52x06 - Baltimore Bridge Collapse

[bunniefuu]

♪ ♪

NARRATOR:
March 26, 2024.

A heavily loaded container ship
careens out of control

and heads straight
toward one of the supports

of the Francis Scott Key Bridge
in Baltimore.

OFFICER (on radio): C-13 Dispatch,
the whole bridge just fell down.

The whole bridge just collapsed.

SEARCH UNIT MEMBER:
Key Bridge is down.

Several vehicles in the water.

NARRATOR: It's a
race to find survivors...

OFFICER 2: They're
bringing a victim in now.

OFFICER 3: Okay.



NARRATOR: and remove
the 50,000 tons of debris

that completely
cut off this vital port.

ESTEE PINCHASIN: People
are looking at us and saying,

"What's the plan?"

NARRATOR: The scale of the
salvage operation is daunting.

They need to reopen
this crucial shipping route

as quickly as possible.

ROBYN BIANCHI: You could
instantly feel the ripple effects

on our economy, on Baltimore.

PINCHASIN: We knew that it was

gonna be very dangerous,

very complex.

STEPHEN SKIPPEN: It will
certainly make your hair stand up

on the back of your neck

seeing the steel drop
as you're making cuts.

NARRATOR: Investigators
scramble to uncover what went wrong,

asking, how did a
modern ship suffer

such a catastrophic
loss of control?

And why did a
single point of impact

cause the entire
bridge to collapse?

The problem you have
is that ships have gotten

bigger and larger,

and the infrastructure
has not kept up with them.

NARRATOR: An estimated
two-and-a-half thousand U.S. bridges

remain at risk of ship strikes.

ABI AGHAYERE: This
could have been prevented.

NARRATOR: As
vessels grow in size,

can our infrastructure
handle it?

"Baltimore Bridge Collapse,"
right now on "NOVA."

♪ ♪

♪ ♪

NARRATOR: The port
of Baltimore, Maryland,

is one of the busiest
ports on the East Coast,

and its history is
as long and storied

as the United States itself.

So much of Baltimore's
identity is actually

wrapped up in its port.

The Port of Baltimore has been
one of the earliest trade points

for not just the state,
but for this country.

I mean, that port is

our economic heartbeat
in the state of Maryland.

NARRATOR: Every year,

it handles cargo worth
more than $80 billion

and supports more
than 20,000 jobs.

♪ ♪

The Port of Baltimore
supplies the nation

with critical goods from
food to pharmaceuticals.

The port has 17
separate terminals

for container operations,
cruise ships, and bulk cargo.


here every year.

It can handle some of
the world's largest ships,

each carrying more
than 15,000 containers.

To reach the port terminals,

all ships must pass under
the Francis Scott Key Bridge,

which carries four
lanes of road traffic



The ships must negotiate
a narrow shipping channel

that runs between the
main supports of the bridge.

♪ ♪

MOORE: From a practical
perspective, the Key Bridge

gets you to the
Port of Baltimore.


much more than that.

It's our skyline.

The backdrop for Baltimore.

♪ ♪

NARRATOR: In the early hours
of Tuesday, March 26, 2024,



At 12:36 A.M.,

one sets sail for Sri Lanka

with 21 crew and two
local pilots onboard.

It's called Dali,

a 124,000-ton,


It's part of a modern
class of ships so massive

that only certain ports
have channels deep enough

to allow them to pass.

The vessel is almost full,

laden with nearly


carrying everything from
soybeans to perfume.

But as the ship
approaches the bridge,

there's a sudden loss
of electrical power.

The ship is plunged
into darkness.

At 1:26 A.M., one
of the pilots onboard

sends out a distress call,
which alerts the police.

DISPATCHER: Hold all
traffic on the Key Bridge.

There's a ship approaching

that has just lost
their steering.

OFFICER: I'm
holding traffic now.

I was driving, but we
stopped prior to the bridge.

MOORE: We had
workers on that bridge.

These are people
who are fixing potholes.

They were fixing
potholes while we slept.

DISPATCHER: Just make sure
no one's on the bridge right now.

If there's a crew up there,

you might want to notify
whoever the foreman is,

see if we can get them
off the bridge temporarily.

OFFICER: Once you get here,

I'll go grab the workers
on the Key Bridge

and then stop the outer loop.

NARRATOR: But the police are
unable to reach the workers in time.

♪ ♪

OFFICER: C-13 Dispatch,
the whole bridge just fell down.

