- In 1977 Citicorp built a new headquarters on a Manhattan block that could not touch the existing St. Peter’s Church. The church had to remain structurally independent, forcing the tower to be supported on four "stilts" placed at the mid‑points of each face rather than at the corners. - Architect Hugh Stubbins and structural engineer Bill LeMessurier were tasked with creating a slender, high‑rise that maximized floor area while respecting the church’s constraints.

- **Gravity loads:** Half of the building’s weight had to be carried by the four mid‑face columns (the stilts) and the rest by a central core. - **Wind loads:** With no corner columns, the tower was unusually flexible, requiring a system that could transfer lateral forces efficiently.

- **Chevron (diagonal) bracing:** LeMessurier sketched a series of six‑layer diagonal braces on each face. By removing the intermediate columns, each brace acted as an independent load‑path, channeling both gravity and wind forces to the mid‑face stilts. - **Tuned Mass Damper (TMD):** To control sway, a 400‑ton concrete block (the “great block of cheese”) was installed near the roof, suspended on springs and viscous dampers. The damper moves out of phase with the building, dissipating kinetic energy and reducing motion by roughly 50%.

- **Quartering winds:** LeMessurier initially designed for wind hitting a face directly. Later calculations showed that wind striking the building at a 45° angle (quartering wind) increased forces on the chevron joints by about 40%. - **Bolted connections:** To save $250,000, the contractor used high‑strength bolts instead of welds on many brace joints. The original bolt count (four per joint) was based on perpendicular‑wind loads and did not account for the higher tension from quartering winds. - **Dynamic analysis:** Wind‑tunnel tests revealed that, when the building sways, stresses could be up to 60% higher than static calculations predicted. The weakest joints, especially around the 30th floor, were far under‑designed.

- LeMessurier realized that a 110 km/h wind—common in New York storms—could cause catastrophic failure, with a statistical chance of a collapse roughly once every 67 years (about 1 in 16 per year). - He faced an ethical dilemma: disclose the flaw and risk lawsuits, professional ruin, and public panic, or stay silent and risk thousands of lives.

The Near‑Catastrophe of New York’s Citicorp Center: How One Engineer Saved a Skyline — Summary

Veritasium

Jan 12, 2026

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4 min read

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Channel: Veritasium

The Near‑Catastrophe of New York’s Citicorp Center: How One Engineer Saved a Skyline

Background

In 1977 Citicorp built a new headquarters on a Manhattan block that could not touch the existing St. Peter’s Church. The church had to remain structurally independent, forcing the tower to be supported on four "stilts" placed at the mid‑points of each face rather than at the corners.
Architect Hugh Stubbins and structural engineer Bill LeMessurier were tasked with creating a slender, high‑rise that maximized floor area while respecting the church’s constraints.

Design Challenges

Gravity loads: Half of the building’s weight had to be carried by the four mid‑face columns (the stilts) and the rest by a central core.
Wind loads: With no corner columns, the tower was unusually flexible, requiring a system that could transfer lateral forces efficiently.

Innovative Solutions

Chevron (diagonal) bracing: LeMessurier sketched a series of six‑layer diagonal braces on each face. By removing the intermediate columns, each brace acted as an independent load‑path, channeling both gravity and wind forces to the mid‑face stilts.
Tuned Mass Damper (TMD): To control sway, a 400‑ton concrete block (the “great block of cheese”) was installed near the roof, suspended on springs and viscous dampers. The damper moves out of phase with the building, dissipating kinetic energy and reducing motion by roughly 50%.

The Hidden Flaw

Quartering winds: LeMessurier initially designed for wind hitting a face directly. Later calculations showed that wind striking the building at a 45° angle (quartering wind) increased forces on the chevron joints by about 40%.
Bolted connections: To save $250,000, the contractor used high‑strength bolts instead of welds on many brace joints. The original bolt count (four per joint) was based on perpendicular‑wind loads and did not account for the higher tension from quartering winds.
Dynamic analysis: Wind‑tunnel tests revealed that, when the building sways, stresses could be up to 60% higher than static calculations predicted. The weakest joints, especially around the 30th floor, were far under‑designed.

