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...

Concrete - the most prolific building material on Earth.

And a multitude of ways to fail.

Dams don't just hold water,

tailings dams hold mining waste -

or at least, they should....

Asbestos... Water proof.

Fire proof. Sound proof. And deadly.

Elevators...

Offering a speedy lift to the high life...

But for some, not speedy enough...

Concrete is the second most widely used substance

on the planet, only beaten by water.

Essentially just sand and gravel glued together

with cement.

Every year twice as much concrete is used as steel,

aluminum, plastic and wood combined.

It is the most important building material on Earth.

It is literally the foundation of the modern world -

part of the weird, the wonderful

and every multi-story parking lot.

When it fails, the consequences can be cataclysmic.

As the travellers at the Bardhaman Railway Station

building in West Bengal, India discovered in January 2020.

Just after 8 pm on a busy Saturday evening,

a portion of the roof collapsed.

In front of platform 1, part of the portico roof

of the two-storey station building failed.

So, what went wrong?

Concrete may mimic stone, but it doesn't last like stone.

It fails and fractures in dozens of ways.

Heat, cold, chemicals, salt and moisture

all attack the seemingly solid artificial rock,

working to weaken and shatter it from within.

Maintenance work is essential, but it can also be challenging.

Construction and repair work was underway

at the 166-year-old Bardhaman station

when the collapse took place.

Some suggested the project went ahead

without proper input from heritage experts.

Buildings constructed in the 19th century

commonly used lime-stone concrete.

This was later replaced with something

called Portland cement.

Portland cement is quicker setting and more robust.

It's named for a stone found on the Isle of Portland

in southern England.

And it's a key ingredient in today's concrete recipe:

water, Portland cement and aggregate -

Rock, sand, or gravel.

The Portland cement and water form a paste

that coats the surface of the fine

and coarse aggregates.

It gets stronger as it hardens,

creating the rock-like mass we know as concrete.

However, using Portland cement to repair structures

originally built using lime mortar...

can be hazardous.

Was the type of cement to blame?

Like baking, the concrete recipe is crucial.

Cement, water and aggregate measurements

have a significant influence on the concrete's

final strength, porousness and durability.

The amount of water used can also influence

how well concrete bonds.

It's essential to get the mix right.

The ambient temperature when the concrete is laid

can also have an effect.

Temperatures above 32 degrees Celsius

make producing quality concrete challenging.

Precautions need to be taken.

Often this means laying the concrete early

or later in the day.

Was the weather in West Bengal too hot

when the concrete was poured?

An increase of 12 degrees Celsius can reduce

the concrete setting time by as much as 50 per cent.

This can lead to reduced strength and durability

and additional drying shrinkage

when the concrete hardens.

Concrete has been around in some form for thousands of years.

And it was arguably the Romans who first mastered it.

The Pantheon is the largest non-reinforced concrete dome

in the world.

It's a supreme example of Roman concrete

that's still standing after 19 centuries.

And it's not alone, many Roman concrete structures

are still with us centuries later.

They're a testament to the durability of Roman concrete,

but the recipe is lost.

Our modern concrete structures will not last nearly as long.

One problem?

We're running out of one of concrete's

essential ingredients: sand.

Though the planet contains plenty of it -

desert sand grains are too smooth and fine

to bind together for building materials.

The right kind of sand is found in riverbeds,

floodplains and beaches - and is a limited resource.

It's popular in reinforced concrete,

widely used in construction today -

poured over steel rods or mesh,

to give it extra tension and strength.

This can last about a hundred years

without major repairs or replacement.

So, concrete failure is a growing concern.

At Bardhaman station the renovation work

had already started, but could this have been

part of the issue?

Could the modern equipment used for the renovations

have damaged the station's structural strength?

Hammers were used to replace the station floor tiles.

Could the vibrations have led to its collapse?

The lack of supports underneath the renovation area

also caused concern.

Perhaps this triggered the roof to fall in...

The exact cause of the incident remains unknown,

but a committee has been assigned to find answers.

It's a mineral you can weave into flexible fabric.

A rock you can shape into shingles.

Wrap it around pipes,

put it in the walls,

install it in ceiling tiles.

Even mix it into concrete.

Water proof.

