An unconventional bridge designed nearly five hundred years ago by Leonardo Da Vinci to span the Golden Horn in Istanbul has finally been built.
The bridge now spans a motorway in the less exotic setting of Aas, a small town 20 miles north of Oslo, Norway. However, it is the first major civil engineering project to be built from Da Vinci鈥檚 drawings.
Da Vinci first sketched the bridge in 1502 for Sultan Bajazet II, one of many proposed designs for a new bridge. But none of the Sultan鈥檚 engineers believed it could be built. Rather than using a number of consecutive arches to hold the bridge up, Da Vinci proposed using three separate arches, as big as the bridge itself, two leaning inwards on either side.
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鈥淭here were no bridges in this period that looked like this,鈥� says Martin Kemp, a historian with knowledge of Da Vinci鈥檚 engineering work. 鈥淚t is was on an astonishing scale for a start.鈥�
Sound structure
The new bridge is smaller and simpler than the one first sketched by Da Vinci, but it exploits the same structural principles. One arch supports the bridge from below, with two more leaning inwards to distribute its weight to the banks on either side.
Architect Tarja Koskinen helped adapt Da Vinci鈥檚 original design for the Norwegian firm Selberg Arkitektkontor. She believes the original bridge would have needed to be broader but would have worked just as well.
鈥淭hey would most probably have been able to construct it with some modifications,鈥� Koskinen told New Scientist. 鈥淏ut it may not have been economically viable.鈥�
The new bridge has been built from wood and spans 100 metres. Da Vinci鈥檚 original design was to be made from stone and cross the 340 metres of the Golden Horn.
Jim Eyre of Wilkinson Eyre architects says the construction process would have required extraordinary effort, but the basic design principles are sound. 鈥淎rchitecturally, it was ahead of its time,鈥� he says.