The Mechanism Reaserch Of Driver's Autonomous Safety Speed Selection Under The Influence Of Visibility

High visibility is the key to ensure safe driving for drivers.Low visibility has become one of the main causes of major traffic accidents,which seriously threatens road traffic safety.Reasonable and safe driving speed is an important guarantee for driving safety.Driver's autonomous safety speed is greatly influenced by visibility and road alignment,especially,when visibility changes,the speed fluctuates greatly.Driving too fast will not only affect drivers' psychological reaction,but also lead to tension,which may result in driving errors.Besides,it will also lead to increased braking distance and influence traffic safety.The paper explores drivers' autonomous safety speed selection behavior under different visibility and road alignment conditions,and find out the relationship among autonomous safety speed,visibility and road alignment parameter.A model with four parameters of heart growth rate,visibility,autonomous safety speed and road alignment parameter was established,and the limit value of autonomous safety speed can be calculated according to the given visibility and road alignment parameters.The conclusion can provide theoretical reference for speed management under low visibility,and important guiding significance for reducing traffic accident rate under low visibility.The paper is based on the content of National Natural Science Foundation of “Accident Risk Assessment of Highway Traffic Flow and Optimization of Safety Design Parameters under the Influence of Visibility(NO.51578207)”,and the main contents of this article are as follows:(1)A questionnaire survey of drivers' autonomous safety speed selection behavior in low visibility was designed,then the reliability and validity were tested.Pearson correlation coefficient and structural equation model were used to investigate the relationship between drivers' personal attributes and speed selection behavior.The results show that: Under low visibility conditions,gender is positively correlated with speed selection behavior on roads with a speed limit of 60 km/h and 120 km/h;the frequency of expressway use and annual mileage in the past year have significant effects on drivers' speed selection behavior on roads with speed limits of 80 km/h and 120 km/h;Under low visibility,driving skill has positive effect on speed selection behavior,while risk perception has the opposite effect.(2)A driving simulator experiment was carried out,to explore the influence of visibility and road alignment parameter on the behavior of speed selection.Single factor analysis was used to analyze that whether there is a significant difference in the speed of autonomous safety under different visibility conditions.The results show that the driving speed on the road with speed limit of 60km/h and 80km/h and upslope section on speed limit of 60km/h road is significant different among various visibility.Moreover,the visibility classification is reasonable and can be used as a reference for the management of graded speed limit under low visibility.The three-dimensional regression model of drivers' autonomous safety speed,visibility and road line parameters is established by using Origin software.(3)Partial correlation analysis was used to explore the relationship between heart rate characteristics and autonomous safety speed,visibility,road alignment parameter.A model with four parameters was established,and the limit value of autonomous safety speed based on driver's own physiological characteristics can be calculated,according to the heart rate threshold,visibility and road alignment parameters.It is helpful to provide theoretical guidance for the actual road traffic safety management in low visibility.