The whole bridge just collapsed.

♪ ♪

MOORE: My chief of staff,

he sent me a, a note saying,
"I just sent you a video."

The video was of
the bridge collapsing

and it literally took
my breath away.

Uh, it just didn't look real.

♪ ♪

We knew that

one of the most tragic
moments in our state's history

had just occurred.

BYSTANDER: That's the
Key Bridge, Key Bridge.

OFFICER: Yeah, it
is. BYSTANDER: Wow!

NARRATOR: The
container ship Dali

has smashed into and
destroyed the bridge.

Immediately, Coast Guard
and police search teams

race to the scene.

MAN: The whole
bridge has collapsed.

And the bridge is sitting
on top of the container ship.

DAVID O'CONNELL:
We started searching

almost instantaneously

'cause our station
was very close.

If you just get us near where

the other Fire Department
assets are out there.

MAN: You got it, you got it.

SEARCH UNIT MEMBER:
Key Bridge is down.

It was last reported,

at least several
vehicles in the water

and several people
still unaccounted for.

O'CONNELL (voiceover):
It was night time,

it was a fairly clear night
though so they could see,

they had visibility.

They had lights as well.

RESCUE OFFICER:
Hey what's going on, man?

We've got one out
of the water. Okay.

O'CONNELL (voiceover): There was
one survivor that went into the water

in his vehicle

and he was clinging
to a piece of debris

when he was picked up.

RESCUE OFFICER: They're
bringing the victim in now.

Okay.

O'CONNELL (voiceover): Incredible
that somebody would survive

that fall and be rescued.

It gave hope to the rescuers
that we were gonna find

other victims as well
that survived the fall.

SEARCH UNIT: 343 Sierra.

I have nothing at the moment.

NARRATOR: The search teams
have rescued one construction worker,

but six are still missing.

First light reveals

the full scale of the disaster.

♪ ♪

POLICE OFFICER (on radio): God.

POLICE OFFICER 2 (on
radio): Natural one to Command.

NARRATOR: The Dali
had so much momentum,

it completely destroyed
one of the main support piers

that held up the Key Bridge.

The ship has run aground,

and is trapped by the wreckage.

Almost 3,000
feet of the crossing

have collapsed into
the Patapsco River.

OFFICER (on radio): We've
got some investigators onboard,

we'll be in the area
of the, uh, bridge.

NARRATOR: Fortunately,
the Dali's crew is unscathed

and the hull has
not been breached.

But no ships can get in or
out of the Port of Baltimore.


completely block

the main shipping channel;
the port is shut down.

As the day ends,
there's still no sign

of the six missing workers.

MOORE (voiceover): I
remember speaking with the person

who was running the
operation from the Coast Guard,

and I said,

"What is the probability

that we're gonna find
someone alive at this point?"

And the answer that
he gave was "Governor,

"my professional
assessment is zero.

There's a zero percent chance."

♪ ♪

I remember one of the
family members who said

"Quiero el cuerpo."

Which is "I, I want the body."

♪ ♪

♪ ♪

NARRATOR: While the search

for lost workers continues,

the city begins to grapple with
the sheer scale of the problem.

PINCHASIN: Never seen
anything of that magnitude before.

We had the bridge collapse

with the vessel,

everything mangled

up on top and around.

You had these big, large spans

that were just
laying in the water.

You see four-inch steel

that's been bent... bent!

How can you even start
to think about the force?

♪ ♪

People are looking at us

and saying, "What's the plan?"

NARRATOR: The stakes are high.

Every day the
port is closed costs

$15 million in lost revenue,

and more than a thousand

containers a day
cannot move in or out.

There are fears the closure
could impact the wider economy,

affecting commerce
across the country.

The U.S. Army Corps of Engineers

and the U.S. Coast Guard

bring in the Navy

and three specialist
salvage teams.

PINCHASIN: The
number one priority

was recovering the
missing personnel.

The number two priority
was opening the channel.

NARRATOR: The situation
calls for a rapid response

of unprecedented scale.

The team must free the Dali

from the 5,000
ton bridge section

that pins down its bow, so
they can tow the vessel away.

But before they can
fully reopen the port,

they must also cut the
collapsed sections of bridge

into smaller pieces and
lift them from the river.


steel and concrete.

It's a huge challenge.

BIANCHI: And
you just think, how?

How are we going to?

Seeing it on the news,
seeing it in photos,

I was not prepared to see it,

you know, up close and personal.

