All language subtitles for NOVA.S52E06.Baltimore.Bridge.Collapse.1080p.WEB.h264-BAE_track3_[eng]

♪ ♪

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.

(helicopter whirring)

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.

2,000 vessels dock 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

1.7 miles across the bay.

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.

(chuckles):
But it's so much more than that.

It's our skyline.

The backdrop for Baltimore.

♪ ♪

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

12 ships are docked in the port.

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,
947-foot-long ship.

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 4,700
containers,

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.

50,000 tons of debris
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.

50,000 tons of mangled 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.

(respirating)

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.

(respirating)

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.

(metal buckling)

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.

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 100,000 ton ship

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.

11 ships are 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.

(metal scraping,
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 1000 is capable
of lifting

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.

(seagulls squawking)

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.

(helicopter whirring)

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.

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 30 feet
of planking

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

30 seconds earlier,
30 seconds later,

you probably don't have
the collapse

of the Key Bridge.

30 seconds earlier, the ship
may have side swiped the pylon,

it may have gone aground
inside the bridge.

30 seconds later,

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,

explosives 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 explosion.

But at the end of the day,

it turned out to be a pretty big
explosion.

(explosion booms)

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.

(explosion booms)

♪ ♪

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 5,000
horsepower tugs

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 killed 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 1.6 ship lengths

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.

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.

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.

(electricity buzzing)

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,

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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