| Promoting the high-quality development of expressway is an important measure to further implement the strategy of traffic power.At present,the construction of eight-lane and above multilane expressway is in the ascendant,and the setting of export guide signs is an important part.Reasonable setting of highway exit guide signs can enable drivers to obtain effective information timely and accurately,and take corresponding operations to ensure traffic safety.The provisions on the setting of export guide signs in the current specification are highly targeted for four-lane and sixlane highways.For the eight-lane highway,the traffic volume is large,the number of lanes is large and the lane change behavior is frequent and complex,so it is not suitable to simply apply the existing norms.It is necessary to study the setting of the exit guide sign.From the perspective of driving load,this paper puts forward different setting schemes for the exit guide sign of eight-lane highway and conducts driving simulation tests to obtain the recommended scheme.Firstly,on the basis of summarizing the research status,this paper analyzed the main factors affecting the setting of export guidance signs from the perspectives of drivers,road design indicators and traffic operation environment,and summarized the common driving load quantification methods.Secondly,considering the most unfavorable situation of lane change,the last exit guide sign is relatively important as the last hint.Based on the theory of acceptable gap,the theoretical value of the front distance of the last exit guide sign is 798.48 m,which is rounded up to 800 m.Thirdly,according to the specification requirements and combined with the actual project(Shanghai-Nanjing Expressway)completion data,using UC-win / Road software to build driving simulation scenarios.Relevant traffic operation data were collected through field traffic survey,so as to complete the traffic parameter calibration of driving simulation scene and ensured the consistency of test scene.Considering the standard value and theoretical value,the front distances of the last piece of export guide sign were controlled to be 500 m,600 m,700 m,800 m,900 m and 1000 m,respectively,forming the control test group.The experimental data were collected by biofeedback instrument and eye tracker.Then,multiple dimensions were analyzed,and indexes such as pupil diameter growth rate,EEG index β / θ,heart rate variance,steering wheel angle extremum and vehicle acceleration standard deviation were selected to characterize driving load.Two main factors,driving operation load F1 and perceived decision-making load F2,were obtained by using factor analysis method to reduce the dimension.On this basis,the comprehensive index CIDL of driving load was established.The results showed that the driver ’ s driving load in the export section decreased with the increase of the front distance of the guide sign.Appropriate extension of the front distance of the guide sign can effectively reduce the driving risk and ensure the driving safety,which verifies the rationality of the last front distance of the guide sign 800 m.Finally,considering the factors of driving load,driver ’ s short-term memory theory,traffic efficiency,vehicle lane change and sign specification requirements,four sets of multi-level exit sign setting schemes were proposed.By introducing five indexes of search memory difficulty,driving load,driving style,lane changing times and sign number,a linear comprehensive evaluation model was constructed based on CRITIC method.It is considered that 500m-1000m-1500m-2000m-3000 m fivelevel sign and 800m-1500m-2500 m three-level sign perform better for different setting schemes.This study explores the internal relationship between driving load and driving behavior at the exit section of expressway,and provides a theoretical reference for the construction of multi-lane expressway traffic engineering.At the same time,it has theoretical and practical significance to improve highway traffic safety. |
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