NARRATOR: Robyn Bianchi is
part of a salvage team brought in

to clear the bridge wreckage
from the main shipping channel.

WORKER: This is gonna
be a hell of a clean-up.

BIANCHI: And it was just so
unfathomable, the amount of damage

and wreckage and how
massive everything was.

And we instantly knew,
well, we can't make any plans

on how to raise this
wreckage out of the water

until we know what it
looks like under the water.

NARRATOR: The
salvage team's first task

is to send divers down into
the mass of twisted steel.

They must try to make sense
of how the mangled beams

and smashed road are
positioned on the riverbed.

It's a key step before
they can make a plan

to disassemble the
tangled structure safely.

BIANCHI: They're entering a
very inherently dangerous situation.

SALVAGE TEAM MEMBER: You have
the hanger, go back to the hanger part.



BIANCHI: Like,
there was no visibility,

so I kind of compared it to

a metal jungle gym underwater.

Right, you have this
rusty, metal jungle gym

that was plopped
into zero visibility.

You turn off all the lights in
the room and try and tell me

all the pieces

of where they connect,
of that metal jungle gym.

Oh, and by the way the
jungle gym's completely twisted

and it looks nothing like it did
when it was built to perfection.



SALVAGE TEAM MEMBER: How far
from the first gusset that you just left?

DIVER: Maybe about six foot?
SALVAGE TEAM MEMBER: Okay.

BIANCHI: You want to really
meticulously guide them through.

All right, when you have
your hand on this section,

we're gonna call this
section J, so I'd have them

mark it with a little,
um, underwater marker

and that correlated to section J

on this specific
engineering plan.

SALVAGE TEAM MEMBER: Can
you see the other side of that pendant?

Is it disconnected?

DIVER: Yeah, it looks
still connected to a beam,

uh, like a truss.

BIANCHI: We were
able to kind of map out

what it looks like underwater.

You verify and
validate with comms,

and then you move
on to the next objective.

SALVAGE TEAM MEMBER: So
how much do you have exposed

from the mudline to the
top of the gusset plate?

DIVER: Standby,
I'll grab the tape.

BIANCHI: It was very
dangerous for divers

because you'd turn left

and you went
underneath something,

like a piece of rebar
that's sticking out,

you have to remember that that's
where you have to come back out

otherwise you could
become trapped.

Everything that
could make diving

more difficult, it
was on this job.

♪ ♪

NARRATOR: Visibility is
no more than one or two feet.

To give the divers
a clearer picture,

the team deploys
underwater drones

equipped with sonar
to map the wreckage.

Together with the
hands-on dive surveys,

these scans will
help the team decide

where to cut and lift
each section of debris.

SUAREZ: This volumetric sonar

uses very precise location data

from various scans

to essentially stitch together

multiple scans to create

a 3D model.

The picture spoke
a thousand words.

It just gave a really
high fidelity view

of exactly what everyone
was dealing with on the bottom.

PINCHASIN: Down at the
bottom is where you had

a big, mangled mess, especially
in the center of the channel.

Not just the steel,

but the reinforced
concrete from the road bed.

What we didn't realize
until we were able to get

some 3D imagery

of just how catastrophic
the collapse was.

♪ ♪

NARRATOR: While
the salvage teams

prepare their work plans,

the National
Transportation Safety Board

begins an investigation

to answer the questions... what
caused the ship to lose power

and collide with the bridge?

And why did the structure
collapse so catastrophically?

♪ ♪

Investigators board the Dali
on the day of the accident.

They document the scene,

and meticulously gather
physical and electronic evidence.

They interview the
captain and 20 crew,

all of whom remain on the
ship because of visa restrictions.

They retrieve the ship's
voyage data recorder,

which stores audio
from the Dali's bridge

and details engine
and rudder commands.

Marcel Muise is the investigator

in charge of the Dali accident.

We're looking at
different aspects

of the incident

to answer, how do we stop ships

from losing power?

Assuming that we can't
stop ships from losing power,

how do we stop them
from hitting things?

Assuming we can't stop
ships from hitting bridges,

how do we stop them
from falling down?

NARRATOR: To
answer this question,

the team must study
the structure of the bridge

to understand how it collapsed.

♪ ♪

The critical structural
element that allowed

the Key Bridge to reach
all the way across the river

was its massive truss,
a lattice of steel beams

arranged in triangles that
made it light yet strong.