Fire proof.

Sound proof.

From the ground up, asbestos became

the cornerstone of construction materials.

A miracle product that seemed too good to be true...

Because, it was.

While asbestos was great for buildings -

it was very bad for the builders.

4000 years ago, miners discovered a stone

composed of millions of fibers that was strong

and flexible.

The ancient Greeks called it "Asbestos",

meaning "Indestructible."

The Egyptians wrapped their Pharaohs in asbestos shrouds

to prevent decomposition

But even the Romans knew that asbestos was problematic.

Workers who built the coliseums suffered

from a "disease of the lungs."

Still, working with asbestos continued for centuries.

During the Industrial Revolution,

asbestos was used as a fire retardant for steam engines

and electric turbines, ovens and boiler rooms.

Asbestos production surged during World War II.

And asbestos - related illness

became an unexpected casualty of war.

Because the same properties that makes asbestos

such a versatile construction material

also make it destructive to the body.

Breathing asbestos fibres is like inhaling

millions of tiny needles.

Asbestos contains iron, which damages the DNA,

and can lead to a deadly lung cancer.

In spite of the warning signs, asbestos production continued

to build throughout the 20th century,

peaking at 5 million tons per year.

Asbestos found its way into every home.

Mixed into the foundation, insulating walls,

laid into flooring and roofing.

Asbestos textiles and irons kept you safe from fire -

and exposed you to life threatening illness.

By the late 20th century, the risk was undeniable.

Over 60 countries have since banned

the use of asbestos.

But many homes built before 1980 still contain it.

The real danger is to renovators,

who pull insulation out of the walls,

or scrape away flooring tiles.

They need to wear protective gear

so they don't inhale the airborne fibers.

The reputation of asbestos has grown so dire,

that in 2019, even the town of Asbestos,

voted to change their name.

They have yet to decide on something

a little more user friendly.

It looks like a special effects scene

out of a blockbuster movie.

But this is no Hollywood fiction.

It's the all too real catastrophic failure

of a tailings dam - caught on camera

at the Córrego do Feijao iron ore mine

in Brumadinho, Brazil,

January 2019.

As the 86 metre dam suddenly failed...

It released almost 12 million cubic metres

of tailings in one massive burst.

Within seconds, a tsunami of red sludge

was surging down the valley.

Travelling at over 70 kilometres per hour...

and destroying everything in its path.

Devastating the mine's canteen,

where dozens of workers were gathered for lunch,

obliterating surrounding buildings and over 100 metres

of railway track.

So, what went so catastrophically wrong?

A tailings dam is not a conventional dam,

like those built for hydro power and flood control.

A tailings dam is a common above ground storage

in the mining industry.

The tailings dams are actually made up

of the waste by products left behind by the mining process.

At most metal mines, rock is ground to extract

the valuable metal from the rock ore.

The waste left behind - finely ground sand,

chemicals, minerals and water -

is known as tailings and is usually highly toxic.

The cheapest way for mining companies

to store these by-products is to contain them

in what becomes the dam.

The solids settle to the bottom, the water drains away

for re-use in the mine,

and the waste sludge hardens.

It is estimated that there are over 3,500

Tailings dams in the world.

And they are designed to permanently contain

this mining waste -

meaning they should remain in place forever.

Unlike water-retaining dams, these by-product dams

are not built with reinforced concrete.

The dam walls are constructed of layer upon layer

of "tailings".

This design results in a steep upstream constructed slope -

called an upstream tailings dam.

But this type of dam is susceptible to cracking

if it becomes waterlogged.

And these cracks can cause the structure to collapse.

Perhaps the structure was affected by an earthquake?

Nearly four kilometres wide, the blanket of sludge

raged for 10 kilometres.

Homes were destroyed.

Hundreds were killed.

But no seismic activity or explosions

were recorded in the area.

Tailings dams are continually raised

throughout the life of the mine.

So, was the design of the dam itself a major factor

in the collapse?

These kinds of tailings dams are the most common

in the mining industry, and the least safe.

They are unstable and more prone to leakage.

Keeping excess water out is a big issue.

But, the remains of iron ore can bond with the sand

and prevent water from draining properly.

Excess water means added pressure in the dam.