The Crisis Unfolds

LeMessurier realized that a 110 km/h wind—common in New York storms—could cause catastrophic failure, with a statistical chance of a collapse roughly once every 67 years (about 1 in 16 per year).
He faced an ethical dilemma: disclose the flaw and risk lawsuits, professional ruin, and public panic, or stay silent and risk thousands of lives.

Emergency Repair – Project Serene

Immediate actions: Emergency generators were installed for the TMD; a covert “Special Engineering Review” was launched.
Night‑time welding: Over 200 brace joints were reinforced with two 5 cm‑thick steel plates on each side, starting with the critical 30th‑floor joints.
Monitoring: Strain gauges were placed on key members, and a dedicated telephone line was set up for real‑time data transmission.
Evacuation planning: Citicorp coordinated with the Red Cross to develop a 10‑block evacuation plan in case a storm struck before repairs were finished.
Timeline: Repairs were completed by October 1978, six weeks after the crisis was identified, just before Hurricane Ella passed harmlessly.

Secrecy and Public Reaction

The repair program was kept secret; the New York press went on strike, providing a convenient blackout.
Citicorp issued a vague statement on August 8, 1978, and the true nature of the danger remained unknown to the public for over a decade.
In 1995, The New Yorker revealed the story, portraying LeMessurier as a hero who chose responsibility over reputation.

Aftermath and Legacy

The incident prompted revisions to building codes worldwide, mandating quarter‑wind calculations for tall structures.
Tuned mass dampers became standard in super‑tall buildings (e.g., Taipei 101’s 660‑ton pendulum).
The Citicorp case is now a staple of engineering‑ethics curricula, illustrating the duty of engineers to protect public safety even at personal cost.

Key Takeaways

Innovative structural concepts can introduce unforeseen vulnerabilities.
Thorough wind analysis—including diagonal winds—is essential for skyscrapers with unconventional column layouts.
Ethical responsibility can demand swift, costly action, but it ultimately preserves lives and advances the profession.

Bill LeMessurier’s decision to confront a hidden, deadly flaw—despite personal and professional risk—saved thousands of lives, reshaped skyscraper engineering, and set a lasting example of ethical responsibility in the built environment.

We use AI to generate summaries. Always double-check important information in the original video.

Key Points

In 1977 Citicorp built a new headquarters on a Manhattan block that could not touch the existing St. Peter’s Church. The church had to remain structurally independent, forcing the tower to be supported on four "stilts" placed at the mid‑points of each face rather than at the corners.
Architect Hugh Stubbins and structural engineer Bill LeMessurier were tasked with creating a slender, high‑rise that maximized floor area while respecting the church’s constraints.