Spanning 1,200 feet,

it was the third longest
continuous bridge truss

ever constructed.

But at this extreme length,

it would have buckled
under its own weight

without support.



It needed two large reinforced
concrete piers to hold it up,

dividing it into
three shorter spans.

The Key Bridge was a
feat of structural engineering

but it had a
fundamental weakness.

♪ ♪

AGHAYERE: If you take
away a critical element,

you lose that equilibrium and
the structure is gonna collapse.

NARRATOR: With one of the
main support piers destroyed,

the bridge cannot
span such a distance,

and begins to break apart.

These two span becomes one span

for which this bridge
was not designed.

You can see separation
happening at the bottom.

The collapse is
progressing, actually.

And that part is gonna separate,

and you can see
it's breaking off

because of that tension.

NARRATOR: Without the rest
of the truss to hold it in tension,

the remaining span
becomes unbalanced

and collapses
under its own weight.

AGHAYERE: A typical progressive

collapse, uh, scenario.

♪ ♪

Let's take a test run
on this bridge right now.

♪ ♪

NARRATOR: When the Francis
Scott Key Bridge was opened in 1977,

a failure on this scale must
have seemed impossible.

But back then, the
largest container ships

were less than half
the size of the Dali.

So the main piers
of the Key Bridge

were built with concrete
and timber fenders,

designed to absorb the
impact of ships at the time.

AGHAYERE: There's no way
that they could have envisioned

that it would be a


striking the bridge.

REPORTER (voiceover):
So I've just completed

the maiden voyage
for NewsWatch 2

across the Francis
Scott Key Bridge,

and starting Wednesday
at 10:00 A.M.,

you'll get your chance.

♪ ♪

SAL MERCOGLIANO: We move more goods
today than at any time in our history.

The problem you
have is that ships

have gotten bigger and larger,

and the infrastructure
has not kept up with them.

Lifespan for bridges
is about 75 years.

Ships on the other
hand can last anywhere

from 20 to 30 years,

and so two to three different
generations of ships can happen

during the lifespan
of just one bridge.

Infrastructure can't change

as fast as shipping can change.

AGHAYERE: The
force from the Dali

was huge.

It was a huge, huge force.

NARRATOR: The
ship's enormous mass

acts as a multiplier
of its velocity

to devastating effect.

AGHAYERE: There's
truly no bridge that I know

that would be designed

for 34 million pounds
of impact force.

So it's not surprising
that it went down.

What is surprising is that
there was no protection

of those piers.

This could have been prevented.

♪ ♪

NARRATOR: Five
days after the collision,

four construction
workers are still missing.


trapped in the port,

many more unable
to get into the port

are diverted as far south

as Brunswick, Georgia,
over 700 miles away.

The sonar scans reveal that huge
sections of the collapsed bridge

are anchored deep in
the mud on the riverbed.

This will make the task

to remove the
wreckage even tougher.

Engineers bring in 22
massive floating cranes,

some urgently reassigned
from other jobs 130 miles away.

These cranes can
lift up to 500 tons.

But even that isn't enough.

BIANCHI: Some of those pieces

were more than a thousand tons.

NARRATOR: They must risk
destabilizing the tangled mess

by cutting the
massive truss sections

into more manageable pieces.

BIANCHI: So we kind
of had to figure out

how many bites
do we have to take

out of this large structure
that's underwater?

How do you eat an elephant

one bite at a time?

NARRATOR: But each bent steel
beam holds a potentially lethal surprise

for the workers about
to cut through them.

They're loaded with
enormous stored energy,

just like compressed springs.

SKIPPEN: As we started
cutting and removing

the first sections of steel,
it was really challenging

to figure out where
the energy was stored

in different members
and how they would react.

BIANCHI: That stored
energy of the bridge,

I like to describe
it like taking

a metal Slinky

that has all that energy

that wants to come like this,
but it's held with the steel.

When you cut that,
all the energy is free

and it'll break apart like that,

and sometimes it's very
dynamic and dramatic.

PINCHASIN: We have people,

crane operators,

operating very
close to this massive

Jenga, pick-up-sticks,
loaded spring of a problem

where members are being cut

and then they spring back.


water splashing)

It's very dangerous.

SKIPPEN: It'll certainly
make your hair stand up

on the back of your neck

seeing the steel drop

as you're making cuts.

♪ ♪

NARRATOR: To speed
up the job and lift out

the biggest sections of bridge
possible, the team calls in

the largest floating
crane on the East Coast.

