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MIT Students Show How the Inca Leapt Canyons
PCOL writes "When Conquistadors came to Peru from Spain in 1532, they were astonished to see Inca suspension bridges achieve clear spans of at least 150 feet at a time when the longest Roman bridge in Spain had a maximum span of 95 feet. The bridges swayed under the weight of traffic terrifying the Spanish and their horses, even though, as one Spaniard observed, they were almost as "sturdy as the street of Seville." To build the bridges, thick cables were pulled across a river with small ropes and attached to stone abutments on each side. Three of the big cables served as the floor of the bridge, two others served as handrails and pieces of wood were tied to the cable floor before the floor was strewn with branches to give firm footing for beasts of burden. Earlier this year students at MIT built a 70-foot fiber bridge in the style of the Incan Empire. The project used sisal twine from the Yucatan Peninsula and anchored it by wrapping it around massive concrete blocks. The weekend's burst of activity was preceded by 360 hours of rope-twisting as the 50 miles of sisal twine was turned into rope. Working together as a group was part of the exercise. "A third of the time was spent learning to work together," one of the students said. "But after a while, we were banging those cables out.""
Haha, talk about a late story at a completely random time. I was one of the leaders on the project, lots of late nights twisting twine together. If anyone has any questions feel free to ask.
You gotta find first gear in your giant robot car
I was walking around campus one day and saw the cement pillars going up. They were BIG concrete boxes, about 4 stacked up taller than me and about 2-3 feet on a side. I'm not sure what happened to that concrete but it seemed wasteful to make _just_ rectangular prisms. No offense, especially since I'm a 'utility-focused' engineer, myself, but I did think-- wow, these are harsh. It might have been fun to paint, or sculpt them (before being set, or with plaster afterwards), with Incan designs or information about the construction process.
The rope bridge itself looked fun to walk on, but it had a sign saying no trespass. That sign was up the whole time the bridge was there, though it is possible people might have walked around the bridge for fun and jumped around to see how it swayed and bubbled. At that point the bridge might have been up a while and losing tension and so the sides of the shallow creek interfered with the hanging bridge aspect.
It's great to see thought provoking structures go up around campus. Rock on.
Actually, the engineering of the pyramids is still surprising us; not only was the construction of the pyramid incredible, but the actual quarrying and shaping of the stones is still unsurpassed. Sheets of paper won't fit through the gaps between blocks, and there's no mortar.
Attempting to build a duplicate pyramid today would still be a massive undertaking that would take years; hardly a trivial task.