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Full Transcript

This is Citicorp Center.
In the summer of 1978,
it had been open for less than a year
when its structural
engineer, Bill LeMessurier,
made a terrifying discovery.
His cutting edge skyscraper,
an engineering marvel
had a fatal flaw.
Winds of just 110 kilometers per hour
could cause it to collapse
in the middle of Manhattan,
potentially killing thousands.
Over 200,000 people lived and worked
in the surrounding area,
and hurricane season was only weeks away.
Here I am, the only man
in the world who knew this.
This thing is in real trouble.
LeMessurier
faced a stark choice.
He could stay silent
and hope for the best,
or he could try to fix it
and risk professional ruin and mass panic.
But Citicorp Center had a 100% probability
of total collapse by
the end of the century.
How could he save New York
from a near certain disaster?
And how was this allowed
in the first place?
Veritasium producer and
engineer, Henry van Dyck,
traveled to New York
to investigate further.
So in the 1960s, the
financial giant, Citicorp,
was trying to build a new
headquarters in Manhattan.
So just down the street from
their original headquarters
was this entire city block,
which was up for sale.
Well, everything except for
this church, Saint Peter's.
So Citicorp came to the
pastor, Ralph Peterson,
and asked, "What's it gonna
take for you guys to leave?"
And he came back and
said, "We're not leaving.
Anything that Citicorp builds
has to involve the church as part of it."
What the pastor wanted was for the church
to have its own separate identity.
So eventually they agreed on two things.
One was to replace this
old crumbling gothic church
with a brand new one, which
you see in front of you.
And the second thing was that the church
had to be physically
distinct from the new tower.
In other words, it had to
be completely independent.
And again, most importantly,
two thirds of the space
above the church had to be
free and clear, had to be open.
Citicorp then
hired architect Hugh Stubbins
to design the tower and the church
and Bill LeMessurier as
the structural engineer,
Stubbins explained the
constraints they faced.
The church needed to be
in the exact same spot
and they needed to build
the tower around it.
If they were to maximize the
floor area, they would have to
notch out one corner of
the tower for the church.
LeMessurier agreed that could work,
but why not notch two, three,
or even all four corners,
essentially constructing
the skyscraper on stilts.
So it's probably the
first time in history
that an engineer has come
to an architect and said,
"Let's make our job harder for us."
The stilts would
serve two main purposes.
First, they would need
to support at least half
of the building's gravity load.
The rest would be held up
by a larger central column.
Second, they would need
to withstand the load
due to high winds.
But unlike an ordinary structure,
the stilts wouldn't be at the corners.
They would be at the center of each face.
Imagine a chair, and
instead of the columns
or the supports on each
corner of the chair,
it's at the midpoint of each side.
Obviously, it's not an ideal situation.
It doesn't seem very stable.
Exactly. So it created
an engineering problem.
As LeMessurier
considered the problem,
he suddenly had a flash of inspiration.
He grabbed a napkin and
sketched out an idea.
He drew six layers
of diagonal braces up
each face of the tower.
These chevrons would transfer
the forces to the middle
of each face and down to the stilts.
Now we have to see the
gravity loads, right?
But now here's the trick.
The gravity loads are
coming down the column.
When they get to the brace,
they need to find their
way into the brace.
Okay.
So what you do
is you take out that column right there.
There is no way that load can jump over
and go to that column.
And now they're coming
down into the braces.
They get down to the bottom here,
and now they continue to go down.
You take that column out,
it has nowhere to go
except into the brace.
By removing the columns at the top
and middle of each chevron,
every tier acted as a separate unit.
They were only connected to the braces
and through the central core.
So every eight stories,
half of the gravity load
would be forced through the chevrons
to the midface columns,
leading down to the stilts.
Can you tell me how big
of a new idea was this?
Yeah, well, this particular
system was entirely unique,
driven by the placement of the columns,
driven by the conditions of the building.
As satisfied the chevrons
could transfer the gravity load,
LeMessurier turned his
attention to the second problem,
the wind.
When wind hits the left
side of a normal building
with corner columns, the