The Chesapeake


up to a thousand tons.

BIANCHI: You're not just dealing
with weight, you're dealing with

all the forces that are
working against you.

There were days
where we were battling

specific sections
due to mud suction.

You have this force
that wants to keep it

sucked down in the mud

and you're trying to
apply a force that's coming

opposite of that, so you have
to break that suction force.

And then as you're
coming up out of the water,

you have all this
material just hanging off,

dangerous road
bed, rebar and stuff.

We had to get under
there with small boats

and torch cut and get
that off of the structure.

So from start to finish,

just a very inherently dangerous

world that we live in.

♪ ♪

NARRATOR: The salvage team

hopes to recover
the bodies of the four

missing construction workers

as they remove the
layers of steel and concrete.

PINCHASIN: To get
out onto the water,

you go past the memorial,

you see all the flags
from their home countries

and the people that
are gathered there,

the families that
were gathered there.

When anyone was recovered,

everything stopped,
it was a very

solemn and respectful moment.

We were able to then
return those people

to their families.

♪ ♪

♪ ♪

NARRATOR: The
complexity of the salvage

leaves Baltimore's main shipping
channel completely blocked

more than three
weeks after the collision.

Hundreds of ships
are unable to dock.

To get shipping moving again,

engineers open three temporary
channels for smaller vessels...

to restore around 15% of
commercial shipping to the port.

The next priority is to
clear a 300-foot-wide section

of the deeper main
shipping channel

that will allow single lane
traffic for larger vessels,

and restore around 70%
of shipping to the port.



It takes almost four weeks to
haul this wreckage from the mud.

PINCHASIN: When they
opened the limited access channel

and you saw the
scale of the ships

that we were able to bring in

we just knew that we
were getting one step closer

to bringing Baltimore
back to full functionality.

NARRATOR: But this access channel
creates another challenge for the team.

Larger vessels disturb
the water so much,

that the Dali could
start to rock and roll.

There's a risk the
vessel could break free,

swing around and
block the channel again.

The team urgently
needs to stabilize the ship,

so they pump water into
the ballast tanks at the front

to weigh down the bow
and lock it into the riverbed.

To secure the stern, they
drop four massive anchors,

and they send in powerful
tugboats to restrain the Dali

should the ship
break its chains.

As the team races
to secure the vessel,

they must also devise
a plan to remove

the 5,000-ton truss

resting precariously
across the bow.

The bridge section on the Dali

was very unstable.

There was bolts falling off
it, pieces of seal falling off it.

Taking care of the
truss on the ship

was gonna be
challenging and dangerous.

NARRATOR: The cost
of the port shutdown

exceeds $15 million a day.

And this is not

the first time in America that
a ship colliding with a bridge

has led to catastrophe.



An incident more
than 40 years earlier

highlights the
vulnerability of bridges,

but also shows how to
protect them from ship strikes.

In 1980,

a freighter called
"Summit Venture"

brought down a section

of the Sunshine
Skyway Bridge in Florida.

ACCIDENT SURVIVOR: And as I
came to the very top of the bridge here,

I saw the rest of
the bridge was out

and applied the
brakes immediately

and I stopped within
about two feet of going in.

NARRATOR: But 35 people
lost their lives in this tragedy.

♪ ♪

The new bridge was built
with engineered islands

to protect the main
piers from ship collisions.

Vast underwater
pillars called "dolphins"

guard the piers that
hold up the roadway.

AGHAYERE: Dolphins, they are
really anchored all the way down

into the seabed and
filled with concrete,

so they are massive,
they're not pushovers.

They dissipate the energy
and bring the ship to a stop.

NARRATOR: After 1991,

all new bridges had to
be built with pier protection.

Bridges built before then

were not required
to be protected.

They were kind of

just left alone.

So that's why a bridge like
the Francis Scott Key Bridge

was left unprotected.

♪ ♪

NARRATOR: But
retrofitting pier protection

to older bridges is possible.

Operators of the
Delaware Memorial Bridge,

which opened in 1951,

decided to spend $93 million

to install eight new dolphins.

It would cost almost
$2 billion to replace

the Delaware Memorial Bridge
in the event of a collapse...

more than 20 times
the cost of the dolphins.

In the 1970s, the Key Bridge

was built with four dolphins,

but they were all
positioned over 400 feet

from its main piers.

AGHAYERE: The dolphins
were so far away from the piers

that they were basically useless

in terms of
protecting the piers.

