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Narrator: the empire state
Building in new york --
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The world's most
Famous skyscraper,
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A spectacular icon
Of american engineering...
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It's amazing what they got done
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With the tools
They had to work with.
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Narrator: ...Upheld by many as
The eighth wonder of the world.
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♪♪
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Today, investigators
Explore the secret history
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That hides behind
Its gleaming facade.
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Why is this skyscraper's mast
Never used
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For its original purpose
As an airship station?
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We're seeing
Very violent motions.
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Narrator: and how does it
Survive the unforeseen impact
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Of an aircraft?
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The forces that are created
By this sort of an impact
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Are immense.
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Narrator:
To solve these mysteries,
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We'll break apart
The empire state building's
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Limestone walls,
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Uncover the
Incredible engineering
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That supports
This super tall skyscraper,
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And reveal the secret stories
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Hidden within
This iconic building.
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♪♪
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--captions by vitac--
Www.Vitac.Com
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Captions paid for by
Discovery communications
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♪♪
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In the heart of manhattan
Stands an american icon --
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The empire state building,
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An engineering wonder
Of the modern world.
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When it opens in 1931,
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It's the tallest building
On the planet,
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A title it holds
For more than 40 years.
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♪♪
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Today, its sky-piercing outline
Is familiar to to billions.
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But there are
Mysteries concealed
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Within this megastructure.
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♪♪
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Its skin is a wall
Of 200,000 cubic feet
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Of limestone and granite blocks
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And more than 6,500 windows.
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♪♪
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Inside, 60,000 tons of steel
Form a rock-solid backbone
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Held together by 100,000 rivets.
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73 elevators speed through
A combined 7 miles of shafts,
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Rising 1,250 feet.
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The empire state building
Is the first skyscraper
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To top 100 stories.
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♪♪
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What does its
Record-breaking height
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Reveal about
Its forgotten history?
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♪♪
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New york engineer don friedman
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Restores and rebuilds some
Of america's oldest structures.
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♪♪
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Friedman:
We're in herald square,
Which is one of the busiest
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And most crowded parts
Of the city,
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And there's
The empire state building
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In front of us at fifth avenue.
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♪♪
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Narrator: don believes
The empire state building's
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Distinctive spire sets it apart
In the city's crowded skyline.
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With that, you go, "Oh.
That's the empire state."
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Narrator: but this mast
Also hides a secret.
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In 1929, the architects
Set out to construct
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A very different building.
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Friedman:
This is an early drawing.
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There's one thing missing here,
Which is the spire,
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Because this drawing was created
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Before the spire
Was added to the building.
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Narrator: the blueprints reveal
That empire state building's
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Elaborate spire
Is a very late addition.
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Engineers shoehorned it
Into the design
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Only after construction starts.
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Why add extra height
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To an already
Record-breaking building?
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♪♪
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In 1950, the steel-and-glass
Spire starts taking shape.
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♪♪
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At the top, on floor 102,
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An observation deck
Offers breathtaking views.
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One floor above
Is a strange balcony,
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With a knee-high wall
As the only barrier
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To a 1,250-foot drop.
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The architects declare that this
Is for giant airships to dock
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And unload passengers directly
Into the empire state building.
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But is this the real reason
For the spire?
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♪♪
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In the early 1930s, docking
And airship with a skyscraper
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Is a radical new idea.
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Airships don't need runways.
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They attach to towers
Or masts using ropes.
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Forward-thinking building
Designers place mooring points
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On the top of their buildings
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In preparation for a future
Of airship-filled skies.
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♪♪
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In 1931, airships try to dock
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At the empire state
Building's spire.
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It's such a jaw-dropping site,
Crowds block the sidewalks
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And the busy streets below.
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One airship clings on
For 3 minutes.
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Another drops a bundle
Of newspapers.
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No passengers disembark,
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And this achievement
Is never replicated.
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Why is this airship
The only one to dock
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At the empire state building?
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Civil engineer
Maarten van reeuwijk
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Thinks he knows the answer.
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He's investigating
The empire state building's
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Forgotten airship port.
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He's recreating the conditions
Faced by the docking airship
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In this wind tunnel
At imperial college london.
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Maarten wants to find out if an
Airship could offload passengers
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At the top of the world's
Tallest building.
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What I have here is a balloon,
Which is filled with helium,
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And this is going to be
A very rough approximation
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To the airship,
And what I'm going to do is,
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I'm going to moor this airship
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On the top of the building
Right here.
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Narrator: first,
The tunnel's fans start up.
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♪♪
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Maarten adds smoke to track
Where the wind goes.
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♪♪
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So here, you can see the flow
As it goes around this airship.
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Narrator: the wind that hits
The top of the building
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Must go somewhere.
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It deflects to
The building's sides,
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But it also goes up.
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You see that this highly
Unsteady flow in the wake
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Causes huge response
From our airship.
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Narrator: the airship
And all its furniture, luggage,
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And passengers would be
Hurled around inside.
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Van reeuwijk: we're seeing very
Violent motions of the airship.
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Full-scale, these would be
Ups and downs of the airship
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Of 10, 20 meters.
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This would be hugely dangerous.
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Narrator:
Mooring an airship to a high
Mast takes considerable skill.
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Even at ground level, it can
Be a treacherous maneuver.
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This is the uss los angeles.
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In 1926, a shift in temperature
At ground level causes warm air
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To flip the airship
Vertically on its moorings.
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Luckily, no one is onboard.
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It's not the greatest of ideas
To try to moor an airship
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On a building like
The empire state building.
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♪♪
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Narrator: tall structures
Like skyscrapers
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Generate strong updrafts of wind
And unpredictable gusts.
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♪♪
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To stop moored airships
From tipping up in the updrafts,
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They need a second tether
To hold their tails in place.
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♪♪
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The tail tether can rotate,
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Allowing the airship to align
With gusting winds.
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But the empire state building
Doesn't have this mechanism.
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Any airship can only moor
For a few minutes
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Or drop a bundle of newspapers
Before moving on.
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♪♪
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Tethered precariously just
To the mast of the skyscraper,
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This is all they can
Safely achieve.
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In 1931, the world's
Top airship captain,
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Germany's hugo eckener,
Visits new york.
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He concludes that any attempt
To drop off passengers
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At the empire state building
Would end in disaster.
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A few years later, the explosion
Of the nazi airship hindenburg
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Underlines the dangers.
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♪♪
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Man: the world's largest
And most luxurious airship,
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The hindenburg,
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Burns in a disaster.[ crowd screaming ]
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This tragedy dramatically ends
A future era of airship travel.
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♪♪
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Narrator: don believes
The real reason for the mast
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Lies with an intense rivalry
That grips the city.
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People were building taller
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And taller buildings
In new york.
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Chrysler building was the
Tallest building in the world
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For about a year.
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By adding the spire onto
The empire state building,
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It went up about
Another 15 stories in height.
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Narrator: the spire allows
The empire state building
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To soar above its rivals,
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And it protects its title
Far into the future.
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Friedman:
Any publicity will help,
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And constructing the tallest
Building in the world
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Is one way to get
A lot of free publicity.
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♪♪
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Narrator:
The plans for an airship station
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Might have been unrealistic,
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But the empire state building is
Still a revolutionary structure.
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For a building to climb 1,200
Feet tall today is astonishing.
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00:10:02,172 --> 00:10:05,620
To reach such heights
90 years ago
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In the middle of the great
Depression is truly incredible.
