It's pretty obvious that all of us here at SmartPlanet love hearing about innovative technologies that not only give people a leg up on their lives, but do it in a sustainable way. Ultimately though, we'd be hard pressed to come up with anything greener than the kind of solutions engineered with the help of mother nature herself.
A fine example of this can be found in a forest region of India called Nongriat, where locals have been -- get ready for this -- growing their own bridges. Yes, literally, as in there even photos and video to prove it.
The living structures, some of which stretch over one hundred feet in length, are sturdy enough to support the weight of more than 50 people. Beyond their utilitarian function, enabling natives to cross distant ridges, the bridges are essentially the roots of a type of rubber tree called ficus elastica. Left unfettered, the roots expand in more unwieldy pattern (hint: they're definitely not being so accommodating out of their own free will). But at some point roughly 500 years ago, indigenous tribespeople discovered that they could guide the formation of this outgrowth using betel nut trunks as tools. Once the roots reach the opposite bank, they form a stable foundation from which to they continue to grow and strengthen.
Admittedly, the process, known as tree shaping, isn't nearly as efficient as modern construction methods. Whereas it took three years to construct the world's longest sea-bridge in China, nurturing a, say, organic version takes about 10 to 15 years. So you'd have to figure that the Khasis, who've been in the bridge growing business for more than 500 years, must be some really patient people.
I guess what I really like about their approach is the idea of intervening upon the environment only as much as necessary to fix a problem -- no matter how long it takes. No deforestation, hazardous waste or expenditure of fuels.
And interesting enough, the living bridges are actually stronger than ones built from wood. Since the Cherrapunji region gets about fifteen meters of rainfall yearly, their proven durability demonstrates that the structures can better withstand being bombarded by flash floods and other destructive forces.
Faced with such hazards, it's nice to know that nature on its own can provide that kind of support, aided slightly by technology.