
PhoÂto by Gretchen Ertl, via MIT News
UnforÂtuÂnate though it may be for the dreamÂers of the world, we’re all judged not by what we imagÂine, but what we actuÂalÂly do. This goes douÂble for those specifÂiÂcalÂly tasked with creÂatÂing things in the physÂiÂcal enviÂronÂment, from engiÂneers and archiÂtects to invenÂtors and artists. LeonarÂdo da VinÂci, the origÂiÂnal “RenaisÂsance man,” was an engiÂneer, archiÂtect, invenÂtor, artist, and more besides, and five cenÂturies after his death we conÂtinÂue to admire him for not just the works of art and techÂnolÂoÂgy he realÂized durÂing his lifeÂtime, but also the ones that nevÂer made it off his drawÂing board (or out of his noteÂbooks). And as we conÂtinÂue to disÂcovÂer, many of the latÂter weren’t just flights of fanÂcy, but genÂuine innoÂvaÂtions groundÂed in realÂiÂty.
Take the bridge LeonarÂdo proÂposed to SulÂtan Bayezid II, who in 1502 had “sent out the RenaisÂsance equivÂaÂlent of a govÂernÂment RFP (request for proÂposÂals), seekÂing a design for a bridge to conÂnect IstanÂbul with its neighÂbor city GalaÂta,” writes MIT News’ David L. ChanÂdler. WritÂing to the sulÂtan, LeonarÂdo describes his design as “a masonÂry bridge as high as a buildÂing, and even tall ships will be able to sail under it.”
At the time, such bridges required the supÂport of piers all along their spans, which preÂventÂed large ships from passÂing underÂneath. But LeonarÂdo’s design would do the job with only “a sinÂgle enorÂmous arch.” About ten times longer than the typÂiÂcal bridge of the earÂly 16th cenÂtuÂry, it took a page from the bridges of ancient Rome, designed as it was to “stand on its own under the force of gravÂiÂty, withÂout any fasÂtenÂers or morÂtar to hold the stone togethÂer.”

Image via WikiÂmeÂdia ComÂmons
Alas, LeonarÂdo, who had betÂter luck with ItalÂian patrons, didÂn’t win this parÂticÂuÂlar comÂmisÂsion. His bridge design must at least have impressed the sulÂtan with its sheer ambiÂtion, but would it have held up? A team at MIT conÂsistÂing of gradÂuÂate KarÂly Bast, proÂfesÂsor John Ochsendorf, and underÂgradÂuÂate Michelle Xie recentÂly put it to the test, scruÂtiÂnizÂing the mateÂrÂiÂal LeonarÂdo left behind, repliÂcatÂing the geoÂlogÂiÂcal conÂdiÂtions of the proÂposed site, and buildÂing a 1:500 scale modÂel out of 126 3D-printÂed blocks. Not only could the modÂel bear weight using only the strength of its own geomÂeÂtry, the design also came with othÂer feaÂtures, such as staÂbiÂlizÂing abutÂments (which ChanÂdler comÂpares to the legs of “a standÂing subÂway ridÂer widenÂing her stance to balÂance in a swayÂing car”) to keep the bridge upright in that earthÂquake-prone area of modÂern-day Turkey.
That parÂticÂuÂlar locaÂtion didÂn’t get a bridge until 1845, when Valide SulÂtan ordered the conÂstrucÂtion of the first, woodÂen, GalaÂta Bridge. It stood for 18 years until its replaceÂment by anothÂer woodÂen bridge, part of an infraÂstrucÂture-buildÂing push before Napoleon III’s visÂit to IstanÂbul. The third GalaÂta Bridge, comÂpletÂed in 1875 from a design by a British engiÂneerÂing firm, floatÂed on ponÂtoons. The fourth was a GerÂman-designed floatÂing bridge in use from 1912 until a fire damÂaged it in 1992. Only the fifth and curÂrent GalaÂta Bridge, with its tram tracks above, its pedesÂtriÂanÂized deck full of shops and marÂket spaces below, and it drawÂbridge secÂtion in the midÂdle, was built by a TurkÂish comÂpaÂny. In all its iterÂaÂtions, the GalaÂta Bridge has become one of IstanÂbul’s culÂturÂal refÂerÂence points and major attracÂtions as well — not that havÂing been designed by LeonarÂdo would have hurt its image any.
via MIT News/PopÂuÂlar MechanÂics
RelatÂed ConÂtent:
LeonarÂdo da VinÂci Draws Designs of Future War Machines: Tanks, Machine Guns & More
An AniÂmatÂed HisÂtoÂry Of AviÂaÂtion: From LeonarÂdo da Vinci’s SketchÂes to ApolÂlo 11
Based in Seoul, ColÂin MarÂshall writes and broadÂcasts on cities, lanÂguage, and culÂture. His projects include the book The StateÂless City: a Walk through 21st-CenÂtuÂry Los AngeÂles and the video series The City in CinÂeÂma. FolÂlow him on TwitÂter at @colinmarshall or on FaceÂbook.












