Leonardo da Vinci, the ultimate Renaissance man, was not only a famous painter but a prolific inventor. Today, he is credited with inventing an instrument that measures the speed of wind, proto-flying machines, scuba gear and more. It turns out, the Italian Renaissance polymath was also an apt architect—something which was recently proven by a team from MIT, which recreated a bridge design by da Vinci using a 3D printer.
In 1502, da Vinci responded to a request for proposals sent out by the Sultan Bayezid II who sought to build a bridge between Istanbul and Galata, across the Golden Horn waterway. Though his design was not ultimately chosen, da Vinci’s bridge would have—at the time—been the longest bridge span in the world.
Fast forward over 500 years, and the famed inventor’s bridge design still incites interest. So much so that a team from MIT recently set out to recreate a small-scale version of the bridge to test its integrity and strength.
The team consisted of John Ochsendorf, a professor of and of civil and environmental engineering, recent graduate student Karly Bast MEng ’19 and undergraduate student Michelle Xie. Together, the three studied the drawings and documents made by da Vinci as well as common building materials of the time, construction methods and the geological conditions of the Golden Horn.
Based on this in depth research, the team 3D printed a 1:500 scale model of the 16th century bridge and tested it to see how it could support weight and withstand settlement of its foundations. It turns out, the innovative bridge design conceived of by da Vinci likely would have worked!
The da Vinci bridge
When da Vinci sent his bridge design to the sultan, existing bridges looked very different. At the time, most masonry bridge supports were constructed as semicircular arches. Because of the width of the waterway, however, this structure would have been difficult to implement across the Golden Horn, requiring 10 or more supportive piers along the span of the bridge.
da Vinci’s bridge, however, introduced a wholly new design: a flattened arch that would not require any piers but would still be tall enough to let a sailboat pass underneath. Had it been built, the impressive bridge would have measures about 280 meters in length—which would have made it about 10 times the length of most bridges built at the time.
Another interesting structural element integrated into the bridge’s design were abutments that splayed outward on either side of the bridge. This feature would have helped to stabilize the bridge against lateral motions.
Indeed, looking at the bridge, it looks quite modern. At the very least, it looks nothing like many of the other bridges built in the early 16th century, which were characterized by circular arches.
Recreating a 16th c. bridge design
Recreating the bridge—even at a small scale—required the team to come up with a lot of educated guesses. For instance, because da Vinci did not mention any construction materials in his bridge design, the research team had to study and analyze the available building materials at the time. Ultimately, they determined that the bridge likely would have been constructed from stone rather than wood or brick.
They also concluded that the bridge would likely have been constructed without any mortar or fasteners and would—like classical masonry bridges—have been held together by the force of gravity.
The team then had to decide how to slice the bridge design up into individual blocks, which could be 3D printed individually and then assembled. Though they determined the full-scale bridge would have been made up of thousands of stone blocks, the 1:500 scale model ultimately consisted of 126 blocks, each of which took about six hours to print.
Once the blocks were 3D printed, the team carefully assembled them using scaffolding inspired by 16th century construction. The scaffolding was removed and the final piece—the keystone was put in place. The resulting structure was a 32 inch long bridge that matched da Vinci’s design was built.
Testing the 1:500 scale bridge
The goal of rebuilding the bridge in such a way was to test if it would have been a viable design in the 16th century. As Bast explained: “It’s all held together by compression only. We wanted to really show that the forces are all being transferred within the structure.”
To test the scale model of the bridge, it was built on two movable platforms, which could be moved to simulate the movement of foundations caused by weak soil or even an earthquake. The bridge reportedly showed resilience to the horizontal movement and deformed only slightly until it was stretched to the point of collapse.
The geometry of the bridge and its performance impressed the students. “This is a strong concept,” said Bast. “It was well thought out… [da Vinci] knew how the physical world works.”