entire frame deforms like this.
So to reduce this deformation,
we could strengthen these
joints, but there's a better way
because beams and columns are
much stronger in compression
or tension than they
are with bending loads.
So if we add diagonal bracing,
they can carry this horizontal load.
The beams sort of act like springs,
and when they're compressed,
they push on the joints.
When they're stretched, they pull inwards.
With braces like these,
the wind load compresses this diagonal
and stretches this one.
The left column pulls down in tension
and the right column
pushes up in compression.
Where the braces meet,
they both push the
bottom beam to the right.
This stretches the left side
and compresses the right one.
But this floor is the
top of the next chevron,
so this lower section
is carrying the force
from the layer above it
and the normal wind load from the side.
And this keeps happening at every chevron
so the wind load builds up
as you go down the building.
But Citicorp can't have
corner columns like this
because of the gravity load.
So in the wind, this entire triangle
wants to rotate like this
and to prevent that from happening,
this chevron pulls down going into tension
and the far chevron
pushes up in compression.
The top and bottom beams
are again forced into
compression and tension.
The wind load ends up wrapping
around the entire building.
So every chevron works
to transfer the wind load
to the section below.
When we think about skyscrapers,
like how big of a deal is wind?
If we made a skyscraper here, you know,
out of all these different
things, you push with your phone,
you get a certain amount of force,
but then you push on my phone as well
with a certain amount of force,
but your phone is also
pushing on my phone.
And so that's the shear in the building,
what we call the building shear.
It increases as you go down the building.
You know, at the 10th floor,
you may have a smaller force
than at the 60th floor,
but the total force of the 10th floor
is like carrying everything above it.
So it's much bigger than what's
going on on the 60th floor.
So these chevrons were key to LeMessurier's design,
but the braces were massive, almost 40 meters long end to end. 
So even if you could fabricate
a steel brace that long,
there would be no way to
get it through Manhattan.
So instead it was sent in pieces
to be welded together on site.
The chevron bracing solved the
wind and gravity load issues,
but it also created a different problem.
Because of the chevron bracing system,
they were able to save a
lot of money and weight.
It was a lighter construct
than most other buildings
in New York, I think it was
22 pounds a square foot,
which is very light.
Unfortunately, that made
the building swayable,
it could move in the wind.
That wasn't necessarily a
structural problem, it was just,
it could have been
uncomfortable for the patrons.
The way they could solve this was just
let's add more structural steel
and make it a lot stiffer.
But the solution that
LeMessurier came up with
was far more elegant.
He adopted something that
had been regularly used
in bridges, power lines and ships,
but never before in a building:
a tuned mass damper or TMD.
So we're here at Stark Laboratories,
and I'm not with Iron Man,
but instead the Columbia Space Initiative,
the student team here on
campus who has helped us build
this incredible tuned mass
damper kind of system.
We'll use this cart to
represent a building.
By pulling it back and releasing it,
we can excite its resonant frequency,
And then we'll put on a
little pendulum, aluminum rod,
and a mass at the bottom.
As the building sways,
it transfers some of its
kinetic energy to the pendulum,
which starts to swing.
Then some of its energy is
dissipated through friction
at the hinge.
The pendulum and the building oscillate
out of phase from each other.
So every time the building
pulls the pendulum
in a different direction,
more energy is lost,
significantly damping
the sway of the tower.
But this system needs
to be carefully tuned
so it has the same frequency
as the building itself
and the right amount of friction.
So first, the mass needs
to be at least one to 5%
of the building's weight to be effective.
And we tune the frequency of the TMD
by adjusting the length of the pendulum.
I assume engineers do
math around this thing,
but we're just doing it by feel.
(both laugh)
Second, by loosening
or tightening the bolt,
we can tune the amount of damping.
We need to dissipate more energy
from friction at the hinge
to stop the swaying faster.
We just tighten the top bolt,
make the whole system a little bit,
you know, add a little
bit more resistance,
and we'll see if we can
dampen it now further.
 