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How do the empire
State's engineers
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Achieve this seemingly
Impossible feat
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And successfully support the
Massive, 365,000-ton building?
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00:10:29,724 --> 00:10:31,793
Narrator:
The empire state building --
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00:10:31,827 --> 00:10:35,482
The world's most
Iconic skyscraper.
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For 90 years, it's been towering
Over the streets of manhattan.
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It's a true
Skyscraping colossus,
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Weighing in at 365,000 tons.
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Why does this
Stone-and-steel monster
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Not sink into the ground?
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00:10:52,965 --> 00:10:54,206
The empire state building
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Is actually a slender
Stepped pyramid,
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Widening towards the bottom.
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00:10:59,965 --> 00:11:03,344
This ingenious shape spreads
The weight of the tower
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Across more than
80,000 square feet.
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♪♪
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Beneath the surface,
Sturdy steel columns
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Firmly lock into huge foundation
Shafts of solid concrete.
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♪♪
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This base is just
Three stories deep,
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00:11:24,034 --> 00:11:26,931
52 feet,
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00:11:26,965 --> 00:11:29,896
A fraction of the tower's
Total height.
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00:11:29,931 --> 00:11:34,137
How can such shallow foundations
Support such a massive building?
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00:11:34,172 --> 00:11:38,172
♪♪
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00:11:38,206 --> 00:11:40,448
Geotechnical engineer
Andrew klaetsch
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Thinks the secret
Lies deep under new york city.
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00:11:43,724 --> 00:11:46,344
♪♪
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00:11:46,379 --> 00:11:47,724
He's at a construction site
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00:11:47,758 --> 00:11:50,827
For manhattan's newest
Supertall skyscraper.
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00:11:50,862 --> 00:11:55,103
They are excavating right now
To build their foundations.
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00:11:55,137 --> 00:11:58,137
Narrator:
Andrew only has to descend
10 feet below street level
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00:11:58,172 --> 00:12:02,034
To hit the city's bedrock.
225
00:12:02,068 --> 00:12:05,931
And right here is the very
Surface of the bedrock today,
226
00:12:05,965 --> 00:12:09,758
Right below 32nd street.
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00:12:09,793 --> 00:12:11,620
Narrator:
The empire state building
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00:12:11,655 --> 00:12:15,965
Weighs 365,000 tons.
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00:12:16,000 --> 00:12:21,827
Similar skyscrapers in london,
Tokyo, and chicago
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00:12:21,862 --> 00:12:25,689
Have foundations
That are twice as deep,
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00:12:25,724 --> 00:12:29,137
But new york stands
On firmer ground.
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00:12:29,172 --> 00:12:31,620
Well, what you see here
Is this rock
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00:12:31,655 --> 00:12:33,862
That was once buried
At great depth
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00:12:33,896 --> 00:12:36,379
And formed under
Enormous pressure.
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00:12:36,413 --> 00:12:39,827
♪♪
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00:12:39,862 --> 00:12:44,310
Narrator:
This gray rock is called schist.
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00:12:44,344 --> 00:12:46,413
It reflects the light.
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00:12:46,448 --> 00:12:48,517
Klaetsch:
It actually looks like glitter,
239
00:12:48,551 --> 00:12:53,172
And that is the mica minerals
In the manhattan schist.
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00:12:53,206 --> 00:12:56,034
♪♪
241
00:12:56,068 --> 00:13:00,034
Narrator: manhattan schist forms
450 million years ago
242
00:13:00,068 --> 00:13:03,172
When two continental
Plates collide,
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00:13:03,206 --> 00:13:05,413
Pushing up vast mountain ranges.
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00:13:05,448 --> 00:13:07,551
♪♪
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00:13:07,586 --> 00:13:09,103
Over millions of years,
246
00:13:09,137 --> 00:13:11,655
The rocks on the surface
Wear away,
247
00:13:11,689 --> 00:13:15,034
Exposing incredible, strong
Cores of compressed schist
248
00:13:15,068 --> 00:13:17,206
That manhattan stands on today.
249
00:13:17,241 --> 00:13:19,310
♪♪
250
00:13:19,344 --> 00:13:22,931
To find out how strong
This manhattan rock is,
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00:13:22,965 --> 00:13:26,137
Andrew takes a sample
To his lab.
252
00:13:26,172 --> 00:13:28,551
He uses a compression machine
To investigate
253
00:13:28,586 --> 00:13:31,241
How much pressure
This stone can withstand.
254
00:13:31,275 --> 00:13:33,827
♪♪
255
00:13:33,862 --> 00:13:35,241
Much stronger.
256
00:13:35,275 --> 00:13:38,931
Andrew's colleague lysandra
Applies increasing pressure
257
00:13:38,965 --> 00:13:41,862
To this 2-inch-thick
Manhattan schist.
258
00:13:41,896 --> 00:13:44,172
This is the load
As it increases with time,
259
00:13:44,206 --> 00:13:47,482
We're only up to
Just over 40,000 pounds.
260
00:13:47,517 --> 00:13:49,586
The sample
Is holding strong.
261
00:13:49,620 --> 00:13:51,551
Almost 60,000 pounds.
262
00:13:56,172 --> 00:13:58,413
[ boom ]Whoa.
263
00:13:58,448 --> 00:13:59,586
[ laughs ]
264
00:13:59,620 --> 00:14:01,931
That was pretty good,
Pretty explosive.
265
00:14:01,965 --> 00:14:04,758
So you can see, it shattered
Into many pieces.
266
00:14:04,793 --> 00:14:08,896
♪♪
267
00:14:08,931 --> 00:14:10,965
This manhattan schist
Can withstand
268
00:14:11,000 --> 00:14:15,965
A staggering 75,000 pounds
Of pressure per square inch.
269
00:14:16,000 --> 00:14:18,206
That's over 100 times
More pressure
270
00:14:18,241 --> 00:14:22,310
Than is required for a structure
Like the empire state building.
271
00:14:22,344 --> 00:14:24,137
It's exceptionally strong.
272
00:14:24,172 --> 00:14:28,206
It's significantly higher
Than any sort of pressure
273
00:14:28,241 --> 00:14:31,482
That we'd be looking at in terms
Of building foundations.
274
00:14:31,517 --> 00:14:34,758
♪♪
275
00:14:34,793 --> 00:14:38,241
Narrator:
This incredibly tough schist
Means the empire state building
276
00:14:38,275 --> 00:14:42,172
Can be firmly anchored
In just a few feet of bedrock,
277
00:14:42,206 --> 00:14:44,862
But it also presents a problem.
278
00:14:44,896 --> 00:14:47,689
It takes months to excavate
Enough of the tough rock
279
00:14:47,724 --> 00:14:51,172
To anchor just
A shallow foundation.
280
00:14:51,206 --> 00:14:53,379
Construction starts
Almost immediately
281
00:14:53,413 --> 00:14:57,137
After the wall street crash
Of 1929.
282
00:14:57,172 --> 00:15:01,448
Money's tight, and time spent
Digging schist means more cost.
283
00:15:01,482 --> 00:15:03,517
♪♪
284
00:15:03,551 --> 00:15:06,206
Fortunately, the architects find
That someone else
285
00:15:06,241 --> 00:15:08,413
Has already done
The job for them.
286
00:15:08,448 --> 00:15:11,517
♪♪
287
00:15:11,551 --> 00:15:15,137
As builders demolish
The old waldorf astoria hotel
288
00:15:15,172 --> 00:15:17,551
That stands on the chosen site,
289
00:15:17,586 --> 00:15:21,034
They uncover foundations
Already 40 feet deep.