And that affects the stability of the structure.

Also, the high iron content in the dam

could have made the construction materials very brittle.

Depending on the type of mining,

tailings can be liquid, solid or a slurry of fine particles.

The Brumadinho dam was slurry.

And if that slurry gets wet, "liquefaction" can occur.

This is when a solid material such as sand

loses strength and stiffness -

and turns to liquid.

Brumadinho had suffered very heavy seasonal rain

which had indeed caused liquefication of the tailings.

In the end, the steep design,

and the lack of sufficient drainage

resulted in high water levels

putting too much stress on the structure.

The liquefied slurry built up

behind the 700 metre wide front wall

and finally burst through.

This was Brazil's worst ever industrial accident.

Brazil has since ruled that all upstream dams

must be decommissioned or removed.

When a Dallas demolition team tried to drop

an 11-story office building, the implosion vaporized

most of the structure.

But the one thing that wasn't going down,

was the elevator.

The 2.5 x 2.5 metre steel box,

suspended in a concrete and steel core shaft

took days to reach the ground floor.

Elevators have been giving people a lift

for 2,500 years.

In Roman times, rope and pulley systems

hoisted everything from building materials to lion cages.

But when Elijah Otis demonstrated his prototype

for the modern passenger elevator

at the 1854 World's Fair,

it led to the construction of skyscrapers,

and changed the way 7 billion people a day

navigate life's ups and downs.

Elevators use a variety of technologies

to move from floor to floor.

And none of them are foolproof -

as this fool proves here.

There are lot of myths around elevator safety.

Like the idea that you can jump in time

to counteract the speed of falling

to avoid getting crushed.

Happily, this little girl hopscotched

out of the way just in time.

An elevator's weight capacity is anywhere

from two to four tons.

But cramming enough people to exceed the maximum load

won't snap the cables.

Because there are at least four times more than required.

Overloading just stops the car in its tracks,

trapping the riders inside until the fire department

comes along and pries them out.

This rider isn't one to hang around

but the longest anybody's been stranded in an elevator

is 41 hours.

While elevators very occasionally go rogue,

most accidents are self-inflicted.

Trying to get in or out between floors

can result in serious injury.

When the door closes make sure you and your stuff

is safely inside the car - or you could lose it.

This woman almost lost her head.

If she hadn't reacted quickly she might have ended up

in the basement and the penthouse.

But taking an elevator is still 20 times safer

than an escalator.

And 20 thousand times safer than riding in a car.

And way safer than the stairs.

So, just go along for the ride.

You never know who you'll bump into.

Hopefully there were no passengers trapped

in this Dallas elevator.

But if there were, are they ever going to be surprised

when they get out.

Whether they're transporting construction materials

to the site or heavy duty goods to the customer,

it's the trucker's mission to get the load

from "here" to "there".

Not here to there.

Or even there.

But as long as the shipper follows

a few simple precautions,

like properly securing the load,

and using the right truck for the job,

the materials will land at their destination.

Instead of on the asphalt.

Or worse.

The wheel is a great invention.

It's what allows construction vehicles

to carry these loads.

But it also allows those loads to roll off truck.

Like these 26 concrete pipes.

Correction. 25 concrete pipes.

Overloading the back of your pickup

and neglecting to tie your building materials down

is either an effective way to weaponize your road rage

Or a profitable practice strongly encouraged

by the windshield repair industry.

Because while one item flying off the back of a truck

and cracking a windshield

is a misfortunate accident...

...Saturation looks like carelessness,

but does vastly improves the chances of hitting the target.

With a little practice you can get 'em coming

and going.

This looks less like a truck losing its cargo -

and more like the cargo's trying to escape.

Whatever - or whoever - is inside that truck

really wants out.

This goofball wins the blue ribbon

for dumbest drop-off by trailing a blue ribbon behind him.

Or maybe that's how he's planning

on finding his way home.

A GPS is probably a better option.

Is there an additional charge for excess baggage in the trunk?

How about a 3-ton drill on the hood?

The guidelines for safe transport all seem pretty much

like common sense.

But not always common practice.

So, if you're loading up the truck for the construction site

be sure to lock down your load.

Or your cargo might end up making an unscheduled stop.

♪ ♪