Design Theory And Methods Of Computer-aided Railway Route Selection Study

Railway location design is one of the most important work in railway construction. Work in plane, profile and cross-section design and in calculating engineering quantity have to be carried out again and again in order to obtain the optimization program. It is impossible to fulfill the object if the traditional method is adopted. Therefore it is necessary to renovate the means of route design. This research aims to bring out new theories and algorithms in the following several aspects:(1) Based on the point-by-point insertion of constructing triangulation digital terrain model, this paper renovates in fast construction of triangle net, fast location of triangles and interpolation of level of arbitrary points by establishing the retrieval and searching mechanisms of points to square grids to triangles. It is helpful in greatly improving the efficiency of location design in that it.(2) An all-purpose model is established for new railway planes and a new unit-piecing method is proposed to assist railway plane designs. In order to improve the speed and accuracy of calculation, a recursive formula is used to express parameter equation of easement curve and a method is adopted to control its errors. At the same time, a fast iterative algorithm is worked out for the calculation of the distance between lines and their projections. The plane CAD programs based on these algorithms have wide applications and it is stable, fast and accurate.(3) Based upon the proposed all-purpose plane model, the method of "successive approximation" in analyzing different forms of roadbeds and the method of construction-point template" in cross-section design have been proposed to overcome the shortcomings brought by some roadbed CAD programs which only take single base and single roadbed into consideration.(4) Comparison of alternative layout is throughout different phases of selecting routes. According to the responder technology of ObjectARX, a new method to optimize railway route is realized for the synchronal cooperative design of the plane, profile and cross-section. According to graph theory, an method of automatic comparison and combination is realized for route selection. With these two methods, the procedures of working out the optimal route can be improved, the design quality be increased and the construction cost be decreased.(5) Aimed at solving the defects of storing data in the form of document with the traditional CAD programs, this paper suggests to adopt the ADO database access technology to store data, and the ActiveX technology for the design output.(6) With the above mentioned theories and key technologies, the CARA (Computer Assisted Route Alignment) system has been designed and developed and put into use. It has greatly improved work efficiency, saving resources both in labor force and funds.