290
00:15:21,068 --> 00:15:23,034
♪♪
291
00:15:23,068 --> 00:15:26,758
So they must only drive
Their piles 15 feet deeper
292
00:15:26,793 --> 00:15:28,689
To securely anchor
The metal skeleton
293
00:15:28,724 --> 00:15:30,413
Of the empire state building.
294
00:15:30,448 --> 00:15:33,413
♪♪
295
00:15:33,448 --> 00:15:36,172
These preexisting foundations
Save dollars
296
00:15:36,206 --> 00:15:38,620
And give the builders
A flying start.
297
00:15:38,655 --> 00:15:40,793
♪♪
298
00:15:40,827 --> 00:15:43,103
Once the construction
Reaches ground level,
299
00:15:43,137 --> 00:15:45,724
The entire structure
Goes from start to finish
300
00:15:45,758 --> 00:15:48,137
In just 7 months.
301
00:15:48,172 --> 00:15:50,517
It's an astonishing achievement.
302
00:15:50,551 --> 00:15:52,379
How is this
Record-breaking structure
303
00:15:52,413 --> 00:15:56,137
Built at such great speed
And why?
304
00:16:07,482 --> 00:16:10,034
Narrator: in 1930,
Construction workers finish
305
00:16:10,068 --> 00:16:12,206
The three-story-deep foundations
306
00:16:12,241 --> 00:16:15,482
Of the new empire
State building.
307
00:16:15,517 --> 00:16:18,000
With a head start
From existing foundations,
308
00:16:18,034 --> 00:16:21,793
It takes them 6 months
To get this far,
309
00:16:21,827 --> 00:16:24,517
But the hard part
Is only just beginning.
310
00:16:24,551 --> 00:16:28,896
They now have to construct
The tallest building in history,
311
00:16:28,931 --> 00:16:32,172
And the longer it takes,
The more money it will cost.
312
00:16:32,206 --> 00:16:34,172
♪♪
313
00:16:34,206 --> 00:16:36,379
The steel frame
Is the key innovation
314
00:16:36,413 --> 00:16:39,034
Of the skyscraper age.
315
00:16:39,068 --> 00:16:41,172
It allows the empire
State building's team
316
00:16:41,206 --> 00:16:44,551
To build
At death-defying heights.
317
00:16:44,586 --> 00:16:46,655
But the breakneck speed
Of the construction
318
00:16:46,689 --> 00:16:49,724
Is due to another miracle
Of modern engineering.
319
00:16:49,758 --> 00:16:54,310
♪♪
320
00:16:54,344 --> 00:16:57,068
"I"-shaped steel beams
Form the skeleton
321
00:16:57,103 --> 00:17:00,275
Of the entire tower.
322
00:17:00,310 --> 00:17:02,862
Thousands of rivets
Bolt them together...
323
00:17:02,896 --> 00:17:07,206
♪♪
324
00:17:07,241 --> 00:17:09,689
...Creating a massive
Three-dimensional frame
325
00:17:09,724 --> 00:17:11,379
Of steel boxes.
326
00:17:11,413 --> 00:17:13,586
♪♪
327
00:17:13,620 --> 00:17:16,275
The builders simply hang
The stone facade
328
00:17:16,310 --> 00:17:18,931
Onto the outside like a curtain.
329
00:17:18,965 --> 00:17:21,896
♪♪
330
00:17:21,931 --> 00:17:23,379
They repeat the same pattern
331
00:17:23,413 --> 00:17:26,517
For floor after floor
After floor.
332
00:17:26,551 --> 00:17:28,758
♪♪
333
00:17:28,793 --> 00:17:31,413
Building nearly a story a day,
334
00:17:31,448 --> 00:17:35,172
They take just 7 months
To reach 1,250 feet.
335
00:17:35,206 --> 00:17:37,482
♪♪
336
00:17:37,517 --> 00:17:38,827
Engineer don friedman
337
00:17:38,862 --> 00:17:41,482
Works with experienced
Metalworker rich bauer
338
00:17:41,517 --> 00:17:44,793
At a steel forge in new jersey
To explore
339
00:17:44,827 --> 00:17:47,724
How the empire state building's
Steel construction kit
340
00:17:47,758 --> 00:17:51,689
Is pieced together
On-site so fast.
341
00:17:51,724 --> 00:17:53,655
Well, right now,
We're heating up the rivet
342
00:17:53,689 --> 00:17:57,241
And making sure
It gets extremely hot.
343
00:17:57,275 --> 00:17:58,931
Narrator:
Rich thinks the humble rivet
344
00:17:58,965 --> 00:18:03,586
Is the real hero
Of the empire state building.
345
00:18:03,620 --> 00:18:05,103
Bauer: once you send it
All the way home
346
00:18:05,137 --> 00:18:06,448
And make the rivet
Completely up,
347
00:18:06,482 --> 00:18:07,758
It's not like a nut or a bolt
348
00:18:07,793 --> 00:18:11,379
That's going to loosen up
Or rattle over time.
349
00:18:11,413 --> 00:18:12,758
Welds could crack.
350
00:18:12,793 --> 00:18:15,689
Rivets, once they cool off,
It contracts.
351
00:18:15,724 --> 00:18:18,068
It makes sure that joint
Is completely tight.
352
00:18:18,103 --> 00:18:21,758
♪♪
353
00:18:21,793 --> 00:18:25,482
You want a nice,
Consistent orange.
354
00:18:25,517 --> 00:18:28,758
Narrator: the rivet comes out
Of the furnace red-hot,
355
00:18:28,793 --> 00:18:30,586
But it takes just seconds
For the metal
356
00:18:30,620 --> 00:18:33,344
To become too cool to work.
357
00:18:33,379 --> 00:18:35,172
Bauer:
I couldn't set this rivet now.
358
00:18:35,206 --> 00:18:36,448
We'd have to throw
That rivet out
359
00:18:36,482 --> 00:18:38,586
And start it over
And try another rivet.
360
00:18:38,620 --> 00:18:40,241
Narrator: from the furnace
In the workshop,
361
00:18:40,275 --> 00:18:43,137
It takes three people
To set a single, red-hot rivet
362
00:18:43,172 --> 00:18:45,827
Before it cools.
363
00:18:45,862 --> 00:18:47,758
The construction of
The empire state building
364
00:18:47,793 --> 00:18:52,275
Requires an astonishing level
Of coordination and teamwork.
365
00:18:52,310 --> 00:18:55,758
It's the first time don has seen
This process in action.
366
00:18:55,793 --> 00:18:58,758
Friedman:
I've read about it, but it's
Something else seeing it.
367
00:18:58,793 --> 00:19:01,137
Installing rivets
Requires a team of people
368
00:19:01,172 --> 00:19:03,172
Working together very closely
369
00:19:03,206 --> 00:19:04,517
To make sure
That everything happens
370
00:19:04,551 --> 00:19:07,448
Before the rivets cool off.
371
00:19:07,482 --> 00:19:10,068
Narrator: this fast cooling
Poses a huge challenge
372
00:19:10,103 --> 00:19:13,517
To workers at the empire
State building.
373
00:19:13,551 --> 00:19:15,620
They need more than
100,000 rivets
374
00:19:15,655 --> 00:19:18,655
To hold the steel
Girders together.
375
00:19:18,689 --> 00:19:23,206
To heat the rivets, engineers
Build furnaces on each floor,
376
00:19:23,241 --> 00:19:28,172
But still, the raw-steel beams
Can be more than 35 feet away.