Woohoo.
Much different. Yeah.
Yeah, that looked
great. That was so quick.
Yeah, that was.
It is cool when an experiment works.
Does not always happen.
There are many
different types of TMDs,
like pendulums, liquid columns,
and a large mass on springs.
LeMessurier used this
last one in Citicorp.
What you see
is a mass of concrete,
which is 29 feet square
and about eight feet thick
and weighs 400 tons.
It was installed on the top floor
and it's affectionately known
as that great block of cheese.
As Citicorp sways to one side,
the block starts to move
in the same direction.
Some energy is dissipated
through separate viscous dampers.
Citicorp's oscillations are damped
through those energy losses
as the block oscillates
out of phase to the building's motion.
LeMessurier expected the
damper to reduce the amplitude
of swaying by roughly 50%,
and he saved around $4 million
by not needing an additional
2,800 tons of structural steel.
With both the chevron bracing
to channel forces to the stilts
and the tuned mass damper to reduce sway,
LeMessurier was convinced
the building was structurally sound.
On Citicorp Center's opening day in 1977,
it was the 11th tallest
building in the world.
It was described by the press
as an acrobatic act of architecture.
Later, the American
Institute of Architects
even gave it an honor award,
calling it a tour de force
as a stylish silhouette in the skyline,
and, for the pedestrian, a
hovering cantilevered hulk.
So then, it's going
swimmingly for years, right?
Well, it's going
swimmingly for about a year.
The first hint of
trouble came in May, 1978.
LeMessurier was talking
with another client
about welding similar chevron braces.
The architect and the
steel fabricator said,
"Tell me, how did those
welded braces work out?"
Seems like overkill, they thought.
And LeMessurier says,
"Yeah, they were fine.
Let me call my guys in
New York and I'll check."
So he put the call into
his office in New York
and they say, "Oh, Bill, didn't you know?
We bolted those connections."
The contractor
had suggested saving
a quarter of a million
dollars by using bolts
to attach the braces instead of welds.
And LeMessurier's firm had agreed.
There is nothing that
says a bolt is inherently
worse or better than a weld.
You use them in different circumstances
for different reasons,
but it's a little surprising to find out,
I thought the connections
in this tour de force,
one of a kind skyscraper, you know,
that's on the cutting edge
of structural engineering,
was connected one way,
but apparently it's connected another way.
But if the braces are going like this,
where are they gonna go?
You know, you only need the weld
when the braces are going like this.
Since the gravity load
was always compressing the
braces, some of the chevrons
only went into tension
under very high winds.
And even then, it wasn't a lot of tension.
LeMessurier trusted that his team
did the right calculations,
and the substitution was fine,
logical, even.
(phone ringing)
But around a month later,
LeMessurier got a phone
call from a student
who wanted to ask some questions
about the Citicorp Center.
And his teacher said to him,
"That engineer didn't know what he's doing
and nobody should put the
columns in the middle.
They should put 'em in the
corners. That's silly."
And I told the student, I said,
"Well, you're a professor's full of it.
He doesn't understand the
problem we had to solve."
LeMessurier went
through the calculations
with the student
to reassure him the stilts
were in the right place.
But the interesting thing
is, is in that moment,
he's thinking about wind
loads from all directions.
You know, late spring,
early summer of 1978,
Bill LeMessurier is working
on the back of a Hilton Hotel
that, in plan, forms a
triangle, not a rectangle.
Now you got a triangle. What's
your orthogonal direction?
You just have to give up and say,
"We're gonna analyze it
from every direction."
That's going on the moment
that Bill LeMessurier
gets this phone call.
Then I called him back
and pointed it out to him
that there's some peculiar
things about this building.
The worst loading case
was not the diagonal,
but it was the ordinary wind
that everybody thinks about.
The wind pushes straight on the building.
That was the critical case.
He said, you know what,
I've been getting all these
calls from all these people.
I'm gonna sit down and explain this thing.
He decided to double check
what happens to the
building if wind is hitting
a corner of the building, not
straight on one of the faces.
These are also known as quartering winds.
So he split the wind into
its perpendicular components.
So the west side and north
side are hit by the force
divided by the square root of two.
He computed the forces for
each, as we did before,
and summed up the result,
but then he noticed something strange.
Then now we
look at the diagonals,
the stresses in half of them vanish,
and in the other half, double.
Since the force on each side
was F over the square root of two,
these beams get double that.
Compared to LeMessurier calculations
for the perpendicular wind load,
the forces here were 40% higher.
So 1.4 by itself is not
enough to wreck havoc.
