Engineer Karly Bast shows off the scale model of a bridge designed by Leonardo da Vinci that she and ... [+]
In 1502 Italian Renaissance polymath Leonardo da Vinci sent a letter to the Ottoman sultan Bayezid II, offering his service as an engineer. The sultan was seeking proposals for a bridge to connect his capital with the former Genoese settlement of Galata — modern Karakoy — across the Golden Horn waterway, a river inlet of the Bosphorus in Istanbul, modern Turkey.
Leonardo describes his bridge design in the letter to the sultan, and a small sketch survives in one of his notebooks, rediscovered in 1952. He proposed one flattened "masonry bridge as high as a building, and even tall ships will be able to sail under it," spanning more than 366 meters (1,201 ft) over the river. Splayed abutments would extend outwards at each end of the bridge to stabilize it against winds, and for Istanbul even more interesting, against earth movements.
Leonardo da Vinci’s original drawing of the bridge proposal (top left), showing a bird's eye view at ... [+]
The city of Istanbul, a densely populated region and one of the most important harbors in the Mediterranean Sea, sits atop the North Anatolian Fault (NAF), a tectonic boundary separating the Anatolian- from the Eurasian-plate. As one plate moves along the other, friction builds up and eventually the accumulated energy is released as a a strong earthquake.
Leonardo's design was rejected and a bridge over the Golden Horn was realised only in the 19th century. Had the 1502 design been implemented, it would have been the longest bridge in the world at the time, and it would still be the longest single masonry arch span in the world. New research by a team of engineers at the Massachusetts Institute of Technology suggests, that the bridge would have been structurally viable. Using a detailed 1:500 model of the bridge and two movable platforms, the team simulated movements in the bridge's foundations like experienced during a real earthquake. The construction, made up of 126 individual blocks held together by their own weight and the force of gravity, deformed only slightly, demonstrating the design's stability.
Just 54 years after Leonard's letter to the sultan, Constantinopel, as Istanbul was called at the time, was hit by a series of strong earthquakes. Many buildings in the city collapsed, claiming estimated 13,000 victims.
Da Vincis's design proved to be not only feasible as a model, but also in reality. In 2001 a 109 meters (358 ft) wide pedestrian bridge based on his drawing was realized in the town of Ås, Norway. Future plans, announced in 2012, include a bridge over the Golden Horn in Istanbul, as Leonardo had proposed.
Leonardo Da Vinci's bridge design recreated as a pedestrian crossing in a much smaller scale in Ås, ... [+]