377
00:19:28,206 --> 00:19:31,275
Incredibly, workers
Throw the rivets.
378
00:19:31,310 --> 00:19:34,206
♪♪
379
00:19:34,241 --> 00:19:36,517
They were trying
To throw these rivets
380
00:19:36,551 --> 00:19:39,586
10, 15, 20, 30 feet
Up in the air,
381
00:19:39,620 --> 00:19:40,862
And they had to make sure
They do this
382
00:19:40,896 --> 00:19:43,724
All before it cooled off.
383
00:19:43,758 --> 00:19:46,448
Narrator: throwing hot rivets
Solves a problem,
384
00:19:46,482 --> 00:19:49,482
But it's very dangerous.
385
00:19:49,517 --> 00:19:51,862
It took enough skill to do this,
And you think about doing it
386
00:19:51,896 --> 00:19:54,827
In the circumstances of actually
Building a high-rise building,
387
00:19:54,862 --> 00:19:57,344
And it's just incredible.
388
00:19:57,379 --> 00:20:00,620
Narrator:
Hot riveting is key to
The strong and fast construction
389
00:20:00,655 --> 00:20:03,344
Of the empire state building.
390
00:20:03,379 --> 00:20:06,275
It is built like
Prefabricated furniture,
391
00:20:06,310 --> 00:20:09,379
A 60,000-ton made-to-order
Metal framework
392
00:20:09,413 --> 00:20:12,206
Assembled simply on-site.
393
00:20:12,241 --> 00:20:14,931
And as soon as this
Basic framework is complete,
394
00:20:14,965 --> 00:20:17,275
Other teams
Can finish each floor.
395
00:20:17,310 --> 00:20:21,034
♪♪
396
00:20:21,068 --> 00:20:25,137
Workers fill temporary
Wooden floors with concrete
397
00:20:25,172 --> 00:20:27,655
And reinforce them
With wire mesh.
398
00:20:27,689 --> 00:20:31,689
♪♪
399
00:20:31,724 --> 00:20:36,482
As soon as the floor is set,
They lay down railway tracks
400
00:20:36,517 --> 00:20:40,206
To move materials quickly from
Elevators to the outer edges.
401
00:20:40,241 --> 00:20:43,413
♪♪
402
00:20:43,448 --> 00:20:46,068
Other teams construct
Makeshift cafeterias
403
00:20:46,103 --> 00:20:47,793
On the uppermost floors
404
00:20:47,827 --> 00:20:51,068
So builders don't waste time
Going to the bottom to eat.
405
00:20:51,103 --> 00:20:53,344
♪♪
406
00:20:53,379 --> 00:20:56,862
Finally, workers at the top
Simply hang the external walls
407
00:20:56,896 --> 00:20:59,689
On the steel skeleton.
408
00:20:59,724 --> 00:21:04,827
The building soars
At a lightning-quick pace.
409
00:21:04,862 --> 00:21:07,862
The empire state building
Takes less than 14 months
410
00:21:07,896 --> 00:21:11,655
To build, completing in 1931.
411
00:21:11,689 --> 00:21:13,344
President hoover
Turns the lights on
412
00:21:13,379 --> 00:21:16,275
From the white house
In a spectacular ceremony.
413
00:21:16,310 --> 00:21:19,172
♪♪
414
00:21:19,206 --> 00:21:22,758
But by building higher
Than anyone else in history,
415
00:21:22,793 --> 00:21:26,517
The architects face
A new problem --
416
00:21:26,551 --> 00:21:28,586
Hurricanes.
417
00:21:28,620 --> 00:21:31,034
The empire state building
Will soon be tested
418
00:21:31,068 --> 00:21:34,448
By one of the mother nature's
Most destructive forces.
419
00:21:44,896 --> 00:21:47,310
Narrator: new york's iconic
Empire state building
420
00:21:47,344 --> 00:21:49,448
Towers over manhattan,
421
00:21:49,482 --> 00:21:53,103
Just as it has for 90 years.
422
00:21:53,137 --> 00:21:56,344
These 103 stories of glass,
Stone, and steel
423
00:21:56,379 --> 00:22:01,689
Face an invisible
And unpredictable threat --
424
00:22:01,724 --> 00:22:04,034
Hurricane-force winds.
425
00:22:04,068 --> 00:22:07,379
♪♪
426
00:22:07,413 --> 00:22:09,206
Research scientist mark arend
427
00:22:09,241 --> 00:22:11,206
Tracks the wind speeds
Over manhattan
428
00:22:11,241 --> 00:22:15,551
From the city college
Of new york's weather station.
429
00:22:15,586 --> 00:22:18,103
Arend: so, we're on top
Of a tall building,
430
00:22:18,137 --> 00:22:21,862
About 5 miles from
The empire state building
431
00:22:21,896 --> 00:22:24,551
And midtown manhattan.
432
00:22:24,586 --> 00:22:26,931
Narrator: his research
Investigates the wind patterns
433
00:22:26,965 --> 00:22:28,620
Flowing across the city.
434
00:22:28,655 --> 00:22:30,586
♪♪
435
00:22:30,620 --> 00:22:33,724
Manhattan, perched
By the atlantic coast,
436
00:22:33,758 --> 00:22:37,724
Is exposed to nature's worst.
437
00:22:37,758 --> 00:22:39,379
Arend: there have been
A number of hurricanes
438
00:22:39,413 --> 00:22:42,379
That have actually hit manhattan
439
00:22:42,413 --> 00:22:44,586
And caused a lot of damage.
440
00:22:44,620 --> 00:22:49,068
♪♪
441
00:22:49,103 --> 00:22:50,896
Narrator: the top of
The empire state building
442
00:22:50,931 --> 00:22:55,931
Faces a battering ram
Of pressure from all directions.
443
00:22:55,965 --> 00:22:58,482
To understand
The threat it faces,
444
00:22:58,517 --> 00:23:04,000
Mark analyzes measurements
Recorded over the last 10 years.
445
00:23:04,034 --> 00:23:07,206
We've taken data
From various weather stations
446
00:23:07,241 --> 00:23:12,034
That are located on the ground
In the new york city metro area.
447
00:23:12,068 --> 00:23:15,586
Up here in central park,
89 miles per hour.
448
00:23:15,620 --> 00:23:19,103
It was a maximum
3-second wind gust.
449
00:23:19,137 --> 00:23:20,758
Down here in
Midtown manhattan --
450
00:23:20,793 --> 00:23:24,137
41 miles per hour.
451
00:23:24,172 --> 00:23:28,310
Narrator:
But powerful gusts of wind
Are only part of the problem.
452
00:23:28,344 --> 00:23:30,137
In midtown manhattan,
453
00:23:30,172 --> 00:23:34,689
The huge concentration
Of tall buildings disrupts wind.
454
00:23:34,724 --> 00:23:39,103
Avenues of skyscrapers
Act like vast wind tunnels,
455
00:23:39,137 --> 00:23:43,586
Funneling and amplifying
The wind to dangerous speeds.
456
00:23:43,620 --> 00:23:46,034
You have very tall buildings.
457
00:23:46,068 --> 00:23:47,655
That creates a lot of turbulence
458
00:23:47,689 --> 00:23:52,103
And makes the wind
Very difficult to measure.
459
00:23:52,137 --> 00:23:53,793
Narrator: how does
The empire state building
460
00:23:53,827 --> 00:23:58,241
Stay upright in these
Phenomenal wind conditions?
