Original subtitles

[Narrator] Construction. Heavy machinery.

Tight schedules. Millions at stake.

What could go wrong?

Everything.

Whether it's faulty equipment, poor design, human error...

or just bad luck...

These are...

Construction Fails.

In this episode...

A new Hard Rock Hotel in the Big Easy...

Turns construction into destruction.

Water towers...

Local town landmark?

Or disaster waiting to happen?

Wall of destruction!

Why some walls are not built to last...

In Denmark, a silo demolition that truly goes sideways.

New Orleans - a city known for its food,

festivals and culture.

Every year more and more tourists visit the Big Easy,

and the city has responded with a construction boom.

In the city's French Quarter the $85 million Hard Rock Hotel

was slated to open just in time for Mardi Gras...

but on October 12th, 2019

construction turned to destruction...

when it suddenly collapsed.

The upper floors of the building

began to fall into each other...

before one side of the building plummeted to the ground.

On the day it collapsed more than 100 workers

were forced to flee the building.

Dozens were injured, and three were killed.

While firefighters searched inside,

another danger loomed large outside.

The collapse left two tower cranes balancing precariously

on the top of the construction site.

One dangerously cantilevering 80 metres in the air -

directly over the street.

The site had to be secured.

The first priority: remove the ominous cranes.

And with the added threat of an approaching tropical storm -

they needed to come down...

fast.

The plan: place explosives at 3 points on each of the cranes.

The goal: the cranes fold into their bases

and fall onto the debris within the site.

On the day things began on a hopeful note.

The storm changed course at the last moment,

avoiding New Orleans.

The area evacuated,

The explosives were planted,

and the detonation set...

It was seen for kilometres,

it echoed through the streets.

Exploding as planned: It was an incredible sight...

The blast dropped the boom and counterweight

of each 90-meter-tall crane

before breaking each tower halfway up.

However, it was not a flawless job...

While most of the smaller crane

fell into the building wreckage;

its arm was left dangling over the street.

Part of it hooked into the debris

stopping it from falling

and was later lashed to the building

with wire to secure it.

Worse yet, the upper section of the taller,

more damaged crane flipped...

and fell like a lawn-dart into the street below.

Fortunately, this caused no injuries or serious damage.

With the cranes no longer a danger,

attention turned to this massive construction fail.

The Hard Rock hotel had collapsed

before it was even finished.

So, what went wrong?

New Orleans experienced a drop in temperature

the day before the hotel fell...

...but the 11-degree swing

shouldn't have been extreme enough

to affect the building materials.

There were rumours of too heavy a load

being placed atop the building.

Even before the collapse, questions had been raised

about whether the temporary shoring supports

were removed too soon.

Had the lack of shoring caused the collapse?

Builders removed temporary support posts

just three days after pouring the heavy concrete

onto the top floor.

And the specifications for this project

called for the building to be shored from top to bottom

as it rose.

But most of the posts were gone from the top floors

when they collapsed - just eight days later.

With the pressure on to open for Mardi Gras,

was the concrete allowed to cure for long enough?

Industry standard states a minimum of two weeks.

In the aftermath, it's been questioned

whether the site was correctly inspected and permitted.

In New Orleans, city inspectors must approve

before concrete is poured on each floor,

which they did at the Hard Rock.

In fact, the concrete on the 18th floor

was poured just three days after a city inspector

deemed it "OK to pour."

However, the New Orleans Department of Safety and Permits

is currently under federal investigation for corruption.

Still, there is presently no evidence

connecting this with the Hard Rock Hotel project.

The concrete floors that gave way were poured

into a different kind - and size -

of metal decking than the city's permitting office had approved.

In large constructions, metal decks are essentially

the moulds that concrete is poured into,

so it hardens into a solid floor.

The city had agreed to seven and half centimetre

standard metal decking, but five centimetre

composite decking was used at the Hard Rock.

More support columns, set closer together,

were also necessary.

But it wasn't just the distance between the columns

that worried the workers inside.

The size of the horizontal steel beams

supporting each floor at the construction's edges

have also raised concerns.

Were the beams too small and too weak

to provide the necessary support?

One side of the building looked like it had melted.

Since the catastrophic collapse,

the City of New Orleans has announced

that nothing will be salvaged,

and the entire building will be demolished.

An official investigation is underway

to determine the reasons the structure failed.

