Leonardo Da Vinci was an Italian polymath of the high renaissance who was active painter, draughtsman, engineer, scientist and architect. He is known for his great paintings such as Mona Lisa and John the Baptist. A model of bridge made by Leonardo Da Vinci to connect Istanbul with neighbor city Galata is now in test by MIT engineers. It was now appointed but MIT engineers wonder how he thought about the bridge and whether it really would have worked.
To study the question graduate student Karly Bast worked with professor of architecture John Ochsendorf and undergraduate Michelle Xie tackled the problem by analyzing documents, possible materials and construction methods at the time. The team built a detailed scale model to stand support weight and to withstand settlements of its foundations.
A flattened Arch
In Leonardo’s time bridge were bade from semicircular arcs but Leonardo’s bridge concept was different. He made a flattened arch that would be tall enough to allow a sailboat to pass. The bridge would have been 280 meters long. Considering the metric system at that time it would been the longest bridge at that time. It was about 10 times longer than typical bridges at that time.
In his notebooks and letter to Sultan, Leonardo provided no details about the material that would have used in construction. The bridge would stand on its own under the force of gravity without any fasteners or mortars to hold the stone together. To prove it they had to build a model and demonstrate its stability. The bridge would have been made of thousands of stone blocks and the design was made from 126 blocks of the model. It was made from scale of 1 to 500. The individual blocks were made on a 3D printer taking about six hours per block to produce. “It was time-consuming, but 3D printing allowed us to accurately recreate this very complex geometry,” Bast says.
Testing the design’s feasibility
It was definitely not the first design produce Leonardo’s basic bridge. There was a test for pedestrian bridge in Norway. “It’s all held together by compression only,” Bast says. “We wanted to really show that the forces are all being transferred within the structure,” which is key to ensuring that the bridge would stand solidly and not topple.
“When we put it in, we had to squeeze it in. It was a critical moment when we first put the bridge together. We had doubts but when we tasted it stood up.” Bast recalls. “It’s the power of geometry that makes it work she says. This is a strong concept and it was well thought out.”
It is still unknown whether the sketch was free handed he did in a minute or sat down thinking deeply about it. It is difficult to know. Bast says, “He knew how the physical world works.”
The design may not have practical implications for modern designers. Today’s material and methods provide more options for lighter and stronger design. But this model provides insight into ambitious construction of materials and methods in early Renaissance. Bast says, “You don’t need fancy technologies to come up with best ideas.”