Zig-zag bridge
From Wikipedia, the free encyclopedia
| Zig-zag Bridge | |
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| A practical marsh bridge at Boxerwood Gardens |
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| Ancestor: | Beam bridge |
| Related: | None |
| Descendant: | None |
| Carries: | Pedestrians |
| Span range: | Short |
| Material: | Post and plank |
| Movable: | No |
| Design effort: | Low |
| Falsework required: | No |
A zig-zag bridge is a pedestrian bridge composed of short segments, each set at an angle relative to its neighbors and usually with an alternating right and left turn required when traveling across the bridge. When constructed of wood, each segment is formed from planks and is supported by posts, while a stone bridge of this type will use short slabs set upon stone footings.
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[edit] As a practical bridge
The post and plank version has an advantage when employed as a crossing of a muddy bottom or marsh: It is structurally stable, where a straight bridge might tend to tip due to the posts moving in the soft mud. Each segment of walkway mutually supports the next from twisting and tipping by being securely fastened to it. This is the same advantage possessed by a zig-zag split rail fence. A bridge of this type is seen in the image at upper right. This particular bridge is used to carry a wildland trail through an area of soft and often wet soil. The use of the bridge has a benefit also to the marsh, since it avoids soil compaction which could damage tree roots and which would also create a fast runoff of water and so possibly cause soil erosion.
[edit] As a decorative or ceremonial bridge
A zig-zag bridge is often seen in East Asian gardens. It may be made of stone slabs or planks as part of a pond design and is frequently seen in rustic gardens constructed according to Zen philosophy and teachings. As it often has no railings, it is quite possible for an inattentive walker to simply fall off an end into the water. The objective in employing such a bridge is to focus the walker's attention to the current place and time - "be here, now"
The zig-zag of paths and bridges also follows a principle of Feng Shui. Negative energy and bad spirits are believed to have problems navigating corners, while people and good energy have no such problem.
