Epic Engineering: Building the Brooklyn Bridge - Alex Gendler

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In the mid-19th century, suspension bridges were collapsing all across Europe. Their industrial cables frayed and snapped under the weight of their decks. So when German American engineer John Roebling proposed building the largest and most expensive suspension bridge ever conceived, New York City officials were understandably skeptical. Alex Gendler details the building of the iconic Brooklyn Bridge.

Lesson by Alex Gendler, directed by Jeremiah Dickey.

In the mid-19th century,

suspension bridges
were collapsing all across Europe.

Their industrial cables
frayed during turbulent weather

and snapped
under the weight of their decks.

So when a German-American engineer
named John Roebling

proposed building the largest
and most expensive suspension bridge

ever conceived
over New York’s East River,

city officials
were understandably skeptical.

But Manhattan
was increasingly overcrowded,

and commuters from Brooklyn
clogged the river.

In February of 1867, the government
approved Roebling’s proposal.

To avoid the failures
of European bridges,

Roebling designed
a hybrid bridge model.

From suspension bridges,

he incorporated large cables supported by
central pillars and anchored at each bank.

This design was ideal
for supporting long decks,

which hung from smaller vertical cables.

But Roebling’s model
also drew from cable-stayed bridges.

These shorter structures
held up their decks with diagonal cables

that ran directly to support towers.

By adding these additional cables,
Roebling improved the bridge’s stability,

while also reducing the weight
on its anchor cables.

Similar designs had been used
for some other bridges

but the scope of Roebling’s plan here
dwarfed them all.

His new bridge’s deck
spanned over 480 meters—

1.5 times longer than any previously built
suspension bridge.

Since standard hemp rope
would tear under the deck’s 14,680 tons,

his proposal called for
over 5,600 kilometers of metal wire

to create the bridge’s cables.

To support all this weight,

the towers would need to stand
over 90 meters above sea level—

making them the tallest structures
in the Western Hemisphere.

Roebling was confident
his design would work,

but while surveying the site in 1869,

an incoming boat
crushed his foot against the dock.

Within a month,
tetanus had claimed his life.

Fortunately, John Roebling's son,
Washington, was also a trained engineer

and took over his father’s role.

The following year, construction
on the tower foundations finally began.

This first step in construction
was also the most challenging.

Building on the rocky river bed involved
the use of a largely untested technology:

pneumatic caissons.

Workers lowered these airtight
wooden boxes into the river,

where a system of pipes pumped
pressurized air in and water out.

Once established, air locks
allowed workers to enter the chamber

and excavate the river bottom.

They placed layers of stone
on top of the caisson as they dug.

When it finally hit the bedrock,
they filled it with concrete,

becoming the tower’s
permanent foundation.

Working conditions in these caissons
were dismal and dangerous.

Lit only by candles and gas lamps,
the chambers caught fire several times,

forcing them to be evacuated and flooded.

Even more dangerous was
a mysterious ailment called "the bends."

Today, we understand this
as decompression sickness,

but at the time, it appeared to be
an unexplainable pain or dizziness

that killed several workmen.

In 1872, it nearly claimed the life
of the chief engineer.

Washington survived,
but was left paralyzed and bedridden.

Yet once again,
the Roeblings proved indomitable.

Washington’s wife Emily
not only carried communications

between her husband and the engineers,

but soon took over
day-to-day project management.

Unfortunately,
the bridge’s troubles were far from over.

By 1877, construction was over budget
and behind schedule.

Worse still, it turned out
the bridge’s cable contractor

had been selling them faulty wires.

This would have been a fatal flaw
if not for the abundant failsafes

in John Roebling’s design.

After reinforcing the cables
with additional wires,

they suspended the deck
piece by piece.

It took 14 years, the modern equivalent
of over 400 million dollars,

and the life’s work
of three different Roeblings,

but when the Brooklyn Bridge
finally opened on May 24, 1883,

its splendor was undeniable.

Today, the Brooklyn Bridge
still stands atop its antique caissons,

supporting the gothic towers
and intersecting cables

that frame a gateway to New York City.