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...

An icon of France goes up in flames...

...but the fire goes undetected.

Scaffolding... putting workers face to face with their work...

...and sometimes our mortality.

When the earth shakes, things fall down...

Is there such a thing as an earthquake proof building?

Construction...

a dangerous business at the best of times...

... but when things get really bad, timing is everything.

April 15, 2019.

Inside, Notre Dame cathedral in Paris...

The six o'clock mass is underway.

Outside, Notre Dame cathedral is on fire.

The citizens of Paris stare in shock

as their 850-year-old church burns.

Around the world, people watch in real time

as an icon of France goes up in smoke.

It's one of the darkest days in the City of Light.

The fire started just before 7pm local time.

In less than one hour, the roof was engulfed in flames.

The church's iconic spire, 460 tonnes of wood

and 226 tonnes of lead, was next.

The cross that had stood 90 metres over Paris

for centuries...

dropped into the heart of Notre Dame.

The collapse of the spire was like a bomb

dropping into the inferno.

The detonation slammed shut all the cathedral doors,

and destroyed several stone vaults in the nave below.

500 firefighters were on the scene.

Inside the Northern Tower, eight giant bells

hung precariously on wooden beams

that threatened to burn.

If the beams collapsed, firefighters feared,

the falling bells could act like wrecking balls

and destroy the tower.

If the northern tower fell, the firefighters believed

it could bring down the south tower,

and the cathedral with it.

France held its breath...

By 9:45, less than three hours after it began,

the fire was under control.

Notre Dame was not lost...

...but the cathedral's roof was gone...

...and the Paris sky had a toxic plume of lead smoke.

The next day as the city awakened

to the reality of its damaged icon...

...one question was on everyone's lips:

What went wrong?

So began the greatest fire investigation

in the history of the French Republic.

The church's roof had been under extensive renovations.

Scaffolding reached 30 metres into its rafters.

Inside the vast wooden web that supports the roof,

an array of equipment presented every kind of hazard.

Power tools and welding equipment

were in constant use.

Could a spark have ignited the 850-year-old wood?

Or was it a cigarette?

The contractors admitted workers had been smoking

against regulations.

But the company denied a cigarette

had caused the conflagration.

It didn't help that the fire started

in an almost inaccessible part of the roof.

But there was another question:

Why did the fire go undetected for so long?

The answer is part history,

part preservation.

One expert said, "The only thing that surprised me

is that this disaster didn't happen sooner."

Modern buildings are designed with fire prevention

and control in mind.

But Notre Dame was completed three hundred years before

France's first fire brigade was established.

Maintaining a building this old

is an expensive and continuous task.

According to news reports, there were conflicts

over who should pay for the cathedral's upkeep.

Urgent maintenance issues had been allowed to mount...

...especially in the attic.

Although the cathedral appears to be made entirely of stone,

its structure is supported by timber.

The attic, famously known as the forest

because of its long oak beams,

had accumulated a dangerous amount of flammable dust.

The wood itself, harvested from 5000 oak trees,

was tinder dry.

It was a fire waiting to happen.

Then there's the matter of historical preservation.

You can't just stick a sprinkler system

into the ceiling of a 850-year-old building.

But you can add smoke detectors.

And Notre Dame had one of the most extensive

and complex fire detection systems in the world.

The fire detection system worked.

A light blinked on a panel.

But the response to the alarm did not work.

The employee monitoring the alarms

had been on the job for only three days.

His replacement had not reported for work.

So the employee was on his second eight-hour shift.

It gets worse.

The fire detection system misled the employee.

A single warning light alerted the fire security employee

that there was a fire in the attic...

...he radioed a church guard to go check

if there was a fire...

...it remains unclear who got the message wrong,

but the guard went to the attic in another building

and radioed the all-clear.

The fire security employee

still didn't alert the fire department...

...instead he called his supervisor

who called the guard and told him

to go to the main attic.

By the time the fire department was alerted,

Notre Dame's 850-year-old timbers were burning.

