Monday, November 12, 2012

Living Bridges - A Feat of Organic Engineering

A living bridge [photo: Timothy Allen]

Going through the pictures I found on the internet, I couldn't help but imagine hobbits using these bridges. Literary and movie references point to the fact that they built their homes and structures as organically as possible, living and blending their structures into nature so well that they became part of the landscape. Unlike hobbits these bridges actually exist. Bridges around the world, constructed of steel and concrete, have a kind of beauty, these bridges are beautiful in an entirely different way. 

[photo: Timothy Allen]

[photo: Timothy Allen]
During monsoon season the Meghalaya region of northern India is said to be the wettest place on earth. Bridges build of materials available to them - wood or woven vines - would decay and rot quickly in the humid conditions. The living bridges only grow stronger with time.


Ficus Elastica tree

The Ficus Elastica tree is a kind of rubber tree that has aerial or secondary roots. These are the trees growing along the river banks in the Meghalaya region of India. The local engineers use hollow betal tree logs to train aerial roots and branches in the direction they are needed to form the bridge structure. Once the tree roots have grown long enough, the builders allow the root to come in contact with the earth on the other side of the river and anchor there.

The bridge's structure is filled in by training branches and roots to form the body of the bridge and the bridges even handrails.

A bridge trainer at work [photo: Timothy Allen]

[photo: Timothy Allen]

This is bridge formed around a rock cliff face [photo: Timothy Allen]

In some places the bridges are so steep they're ladders
[photo: Timothy Allen]

[photo: Timothy Allen]

Living ladder [photo: Timothy Allen]

[photo: Timothy Allen]

As you can imagine the planning for these bridges and the actual bridge formation take ten or fifteen years to become fully functional. Unlike other bridges, these structures grow stronger with time and some are said to be over 500 years old. Also, bridge maintenance is minimal as they leave the growing and maturing to the host trees. 

Larger bridges are over 30m (100 ft) and can hold up to 50 people.










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