Original subtitles

[Narrator] Construction. Heavy machinery.

Tight schedules. Millions at stake.

What could go wrong?

Everything.

ether poor design,

human error or just bad luck, these are...

Construction Fails.

In this episode...

Controlled demolition blows buildings to bits...

So, why did this Vegas hotel refuse to follow suit?

That sinking feeling:

The ground beneath your feet is not as solid as it looks...

...especially when it's under your wheels.

Why, oh why, do we DIY?

The do-it-yourself spirit hits the wall of human error.

The excavator:

Perfect for digging holes, good at falling into them.

In Las Vegas, things happen in a flash.

One minute you're up...

The next minute, you're down.

And lady luck isn't just for the gamblers

betting it all on a roll of the dice.

The hotels themselves are subject

to the ups and downs of life in Sin City.

As long as developers have built hotels

in this desert oasis,

developers have been knocking them down.

And like everything in this strangest of cities,

even a demolition is a stage show.

Welcome to Las Vegas,

the controlled demolition capital of the world...

...where a 30-story building can disappear

with the push of a button.

Since 1993, 12 hotels have been blown to bits

lled demolition.

Debbie Reynolds' Clarion Casino Hotel

was slated to be lucky number 13.

The Clarion's date with destruction

was February 10, 2015.

In Vegas, controlled demolition is a spectator sport.

The Clarion put on quite a show.

But when push came to shove, an entire section

of the building refused to fall.

So what should have happened?

In a conventional demolition,

there are no explosions.

Wrecking balls smack a building's supporting pillars...

...while giant claws gnaw through walls from the top down.

It gets the job done but it takes time.

And time is money.

A controlled demolition is a special event.

It's an awesome vanishing act.

But like everything that looks easy,

these take-downs are painstakingly planned...

and skillfully executed.

It's a sophisticated combination of timing, physics...

and dynamite...

...Lots of dynamite.

The idea is not to blow a building up -

but to blow it in.

The techniques are adapted from mining,

where precision explosions clear obstructions

and expose rock face...

Just enough boom to get the job done.

The goal is to drop the building into its own footprint -

to avoid falling on the neighbours.

to weight-bearing points explon the structure.

Every explosion produces a shockwave of hot gas,

blasting 4000 kilopascals of pressure.

And shattering the concrete into portable pieces.

This sequence of well-timed detonations

smashes those weight-bearing points to bits

and the building implodes.

The support columns crumble and fall

towards the centre of the building,

collapsing inwards and dropping like a house of cards.

In a 30-storey building like this one,

the demo team might only need blow the columns

on the first and second floor

and the 15th and 17th floor.

That's enough pin-point destruction

to drop it in its place, raining debris as it falls.

Because it's not the dynamite that brings the house down.

It's gravity.

Another Vegas hotel, the Riviera Complex,

with its multiple towers, crumbled on cue.

All the pieces fell in the right place.

[crowd cheering]

So what went wrong with the Clarion?

The blasters did everything to plan.

They studied the blueprints and surveyed the 12-floor hotel.

They targeted key weight-bearing support columns,

boring holes in the concrete

and packing them with 2000 kilograms of dynamite.

It was more than enough TNT to take down the Clarion.

While the rest of the hotel buckled,

the tower housing the elevator shafts stayed upright.

It dropped a bit...

but not enough.

That's because there's more blast-resistant

structural steel in the walls of the elevator shaft

than any other part of a building.

But they knew that.

What the demolition crew couldn't anticipate

was where the debris would land.

As the rest of the hotel collapsed into the centre,

the chunks of concrete piled up at the base

of the elevator column, packing tightly around the base

and locking it in place.

It was not an elegant ending.

The only way to bring the stubborn column to earth

was to pull it down.

The next day, engineers looped heavy duty cable

around the tower, secured it to a crane

d ed on the shaft 'til it gave way.

The Clarion should've been gone in 15 seconds.

Instead it took 13 hours to bring it down.

Did the Master Blasters blow it?

Or was it just plain bad luck?

Either way...

Construction sites are dangerous places.ail.

Tons of material...

Giant machines...

Dizzying heights...

No matter the scal of t j

Workers protect themselves from falling things...

or falling into things.

They wear hardhats, steel-toed shoes

and reflective vests.

Anything they can do to stay safe

once construction begins.

But what if the construction site itself is the accident?

What if the job was wrong from the beginning?

That's what happened in Shenzen, China

in July of 2015.

Crews had begun preparing a site

for a massive commercial development:

a 56 billion-dollar financial district

billed as "The Manhattan of the Pearl Delta".

Anyone can dig a hole.

The key to building a foundation is from falling into the hole.

Once the excavators have done their digging,

engineers construct a retaining wall.

A concrete dam that holds back

tons of surrounding rock and soil.

er wer the hole,

the stronger the retaining wall needs to be.

In Shenzen, the retaining wall was massive.

The size of a city block.

But the surrounding soil was unstable,

it wanted to fall into the big hole next door.

So it did what came naturally...

e rkers heard the trouble before they saw it.

A low rumble like the sound of an oncoming avalanche.

The workers did what everyone does today,

they pulled out their phones and pressed record...

And then moved to a safe distance

to watch the inevitable.

What was once a construction site

looked like the aftermath of a landslide.

use that's what it was.

So what went wrong?

The most likely culprit was what geologists call

'land subsidence'.

And it happens when a foundation is dug in unstable soil.

It happens all the time.

This is a view of a similar site in Nanning, China.

Prolonged rainfall weakened the subsoil deep below.

The massive retaining wall was no match for hundreds of tons

of shifting soil.

What causes land subsidence?

A drop in the water table can cause the subsl

to compact and the earth to shift.

But human activity is often to blame.