Walls keep the outside out and the inside in.

They form a border between friendly neighbours.

And keep enemies at bay.

Built of bricks and mortar, stone, steel and cement,

walls are an essential part

of a building's support system.

We don't give walls much thought.

Until they come tumbling down.

Why do some walls stand tall for centuries?

While others collapse before the last brick is laid?

Two forces can make up - or break up -

a wall's structural integrity.

Compression is the "vertical stress"

exerted by pressure of the wall's own weight,

forcing it down -

while the ground pushes up with equal force.

So there's more compression on the bottom

than the top of a wall.

The way a load bearing wall holds up the roof.

Or doesn't.

Tension is the "horizontal stress"

exerted by putting pressure on the wall's surface.

The way a retaining wall holds back water or soil.

Or doesn't.

A wall's survival depends on its structural integrity

and how its construction materials hold up.

And that material is often brick.

Sustainable, reliable and durable,

brick has been the go-to building material

for thousands of years.

Bricks are made by crushing shale and clay,

moulding it and baking it into lightweight,

stackable shapes.

Combined with the right mortar and the right technique,

brick walls are durable, weatherproof

and will last a lifetime.

Some of the of the time.

Brick walls need to breathe.

Changes in temperature cause bricks and mortar to expand -

and without expansion joints to relieve the pressure,

bricks flake, and the mortar cracks,

causing the walls to bow and then...

[Voice] Whoa!

[Narrator] And if a wall is off its centre of gravity

because it's leaning on a slanted surface,

that tension will pull at the mortar until the wall snaps,

tilts and topples.

Whether it's the force of physics or the force of nature,

it's wise to remember that walls don't

necessarily hold up forever.

And when something goes wrong -

you want to be on the right side of the street.

Water towers.

Dotting our skylines, proudly proclaiming the names

of towns they serve,

but these ingenious giants

don't just store water.

Their height and simple design helps pressurise and deliver it.

Water demands fluctuate throughout the day -

mornings are busy, but fewer people

are taking showers at 3am.

Excess water from the treatment plant

is pumped into the water tower for storage.

Then when water demands rise beyond what the pump can supply,

the water stored in the tower flows out.

This means regions can buy smaller, cheaper,

water pumps with the tower helping to provide

the extra water and pressure during peak times.

Water towers are usually designed to hold enough water

for that particular town or city for a day.

But when it's time to take them down

it's best to make sure they're empty.

Not all tower collapses go to plan,

and some aren't planned at all.

As they discovered in West Bengal, India

in January 2020,

when a tank holding 70,000 litres

for nearby villages failed.

Locals noticed cracks on the pillar

and informed the authorities, but it fell on deaf ears.

Less than four years after construction -

the tower collapsed

because its foundation gave way.

Could this be what happened in Fredericton Canada?

Midafternoon on December 19th, 1990

the city's brand new water tower had just been filled

for the first time with nearly 2 million litres of water.

But only minutes later the 27 metre high

steel and concrete tower collapsed.

Waves a metre high flooded the streets,

swamping cars.

Windows were smashed,

and basements were flooded.

Residents said it felt like an earthquake

and looked like a bomb had exploded.

So, what went wrong?

The average temperature in Fredericton in December

is -7 degrees Celsius.

Perhaps the water had frozen, and ice was to blame...

But the tower had just been filled for the first time,

so water didn't have time to freeze.

And as water towers are constantly being drained

and refilled, the water inside can't freeze.

Was it filled with too much water?

The water level in towers is regulated by pumping

in clean water from the treatment plant.

Flow is increased when the water level

in the tower is low and reduced when it's full.

This prevents overfilling.

Maybe the pump was faulty...

When water is needed, water pumps use

the pull of gravity to provide high water pressure.

Because they work with gravity, they have to be taller

than the buildings they're providing water for

to reach the highest floors.

The taller the tower, the higher the water pressure.

The pumped had successfully filled the water tower,

but was it just too tall?

Structures on slender supports, like those on water towers,

have a critical buckling load

and the slimmer the supports, the easier they buckle.

Were the supports to blame or was it the tank itself?

In the end, investigators discovered that the steel

at the bottom of the tank was 12 mm thick,

where it should have been twice that.

On top of that, the buckling formula

of the tower was incorrectly calculated.

