The jing kieng jri or living root bridges — aerial bridges built by weaving and manipulating the roots of the Indian rubber tree — have been serving as connectors for generations in Meghalaya. Spanning between 15 and 250 feet and built over centuries, the bridges, primarily a means to cross streams and rivers, have also become world-famous tourist attractions. Now, new research investigates these structures and proposes to integrate them in modern architecture around the world, and potentially help make cities more environment-friendly.
Researchers from Germany investigated 77 bridges over three expeditions in the Khasi and Jaintia Hills of Meghalaya during 2015, 2016 and 2017. Taking into account structural properties, history and maintenance, morphology and ecological significance, the study, published in the journal Scientific Reports, suggests that the bridges can be considered a reference point for future botanical architecture projects in urban contexts.
“The findings relating to the traditional techniques of the Khasi people can promote the further development of modern architecture,” said Professor Ferdinand Ludwig of the Technical University of Munich, one of the study authors and founder of a field of research called “Baubotanik” that promotes the use of plants as living building materials in structures.
While stressing they are “not planning to create new living bridges for contemporary cities” right away, the researchers believe this extraordinary building technique can help facilitate “better adaptation to the impacts of climate change”. “We see a great potential to use these techniques to develop new forms of urban green in dense cities,” said Ludwig. “By understanding the growth history, we can learn how long the bridge has taken to grow to its current state and from there design future growth or repairs, or growth of other bridges,” said Wilfrid Middleton, one of the co-authors.
A root bridge uses traditional tribal knowledge to train roots of the Indian rubber tree, found in abundance in the area, to grow laterally across a stream bed, resulting in a living bridge of roots. “Let us redefine these bridges as ecosystems,” said Bengaluru- and Shillong-based architect and researcher Sanjeev Shankar. In 2015, in one of the earliest studies on these structures, Shankar wrote, “The process begins with placing of young pliable aerial roots growing from Ficus elastica (India rubber) trees in hollowed out Areca catechu or native bamboo trunks. These provide essential nutrition and protection from the weather, and also perform as aerial root guidance systems. Over time, as the aerial roots increase in strength and thickness, the Areca catechu or native bamboo trunks are no longer required.”
Ficus elastica is conducive to the growth of bridges because of its very nature. “There are three main properties: they are elastic, the roots easily combine and the plants grow in rough, rocky soils,” said Patrick Rodgers, an American travel writer who has done many solo expeditions to these areas since 2011 and has also contributed his expertise to the new study.
What is crucial for a root bridge to survive is the development of an ecosystem around it. “Specifically the entire biology, the entire ecosystem, and the relationship between the people and the plants, which have, over the centuries, kept it going,” said Shankar, who is working with the Meghalaya government along with indigenous communities and other academics to formalise policies and regulations for conservation and responsible development of these ecosystems.
“Regarding the techniques and approaches of Living Root Bridges, we are in an early research phase. There are first concepts how to transfer the idea, but no concrete plans for projects yet,” Ludwig said in an email.
Shankar said: “We should ask: where will a plant be happy? Will it be happy in a highly toxic environment of a polluted city, where thousands will walk on it, where cars, trucks and buses are on it, or is the plant a living entity which grows in a specific microclimate?”
A pointer might lie in the deteriorating health of certain root bridges in Meghalaya. While there are hundreds of such bridges, the two most popular (Riwai Root Bridge and Umshiang Double Decker Bridge) have borne the brunt of recent tourism growth.
“Both these bridges have been adversely affected in the past ten years. This is because of the introduction of modern architecture such as new concrete footpaths, building etc around the bridge that have impacted that bridge health. There are cracks in them,” said Morningstar Khongthaw, 23, a villager who started The Living Root Foundation in 2018. “My ancestors made these bridges for a practical need: to cross streams and rivers. Now the bridges are too weak to accommodate people beyond a capacity,” said Khongthaw.
“My personal opinion is that the basic idea — architectural structures made of Ficus elastica plants — is sound in urban environments. This is because of the robustness of the plant itself,” Rodgers said, by email. He added, however, that factors like “civic planning, good governance, preventing people from damaging the bridge” also need to be taken into account. “Certainly, there is no technical impediment to there being living architecture in urban areas.” he said.
Shankar feels the Ficus benghalensis (banyan tree) is a related species that can potentially be tried. “How we can apply it to future buildings and structures, and to what extent this integration is appropriate and viable, is a very important question and only a real test in the envisioned environment can prove its feasibility,” he said.
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