Epic Engineering: Building the Brooklyn Bridge - Alex Gendler
-
0:07 - 0:09In the mid-19th century,
-
0:09 - 0:13suspension bridges
were collapsing all across Europe. -
0:13 - 0:16Their industrial cables
frayed during turbulent weather -
0:16 - 0:19and snapped
under the weight of their decks. -
0:19 - 0:23So when a German-American engineer
named John Roebling -
0:23 - 0:27proposed building the largest
and most expensive suspension bridge -
0:27 - 0:30ever conceived
over New York’s East River, -
0:30 - 0:33city officials
were understandably skeptical. -
0:33 - 0:35But Manhattan
was increasingly overcrowded, -
0:35 - 0:39and commuters from Brooklyn
clogged the river. -
0:39 - 0:45In February of 1867, the government
approved Roebling’s proposal. -
0:45 - 0:48To avoid the failures
of European bridges, -
0:48 - 0:50Roebling designed
a hybrid bridge model. -
0:50 - 0:52From suspension bridges,
-
0:52 - 0:58he incorporated large cables supported by
central pillars and anchored at each bank. -
0:58 - 1:02This design was ideal
for supporting long decks, -
1:02 - 1:04which hung from smaller vertical cables.
-
1:04 - 1:09But Roebling’s model
also drew from cable-stayed bridges. -
1:09 - 1:13These shorter structures
held up their decks with diagonal cables -
1:13 - 1:15that ran directly to support towers.
-
1:15 - 1:20By adding these additional cables,
Roebling improved the bridge’s stability, -
1:20 - 1:24while also reducing the weight
on its anchor cables. -
1:24 - 1:27Similar designs had been used
for some other bridges -
1:27 - 1:31but the scope of Roebling’s plan here
dwarfed them all. -
1:31 - 1:35His new bridge’s deck
spanned over 480 meters— -
1:35 - 1:401.5 times longer than any previously built
suspension bridge. -
1:40 - 1:46Since standard hemp rope
would tear under the deck’s 14,680 tons, -
1:46 - 1:51his proposal called for
over 5,600 kilometers of metal wire -
1:51 - 1:53to create the bridge’s cables.
-
1:53 - 1:55To support all this weight,
-
1:55 - 1:59the towers would need to stand
over 90 meters above sea level— -
1:59 - 2:04making them the tallest structures
in the Western Hemisphere. -
2:04 - 2:06Roebling was confident
his design would work, -
2:06 - 2:09but while surveying the site in 1869,
-
2:09 - 2:13an incoming boat
crushed his foot against the dock. -
2:13 - 2:18Within a month,
tetanus had claimed his life. -
2:18 - 2:23Fortunately, John Roebling's son,
Washington, was also a trained engineer -
2:23 - 2:26and took over his father’s role.
-
2:26 - 2:31The following year, construction
on the tower foundations finally began. -
2:31 - 2:35This first step in construction
was also the most challenging. -
2:35 - 2:40Building on the rocky river bed involved
the use of a largely untested technology: -
2:40 - 2:42pneumatic caissons.
-
2:42 - 2:46Workers lowered these airtight
wooden boxes into the river, -
2:46 - 2:52where a system of pipes pumped
pressurized air in and water out. -
2:52 - 2:55Once established, air locks
allowed workers to enter the chamber -
2:55 - 2:58and excavate the river bottom.
-
2:58 - 3:02They placed layers of stone
on top of the caisson as they dug. -
3:02 - 3:05When it finally hit the bedrock,
they filled it with concrete, -
3:05 - 3:08becoming the tower’s
permanent foundation. -
3:08 - 3:12Working conditions in these caissons
were dismal and dangerous. -
3:12 - 3:17Lit only by candles and gas lamps,
the chambers caught fire several times, -
3:17 - 3:21forcing them to be evacuated and flooded.
-
3:21 - 3:25Even more dangerous was
a mysterious ailment called "the bends." -
3:25 - 3:28Today, we understand this
as decompression sickness, -
3:28 - 3:33but at the time, it appeared to be
an unexplainable pain or dizziness -
3:33 - 3:35that killed several workmen.
-
3:35 - 3:39In 1872, it nearly claimed the life
of the chief engineer. -
3:39 - 3:44Washington survived,
but was left paralyzed and bedridden. -
3:44 - 3:47Yet once again,
the Roeblings proved indomitable. -
3:47 - 3:51Washington’s wife Emily
not only carried communications -
3:51 - 3:53between her husband and the engineers,
-
3:53 - 3:57but soon took over
day-to-day project management. -
3:57 - 4:01Unfortunately,
the bridge’s troubles were far from over. -
4:01 - 4:05By 1877, construction was over budget
and behind schedule. -
4:05 - 4:09Worse still, it turned out
the bridge’s cable contractor -
4:09 - 4:11had been selling them faulty wires.
-
4:11 - 4:15This would have been a fatal flaw
if not for the abundant failsafes -
4:15 - 4:18in John Roebling’s design.
-
4:18 - 4:21After reinforcing the cables
with additional wires, -
4:21 - 4:25they suspended the deck
piece by piece. -
4:25 - 4:30It took 14 years, the modern equivalent
of over 400 million dollars, -
4:30 - 4:33and the life’s work
of three different Roeblings, -
4:33 - 4:38but when the Brooklyn Bridge
finally opened on May 24, 1883, -
4:38 - 4:41its splendor was undeniable.
-
4:41 - 4:45Today, the Brooklyn Bridge
still stands atop its antique caissons, -
4:45 - 4:48supporting the gothic towers
and intersecting cables -
4:48 - 4:51that frame a gateway to New York City.
- Title:
- Epic Engineering: Building the Brooklyn Bridge - Alex Gendler
- Speaker:
- Alex Gendler
- Description:
-
View full lesson: https://ed.ted.com/lessons/epic-engineering-building-the-brooklyn-bridge-alex-gendler
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.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:52
lauren mcalpine edited English subtitles for Epic Engineering: Building the Brooklyn Bridge | ||
Elise Haadsma approved English subtitles for Epic Engineering: Building the Brooklyn Bridge | ||
Elise Haadsma accepted English subtitles for Epic Engineering: Building the Brooklyn Bridge | ||
lauren mcalpine edited English subtitles for Epic Engineering: Building the Brooklyn Bridge |