Abstract：Research purposes： In the railway second line plane design, it may cause these problems by different methods, such as the distances between centers of lines are not same and no good to maintenance and repair in unchanging distances range, and the distances are too much to waste area in changing distances range. It involves a number of calculation and creating the drawing and table, and the operation is complicated. Therefore, this paper puts forward a set of general and feasible method about railway second line plane automated design, which improves the design efficiency.
Research conclusions：(1) Use strictly concentric circles method in unchanging distances range to ensure the least land and the distances between centers of lines are equal everywhere. (2) According to the distance control of ZYN and the head and tail change of curve area calculated second line curve data in changing distances range, to ensure the distances between centers of lines gradual transition and economize land. (3) Designed the program and simplified the operation, it could realize the functions by one step, included all curves widen design, second line curve data calculation, internal broken chain calculation, creating the table and the second line plane drawing, which significantly improved the design efficiency. (4) Simplified the formulas deducing by using coordinate analytic method, and improved the calculation accuracy and algorithm generality by using numerical calculation method. (5) This research result can provide reference for the plane design of all levels of newly built double-line railway, increased built second line and rebuilt existing line.
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