461
00:23:58,275 --> 00:24:02,827
The force of the wind pushing
Onto the facade can be immense,
462
00:24:02,862 --> 00:24:05,551
But the rigid stone
Stays firm.
463
00:24:05,586 --> 00:24:08,655
It channels
The wind energy inside
464
00:24:08,689 --> 00:24:12,034
To the steel frame within.
465
00:24:12,068 --> 00:24:13,655
At its heart is a backbone
466
00:24:13,689 --> 00:24:16,965
Reinforced with diagonal
Steel cross braces.
467
00:24:17,000 --> 00:24:22,172
♪♪
468
00:24:22,206 --> 00:24:25,379
They're encased
In solid concrete
469
00:24:25,413 --> 00:24:30,344
That is not only strong
But incredibly stiff.
470
00:24:30,379 --> 00:24:34,931
Together, the steel and concrete
Form a rock-solid core,
471
00:24:34,965 --> 00:24:39,413
But can this 1930s technology
Stop the tower swaying violently
472
00:24:39,448 --> 00:24:42,103
In today's
Hurricane-force winds?
473
00:24:42,137 --> 00:24:44,034
♪♪
474
00:24:44,068 --> 00:24:46,655
Don friedman examines
How new york's skyscrapers
475
00:24:46,689 --> 00:24:50,551
Behave in extreme conditions.
476
00:24:50,586 --> 00:24:53,206
Friedman:
There are actually buildings
Pretty much all over the place
477
00:24:53,241 --> 00:24:57,896
That are famous for being
A little too limber in the wind.
478
00:24:57,931 --> 00:25:00,172
Narrator: a badly designed
Skyscraper will result
479
00:25:00,206 --> 00:25:03,517
In disastrous damage
And collapse.
480
00:25:03,551 --> 00:25:05,034
Don and his colleague shaquana
481
00:25:05,068 --> 00:25:08,620
Model the empire state
Building's inner steel skeleton.
482
00:25:08,655 --> 00:25:11,068
Okay. So, let's take a look
At this model.
483
00:25:11,103 --> 00:25:14,827
So we did a comparison of
A moving frame of a building.
484
00:25:14,862 --> 00:25:16,896
One is without
Any cross bracing.
485
00:25:16,931 --> 00:25:19,551
Narrator:
As the wind speed increases,
486
00:25:19,586 --> 00:25:22,068
The model building
Starts to move.
487
00:25:22,103 --> 00:25:26,896
Over here on this screen,
We have the cross bracing,
488
00:25:26,931 --> 00:25:28,793
Which you can see
Is a drastic difference
489
00:25:28,827 --> 00:25:32,068
In how the building
Behaves altogether.
490
00:25:32,103 --> 00:25:35,793
Wind clearly affects the two
Frames in different ways.
491
00:25:35,827 --> 00:25:37,310
Friedman:
What the simple models show
492
00:25:37,344 --> 00:25:39,068
Is that the addition
Of cross bracing
493
00:25:39,103 --> 00:25:42,310
Reduces the side sway
Under wind load
494
00:25:42,344 --> 00:25:45,482
To about 1/8
Of what it previously was.
495
00:25:45,517 --> 00:25:49,689
And people notice
When buildings move too much.
496
00:25:49,724 --> 00:25:53,206
Narrator: cross bracing gives
Stability to simple structures
497
00:25:53,241 --> 00:25:56,000
And supertall skyscrapers.
498
00:25:56,034 --> 00:25:59,517
It reduces any sideways
Movement dramatically.
499
00:25:59,551 --> 00:26:01,724
This simple
But effective engineering
500
00:26:01,758 --> 00:26:03,965
Solves a potentially
Catastrophic problem
501
00:26:04,000 --> 00:26:06,241
For the empire state building.
502
00:26:06,275 --> 00:26:08,448
The old buildings
Were very well-designed,
503
00:26:08,482 --> 00:26:11,034
Even with the more
Primitive tools.
504
00:26:11,068 --> 00:26:14,241
Narrator: with access
To today's computer models,
505
00:26:14,275 --> 00:26:16,172
The building's engineers
Might have found
506
00:26:16,206 --> 00:26:18,103
A very different solution.
507
00:26:18,137 --> 00:26:20,965
♪♪
508
00:26:21,000 --> 00:26:23,379
As wind rushes around
A skyscraper,
509
00:26:23,413 --> 00:26:27,965
It creates swirling eddies that
Push the tower side to side,
510
00:26:28,000 --> 00:26:31,931
Making it sway dangerously.
511
00:26:31,965 --> 00:26:34,000
So modern, supertall skyscrapers
512
00:26:34,034 --> 00:26:37,827
Are designed
With ingenious profiles
513
00:26:37,862 --> 00:26:40,620
That disrupt the wind
And stop the sway.
514
00:26:40,655 --> 00:26:43,068
♪♪
515
00:26:43,103 --> 00:26:44,413
Some buildings,
516
00:26:44,448 --> 00:26:48,103
Like the super skinny
Park avenue tower in new york,
517
00:26:48,137 --> 00:26:51,344
Have holes to simply
Let the wind pass through.
518
00:26:51,379 --> 00:26:54,068
♪♪
519
00:26:54,103 --> 00:26:57,517
Other have mass dampers inside,
520
00:26:57,551 --> 00:27:00,551
Huge traveling weights that
Counteract the swaying force
521
00:27:00,586 --> 00:27:02,413
And keep the building steady.
522
00:27:02,448 --> 00:27:05,000
♪♪
523
00:27:05,034 --> 00:27:07,655
The empire state building
Is a textbook example
524
00:27:07,689 --> 00:27:09,965
Of solid engineering,
525
00:27:10,000 --> 00:27:14,172
Built to withstand everything
That nature can throw at it.
526
00:27:14,206 --> 00:27:18,965
But in 1945, a totally
Unexpected force strikes it,
527
00:27:19,000 --> 00:27:21,655
One engineers couldn't foresee.
528
00:27:32,172 --> 00:27:34,862
Narrator: on july 28, 1945,
529
00:27:34,896 --> 00:27:39,103
Disaster strikes
The empire state building.
530
00:27:39,137 --> 00:27:42,827
A b-25 bomber
With three crewmen onboard
531
00:27:42,862 --> 00:27:44,620
Is on a routine transport flight
532
00:27:44,655 --> 00:27:48,586
From an army base
In massachusetts.
533
00:27:48,620 --> 00:27:50,310
It's flying over manhattan,
534
00:27:50,344 --> 00:27:53,724
Headed for newark airport
Just across the city.
535
00:27:53,758 --> 00:27:56,103
The weather is relatively bad.
The visibility is poor.
536
00:27:56,137 --> 00:27:58,655
There's fog across manhattan.
537
00:27:58,689 --> 00:28:02,758
Narrator: what happens next
Has no warning.
538
00:28:02,793 --> 00:28:05,068
Traveling at over
200 miles an hour,
539
00:28:05,103 --> 00:28:08,206
The bomber flies straight
At the empire state building.
540
00:28:08,241 --> 00:28:12,724
♪♪
541
00:28:12,758 --> 00:28:15,551
It tears
A 250-foot-square-foot hole
542
00:28:15,586 --> 00:28:18,206
In the 79th floor,
543
00:28:18,241 --> 00:28:21,310
Carving a path of destruction,
544
00:28:21,344 --> 00:28:23,275
Starting fires,
545
00:28:23,310 --> 00:28:26,896
And snapping elevator cables.
