PURPOSE: To restrain, to a maximum possible extent, a car from swaying and accelerating to the right and the left on passing through a branching point, and to improve maximum speed available for passing through the branching point by a method wherein the origin of an easement curve is taken on a virtual point on a fixed track girder and bending angles for a movable main girder, movable sub-girders and an easement rail are respectively made symmetrical in both ways on the front and the rear of the center of the branching point.

CONSTITUTION: The cubic parabola theory, generally used in railways, is used for controlling vibrations of cars passing through a branching device of a multi-joint type girder track. However, the datum point for branching alignment is taken not on the fulcrum 7 for a fixed girder 4 and a first movable follower 6, but on a virtual point 0 on a position closer to the starting-side by the length (d) of a movable sub-girder on the main line, and a virtual point 14 is set on a main movable girder 3 on a position separating by the length (d) of the movable sub-girder from the left end of the main movable girder. Then, the theory of easement curve is applied, based on specified procedures and calculation formulas. Bending angles for fixed girders 1, 2 and 4, the main movable girder 3, movable sub-girders 5a, 5b and 5c, and easement rails 6a, 6b and 6c are respectively made symmetrical in both ways, and bending angle ratios on branchings are determined so that equivalent curvature 1/ρ becomes proportional to the horizontal distance X that extends from the branching point 0 in the direction where the car originally proceeds.