Okay? It may be, but it may not be.
Okay.
So then the question is,
well, what happens?
This increase in
forces wouldn't have mattered
in the original design
since the chevrons were
fully welded together.
But that wasn't the case anymore.
LeMessurier remembered
his earlier phone call.
The welds holding the chevrons together
were swapped for bolts.
How did his team calculate
the number of bolts per joint?
Did they consider quartering winds?
It would be a miracle if
they ever thought that through,
to think about the diagonal wind.
It just wasn't in the nature of anybody.
So I had a bit of a worry.
I didn't panic right away,
but I decided to go down
to New York to my office.
LeMessurier
requested the building diagrams
and poured over all of the connections.
He looked at how his firm
calculated the number of bolts.
There was no question, they
had taken straight on wind,
not the diagonal wind.
Although wind speed is highest
at the top of the tower,
the wind shear builds up as you go lower.
Looking at this brace around
halfway down the tower,
the perpendicular wind load is 454 tons.
Because of the skipped columns,
all of these braces carry
the same gravity load,
just 340 tons, from the
eight stories above.
The gravity load builds
up in the center column,
not in the braces,
which means there are 114
tons of tension in this brace.
If each bolt can withstand around 28 tons,
that would require four bolts.
The original calculations said
just four bolts were enough.
So that was all they used.
But when he added quartering winds,
LeMessurier's calculations
showed there were some braces
that needed far more bolts.
At this particular part of the building,
which I can show you on my
calculations is right about here,
and Bill LeMessurier talked
about the 30th floor,
and I always wondered why
was it the 30th floor?
The 40% increase
from quartering winds
means that this brace has
a wind load of 635 tons.
The tension in the brace is now 295 tons,
over double the original calculation.
So these braces actually need
around 10 bolts, not four.
But then it turned out
they had done something else.
LeMessurier's
firm considered the braces
to be minor structural elements.
They didn't use the right factor of safety
to calculate the number of bolts.
They should have overestimated
the tension in the brace
by underestimating the gravity load.
With only 75% of the gravity load,
the tension in the beam is now 380 tons.
So they really needed 14
bolts, but they used only four.
I thought this
thing is in real trouble.
Imagine, you know,
what Bill LeMessurier was
thinking at that moment.
You see that number and you're like,
"Oh my God, this is serious.
It's really serious."
LeMessurier
was starting to panic.
He didn't wanna rush to conclusions,
so he flew to Canada to
check his calculations
with Alan Davenport at the
Boundary Layer Wind Tunnel.
After running more tests,
they found that it was even
worse than LeMessurier thought.
The estimated 40% increase in stress
was technically correct,
but LeMessurier made his calculations
assuming the building wasn't moving.
This is called static conditions.
But the wind tunnel gave
LeMessurier a dynamic analysis,
how the forces change when
the building is moving around.
To LeMessurier's horror,
the wind tunnel analysis
showed that the stresses could increase
up to 60% more than
originally anticipated.
LeMessurier squirreled
himself away in Maine
and worked through the data
from the wind tunnel again,
joint by joint on every floor.
The weakest joints were at
the building's 30th floor.
If those failed, the
entire building would fall.
But what were the chances
that a storm strong enough
to topple the building would
pass through New York City?
LeMessurier dug through the
historical weather reports.
On average, a storm strong
enough to tear the building apart
occurred every 67 years.
But only if the tuned
mass damper was working.
If a storm knocked out power,
then even 110 kilometer per hour winds
blowing for just five minutes
would collapse the building.
In any given year,
the chance of a storm that
size happening was one in 16.
Just one year before
Citicorp was completed,
wind gusts of 110 kilometers per hour
roared through New York City
as Hurricane Belle passed through.
What do you think this moment
was like for LeMessurier,
when he ran these calculations, like-
Oh, it must have been devastating.
I mean, it just must have
been, I can't imagine the fear.
I can't imagine the feelings.
I mean, like, it just must have been truly
a moment he never thought
he would live through.
That storm was gonna
fall down in my lifetime.
And since this was July,
it could fall down the summer of 1978.
LeMessurier needed to
decide and decide fast.
But revealing this mistake
could mean lawsuits,
bankruptcy and professional ruin.
He could stay silent,
only Davenport knew and he
wouldn't reveal anything,
or he could entirely disappear.
In a later interview he
admitted, "I did say to myself,
I could drive down the Maine Turnpike
at a hundred miles an hour
and deliberately drive
into a bridge abutment.
That would be the end and
all of this would go away.
I thought about that."
