Narrow bridges

Indigenous Architecture: India’s Living Root Bridges Recognized

In India’s northeast state of Meghalaya, one of the wettest places on earth, people rely on ancient bridges to cross the region’s many streams and rivers. But these are not typical viaducts – bridges are alive.

For hundreds of years, the Khasis of Meghalaya have manipulated the aerial roots of the rubber fig tree to build strong bridges, known in the Khasi language as jingkieng jri. There are at least 150 such bridges in Meghalaya today, according to Morningstar Khongthaw, which works to preserve and educate the public about the architectural traditions of the community.

Why we wrote this

How can buildings (or building materials) help the environment, rather than harm it? Some engineers and architects are finding answers in northeast India, where indigenous communities have mastered the art of creating living bridges.

The jingkieng jri are not only a great tourist attraction, but also an important proof of concept for engineers and designers interested in the practice of living architecture. Incorporating plants into architectural design reduces the need for harmful building materials and promotes biodiversity, but it can also take generations to test and develop the right building methods. Bioengineers around the world are studying living root bridges in hopes of applying aspects of the Khasi tradition to projects in their own countries.

“The Khasis have a brilliant understanding of architectural engineering, totally different from the Western way,” says Ferdinand Ludwig, a professor at the Technical University of Munich, adding that their traditions could offer “new solutions for [greening] construction.”

Nongriat, India

Covered in thick subtropical forests and streaked with streams and rivers, the hilly state of Meghalaya in northeast India is one of the wettest places on earth. During the monsoon season, torrential rains turn docile rivers into raging waterways, and people rely on age-old bridges to access farms, schools and markets.

But these are not typical wooden or steel viaducts – the bridges are alive.

For hundreds of years, the Khasis of Meghalaya have manipulated the aerial roots of the rubber fig tree (elastic ficus) to build strong bridges, known in the Khasi language as jingkieng jri. There are at least 150 such bridges in Meghalaya, according to Morningstar Khongthaw, which works to preserve and educate the public about the architectural traditions of the community. The figure includes the famous living two-story bridge in the village of Nongriat, which locals believe is around 250 years old. Mr. Khongthaw’s village, Rangthylliang, has 20 living root bridges. “The oldest is about 700 years old,” he says with great pride.

Why we wrote this

How can buildings (or building materials) help the environment, rather than harm it? Some engineers and architects are finding answers in northeast India, where indigenous communities have mastered the art of creating living bridges.

Today the jingkieng jri are not only a great tourist attraction, but also an important proof of concept for engineers and designers interested in the practice of living architecture. Incorporating plants into architectural design reduces the need for harmful building materials and promotes biodiversity, but it can also take generations to test and develop the right building methods. Bioengineers around the world are studying living root bridges in hopes of applying aspects of the Khasi tradition to projects in their own countries.

“The Khasis have a brilliant understanding of architectural engineering, totally different from the western way,” says Ferdinand Ludwig, professor of green technologies in landscape architecture at the Technical University of Munich. “Their way of thinking forms the conceptual basis for a new way of architecture and engineering that we urgently need to deal with climate change.”

ancient bioengineering

“There are different ways to design, build and grow a living root bridge,” says Khongthaw. The most popular, and fastest, construction pattern is to create a bamboo frame, over which the roots of a nearby rubber fig tree are pulled and intertwined, until the roots reach the opposite bank. The bamboo frame itself acts as a temporary bridge while the living root structure takes shape. Over time, the bamboo rots as the roots grow and coalesce, making the structure stronger and more stable.

A village dog crosses a living double-decker bridge in Nongriat, India. The Khasis also build ladders, tunnels and other structures using traditional techniques passed down from generation to generation.

The time it takes to reach the first functional stage – when the bridge is strong enough to support about 500 pounds, or about three people with loaded baskets – depends on the required length of the bridge. Mr Khongthaw says a bridge crossing a stream would be about the length of a school bus and would take nearly 20 years to become functional, while a bridge crossing a river would take 70 to 80 years. In places where there are no rubber fig trees nearby, villagers should first plant a sapling by the river and wait 10 to 15 years for aerial roots to appear before building the bamboo frame. .

At all stages of their development, bridges require regular maintenance. This happens during the monsoon season when the roots are more flexible. “Everyone in my village is involved in maintaining the bridges,” says Mr. Khongthaw. “Whoever crosses the bridge, spends five or 10 minutes working on the roots to make the structure stronger.”

In the past, construction and maintenance work on bridges was done by men. But that is changing. “Nowadays, women are also involved,” says Mr. Khongthaw.

In addition to bridges, the Khasis build cliffside ladders, tree platforms, swings and tunnels using traditional techniques passed down orally from one generation to the next. Now the Khasis are sharing their knowledge with the rest of the world.

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In Germany, Professor Ludwig has been studying examples of living architecture from around the world for almost two decades. He has designed and supervised the construction of several structures incorporating plants, including a walkway that uses living willow trees as the only supports.

Professor Ludwig first discovered Meghalaya’s Living Root Bridges in 2009, via a documentary, and was struck by the Khasi approach to construction. “They don’t prescribe the structure itself. They only prescribe the goal,” he says. “They want to get from A to B in a safe and comfortable way. They plant a tree and manipulate the root growth in a direction that benefits them.

One of his students at the Technical University of Munich, Wilfrid Middleton, is studying living root bridges in Meghalaya as an example of regenerative design – an increasingly popular concept in which structures are not only sustainable (built with minimal and efficient use of resources), but they also replenish the resources necessary for their operation and enrich their environment, thus having a positive net effect on the environment. In cities, living structures like the walkway designed by Professor Ludwig can help sequester carbon, create a cooling effect and provide habitat for birds and other urban wildlife. The manipulation of ficus or comparable species could open “new solutions for [greening] construction in densely populated urban areas,” adds Professor Ludwig.

Mr. Middleton visited 70 jingkieng jri so far, and with the agreement of the village elders, he photographs the bridges to create precise 3D models. “Each year, as the bridge grows and changes, we are able to capture its incredibly complex structure,” he says. “We are trying to learn from the Khasis.”

Preserving Meghalaya’s Bridges

While there is growing international appreciation for living root bridges, in Meghalaya, Mr Khongthaw says many villagers yearn for a modern lifestyle, with concrete houses and bridges. Fearing that traditional Khasi knowledge might not seem relevant to younger generations, Mr. Khongthaw founded the Living Bridge Initiative in 2016, with the aim of preserving, protecting and increasing the number of living root bridges. He regularly visits educational institutions to talk about his work.

“These bridges, on which our elders worked for so many years, are being forgotten,” he says. “I wanted to start something to recognize their efforts.”

Mr. Khongthaw has also started a sapling planting center to address the shortage of rubber fig saplings, which are not easily found in the forest. The biggest threat to these ancient bridges, however, are development projects in their vicinity.

Byron Nongbri runs a host family with his wife, near the famous double-decker bridge in the village of Nongriat. In 2016, he participated in stopping a road project that would have caused an influx of tourists to the region. Now he worries about an ongoing limestone mining project just 3 miles from his village. “It will surely damage my paradise,” says the father of five.

Meanwhile, Mr. Khongthaw finds hope to build new bridges and honor the wisdom and ingenuity of his ancestors. He recently participated in the construction of seven bamboo bridges, each of which will serve as the framework for a new living root bridge, which will be shaped and maintained by future generations.

“Our knowledge should be recognized not only in Meghalaya but everywhere,” he says.