Building
da Vinci’s
Forgotten
Bridge
W
HEN SULTAN
Bayezid II of the
Ottoman Empire
requested propos-
als for a bridge
connecting capital
city Constantino-
ple (now Istanbul, Turkey) with
the neighboring city, Galata
(Karaköy, Turkey) at the turn
of the 16th century, famed
inventor Leonardo da Vinci waseager to win the contract.
He didn’t get the job, but more
than 500 years later, a team of
researchers at the Massachusetts
Institute of Technology suggests
that maybe he should have. Karly
Bast, who graduated from MIT in
2019 and is now at Buro Happold
Engineering, worked alongside
structural engineer and MIT
professor John Ochsendorf and
undergraduate Michelle Xie to
analyze Leonardo’s sketches and
letters (pulled from Manuscript
L, a small Codex stored in the
Institut de France in Paris). They
also researched historically accu-
rate materials and construction
methods to prove that Leonar-
do’s unique bridge design would
have held up.
The team created a 1:
scale model of the bridge (mak-
ing it about three feet long),
which the inventor described
in a letter to the Sultan as “a
masonry bridge as high as a
building, [so] even tall ships
will be able to sail under it.”
Leonardo’s concept was for a
f lattened bridge with a long
arch—a radically different
style from anything that had
previously been constructed.
At the time, many bridges fea-
tured a semicircular arch, often
half as tall as the span of the
bridge, instead of a sweeping
parabolic arch.
Leonardo’s bridge would
have spanned roughly 918 feet
(280 meters)—neither measure-
ment had been invented yet, so
he used a unit of measurement
called braccia. It would have
been about 10 times longer than
typical bridges of that period in
order to span the river, Bast says.
Like the classic masonry
bridges of ancient Rome, with ▶A 3D printer
created 126
gypsum powder
blocks.
Splayed
foundation
absorbs lateral
movement of
strong winds.GRETCHENERTL/COURTESYMIT^ (BRIDGE);COURTESYMICHELLEXIE^ (RENDERING)18 May/June 2020Science
// BY DAVID GROSSM A N //6