I believe that if you had

dolphins, closer up dolphins,

protecting the Key
Bridge, that direct hit

from the Dali would
not have happened.

The ship would be damaged,

but the bridge would
have been spared.

The lives would
have been spared.

Maritime law is
written in blood.

We tend to wait for an
accident to take place.

It took Titanic's sinking

for us to come up
with a convention

that mandated enough
lifeboats onboard.

It's because we can't
imagine something as bad

as what happens with
Dali ever happening.

♪ ♪

NARRATOR: Since the Francis
Scott Key Bridge opened in 1977,

thousands of ships have
passed safely underneath.

But this disaster
had been foreseen.

Between 2006 and 2016,

meeting notes reveal

that Baltimore's Harbor
Safety Committee

discussed the need
for the Key Bridge

to be protected
from ship strikes.

There were people
really stressing that

there needs to
be pier protection.

You could have ships
lose electrical power,

and if they lose
electrical power,

they could drift

and, and hit the piers.

But the issue of cost

is discussed, and it seems crazy

but nothing was done.

There was a real opportunity
to prevent what happened.

NARRATOR: The Dali
is not even the first ship

to strike Baltimore's
Key Bridge.

On August 29, 1980,

a 400-foot-long cargo ship

also lost power leaving port,

and slammed into the same pier

that the Dali would hit
over four decades later.

REPORTER: Here's where
it happened, a Japanese ship

called the Blue Nagoya

was heading south
out of Baltimore Harbor

when it rammed right into
Key Bridge; as you can see,

it tore off about


and damaged part of the
bridge's support structure.

NARRATOR: The Blue
Nagoya was a large ship for 1980,

but it was only

about a third the
size of the Dali.

Even so,

the ship caused half-a-million
dollars' worth of damage

to the Key Bridge.

AGHAYERE: The fender
was badly damaged,

and had to be replaced,

so that was a warning sign.

It was something that they
knew had happened before.

So if it had happened before,

the probability that
it will happen again

was always there.

NARRATOR: But the damage the
Dali would cause on March 26, 2024,

was completely unprecedented.

♪ ♪

That morning, the ship
was on the correct course

to sail directly between
the main piers of the bridge.

♪ ♪

So what caused it
to veer to the right

and head straight
for the bridge pier?

The ship's data recorder reveals

that Dali lost power
at 1:25 in the morning,

and started to drift rudderless

at nine knots.

At that time, the
vessel was sailing

closer to one side of
the shipping channel,

possibly causing
pressure differences

along the ship's hull

that may have pushed
the bow to the right.

At that precise moment,

the ship passes the
mouth of a river tributary,

whose currents may have
pushed the stern to the left

and set the ship on a collision
course with the bridge pier.

With no propulsion
to correct its course,

the 124,000-ton juggernaut
was only seconds from disaster.

MERCOGLIANO: If they lost power




you probably don't
have the collapse

of the Key Bridge.


may have side swiped the pylon,

it may have gone
aground inside the bridge.



it may have coasted under
the bridge and not hit it.

NARRATOR: It's
now over six weeks

since the Francis Scott
Key Bridge collapsed.

As teams prepare to move

the stranded Dali,
they continue to hunt

for the sixth and final
missing construction worker.

PINCHASIN: The
recovery never stopped

until every single
person was found.

♪ ♪

NARRATOR: Finally, with most
of the mangled mass of steel

out of the way,

they must remove the
truss pinning down the Dali

so they can tow the vessel away
and clear the shipping channel.

This will be a huge challenge.

There's so much pressure,
compressive pressure,

on the beam from
how it's laying;

that's very dangerous if
you have someone in the way

and all of a sudden
it's gonna give way.

So the best thing to do

is to remove the human
from the equation.

Using controlled
demolition was the fastest

and safest way to conduct

that many cuts, all
at the same time.

NARRATOR: Workers
makes cuts at strategic points,

but do not fully
sever the beams.

Then they insert
specially shaped charges,

expl*sives that create
high velocity jets,

to slice through the steel
and complete the cuts.

The charges must now explode,

so the 5,000 ton truss section
falls safely away from the ship.

♪ ♪

It's now seven weeks
since the disaster.

The Dali's crew continues

to assist with
the investigation,

and visa restrictions
still prevent them

from leaving the ship.

With safety measures in place,

they are moved to the
stern, away from the blast.

This is a critical operation

engineers have been
meticulously preparing for.

But have they
thought of everything?

