Study On The Operating Speed Prediction Model And Application Of Freeway Based On Spatial Vision

At present, the highways develop rapidly, but the traffic safety problems are still outstanding. It is very important to eliminate hidden dangers and take safety road design strategy. Speed is the key parameters of road geometry design. The alignment design and evaluation based on operating speed is an effective way to solve safety design problems and the development trend.Taking the volume of spatial effective visual as the mediated index, the quantitative relationship between the highway horizontal and vertical lines as well as sight distance and the operating speed is obtained by studying the speed control and spatial visual. The prediction model of expressway operating speed based on spatial visual field is established. Then the operating prediction models and alignment design consistency evaluation models which are the key technology and theory in alignment safety design and evaluation were studied.On the basis of a large collection of related data and documents as well as testing on several roads, the relationship between driver's visual and his speed control behavior is studied qualitatively. Thus the concept of driver's spatial visual volume is put forward. Combining the sight distance index, the calculation method of driver's spatial effective visual volume based on space differential geometry is also proposed, which considers the model of road 3d alignments built by the horizontal and vertical alignment indexes of road spatial geometric features. According to the operation features of cars and trucks, the prediction model of expressway operating speed based on spatial effective visual and its calculation method are constructed by means of the spatial effective visual volume and driver's expectations as well as the vehicle dynamic performance. On the theory of road safety design and alignment design consistency, evaluation indexes of expressway alignment design which contains speed difference ratio and its variation coefficient between adjacent road, and range ratio of speed difference between cars and trucks are determined to meet the speed coordination and continuity demand. Taken the operating speed as characteristic indexes, the alignment design consistency comprehensive evaluation model was established, while the evaluation standards and methods of alignment design consistency are given. Finally, the research results of operating speed prediction models of expressway and alignment design consistency evaluation are used in the Xi'an to Hanzhong expressways.