page_title: Spiral (railway)
section_title: Taiwan
hierarchical_section_title: Spiral (railway) / List of spirals / Taiwan
caption_attribution_description: English: Plan of a loop in Alishan Forest Railway in Taiwan.日本語: 阿里山森林鉄道のループ線平面図。
context_page_description: A spiral is a technique employed by railways to ascend steep hills.
  A railway spiral rises on a steady curve until it has completed a loop, passing over itself as it gains height, allowing the railway to gain vertical elevation in a relatively short horizontal distance. It is an alternative to a zig-zag, and avoids the need for the trains to stop and reverse direction while ascending. If the train is longer than the length of each loop it may be possible to view it looping above itself.
  The term "loop" is also often used for a railway that curves sharply and goes back on itself: if the railway crosses itself, then it forms a spiral or helix; otherwise, it forms the much more common horseshoe curve or bend.
context_section_description: Triple spiral at Dulishan at 23°32′11″N 120°36′07″E on the Alishan Forest Railway.
caption: Triple spiral loop on the Alishan Forest Railway
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