But there was a 1 in 16 chance
of collapse that very fall.
With thousands of lives at risk,
there was never any
other choice but to act.
After speaking to a few lawyers
and other engineering experts,
LeMessurier told the architect,
Stubbins, and together
they informed Citicorp's
chairman, Walter Wriston.
Within hours of that meeting,
LeMessurier acquired emergency generators
for the tuned mass damper.
The TMD was originally
designed to stabilize
any swaying for comfort,
but now it became the crutch
that the tower leaned on.
LeMessurier pinned all his hopes on it.
He called the confidential
repair plan Project Pandora,
but that sounded ominous,
so he came up with the
Special Engineering Review
of Events Nobody Envisioned,
or Project Serene for short.
Each night, welders
would enter the building
after everyone left,
rip off the sheet rock
around the chevron beams,
and then weld two five-centimeter thick,
two-meter long steel plates on each joint.
Like Band-Aids, literally Band-Aids,
on both sides of these joints.
After, they'd replaced the wall
and clean everything up
before the office workers
came back the next morning,
They needed to weld over 200 joints
and LeMessurier ranked them by importance,
starting with the ones on the 30th floor.
But the repairs wouldn't be completed
before hurricane season.
So Citicorp worked with the Red Cross
to develop a 10 block evacuation plan.
Like, how many people
were at risk in the building
and if it fell, would it
affect other buildings?
Like, were there chances of it
leading to something more disastrous?
Absolutely, this would have toppled
and it would've toppled
into another building,
which would've toppled
into another building,
which would've continued
a horrific process.
So it was untold what the
ultimate effects could have been.
I mean, like,
just the evacuation plans
were how many people?
Thousands, the building
itself housed thousands
and then the residents and the businesses
surrounding the building,
it was into the thousands.
Despite the risk,
they decided not to tell the public
or even the office
workers in the building.
No one wanted a mass panic.
Instead, they fitted strain gauges
on important structural members.
The gauges monitored the
skyscrapers every bend and twist
from a comm center eight blocks away.
At least that would give
them a little bit of warning.
But this plan required new telephone lines,
and the phone company wouldn't get around to doing this
for months.
So Citicorp's chairman immediately called AT&T's president
and the lines were
installed the next morning.
Now you might not be able to install
emergency telephone lines at a whim,
but you can still stay
connected no matter what.
(phone ringing)
It's probably not that important.
Henry, can you hear me? Hello!
Team Veritasium travels all
over the globe for our videos
We traveled here to New York
to visit the Citicorp Center,
and there's one really annoying problem.
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with the rest of the team
while we're on site.
We either have to pay
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hope it actually works,
or search around for public Wi-Fi
that might not be the most secure.
That's not something we
wanna be dealing with
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So Saily makes it incredibly
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Thank you Saily for sponsoring this video.
And now back to Project Serene.
(phone ringing)
(sighs) I mean, should probably take this.
(phone beeps)
But even though LeMessurier
tried to keep Project Serene under wraps,
people started asking questions.
On August 8th, Citicorp
released a statement
about the repairs.
Now, we had to cook up a
line of bull, I'll tell you.
And white lies at this
point are entirely moral.
(class laughs)
You don't wanna spread terror
in the community to people that
don't need to be terrorized.
We were terrorized, no
question about that.
Several
newspapers reported on it,
but they didn't have the details.
Then LeMessurier got a message.
The New York Times
was trying to reach him.
If he didn't respond, they
would know something was up.
So I mixed a martini for myself
and it's one minute past six.
I dialed The New York Times.
I pick it up the phone,
they pick up the phone,
it's a tape recorder saying,
The New York Times has gone
on strike as of six o'clock.
(class laughs)
Not only did The New
York Times go on strike,
but all the newspapers in
New York went on strike
until October.
So we had a press blackout
and that was the greatest
thing that ever happened.
(class laughs)
The press was off their back
and the weather was beautiful.
The repair work continued smoothly.
But late August brought the
news everyone had been dreading.
Hurricane Ella starts
brewing in the Caribbean.
And this is the one storm
that they're nervous about.
The repairs
were halfway done by now.
I think it was a one in 200 year storm
that it could withstand,
but LeMessurier wasn't taking chances
'cause he didn't know the
intensity of the storm.
And this was a strong storm.
So there was, there was a chance.
There was absolutely a chance
and they had to prepare for that chance.
 