Are all their
calculations correct?

BIANCHI: Blast day was set.

The time was set.

We had a blast radius,
so we had to stay out,

outside of and you know,
a safety zone set up.

♪ ♪

O'CONNELL: We were
telling people it wasn't gonna be

as you see in the
movies, a big expl*si*n.

But at the end of the day,

it turned out to be a
pretty big expl*si*n.



BIANCHI: Feeling the boom
and then seeing it fall in the water,

it was pretty magnificent,
it was, it was pretty cool.

I mean,

I, I've never seen
anything like it before.



♪ ♪

But then I was thinking,

"All right, what
do we have to do

to go get this, like,
out of the water?"

♪ ♪

NARRATOR: Finally,

after eight weeks of cutting

and lifting wreckage
from the river,

they free the ship
from the metal.

They pump water out
of the ship's ballast tanks

to help raise the
Dali off the riverbed.

♪ ♪

And that's when she came free,

and floated up and we
were able to pull her off.

♪ ♪

NARRATOR: A fleet of


helps haul the ship away
from the devastated pier.

♪ ♪

♪ ♪

Finally, 11 weeks
after the accident,

the salvage team removes

the last of the wreckage,

fully restoring shipping
to the Port of Baltimore.

BIANCHI: Seeing
the first deep draft ship

come through that channel,

I felt like there should have
been fireworks behind it;

you know, it was an
accomplishment for everyone.

NARRATOR: This
highly coordinated,

complex salvage operation

clears the way for the
Port of Baltimore to reopen.

It costs over $100 million
to clear the wreckage,

and it could cost
almost $2 billion more

to replace the Key Bridge.

A number of lawsuits
against the Dali's owners

allege that poor
maintenance and cost-cutting

cause the ship to lose
power and hit the bridge.

The ship's owners
reject these allegations,

but if upheld,

maritime insurers
estimate that the total claims

could approach $4 billion.

Ever since the crash,

the National Transportation
Safety Board's

lead investigator, Marcel Muise,

has been working to
find out what caused

the Dali to lose power.

His team has now
released preliminary reports

that suggest how a
series of unfortunate events

may have led to this tragedy.

MUISE: Why the ship
lost power is absolutely

the focus of the investigation,
we want to prevent

this from happening again.

Ships are complicated.

They need electrical power

to run a variety of systems,

including propulsion

and steering and navigation.

♪ ♪

NARRATOR: The investigation
reveals that on the night of the crash,

the Dali was running two
of its four power generators.

Together, they produce
over eight megawatts

of electricity to power
nearly everything on the ship,

including the fuel and water
pumps for the main engine

and the hydraulics of
the steering mechanism.

MERCOGLIANO: Ships generate
a great deal of electricity to run,

and much like your own house

where you have circuit breakers

to ensure that if there is
a disruption or a problem,

they'll trip, ships
have them too.

NARRATOR: The investigation
discovers a loose cable,

which lawsuits claim
was shaken loose

by engine vibrations,
causing a power surge

that tripped two breakers,

disrupting the
electrical power supply.

The system should have
automatically switched

to a secondary circuit.

But lawsuits allege the
control was set to manual,

so did not automatically switch,

causing a blackout across
large parts of the ship.

The pumps required
to run the main engine

and the steering all shut down,

which k*lled the propulsion
and locked the rudder in place.

♪ ♪

MUISE: When they were about

three ship lengths
away from the bridge,

the ship lost power.

MERCOGLIANO: Having sailed for
many years on a ship, I can tell you

that the worst
sound you ever hear

on a ship is silence.

When everything
goes quiet and dark,

it is the worst feeling because
at that moment you realize

you don't have control
of the ship anymore.

It is a nightmare,

a nightmare scenario
to be up on a ship

when it loses power
in close quarters.

You have a very short
period of time in which

to try to restore power.

From the time period
that Dali lost power

till it hit the bridge
was four minutes.

NARRATOR: A small
emergency generator kicked in,

and the crew closed
the tripped breakers.

Lighting came back on,

but the engine
was still offline.

MERCOGLIANO:
When the ship goes dark,

the main propulsion engine
of the ship also cuts off,

it's not getting the fuel,
the lube oil, the water.

You basically have
stalled that engine.

NARRATOR: But before
the crew had a chance

to restart the engine, there
was a second blackout.

Investigators discover

that the generators
caused this outage.