546
00:28:26,931 --> 00:28:30,793
One engine rips through
The entire building
547
00:28:30,827 --> 00:28:33,068
And breaks through
The opposite wall.
548
00:28:33,103 --> 00:28:35,241
♪♪
549
00:28:35,275 --> 00:28:38,000
The other engine tumbles down
An elevator shaft,
550
00:28:38,034 --> 00:28:42,034
Falling 1,000 feet
To the subbasement.
551
00:28:42,068 --> 00:28:43,758
How does the empire
State building
552
00:28:43,793 --> 00:28:48,310
Survive this
Catastrophic accident?
553
00:28:48,344 --> 00:28:49,827
Engineer adrian bruegger
554
00:28:49,862 --> 00:28:53,482
Explores this
Engineering mystery.
555
00:28:53,517 --> 00:28:56,827
Bruegger: the bomber pierces
Through the facade.
556
00:28:56,862 --> 00:28:58,448
It's an immense impact,
557
00:28:58,482 --> 00:29:01,482
Like getting punched
By a sledgehammer.
558
00:29:01,517 --> 00:29:03,586
♪♪
559
00:29:03,620 --> 00:29:08,206
Narrator: the b-25 mitchell
Bomber is a formidable machine.
560
00:29:08,241 --> 00:29:12,793
It weighs up to 35,000 pounds
561
00:29:12,827 --> 00:29:17,689
And flies at nearly
300 miles per hour.
562
00:29:17,724 --> 00:29:19,000
It strikes the north wall
563
00:29:19,034 --> 00:29:22,241
With an immense
Amount of energy.
564
00:29:22,275 --> 00:29:27,206
How is it that people inside the
Building survive this disaster?
565
00:29:27,241 --> 00:29:31,275
Steel beams make up the skeleton
Of the empire state building.
566
00:29:31,310 --> 00:29:34,965
Adrian wants to test what force
Of impact they can withstand.
567
00:29:35,000 --> 00:29:37,517
♪♪
568
00:29:37,551 --> 00:29:39,206
Bruegger:
What you see here is a beam
569
00:29:39,241 --> 00:29:42,000
Like you would find
In the floor joists
570
00:29:42,034 --> 00:29:45,103
Or the floor beams
Of the empire state building,
571
00:29:45,137 --> 00:29:47,103
And it would hold up the floors.
572
00:29:47,137 --> 00:29:49,448
What we will see is
How much ductility,
573
00:29:49,482 --> 00:29:51,241
How much ability this steel has
574
00:29:51,275 --> 00:29:54,000
To actually deform
Before it breaks.
575
00:29:54,034 --> 00:29:57,517
Narrator: adrian applies 3 tons
Of force to the steel beam.
576
00:29:57,551 --> 00:30:01,827
♪♪
577
00:30:01,862 --> 00:30:04,034
Bruegger: so now we are
Pushing on the beam still,
578
00:30:04,068 --> 00:30:08,206
And you can see that
It's deflecting very heavily.
579
00:30:08,241 --> 00:30:10,862
[ metal creaks ]
580
00:30:10,896 --> 00:30:13,551
Something moved a little?
581
00:30:13,586 --> 00:30:15,965
But we're okay.
We can keep going.
582
00:30:16,000 --> 00:30:19,793
Narrator: as adrian increases
The weight load to 3.9 tons,
583
00:30:19,827 --> 00:30:23,551
The steel beam
Is still holding strong.
584
00:30:23,586 --> 00:30:25,862
Bruegger: so you can see,
This is absolutely amazing.
585
00:30:25,896 --> 00:30:29,206
The beam is completely
Deformed in the middle,
586
00:30:29,241 --> 00:30:32,586
But it's still holding almost
4 tons of spring energy.
587
00:30:32,620 --> 00:30:33,758
It looks like it failed,
588
00:30:33,793 --> 00:30:37,206
But it's actually
Still doing its work.
589
00:30:37,241 --> 00:30:40,310
Narrator: this steel has
An incredible ductility.
590
00:30:40,344 --> 00:30:43,862
It can bend in half
Before it snaps.
591
00:30:43,896 --> 00:30:47,689
A photo of the impact
The b-25 makes on the building
592
00:30:47,724 --> 00:30:50,482
Proves the incredible strength
Of the beams.
593
00:30:50,517 --> 00:30:52,517
♪♪
594
00:30:52,551 --> 00:30:54,931
Bruegger:
Here, you can see these beams
595
00:30:54,965 --> 00:30:56,896
Look very much like
What we have here.
596
00:30:56,931 --> 00:30:57,965
They're mangled.
597
00:30:58,000 --> 00:30:59,655
They're twisted,
But they're not broken,
598
00:30:59,689 --> 00:31:01,448
And that's important.
They're not fractured,
599
00:31:01,482 --> 00:31:04,344
So they stayed in place,
And that's key.
600
00:31:04,379 --> 00:31:08,379
Narrator: the steel beams
Are bent, not broken.
601
00:31:08,413 --> 00:31:10,482
The structure survives
The main force
602
00:31:10,517 --> 00:31:14,103
Of the initial impact.
603
00:31:14,137 --> 00:31:16,172
Many escape.
604
00:31:16,206 --> 00:31:20,689
Others are rescued
By first responders.
605
00:31:20,724 --> 00:31:23,655
14 people die
In the tragic accident.
606
00:31:23,689 --> 00:31:27,137
[ indistinct conversations ]
607
00:31:27,172 --> 00:31:30,620
But there is a miraculous
Survival story.
608
00:31:30,655 --> 00:31:34,275
Astonishingly, the structure
Saves someone's life.
609
00:31:34,310 --> 00:31:36,241
♪♪
610
00:31:36,275 --> 00:31:37,517
[ elevator bell dings ]
611
00:31:37,551 --> 00:31:42,172
20-year-old betty lou oliver
Is an elevator operator.
612
00:31:42,206 --> 00:31:44,310
She's blasted
Out of her elevator car
613
00:31:44,344 --> 00:31:48,482
On the 80th floor
When the plane hits.
614
00:31:48,517 --> 00:31:52,655
Onlookers hurry her into another
Car to get her to safety.
615
00:31:52,689 --> 00:31:56,482
But as the doors close,
The cable snaps,
616
00:31:56,517 --> 00:31:59,482
And the car instantly drops.
617
00:31:59,517 --> 00:32:01,896
As betty lou's car
Picks up speed,
618
00:32:01,931 --> 00:32:04,827
The emergency brakes fail.
619
00:32:04,862 --> 00:32:07,172
But trapped air
Compresses in the shaft,
620
00:32:07,206 --> 00:32:09,620
Slowing her fall.
621
00:32:09,655 --> 00:32:11,000
And at the bottom,
622
00:32:11,034 --> 00:32:15,517
The severed cable forms a coil
That cushions the impact.
623
00:32:15,551 --> 00:32:17,896
Miraculously, betty lou survives
624
00:32:17,931 --> 00:32:21,827
Falling 1,000 feet.
625
00:32:21,862 --> 00:32:25,689
The empire state building
Survives the plane crash, too.
626
00:32:25,724 --> 00:32:29,344
But the moment of impact causes
Another potential lethal risk
627
00:32:29,379 --> 00:32:33,482
To the structure
And life inside.
628
00:32:33,517 --> 00:32:38,103
The plane's fuel
Ignites disastrously.