Ironically, the church was being restored

when the fire started.

Now Notre Dame must be rebuilt.

Experts say the restoration could take ten years

and cost a billion dollars.

To this day, there is no definitive answer

to what caused this catastrophe...

but one thing is certain:

An overly complex fire detection system

and human error burned up valuable

time where firefighters could have brought the blaze

under control.

850 years of history destroyed in less than two hours.

The system designed to protect the church

actually led to its incineration.

Scaffolding.

It's the building around buildings.

It's a portable, easily put-up-able,

surprisingly supportable structure

that puts workers face to face

with their work...

...whatever the height.

Scaffolding comes in every shape and size.

Vast webs of tube and coupling

climbing hundreds of metres.

Easy to put up, scaffolding is a crucial component

of maintenance and renovation.

But when scaffolding fails,

you sure don't want to be on it.

Or under it.

August 2019.

Reading, England.

A derelict shopping centre was set for demolition.

Huge sheets of durable plastic...

...enveloped a city block of scaffolding.

At 11:15 AM the residents heard

what sounded like a crack of thunder as the scaffolding,

rained concrete debris onto pedestrians below.

First responders dug through the rubble,

to search for buried victims.

Miraculously, there were only three minor injuries.

So, what went wrong?

Did the scaffolding take the building down?

Or was it the other way around?

Scaffolding is a light-weight grid of hollow tubes

connected to each other with couplings.

It's designed to support the people

and their equipment working on the exterior of the building.

It's not designed to support the building.

Scaffolding is strong...

...but not that strong.

On the British territory of Gibraltar,

a powerful wind took hold of the plastic

wrapping this highrise...

The wrapping yanked the scaffold poles from their moorings,

plunging them 18 floors onto the cars below.

But there was no wind in Reading

on the morning of the accident.

Scaffolding can fail from the bottom up...

If you're setting up on an uneven surface,

base plates distribute the weight.

Without them, just standing on the platform

becomes a balancing act.

Scaffolding is movable.

But not when someone is standing on top of it.

In one terrifying moment

this guy went from construction worker to stunt man.

He probably wants his old job back.

Even if properly installed,

a scaffold can easily get overloaded,

and hit the street.

But the Reading scaffold was erected

on a stable surface, a sidewalk.

Investigators have yet to determine

what caused the mess in Reading...

But it's likely the weakened building collapsed

and took the scaffold with it.

While scaffolding continues to be an essential tool

in construction,

there's growing concern about using scaffolding

for demolition.

The web of pipes and platforms surrounding a building

give passers-by a false sense of security.

So best to watch your step - and keep an eye out.

Because walking under a scaffold

could turn out to be very bad luck.

It's true some people are handy.

These people are not.

When it comes to DIY a positive attitude

is no substitute for skills or smarts.

Which begs the question: DI - why didn't they hire

a professional?

This wannabe handyman really wants to help out.

But if there's nothing broken there's nothing to fix.

Problem solved.

It's nice to keep an eye on your employees

while they toil away in the office.

You wouldn't want anyone to take advantage of you...

by just hanging around.

When using a public facility you want your privacy.

This stall is double locked for double security.

Hopefully the same handy person didn't install

the toilet you're sitting on.

Nobody's telling you what to do -

but maybe if you plugged it in you wouldn't need the hammer.

Everyone knows that a basement is prone to flooding...

But usually the flood is caused by water...

Not concrete.

Did I forget to turn off the gas?

Lock the door?

Oh. That's right.

If you are going to do it yourself,

the first thing you want to build is confidence.

And that's all there is to it.

[Narrator] Here's a tip.

Maybe wait to share your wisdom...

Normally it's pretty simple.

[Narrator] ...until you have enough to go around.

Earthquakes.

No other natural phenomenon has such a devastating impact.

When the earth moves, everything moves with it.

Walls can peel off like a layer of paint.

The ground beneath us is constantly shifting.

On any given day, there are 50 measurable earthquakes

around the world.

That's more than 18,000 earthquakes a year.