One lawsuit claims that
after the first blackout,

the pump supplying the
generators with fuel shut down,

and even when the
power came back on,

this pump did not
restart automatically.

The generators would then
have lacked fuel pressure,

which could have caused
them to run erratically,

creating power fluctuations
that trip the breakers

and cause the ship
to go dark again.

They never were able to
get propulsion going again.

After the second blackout,

the ship was about


away from the bridge.

NARRATOR: The timing of the
blackout was exceedingly unlucky,

but the blackout itself
was far from unusual.

Ship blackouts happen
surprisingly frequently.

On average, over five
large vessels lose power

every week in the U.S. alone.

Fortunately, few of
these result in collisions.

MERCOGLIANO: Most of the
time these blackouts occur at sea,

when the ship is
sailing out in the ocean.

It takes a bit of time to
find the underlying cause

that is creating the fault.

And as Dali was approaching
the Francis Scott Key Bridge,

the one thing that crew did not
have was time on their hands.

NARRATOR: The Dali's log
reveals that in a last ditch attempt,

the crew tried to power
up the bow thrusters

and drop an anchor.

But the thrusters were offline.

And the break to
lock off the anchor

could not be applied.

MERCOGLIANO: By the
time the anchor was dropped,

they were coming up
on top of the bridge,

the crew member on
the bow had to evacuate

before Dali hit the bridge.

The ship slowly
drifted to starboard,

and they contacted
pier 17 of the bridge.

♪ ♪

NARRATOR: The NTSB's
preliminary report reveals

the night of the accident

was not the first time

that the Dali had
experienced blackouts.

The day before,
while still in port,

the ship lost power twice.

This resulted in power being
rerouted to a second circuit

which had not been
used for months.

This is the circuit
with the loose cable

that's alleged to
have possibly caused

the fateful blackout
the following morning.



This loss of electrical power

triggered a cascade of disasters

that affected the lives
of countless people.

None more so than
the construction workers

who were fixing potholes

on the Key Bridge that night.

♪ ♪

MOORE: I know the journey
of healing for Baltimore

is gonna be a long road.

Uh, I, I know that for those
families who lost individuals,

this is a burden they will
feel for the rest of their lives.

NARRATOR: Six lives
were lost in the collapse

of the Francis Scott Key Bridge.

But the accident could
have been far worse.

MERCOGLIANO:
You have to remember,

this didn't happen during
rush hour in Baltimore

when that bridge

has hundreds, if not thousands
of people going over it.

♪ ♪

NARRATOR: When
the Dali first lost power,

one of the ship's pilots
put out a distress call.

Maryland Police were
controlling traffic around a lane

closed off for the roadworkers,

so quickly began to
shut down bridge traffic.

Cars would have kept coming,
had they not stopped traffic

and by the time the
people driving the vehicles

would have realized
the bridge was gone

it just would have
been too late.

I can't tell you how
many lives they saved,

because the answer's countless.

NARRATOR: The last moving
vehicle cleared the bridge

just 40 seconds before the
Dali brought it crashing down.

POLICE OFFICER: We got a call,

I mean, like, probably a minute

if that, before it hit it.

NARRATOR: Unfortunately,
the police were unable

to reach the
construction workers

to warn them of the danger.

♪ ♪

NARRATOR: The
Francis Scott Key Bridge

only stood for 47 years,

but saw profound
changes to shipping.

MERCOGLIANO: In 1977,

very few people foresaw
a ship the size of Dali.

What we've seen is
kind of the exponential

increase in the amount
of goods we move by sea.

Bridges and safety
measures have to keep pace

with the way we're
changing ocean shipping.

NARRATOR: An
estimated 2,500 U.S. bridges

remain at risk of ship strikes,

including the 72-year-old
Chesapeake Bay Bridge,

just 20 miles
south of Baltimore.

AGHAYERE: We can't let
our old bridges be sitting ducks.

We can't just leave
them unprotected.

Structural pier protection,

having tug boats lead the ships,

but doing something,

not just sitting and waiting

and hoping that nothing happens.

NARRATOR: The National
Transportation Safety Board

has been calling
on the Coast Guard

and the Federal
Highway Administration

to review the adequacy of
bridge pier protection since 1988.

♪ ♪

Now, an urgent assessment
of ship collision risk

is underway across the nation.

It's possible that
recommendations will include

vast investment to
safeguard the country's bridges.

And in the end,

many hope the lessons learned

from the tragic loss
of the Key Bridge

will not be forgotten.

♪ ♪

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