For example, when developers build on reclaimed land.

Reclaimed land is new land created with landfill.

But unless it's allowed to set for years,

reclaimed land can be a false friend.

The underlying soil won't have enough time to compact

and gain stability.

That's what happened beneath this railway station.

The solid ground suddenly turned elastic,

creating a landslide that nearly swallowed the building.

In every instance, developers built,

or tried to build on reclaimed land.

AndAnd what was once under construction.

is now back underground.

One mont you are crsitr

minding your own business...

...the next moment, without warning,

the earth opens beneath you.

And you find yourself crawling out of a giant hole.

The sinkhole is a scary reminder

that the streets and sidewalks we take for granted

are not always on solid ground.

It can happen to anyone and anything...

from the minivan...

...to the Rolls Royce.

The heavier the object, the quicker the fall.

It can happen at any time...

...day or night...

The ground disappears...

...and you disappear with it.

Sinkholes come in all sizes,

om the humble pot hole...

...to this monster.

It swallowed a chunk of this city in El Salvador.

It was wider than a football pitch is long

and 70 metres deep.

How can something so devastating happen so easily,

without warning?

Even earthquakes signal their imminent arrival.

The more we dig...

...the deeper we dig...

...the more we build...

the more sinkholes we get.

What we call the ground is in fact a large blend

of component materials,

soil, sand, clay,

rocks and minerals.

When water seeps into the blend,

erosion can slowly move the lighter material,

breaking the bond that holds the earth in place.

This eroding highway is like one half of a sinkhole.

The continuous flow of water washes away the soil base

supporting the road way.

When the structure becomes too weak to support

the surface of the earth, it collapses

and opens up a hole.

Sinkholes form from the bottom

and move up as layers give way.

Ground erodes upwards.

Over time, as the subsoil is displaced by erosion,

a small cavern forms underneath the surface soil.

Eventually, the supporting surface becomes so thin

that it suddenly collapses into the cavbew.

We have no one to blame but ourselves.

Most sinkholes are caused by our machines.

Underground activity such as mining

can wreak havoc at the surface.

Improperly compacted soil after excavation work,

or even heavy traffic can result in different sizes

of sinkholes.

Water from a broken main will burrow through

and weaken soil...

...out of sight...

until...

...a spectacular collapse.

You can see the water splashing out from this sink hole.

The clean up is immense.

Some clean ups are more immense than others.

e El Salvador disaster was blamed on land subsidence...

New construction on reclaimed land...

too soon.

New means of detection can help prevent sinkholes.

This rolling machine is a ground penetrating radar.

It provides an accurate picture of subsuactivi,

including broken water mains.

But as the number and the size of cities grow worldwide,

the number of sink holes will grow with them.

So if you get that sinking feeling, just remember:

this is a problem that's almost bottomless.

Weekend warriors.

They are the masters of DIY.

Do it yourself.

But sometimes you just have to ask...

[Man] Oh my... what did you do?

[Narrator] Why Did You?

Now there are two ways into this room.

Do you need a ladder?

[Narrator] No wonder it doesn't fit.

The track is supposed to go under the train.

This can't be what they mean by "plugging a leak".

Every plumber knows to turn off the main water supply

fore you loosen the pipes.

But this guy isn't a plumber.

And you don't want to be in his shoes right now.

Of course there is the odd success story.

But for every life hack there are a hundred sad sacks.

When the foreman sees how you're spreading that cement,

he's gonna go through the roof.

Or you could beat him to it.

Because a roof won't stand

if you remove a weight-bearing beam.

And when it's your weight it's bearing,

you want to avoid standing on top of it.

Or, for that matter, under i

After a six beer lunch

the guy carrying the bag

is half in the bag himself.

Break time.

[Man] Just turn that alarm box off there Zach.

Just give it a quick nudge.

[Narrator] Just putting on the final touches.

And... done.

[Man] What have you done?

[Narrator] It to w ls time efyou thought.

In fact just thinking about it,

got this job done.

e moral of t: If you want something done right...

...and you don't know what you're doing...

DY don't.

Excavators are Construction's multi-taskers.

...to clawing their way Frthrough the toughest debris.

Powerful hydraulics control triple-jointed arms.

Sharp toothed shovels bite into the dirt,

scooping up bucket-loads weighing in the tons.

In the hands of an expert, the excavator

is a nimble extension of the operator.

So dexterous it can even make climbing up

onto a truck bed look easy.

But in the hands of the inexperienced

it's just as easy to fall off one.

Excators come in all sizes,

weighing as much as 14,000 tons.

This one's just heavy enough to turn the truck bed

into a catapult.

Operating an excavator

takes a couple of levers and joysticks.

And if you're used playg vi

takes a couple of leveit's child's play.

Just ask this child.

Good thing he's not driving into traffic.

If he gets busted, he's in for a stern talking-to.

Or up for a well-paying job.

Excavator tracks can handle the steepest grades.

As long as they're on solid groun

This surface was flimsy.

As was the operator's judgment.

It's important to point the tracks

perpendicular to the hill you're working on.

Nap time.

And try to keep the boom and bucket low

and facing the same way asou're sitting.

Or you'll be taking corners on two wheels.

Or

Or no wheels.

Excavators are often enlisted to dredge swampland.

In fact, some excavators are amphibian.

Just not this one.

Good thing the driver floats.

Looks like mom's coming to rescue.

Here's an excavator demolishing a building.

d a ilding shan excavator.

Apparently the penthouse suite comes with its own excavator.

This might be taking DIY a little too far.

Not sure what you'd be digging up here.

Except maybe your own grave.

Nothing to do but sit tight till they build the elevator.

On a construction site

an excavator can do the work of 20 people.

If you're not careful they can drive you to distraction.

Or destruction.

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