It was worked out for lighter aerospace steel

rather than construction steel.

The ill-fated water tower in Fredericton

didn't stand a chance.

April 2018 in Vordingborg, Denmark

this 53-metre high silo was slated for demolition.

The silo stood in the harbour for 36 years

and was slated to make way for new development.

The plan was to take out one side

of the obsolete concrete silo,

letting the structure fall safely away

from the nearby buildings.

In the old ferry town, hundreds gathered

with excitement to watch the planned explosion.

Excited onlookers clapped as the explosives went off

and the silo began to tumble as planned,

into the space, prepared for its landing.

However, there was a sudden shift in its path,

as the crowd looked on aghast.

It slowly began to topple and head in the opposite direction -

toward the town's library, music school,

and cultural centre.

This demolition took six months of meticulous planning,

so the question was...

What went wrong?

There are 3 main methods for demolishing chimneys

and silos:

a collapse in the locality,

folding or overlapped collapse,

and directional collapse.

If there is not enough open ground in any direction

around the tower "collapse in the locality" is used.

This is the most challenging method,

especially on structures more than 30 metres high

like the Vordingborg silo.

If there is open ground, more than half the height

of the structure in all directions,

the folding or overlapped collapse method can be used.

But the most popular is the directional collapse.

This method requires open space on at least one side

longer than the height of the structure when it falls.

This was the option chosen in Vordingborg.

There are always risks using explosives,

but how could the "Blasters" have gotten it so wrong?

Were enough explosives used?

Engineers used 10 kilograms of explosives to bring it down,

but as it fell in the opposite direction to the plan,

was that wrong?

Were the explosives used strong enough?

The silo did collapse, just not in the right place.

Could it have been the placement of the explosives

that was incorrect, causing the silo to collapse

into the buildings on the other side?

The Danish Explosives Association

said the detonation was correctly prepared for.

If all the explosives went off as intended,

was it an error in the preparation and calculations?

Just because all the explosives went off as planned,

doesn't mean the plan was right to begin with!

For a successful directional collapse of a silo,

the blasting cut must be accurate -

this is what makes it fall in the chosen direction.

A blasting cut is a wedge

taken out of the structure to weaken it;

in much the same way a lumberjack

chops a notch out of a tree to make it fall.

It is then supported by blocks carrying explosives.

At the Vordingborg silo they had pre-weakened the structure -

but it just wasn't enough.

If the calculations had been correct

and the structure had been properly weakened,

would the silo have fallen where it was meant to?

Building things right in the first place

is the best way to prevent construction fails.

This isn't all about masterful machinery -

it needs the human touch.

This worker doesn't so much "lay" bricks as deal them out

with the flair of a Vegas card shark.

At 2 bricks per second, he can get an entire driveway done

before his back gets the better of him.

This double domino effect isn't just a cool party trick -

it's a super-efficient construction method.

On the way there, each brick tips onto the next,

leaning on its edge so it can't hit the ground.

Until it gets to the last one.

Now there's room for it to land flat,

which opens space for the second to last,

which opens a space for the third to last

and so on until all the bricks

settle neatly into position.

This masonry duo juggles bricks and trowels

in perfect harmony.

It better be perfect, or somebody's

getting a face full of cement.

Here's another construction crew training for the circus.

With strength, skill and coordination

they wheelbarrow their partner along the curb

as he pours and smooths out the concrete.

Hopefully, he didn't have cabbage for lunch.

And these urban acrobats fashion a makeshift pulley system

to get these bags of cement upstairs,

by using themselves as counterweights.

These chilled delivery guys devised a cool slide

to unload heavy slabs of ice before they melt

in the 34-degree Celsius heat.

The blocks whiz down the track for a hook up

with a waiting worker.

These creative warehouse employees have figured out

a fast and easy way to load their truck.

They stretched a long piece of fabric

from the 10th floor factory window to the street below,

dropped the shipment in the textile tube

and let gravity do the rest.

In south eastern China this team of 200 excavators

work together to demolish

a 600 metres overpass in just one night.

And the right team doesn't even need big machinery.

This crew looks like exactly what it is -

a team of individuals working in perfect unison

to build a single, well-run machine.

In the absence of heavy-duty machinery

or costly technology, these construction workers

get the job done efficiently and creatively

with the best tools at their disposal.

Their hands.

And their minds.

♪ ♪