings On Driver' Visual Characteristics

Landscape in Inner Mongolia prairie highways is so monotonous,which has small traffic volume,single linear structure,and big horizontal curve radius and long straight lines,drivers driving on grassland highways may accelerate unconsciously,it can easily lead to traffic accidents once crossing the alignment changes if not induced by chevron alignment signs adequately.It is a fact that chevron alignment signs apparently used can not satisfy driver's visual stimulation at a certain normal speed,this low intensity of induction may make them not to be well prepared physically and psychologically.To improve the induction effect of ordinary chevron alignment signs,this study focuses on highways with typical grassland landscape,and conduct the driving tests on simulation driving device.Firstly,stereo chevron alignment sign is designed and selected through qualitative and quantitative analysis methods,the specific attributes can be concluded.Then by combining three kinds of visual illusion deceleration markings,this study aims at obtaining the better combination of a sign and a marking in different radius curves and directions.Finally,the optimal combination and the ordinary chevron alignment sign are compared and analyzed by summarizng eye movement signals laws collected by I View X HED eye tracker.This study can provide references and suggestions for the optimization of traffic safety facilities in prairie highway.The conclusions can be concluded as followings:(1)Through the AHP analysis method and drivers' subjective questionnaire,suitable attributes of stereo chevron alignment sign,concluding color combiantion,3D direction,rotation angle and board size,are obtained.And the combination analysis indicates the ranking of different stereo chevron alignment sign and deceleration markings.(2)Eye movement data of 20 subjects in both the combination scene and the ordinary chevron alignment sign scene are averaged,the obtained value is considered to reflect average level of drivers in the grassland highways of typical landscape,which is defined as the human visual comfort zone in this study.(3)The overall level of drivers' attention(reflected by pupil diameter)in combination scene is higher than in ordinary sign scene,no matter in curves of 300m,900m,1500m(including turn left and right),but the level of cognition(reflected by average fixation duration)can still meet drivers' visual comfort requirements,among this,the applied effect of deceleration markings is significant.(4)Drivers show different visual characteristics and physiological states in different curves.In left curves,the smaller that the radius is,the higher cognitive effort that driver requires,which need the combination of signs and markings to meet their visual needs,similarly,the greater that the radius is,the less pressure that the driver feel,so deceleration markings only can effectively improve traffic safety.In right curves,the combination of signs and markings can provide the driver with enough visual induction in all curve segments,and meet the eye comfort requirements simultaneously,so it is reasonably suggested to be applied in practice.