Yet earthquakes don't generally kill people.

Collapsing buildings and bridges are the killers.

In April of 2017, an earthquake

measuring 6.9 on the Richter scale

shook the Chilean city of Valparaiso.

Six months later, a magnitude 7.1 quake

destroyed buildings throughout Mexico City.

What went wrong?

Why do some buildings remain standing

when others fall down?

Standing structures are designed to resist

a force of gravity...

A vertical force.

But the rolling waves of an earthquake

exert extreme horizontal forces.

Such sudden horizontal movement puts enormous stresses

on a building's structural elements...

...beams, columns, walls and floors,

and the connectors that hold the pieces together.

If those stresses are large enough,

the building can collapse or suffer so much damage

it has to be demolished.

Earthquakes are strongest

where the earth's tectonic plates meet.

These fault lines run all around the world.

But they tend to be strongest along the coasts

of the Pacific Ocean, east and the west.

And yet...

In 1989, a magnitude 6.9 quake hit San Francisco.

But the 48-floor TransAmerica Pyramid sailed through.

During the earthquake the tower shook for more than a minute.

The top floor swayed side-to-side nearly 30 cm.

But the building sustained no structural damage.

So, what went right?

Why did this building stand when other buildings collapsed?

The TransAmerica Pyramid rests on a 16 metre deep foundation

of concrete and steel designed to move with the earth

during a quake.

Across the Pacific Ocean but in a different seismic hot zone,

another earthquake-resistant building is even more advanced.

More than 500 metres high, Taiwan's Taipei 101 tower

is not the world's tallest building.

But it may well be the sturdiest.

Between the 88th and 92nd floors,

a 660-tonne sphere acts as a sway damper.

If the building starts to sway,

the giant sphere counteracts the motion.

And if the earth quakes beneath the damper sways against it.

Huge pistons act like the shock absorbers in a car.

Most damping systems are concealed

but this one is a tourist attraction.

Taipei is built over a tectonic fault line.

San Francisco is built over a fault line.

In fact, that same fault line that shakes San Francisco

runs south under Mexico City

all the way down the Pacific coast of South America...

Under Valparaiso, Chile.

Why do cities on the same fault line

have such different earthquake experiences?

According to the Global Disaster Preparedness Center,

Mexico and Chile are both lagging

in their infrastructure upgrades.

Neither Mexico City nor Valparaiso

has the same level of earthquake resistance

as San Francisco.

The entire wall of this building dropped

because it was not fastened

according to international standards.

Even with all the advances in technology

there is still no such thing

as an earth-quake proof building.

Ironically, when the earth moves,

the building should move with it.

When you put heavy equipment in the hands of fate

there's a chance you're going to land

in destiny's cross hairs.

Close calls and near misses can turn a good day

into a bad day.

But look on the bright side.

It could've been your last day.

This worker was sent to dismantle this crane.

He figures it should take about...

...this long.

That's one way to downsize from a standard to a compact.

The driver looks around wondering if he's still

in this world or the next.

One thing's certain: a freak accident like this

could never happen....

...twice.

With precision timing and perfect aim

this heavy duty pipe comes down like a giant pool cue...

...and sinks this car in the corner pocket.

You can just drop me off here.

It's hard to tell if the passenger

deliberately bailed out

or if the door flung open and tossed him out.

Either way it was good luck he wasn't wearing his seatbelt -

or he'd be sitting under that crane right now.

Hey that little bundle of sticks fell over.

Which is not what you guys

should be worrying about right now.

This crane operator

was in the middle of a rescue mission

when things started to go sideways.

He takes a flying leap to safety

just as the monster crane

take a header down the hillside.

When this crane comes out swinging

semi-fast reflexes keep this guy from getting hooked

and hospitalized.

It's a miracle it didn't scratch his shiny new car.

Now that would've been a real disaster.

Sometimes a fraction of a second or scant centimetres

can make the difference between tragedy and comedy.

But these folks barely got out with their lives.

And that's no laughing matter.

Or is it?

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