The Last Handwoven Bridge, Rebuilt by MIT
Dylan Thuras is a guest blogger on Boing Boing. Dylan is a travel blogger and the co-founder of the Atlas Obscura: A Compendium of the World's Wonders, Curiosities, and Esoterica, with Joshua Foer.
When conquistadors arrived from Spain they were shocked. Spanning vast canyons, and longer than any existing European or Roman bridge was a type of bridge which they had never seen before: an Incan suspension bridge. Today only one example remains.
Made of woven grass, the bridge spans 118 feet, and hangs 220 feet above the canyon's rushing river. The Incan women braid small thin ropes which are then braided again by the men into large support cables, much like a modern steel suspension bridge. Handwoven bridges lasted as long as 500 years and were held in very high regard by the Inca. The punishment for tampering with one was death.
Over time, however, the bridges decayed, or were removed, leaving this single testament to Incan bridge engineering. This previously sagging bridge is now repaired each year, and christened with a traditional Incan ceremonial bridge blessing. The bridge is in extremely good condition and is a perfect location for all of us wishing to indulge in long harbored Indiana Jones fantasies.
Though the Spanish tried many times to build stone arch bridges all were failures until steel and iron bridges were introduced to the mountainous Peruvian countryside. Today the rope suspension bridges are being studied, and even recreated by MIT students. The students made a 60-foot-long version of the Incan bridge which was stretched between two campus buildings.
More on the Atlas here, more on the story of the bridge here, and about the MIT recreation of the bridge here and slideshow here.
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I worked on a movie once where a more substantial rope bridge of vines and planks was built. The vines concealed steel cables, and the whole thing was very strong, but it went over a deep gorge and was still a bit scary to use. It would have been a nice convenience to leave behind after the shoot, but insurance required it to be removed.
I don't care how safe they say it is, I am NOT walking across a 118 foot canyon on GRASS.
Any pictures of the finished bridge? Neither the article or flicker stream have the finis ed MIT bridge.
NOVA had a good show about this in 1998, part of their Secrets of Lost Empires. The video is unfortunately not online, but a blurb and the transcript are:
http://www.pbs.org/wgbh/nova/inca1/
http://www.pbs.org/wgbh/nova/transcripts/2404inca.html
Philanthus
In proper units of measure for MIT and bridges:
The original span is 21.13 Smoots.
The MIT version is 10.75 Smoots.
I can only imagine creating the sweetest tree house ever using those type of bridges.
And, just for fun, here's a suspension bridge, made from recycled plastic grocery bags, and built by the eight- to twelve-year-olds at Tinkering School in 2007: Grocery-bag Suspension Bridge
The bridge was actually strong enough to carry the entire class: Fully Loaded