Research On Stopping Sight Distance Of Multi-lane Expressway

In recent years,China’s highway transportation system has been continuously improved,and multi-lane expressways have become an important development trend in China’s expressway construction.With the improvement of vehicle performance and diversification of lane management methods,the concept of"people-oriented,safety first"has been increasingly valued.As an important index of expressway traffic safety,the stopping sight distance has attracted the attention of many researchers.The paper takes the multi-lane expressway as the research object,and makes a detailed study on the factors and models of stopping sight distance.Combined with the lane management mode of multi-lane expressways in China,the research object of this paper is defined as two-way six-lane and eight-lane expressways with integral sections,lanes are divided according to lane functions,and leading vehicles are proposed.Based on the measured data,the traffic characteristics of multi-lane expressway and the driver’s viewpoint position are analyzed.The relatively free running state is determined through the flow density relationship.Based on this,the running speed distribution intervals of different lanes under different design speeds are analyzed,and Statistical analysis of the 85th percentile driving speed and put forward representative values,And the hypothesis test method was used to fit the head distance distribution model of the middle lane ₁;Statistical analysis of the driver’s lateral viewpoint position;These provide basic parameters and data support for the following calculation and application of stopping sight distance.Analyzing the applicability and deficiency of the traditional calculation model and parameters of stopping sight distance,based on the automobile ABS system and vehicle dynamics,considering the complexity of vehicle braking,the vehicle braking process is re-divided,the whole braking process is simplified to cosine curve,and a new stopping sight distance model is proposed.Analyze and demonstrate the parameters in the model and propose the recommended value of stopping sight distance,and explain the"Code"value from the perspective different from the explanation of the provisions in the"Code".Finally,based on the vehicle type and driving state of the multi-lane expressway,the recommended parking sight distance is applied to the design of highway horizontal and vertical alignment.and the recommended curve radius values for curve sections and longitudinal slope sections are proposed.For the general section of the left-circular curve,the necessity of the first lane meeting the stopping sight distance is discussed based on the emergency parking brake,safe lane change distance and dynamic stopping sight distance of the vehicle,the risk range of the radius of the left deviation curve circle curve is analysed,and safety index are proposed.The safety assurance measures including the adjustment of the horizontal clear distance of the highway,speed control and warning of poor sight distance are proposed.The research results of this paper can provide theoretical reference for stopping sight distance of multi-lane expressways in China,provide basis for curve index of highway alignment design,and play a role in ensuring safe driving.