After the Japanese designers of the railroad reached Muchiliao, they discovered extremely steep slopes that posed a tremendous challenge to construction. The engineers came up with the idea of taking a spiral-shaped path with three full turns around the mountain. After this spiral section, the track makes a figure eight to leave Tulishan.
當初建造阿里山鐵道的日本設計者，到了木屐寮之後，發現山勢陡峭，施工困難，最後才想出螺旋狀的方式環繞獨立山三圈，最後再以一個８字型繞出。