| The plateau area is characterized by complex terrain,harsh climate,frequent and serious traffic accidents,and severe road safety situation.There are great differences between drivers' physiological and psychological conditions in plateau hypobaric hypoxia environment and those in plain areas.Their perception ability,judgment decision-making ability and operation ability are significantly affected.At the same time,vehicle braking performance is also changed due to the low pressure.Therefore,plateau highways have higher requirements for stopping sight distance.In this paper,from the perspective of driver reaction time,combined with driver operation time and vehicle braking reaction time,the stopping sight distance of highway on plateau is studied.Based on the detailed stopping and braking process,driver reaction time is divided into driver braking reaction time and operation time,and the stopping visual distance braking model is further analyzed.There are more factors affecting drivers' reaction time in the plateau area than in the plain area.The factors considered in the test are altitude,light condition,driver's age,gender and driving experience.HTML + JavaScript + CSS is used to compile the response time web page test program.Driver braking response time test is carried out in Nanjing(10m),Bomi(2700m above sea level),Linzhi(3000m above sea level),Lhasa(3650m above sea level),Naqu(4460m above sea level)and Yanghu Scenic Area(4800m above sea level).Using UC-win/Road scenario production software and driving simulator to design driving simulation test,the driver operation time is obtained by comparing with the driver web page test.Based on the data of the altitude test,a normalization processing is used to reduce the difference among different drivers,and the representative value of each driver's reaction time is determined to be the eightieth percentile value through the data probability distribution curve.Further analysis shows that the driver's reaction time is positively correlated with altitude,the longer the response time of the driver with darker light,the slower the driver's reaction time with older age.The difference of sender is not obvious.The variance of driver response time increases gradually with altitudes,and the adoptability of different drivers to plateau environment varies greatly.The test results of 8 drivers with different driving experience showed that driving experience had no significant effect on the test results of reaction time web pages.The driver's operation time was analyzed by using UC-win/Road software and MATLAB programming.The results showed that the driver's operation time was affected by the degree of driving experience,and the novice driver's operation time was relatively long.For safety consideration,the driver's operating time in the stopping sight distance model is 1.0s.Finally,the regression model of braking reaction time and altitude,driving time(illumination intensity)and driver's age is established through the distribution of braking reaction time.Based on the study of driver's operation time and vehicle braking reaction time,the highway sight distance model suitable for highway drivers is established,and the highway stopping sight distance is proposed.At the same time,the horizon model of plateau highway is revised according to cross slope,longitudinal slope and air resistance.In this paper,by analyzing the braking response characteristics of drivers in Plateau environment,combined with the operation time of drivers and the braking reaction time of vehicles,the stopping sight distance model of plateau highway is established.The research results are of great significance to improving highway design standards and driving safety in plateau. |
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