Spatial And Temporal Accessibility Of Subway Station Based On Spatiotemporal Prism

Spatiotemporal accessibility is a comprehensive index to measure the service level of transportation system,which takes the individual spatiotemporal behavior as the basic unit,and on this basis,puts meeting the needs of travelers to reach the activity site in the first place.Compared with the traditional space accessibility,the individual space-time accessibility emphasizes whether the needs of people’s executive activities are met,and highlights the idea of people-oriented.With the rapid growth of Chengdu metro operation mileage and the gradual increase of new lines,it has brought a lot of convenience for residents to travel,and improved the travel efficiency and service level between different regions of the city as a whole.The enhancement of the spatial and temporal accessibility of subway stations and surrounding road network helps to improve the attractiveness of subway traffic,attract more travelers to choose subway travel,and play an important role in adjusting the travel structure in a certain area and improving the public transport sharing rate.The main contents of this paper are as follows:Firstly,this paper studies the theory of spatiotemporal prism in time geography,analyzes the related theories of spatiotemporal network model,introduces the expression form of spatiotemporal prism in detail,and constructs the spatiotemporal network with spatiotemporal prism as a tool of time geography.On this basis,a linear programming model of traffic network optimization about spatiotemporal accessibility is established.Secondly,the algorithm to solve the spatiotemporal network optimization model is studied.This paper briefly introduces the technical principle of Lagrange relaxation method.Lagrange relaxation method obtains the objective function by relaxing the complex constraint function equation,and transforms the original problem into simple short circuit problem and knapsack problem.It not only greatly reduces the difficulty of solving,but also greatly simplifies the steps of solving.Subgradient contraction method is widely used to deal with non differentiable convex functions.By updating Lagrange multipliers,the feasible region is continuously contracted and the relaxed solution is forced to approach the optimal solution of the original problem.Next,the Lagrange relaxation method and subgradient method are combined to solve the spatiotemporal network optimization model.Finally,the spatial and temporal accessibility of Xipu station,Tianhe Road station,Xingye North Street station and the surrounding road network is studied.In order to improve the spatial and temporal accessibility of subway stations in the region,the spatial and temporal accessibility is optimized on the premise of meeting the conditions of road network scale and related costs.