629
00:32:38,137 --> 00:32:41,137
Man:
These exclusive motion pictures
Show the empire state building
630
00:32:41,172 --> 00:32:43,724
Burning like
A great smoky torch
631
00:32:43,758 --> 00:32:46,310
With flames bursting
From the windows.
632
00:32:46,344 --> 00:32:48,344
♪♪
633
00:32:48,379 --> 00:32:52,689
Narrator: fire and skyscrapers
Can be a deadly combination,
634
00:32:52,724 --> 00:32:54,620
But how does
The building survive?
635
00:32:54,655 --> 00:32:57,482
♪♪
636
00:32:57,517 --> 00:33:00,517
Adrian wants to find out
How the empire state building's
637
00:33:00,551 --> 00:33:04,379
Steel skeleton stands up
To the flames and intense heat
638
00:33:04,413 --> 00:33:06,000
To save the people inside.
639
00:33:06,034 --> 00:33:07,241
It's quite sharp.
640
00:33:07,275 --> 00:33:10,758
Thanks.
641
00:33:10,793 --> 00:33:12,896
Bruegger: what we are doing here
Is a good simulation
642
00:33:12,931 --> 00:33:14,620
Of what you would expect
To happen
643
00:33:14,655 --> 00:33:18,310
In, for example, a hydrocarbon
Fire due to an airplane crash.
644
00:33:18,344 --> 00:33:20,620
♪♪
645
00:33:20,655 --> 00:33:23,689
Narrator: he heats the steel
To find its breaking point.
646
00:33:23,724 --> 00:33:26,068
♪♪
647
00:33:26,103 --> 00:33:27,517
Bruegger: go. Go more.
648
00:33:27,551 --> 00:33:30,034
[ gas hissing ]
649
00:33:30,068 --> 00:33:32,241
There you go. That's it.
650
00:33:32,275 --> 00:33:33,862
Narrator:
As the steel is heated,
651
00:33:33,896 --> 00:33:37,689
A machine pulls from both ends
With increasing force.
652
00:33:37,724 --> 00:33:42,344
Steel melts
At 2,500 degrees fahrenheit,
653
00:33:42,379 --> 00:33:44,103
But just a fraction
Of that temperature
654
00:33:44,137 --> 00:33:46,689
Is enough to seriously
Weaken the metal.
655
00:33:46,724 --> 00:33:48,689
♪♪
656
00:33:48,724 --> 00:33:51,551
[ steel snaps ]
657
00:33:51,586 --> 00:33:54,689
Bruegger: there it is.
658
00:33:54,724 --> 00:34:01,689
It's actually about
420 degrees celsius.
659
00:34:01,724 --> 00:34:03,551
Narrator: the fire from
The exploding bomber
660
00:34:03,586 --> 00:34:07,758
Will quickly rage
To double this temperature.
661
00:34:07,793 --> 00:34:10,758
The integrity of the empire
State building's steel skeleton
662
00:34:10,793 --> 00:34:14,310
Will easily fail
With the heat of a fire.
663
00:34:14,344 --> 00:34:17,862
It's vital the flames are put
Out before the skeleton fails
664
00:34:17,896 --> 00:34:21,241
And the building crashes.
665
00:34:21,275 --> 00:34:23,310
Bruegger:
Fire does weaken the steel.
666
00:34:23,344 --> 00:34:25,965
This is the achilles'
Heel of steel.
667
00:34:26,000 --> 00:34:28,310
♪♪
668
00:34:28,344 --> 00:34:30,655
Narrator: the empire state
Building's designers know
669
00:34:30,689 --> 00:34:34,689
That fire could bring
An entire skyscraper down,
670
00:34:34,724 --> 00:34:38,034
So they build in
A hidden safety feature --
671
00:34:38,068 --> 00:34:40,275
Standpipes.
672
00:34:40,310 --> 00:34:42,724
These rigid vertical pipes
Move water
673
00:34:42,758 --> 00:34:47,034
To the top of very tall
Buildings at great speed.
674
00:34:47,068 --> 00:34:51,827
A standpipe acts like
A fire hydrant at height.
675
00:34:51,862 --> 00:34:53,896
Pernal: it provides water
To the firefighters,
676
00:34:53,931 --> 00:34:55,896
Who can hook up their hoses
In the stairwell
677
00:34:55,931 --> 00:34:59,482
And fight the fires
Out on the floors.
678
00:34:59,517 --> 00:35:02,724
Narrator: fire safety officer
Matt pernal checks standpipes
679
00:35:02,758 --> 00:35:06,310
In new york's
Tallest skyscrapers.
680
00:35:06,344 --> 00:35:08,655
The empire state building's
Standpipe system
681
00:35:08,689 --> 00:35:13,172
Consists of an impressive
7,340 feet of pipe
682
00:35:13,206 --> 00:35:15,310
And 6 miles of hose.
683
00:35:15,344 --> 00:35:18,586
♪♪
684
00:35:18,620 --> 00:35:20,862
All right, jose.
We're set up down here.
685
00:35:20,896 --> 00:35:23,517
I'm going to go ahead
And get the churn test started.
686
00:35:23,551 --> 00:35:32,655
♪♪
687
00:35:32,689 --> 00:35:35,689
We were able to reach
The 500 gallons per minute.
688
00:35:35,724 --> 00:35:38,655
The pump is putting out
Enough flow and pressure
689
00:35:38,689 --> 00:35:40,965
In order to reach
The roof level,
690
00:35:41,000 --> 00:35:43,827
And that will help the
Firefighters put out the fire.
691
00:35:43,862 --> 00:35:48,620
♪♪
692
00:35:48,655 --> 00:35:52,758
Narrator: in 1945, fire crews
Use the same standpipe system
693
00:35:52,793 --> 00:35:57,827
To quickly extinguish the blaze
In the empire state building.
694
00:35:57,862 --> 00:36:01,344
The flames are out
Within 40 minutes,
695
00:36:01,379 --> 00:36:05,551
Saving the metal from
Lethal structural damage
696
00:36:05,586 --> 00:36:07,551
And allowing it to reopen
For business
697
00:36:07,586 --> 00:36:09,689
Just two days after the crash,
698
00:36:09,724 --> 00:36:13,310
With tens of thousands of people
Returning to work inside.
699
00:36:13,344 --> 00:36:15,551
♪♪
700
00:36:15,586 --> 00:36:18,137
The empire state building's
Colossal structure
701
00:36:18,172 --> 00:36:22,068
Can absorb the impact
Of a world war ii bomber.
702
00:36:22,103 --> 00:36:26,068
It can also survive
Hurricane-force winds.
703
00:36:26,103 --> 00:36:30,000
How does its gleaming facade
Stand up to the test of time?
704
00:36:38,724 --> 00:36:41,827
Narrator: new york's empire
State building is such an icon,
705
00:36:41,862 --> 00:36:45,310
It's been called
An eighth wonder of the world.
706
00:36:45,344 --> 00:36:50,586
Its gleaming facade is built
From an extraordinary material.
707
00:36:50,620 --> 00:36:53,931
At the time of construction,
Many skyscrapers are coated
708
00:36:53,965 --> 00:36:58,724
In a layer of brick
And ceramic terra-cotta.
709
00:36:58,758 --> 00:37:01,862
The empire state building
Is covered in limestone,
710
00:37:01,896 --> 00:37:04,827
The same stone
As ancient wonders --
711
00:37:04,862 --> 00:37:08,000
The 4,500-year-old
Egyptian pyramids...
