| Traffic safety in the foggy area of the expressway is a worldwide problem.The dumpling fog of expressway is more sudden,random,difficult to monitor,and difficult to predict than the conventional fog.Taking into account the system of people,vehicles and roads,this paper quantitatively evaluates the driving risks in the foggy sections of the expressway in mountainous areas,and by using the fog area induction system to improve the driving conditions and adjust the driving behaviors of drivers;it is an effective method to improve the driving safety in fog area.Based on the analysis of the characteristics of the dumpling foggy section of the expressway in the mountainous area,this paper constructs a single vehicle risk assessment model,a dumpling fog environmental risk classification model and a visual information control compensation model,and attempts to explore the method of reducing the risk of driving from the perspective of visual guidance.The main work and conclusions of the paper are as follows:(1)The characteristics of the dumpling fog of expressway are analyzed.Based on the data of the dumpling fog of national expressway from 2014 to 2017,the characteristics of fog length,fog frequency,and dumpling fog elimination are analyzed for the dumpling foggy sections of expressway.After analysis,when the length of the dumpling foggy sections of expressway is less than or equal to 4km,the fog segment has the largest distribution and the highest frequency;Therefore,based on the catastrophe theory,the transient mutation model of the driving behavior of the expressway dumpling foggy section is constructed with the driving speed,visibility and time of the sections with the fog length less than 4km.(2)Based on the field theory,the risk of a single vehicle in the expressway dumpling fog section is analyzed.If the support the fog sections of expressway are often accompanied by rain,ice,snow and other complex climate.Therefore,it is of great significance to evaluate and research the accident risk of expressway considering the coupling of complex factors such as fog,rain and snow ice.Based on the aforementioned analysis of the characteristics of the dumpling fog segment,on the basis of introducing the field theory,the risk field model of expressway in fog area was established.The single vehicle risk in the foggy sections of the foggy environment and the multi-climate-coupled environment is analyzed.(3)Based on probabilistic risk analysis(PRA),the risk of expressway dumpling fog is classified.Based on the risk analysis of a single vehicle in the dumpling fog segment,and the parameters and risk classification of were studied based on the model.Based on field theory and probabilistic risk analysis method,the risk classifying index of expressway dumpling fog segment matching with the current domestic meteorological early warning grading is given.The risk of the foggy sections is classified into four levels,of which the highest level of driving risk is the first level.It is suggested that the road traffic guidance is carried out on the dumpling fog segment with the highest risk level through the classification result.This classification can be used as the basis for the layout of the late induction equipment.Based on the classification,the range and length of the fog segment can be determined.(4)Driving visual needs in expressway dumpling fog environment are analyzed.Human visual impairment caused by sudden changes in visibility is the main reason for the safety of the group fog environment.In order to study the visual information demand characteristics of low-visibility dumpling fog environment,the visual information is compensated by equipment such as fog lamps to improve driving safety.Based on the Fragrant Dragon Theorem and feedback control theory,this paper constructs a driving visual information demand model based on visual information input and output of dumpling fog environment,and selects two types of the foggy sections with the same visibility and no induction light for blood pressure,heart rate and driving.A real vehicle experiment that looks at the field test.The actual vehicle experiment based on blood pressure,heart rate and driving gaze field was carried out by selecting two types of dumpling fog segments with the same visibility and induction lamp and non-induction lamp.The study found that under low visibility,the radius of the human visual gaze field becomes smaller,and the gaze point range is mainly concentrated in front of the front of the vehicle,and the lower the visibility,the smaller the range of the field of view;after the driver encounters the dumpling fog,he/she can't decelerate in time to the safe speed required by the driver,the driver's blood pressure index will obviously increase,and the heart rate indicator will become larger;the main reason for the aforementioned physiological characteristics is that the amount of driving information acquired by the driver in the dumpling fog environment is instantaneously reduced,which cannot meet the information demand of driving cognition,and breaks the driving dynamics of the driver based on speed,visibility and other road conditions;However,the induced light in the fog environment compensates the driver's visual information,increasing the visual input of the human eye,that is,the induction lamp in the dense fog environment has a slowing effect on the driver's blood pressure and heart rate.(5)Based on simulation experiment,the line-of-sight induction of the dumpling fog is studied.Color combinations and strobes of fog lights on both sides of the road are designed from the perspective of road landscape color.The cumulative effect of fog light color and strobe on driver's visual psychology is studied.Through eye tracker and UC-win/Road simulation software,it is verified that the visibility is 200m~500m and the driving speed is less than 70km/h,the fog color and strobe on both sides of the road have a positive impact on the driver's driving safety,among them,red and yellow have the greatest impact on the driver.In terms of color matching,using simulation experiments,the induced fog lamp with a spacing of 30 meters is arranged.Through different visibility and different proportioning schemes,it is concluded that the yellow non-stroboscopic induction lamp is best in the midline of the lane.(6)The proposed models and methods are verified with an engineering example.The models and methods proposed in chapter 2 to chapter 6 are verified and checked,and the engineering applicability and rationality of the model are analyzed.Firstly,the characteristics of road engineering,climate and traffic flow,and accident characteristics of black spot are analyzed.Then the risk analysis model of single vehicle in chapter 3 and the risk classification method in chapter 4 are used to evaluate the road risk in the case section based on the expressway section itself and the risk assessment focusing on driving in the foggy sections of the expressway.The induction pattern and the induction strategy were matched according to the results of risk assessment.Finally,the error between the model research and engineering practice is discussed. |
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