Made famous by his historical paintings such as “The Last Supper” and the “Mona Lisa,” Leonardo da Vinci was a man of idealistic genius. His incredible, unusual designs and creations earned him the moniker of “The Renaissance Man.”
However, as beautiful and ingenious as his ideas were, most never seemed to leave the drawing board. Statues of giant horses, flying machines, and bell-shaped tanks that were blueprinted and sketched on paper were not worked on for years or even decades, never undergoing practical tests to see whether they would have worked or not.
For one design though, that was about to change.
Leonardo’s grand bridge
In 1502 AD, Bayezid II, Sultan of the Ottoman Empire at the time, put out a request for proposals regarding a bridge design that would connect the capital of Istanbul with its neighbouring city of Galata.
The Italian artist, motivated by the challenge, began sketching blueprints for the grand bridge and sent his proposal to the Sultan.
Typical contemporary bridge supports were built with semi-circular arches that required ten or more piers between the two points of the bridge to support its massive weight.
In his blueprints, however, da Vinci presented a rather revolutionary design, far different than anything that had come before.
Leonardo’s bridge would be ten times longer than most normal bridges at the time, spanning 919 feet from one end to the other, according to an old measurement system.
The bridge would have been built as a single flattened arch tall enough to allow large sailboats to pass through. It also included splayed abutments on either side of the bridge, making it sturdy enough to withstand side-to-side motions associated with the region’s frequent earthquakes.
It would have been the longest bridge in the world at the time, dwarfing even today’s record holder at 541 feet, the Danyang-Kunshan Grand Bridge.
In the end, however, Bayezid rejected da Vinci’s pitch, and his idea of a grand bridge would go unworked on, seemingly, for good. Five centuries after his death, however, a group of engineers at MIT took interest in da Vinci’s work.
MIT engineer John Ochsendorf, together with graduate student Karly Bast and undergraduate student Michelle Xie, came forward to see if Leonardo da Vinci’s bridge design would work.
This was not the first attempt to replicate da Vinci’s design, as a pedestrian overpass in Norway was closely based on the same sketches, but it was built with modern-day materials like steel and concrete that did not accurately reflect available materials at the time.
The team went through documents on the bridge, possible materials, and the geographic conditions at the Golden Horn (Haliç in Turkish), where the bridge was supposed to be.
“It’s incredibly ambitious,” said Bast. “It was about 10 times longer than typical bridges of that time.”
Though da Vinci never specified the materials proposed to build the bridge, the team looked into materials that were available at the time, deducing that stone would have been used to support the titanic structure.
To start, the team built a 1/500th model of the bridge design that was 32 inches long and built with 126 3-D printed blocks, each taking six hours to create.
Putting the bridge to the test
Putting the blocks together, the team used scaffolding to keep the bridge up until they could place the final keystone.
“[The model’s] all held together by compression only,” Bast says. “We wanted to really show that the forces are all being transferred within the structure.”
Finally, the time came for the final piece, the keystone at the top of the arch, to be placed.
“That was the critical moment when we first put the bridge together. I had a lot of doubts,” Bast confessed. However, she held onto hope that the bridge would stay together.
“When I put the keystone in, I thought, ‘This is going to work.’ And after that, we took the scaffolding out, and it stood up.”
“It’s the power of geometry,” that makes it work, Bast adds about her triumphant success. “This is a strong concept. It was well thought out.”
The team then conducted a series of tests and discovered that the bridge could indeed withstand the force of earthquakes.
Leonardo da Vinci’s idea for a grand bridge would have been one of the greatest successes in human history.
New answers, new questions
After replicating da Vinci’s bridge design, more questions arose. The design, rediscovered in 1952, begged the question of whether da Vinci sketched it in less than a minute, or was it something he thought about for a significant amount of time. In any case, considering the MIT team’s success, the man clearly knew what he was doing.
The revered genius that was Leonardo da Vinci, a man born to revolutionize the world, continues to inspire creative hopefuls one generation after another. For those who dare to dream, dream big. The creativity of an artist knows no bounds.