By Friday, September 1st,
Ella was making her way toward New York,
with winds reaching 200
kilometers per hour.
City officials braced
to start the evacuation.
Police would go door to
door to get everyone out
within a 10 block radius.
For 24 tense hours, Ella
stalled around North Carolina.
Like LeMessurier said,
we were sweating blood.
But sometime in the night,
Hurricane Ella veered off into
the sea at the last minute.
It intensified and hit Canada
with peak winds of 225
kilometers per hour.
But Citicorp was safe.
LeMessurier described that
next morning in New York
as the most beautiful day
that the world's ever seen.
They completed the repairs in October,
just six weeks after
LeMessurier told Citicorp.
Now the building,
according to LeMessurier,
can withstand a one in 1000 storm.
The repairs cost
between $4 and $5 million,
but LeMessurier argued
that Citicorp approved
an earlier building design
that cost $5 to $6 million more,
so they were willing to spend that much
on the skyscraper anyway.
And for almost two decades,
the secret was confined
to a small inner circle.
But in 1995, "The New Yorker"
finally brought Project
Serene into the light.
Far from being vilified,
LeMessurier was praised
for owning up to his mistake
and fixing the issue as soon as possible.
After the article, New
York updated the building code
to require quartering wind calculations.
And since that
first damper in Citicorp,
TMDs have spread across the globe.
allowing architects to push
skyscrapers taller and slimmer.
It's in the first tall
building in the world
ever built with mechanical help
to make the structure work.
That's remarkable.
Incidentally, that has been now copied
a hundred times in Japan,
this is ubiquitous,
and when I go to Japan,
I'm treated like a tin god
'cause I'm the father of
the tuned mass damper.
I said, "Really?"
Of the 20 tallest
buildings in the world,
six include the tuned mass damper,
 and they're especially critical in typhoon or earthquake-prone regions.
For example, Taipei 101 has
a massive 660 ton pendulum
that stabilizes the building. It can withstand up to 200
kilometer per hour winds
and earthquakes with magnitudes over 6.8.
But the legacy of this building
is still steeped in controversy.
First, who was the mysterious
student that started it all?
 I think it was spring of 1978. There's a student at Princeton,
an undergraduate student
by the name of Diane Hartley, and she's studying structural engineering.
It was time for her to
consider a senior thesis,
and then they decided that a study
of the new Citicorp
Tower would be wonderful.
It's a remarkable thesis.
It contains a lot of the
original engineering calculations
by the engineers.
She's looking through the documentation,
where did they consider quartering winds?
And she's not seeing it
"I must be wrong," she says.
She's just an undergraduate student
and you guys are award-winning
structural engineers.
The engineer explains to Diane Hartley,
quartering winds are not
a factor in this building.
So she's satisfied. She
graduates, that's it.
Doesn't think about it again.
But a year after "The
New Yorker" article,
the BBC released a
documentary on the crisis.
And so she, she was holding her baby
and she turned on the
television, and lo and behold,
she heard them reference a
conversation with a student,
an engineering student from New Jersey
reaching out to LeMessurier.
And she said, "I almost
dropped my baby." 
And then so she just assumed
for years afterwards,
she assumed that it wasn't me
because I didn't speak to LeMessurier.
But then in 2003,
her thesis advisor told Diane
that he checked all the
other New Jersey engineering
and architecture programs, and no one else
was working on a project
about Citicorp in 1978.
She was the only one.
She never spoke to
LeMessurier personally.
She never claimed to speak
to LeMessurier personally.
The assumption was that either
LeMessurier was mistaken
and that it was Diane
Hartley who made the call,
it was a female, or more likely
that LeMessurier was basically tipped off
by his New York engineers.
Then, in 2011,
a man named Lee DeCarolis came forward.
And the phone call, as we understand it,
came from a student
at the New Jersey Institute of Technology.
His name is Lee DeCarolis.
He's not asking for money,
he's not asking for fame or glory.
He's just saying, "This is interesting.
And I'm the guy who made this call."
And he said, "Yeah,
I had a conversation
with Bill LeMessurier."
And he pretty much lined up
with what LeMessurier himself said.
Sadly, LeMessurier
passed away in 2007
before he could confirm
the student's identity.
Believe it or not, 40
years later, there's still,
I learned, a lot of raw
feeling still on this.
People aren't anxious to talk about this,
especially people that
were involved in it,
even people that weren't involved in it
but were tangentially involved in it.
We reached out to a
LeMessurier Associates
and they refused to
respond to our request.
You think that the namesake
for their company stood up
and did the right thing,
but I don't think they wanna
be associated with mistakes.
Their project
description for Citicorp
doesn't even mention the repairs.
The building was sold to
Boston Properties in 2001,
who renamed it 601 Lexington.
They also didn't respond
to our request for comment
and refused to let us
film inside the building.
Further questions arose
in 2021, with a new study
from the National Institute
of Standards and Technology.
They wanted to see if quartering
winds were more demanding
for a building like Citicorp,
Although they did conclude
that the pressure from
perpendicular winds was greater,
their analysis didn't include
any internal structure
specific to Citicorp.
As for LeMessurier,
the engineering field
still regards his actions as upstanding.
And the Citicorp case is
taught all over the world
as a case of good engineering ethics.
In fact, in my own
engineering ethics course,
I learned about the Citicorp building.
And every structural
engineer experiences this.
When you actually feel the
weight of the responsibility,
you're saying, "Based on my engineering,
that building is gonna stand up."
Nobody else worries about it.
And so if you think about
the emotional pressure
that Bill LeMessurier was under
and then needing to come back
and do something about it
and to mobilize and to hold
that during this entire process,
it's truly a remarkable story.
I mean, I can't imagine
it. I can't imagine it.
I said, look, if you got
a license from the state
and a certification from university first,
then now you're gonna use that license
to hold yourself out as a professional,
you have a responsibility beyond yourself.
If you see something
that is a social risk,
good heavens, this thing
would kill thousands,
you must do something,
you must do something.

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