Research On Line Selection System Of Urban Rail Transit In Three-dimensional Space Based On GIS

Line design is the leading of the whole engineering design for urban rail transit, the scope of which varies widely and quantity is large. It grasps overall layout of projects. Whether the line alignment and the special location selection for line are reasonable or not directly affects project investment, operation period passenger flow, operation costs, degree of implementation,coordination with environment and landscape around.Existing line selection design methods are almost alternate design methods of the plane and profile based on topographic maps and exploration data on the two-dimension design environment.On complicate city environment, various potential conflicts are hard to be found directly through existing design methods,and the design needs repeated verification of interior work and field surveying. It not only has low designing efficiency but also is easy to cause design defects. These methods are difficult to meet the requirements for line selection design for urban rail transit. The realization which uses a 3D GIS platform instead of the traditional 2D CAD platform based on 3D GIS is beneficial to observing and evaluating design effects, and carrying on intelligent space analyses. It is also favorable to implementation of conflict analysis, removal prediction, environmental impact assessment and landscape impact assessment. Based on this idea, with the theme "Research on Line Selection System for Urban Rail Transit in Three-dimensional Space Based on GIS", the paper researched the theories and key technology involved in the research, put forward a set of methods from the aspects of modeling methods and algorithms and realized them.The main research contents and results are as follows:The paper researched some related problems in the environment of 3D GIS such as the construction of large range city scene models, urban rail transit line design, 3D modeling and visualization of lines and line scheme optimization.(1)The rapid generation of massive city 3D scene. According to characteristics of 3D city scene, the data structure of 3D city scene on the ground and 3D underground pipe network was researched systematicly. Based on the requirements of the rapid 3D design of urban rail transit lines, the method for realizing fast modeling of large range of city scenes was put forward. It solved building 3D landscape modeling, road 3D landscape modeling, bridge 3D landscape modeling, 3D underground pipe net modeling problem of models. Based on the streaming model,rapid modeling of 3D city scene from data to scene directly was realized.(2)Research on Plane design subsystem of urban rail transit lines. According to the characteristics of line plane of urban rail transit, it researched the data structure of flat lines and the calculation methods about the line coordinates and parameters. According to the relevant provisions of Code for Design of Metro(GB50157-2013), plane design subsystem of urban rail transit line was researched and developped base on Skyline 3D GIS platform, solved preliminary design of left and right lines, line position adjustment, label display and automatic extraction of parallel section, and realized the rapid design of line plane of urban rail transit.(3)Research on vertical section design subsystem of urban rail transit route. According to the requirements of longitudinal section design and characteristics of Windows forms, researched the data structure required for vertical section design, and developed the vertical section design subsystem of urban rail transit route.It solved the screen sectional design and circuit scheme of segmented display, and realized automatic acquisition of fully parallel high segment information and provided the data basis for line modeling and route optimization.(4)Three dimensional modeling and roaming of urban rail transit lines. According to the characteristics of line 3D models in different parts, it researched the bridge and tunnel structure characteristics which the line is refers to fully parallel high segment and incomplete parallel high segment, constructed 3D models of the whole line, and finished urban rail transit line navigating scheme based on 3D GIS platform according to the characteristics of navigating of Skyline 3D GIS platform.(5)According to the line noise, it researched application modes of Scall03 in urban rail transit line optimization, put forward DXF output method of city 3D scene and 3D models of the line method, built urban rail transit line noise prediction model, and provided a solution for optimizating route schemes.(6)Based on the proposed theory and method, line selection system of urban rail transport in 3D space was researched using Skyine 3D GIS platform and tested the main functions of the system using examples.Verification and test results show that the modeling method and application technology presented in this paper is feasible. It is easy to develop the practical 3D visualization line selection system integrated with 3DGIS technology, virtual reality technology and spatial database technology based on the prototype system established by the method presented in this paper.