| With the rapid development of urban road network,the guide signs need to provide more information,which will cause "information overload".At the same time,dense traffic and heavy traffic on urban roads will also have an impact on drivers’ visual signs.However,domestic and foreign scholars’ research on the characteristics of driver’s visual guide signs is mostly limited to indoor static research,and seldom consider the traffic volume changes in the actual driving scene.Based on this,this paper analyzes the change characteristics of drivers’ reaction time and eye movement index through the information experiment of urban road signs under different traffic volume conditions,and further studies the information content and information density threshold of road signs layout.Firstly,according to the driver’s visual recognition model and cognitive load theory,the change of driver’s cognitive load is analyzed,and the response time,average fixation time,blink frequency and coefficient of variation of pupil diameter are selected as evaluation indexes.According to the level of service(LOS)in the comprehensive specification,the experimental design is carried out by selecting the road load degree V/C of 0(average lane traffic volume of0),0.4(average lane traffic volume of 400 pcu/h),0.7(average lane traffic volume of 700 pcu/h)as the experimental traffic volume,and the number of road names of 3 to 9 as the sign information.The experimental scene is established by UC-win/road to carry out the driver’s visual identification of road signs.This is a driving simulation experiment.The experimental results show that: the increase of traffic volume and sign information will increase the driver’s cognitive load and reaction time,and a comprehensive evaluation method of driver’s cognitive load intensity is proposed by using principal component analysis.Secondly,by analyzing the inflection point of the change curve of the driver’s indicators,it is proposed that when the road load degree V/C is 0,the information threshold of the guide sign layout is 7 road names;when the road load degree is 0.4 and 0.7,the information threshold of the guide sign layout is 6.Based on the analysis of driver’s visual recognition process,the definition and calculation method of information density of guide signs are proposed.According to the visual recognition distance and lead distance,the information density thresholds of road section with load degree of 0,0.4and 0.7 are 37.7,32.1 and 31.72 per kilometer respectively.Finally,the actual road section is selected for the driver’s visual recognition experiment,and the Pearson correlation analysis is used to test the data of driving simulation and real vehicle experiment.The results show that there is a significant correlation between the two,and the correlation is strong,which verifies the research results of driving simulation experiment.The research results put forward the information threshold and information density threshold of guide sign layout under different road load degree,which provides a reference for the information design of urban road guide signs. |
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