712
00:37:08,034 --> 00:37:10,000
♪♪
713
00:37:10,034 --> 00:37:14,448
...And the 2,000-year-old
Roman colosseum.
714
00:37:14,482 --> 00:37:18,862
But what is the secret
To its gleaming facade?
715
00:37:18,896 --> 00:37:22,103
Geologist polly sturgeon
Traces the stone to its source
716
00:37:22,137 --> 00:37:26,275
To explore why
Architects choose it.
717
00:37:26,310 --> 00:37:31,206
This is the empire quarry
In indiana.
718
00:37:31,241 --> 00:37:34,517
In the 1920s, they were pulling
Several hundred million tons
719
00:37:34,551 --> 00:37:37,896
Of limestone out
Of this small stretch of land.
720
00:37:37,931 --> 00:37:41,275
Narrator:
The limestone used to cover the
Empire state building's facade
721
00:37:41,310 --> 00:37:45,310
Can only be found in this
Small area of the united states.
722
00:37:45,344 --> 00:37:47,482
Sturgeon: it's right in the
Heart of the indiana stone belt,
723
00:37:47,517 --> 00:37:49,655
This narrow 30-mile
Stretch of land,
724
00:37:49,689 --> 00:37:51,620
Which has produced up to 75%
725
00:37:51,655 --> 00:37:54,137
Of all limestone buildings
In north america.
726
00:37:54,172 --> 00:37:56,310
♪♪
727
00:37:56,344 --> 00:37:58,000
Narrator:
The indiana limestone is used
728
00:37:58,034 --> 00:38:01,517
In many of the country's
Most important buildings,
729
00:38:01,551 --> 00:38:03,965
Like the pentagon
730
00:38:04,000 --> 00:38:06,620
And the lincoln memorial.
731
00:38:06,655 --> 00:38:08,793
What makes it so sought-after?
732
00:38:08,827 --> 00:38:10,931
♪♪
733
00:38:10,965 --> 00:38:13,827
Polly compares stone cores
Taken from test sites
734
00:38:13,862 --> 00:38:17,172
Across the indiana
Limestone belt.
735
00:38:17,206 --> 00:38:19,241
Sturgeon: so, this is
The indiana limestone.
736
00:38:19,275 --> 00:38:22,724
You can see it's a nice,
Even color and texture.
737
00:38:22,758 --> 00:38:25,793
Narrator: layers of tiny crushed
Prehistoric sea creatures
738
00:38:25,827 --> 00:38:27,896
Make up the limestone.
739
00:38:27,931 --> 00:38:30,758
They give the rock
Its fine grain structure.
740
00:38:30,793 --> 00:38:33,862
There's no large shells
Sticking out or holes in it,
741
00:38:33,896 --> 00:38:35,655
And that's because
Of the ocean environment
742
00:38:35,689 --> 00:38:38,862
That we had 340 million
Years ago here in indiana.
743
00:38:38,896 --> 00:38:42,482
Waves would break all
Of those dead-animal body parts
744
00:38:42,517 --> 00:38:44,275
Into a nice, even size.
745
00:38:44,310 --> 00:38:47,413
Makes it excite for carving
And putting on buildings.
746
00:38:47,448 --> 00:38:50,724
♪♪
747
00:38:50,758 --> 00:38:53,344
Narrator: workers can extract
Limestone from this quarry
748
00:38:53,379 --> 00:38:57,482
In 3-ton, perfectly formed
Blocks without any faults.
749
00:38:57,517 --> 00:39:00,137
♪♪
750
00:39:00,172 --> 00:39:04,896
Gang saws then slice the stone
Into smaller pieces.
751
00:39:04,931 --> 00:39:08,137
Other popular building stones
Like granite or marble,
752
00:39:08,172 --> 00:39:10,241
You can have areas
Of irregularity
753
00:39:10,275 --> 00:39:14,586
With those veins that make it
Difficult to carve large pieces.
754
00:39:14,620 --> 00:39:17,517
Narrator: the limestone can be
Cut and carved in any direction
755
00:39:17,551 --> 00:39:21,034
Without cracking.
756
00:39:21,068 --> 00:39:24,103
It's ideal for cutting the
Identical decorative details
757
00:39:24,137 --> 00:39:27,517
That are seen in the facade
Of the empire state building.
758
00:39:27,551 --> 00:39:29,655
♪♪
759
00:39:29,689 --> 00:39:31,724
Its faultless,
Fine-grain structure
760
00:39:31,758 --> 00:39:36,275
Appears to be the perfect
Building material.
761
00:39:36,310 --> 00:39:40,413
But limestone has one
Potentially serious flaw.
762
00:39:40,448 --> 00:39:43,413
It dissolves in rainwater.
763
00:39:43,448 --> 00:39:46,586
Limestone can weather away
And be dissolved.
764
00:39:46,620 --> 00:39:49,448
Chemically, all of our rainwater
Is slightly acidic,
765
00:39:49,482 --> 00:39:52,586
So it does eat away at the rock.
766
00:39:52,620 --> 00:39:54,965
Narrator: polly uses diluted
Hydrochloric acid
767
00:39:55,000 --> 00:39:58,827
To demonstrate the effect
It has on the stone.
768
00:39:58,862 --> 00:40:00,034
I can put it on there,
769
00:40:00,068 --> 00:40:03,172
And you can see
That it fizzes very rapidly,
770
00:40:03,206 --> 00:40:07,689
And because the indiana
Limestone is so high in calcite,
771
00:40:07,724 --> 00:40:10,137
It always reacts
Very vividly like this.
772
00:40:10,172 --> 00:40:13,931
♪♪
773
00:40:13,965 --> 00:40:17,344
Narrator: new york's acidic
Rainwater is slowly eating away
774
00:40:17,379 --> 00:40:20,586
At the facade
Of the empire state building.
775
00:40:20,620 --> 00:40:23,413
But the indiana limestone
Is so durable
776
00:40:23,448 --> 00:40:25,482
That it takes
A staggering 60 years
777
00:40:25,517 --> 00:40:27,000
Before any work is needed
778
00:40:27,034 --> 00:40:30,862
To repair or replace the stone
Covering the skyscraper.
779
00:40:30,896 --> 00:40:33,068
♪♪
780
00:40:33,103 --> 00:40:35,206
Meticulous cleaning
And renovation
781
00:40:35,241 --> 00:40:40,379
Ensures the limestone layer
Will never dissolve or crumble,
782
00:40:40,413 --> 00:40:42,793
Meaning this modern wonder
Can survive
783
00:40:42,827 --> 00:40:47,551
As long as the
Ancient wonders of the world.
784
00:40:47,586 --> 00:40:52,482
The empire state building
Is an incredible achievement.
785
00:40:52,517 --> 00:40:57,586
It's the first structure
To top 100 stories,
786
00:40:57,620 --> 00:41:03,275
A pioneering icon paving the way
To ever taller skyscrapers.
787
00:41:03,310 --> 00:41:07,034
It's extremely resilient,
With innovative engineering
788
00:41:07,068 --> 00:41:11,000
And farsighted use of materials.
789
00:41:11,034 --> 00:41:13,448
This incredible building
Will stand firm
790
00:41:13,482 --> 00:41:17,344
In manhattan's skyline
For centuries to come.
791
00:41:17,379 --> 00:41:24,896
♪♪
792
00:41:24,931 --> 00:41:32,448
♪♪
793
00:41:32,482 --> 00:41:40,000
♪♪
794
00:41:40,034 --> 00:41:47,551
♪♪
61475
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