Original subtitles

Today on "Impossible Engineering,"

the Tokyo Skytree, the world's tallest tower.

It's a striking landmark.

The world's number-one tower.

To take structural design to new heights...

If you don't get the foundations right,

then that's a recipe for disaster.

...Engineers must look

to the innovative pioneers of the past...

This is unbelievable.

This rocket is just so big.

...To make the impossible possible.

... Captions by vitac... www.Vitac.Com

captions paid for by discovery communications

Tokyo... home to over 35 million people.

With suburbs stretching 14,000 square miles,

its vast sprawl of low-rise buildings

is a direct result of

one singular environmental challenge...

earthquakes.

But for the first time,

as space in this mega-city runs out,

engineers must now look up.

As taller buildings rise,

an expected challenge emerges,

especially for the city's

nearly 1,100-foot-tall communications hub,

the Tokyo tower.

Everyone here,

including high-rise architect David Malott,

can clearly see the problem.

You can almost see it's going to be

knocked out by a building.

The signal is being blocked.

In a nation that experiences 1,500 earthquakes a year,

uninterrupted TV and radio communication is vital.

This problem requires a radical solution.

Here it is... Tokyo Skytree.

Unprecedented in Japan,

the Tokyo Skytree is the world's tallest free-standing tower.

It's double the height of Tokyo tower.

It's got the most advanced engineering and technology

we have available today.

This is the solution for Tokyo's connectivity.

For designer Tetsuo Tsuchiya,

scaling these heights offers a unique challenge.

The record-breaking 2,080-foot-high structure

is more than four times

the height of the great pyramid of Giza.

Its spine is a 1,200-foot hollow concrete core

cloaked in a 37,000-piece steel frame

which morphs from a triangle to a circle.

It has two observation decks.

The tallest, at almost 1,500 feet,

is one of the highest in the world,

and it's topped by the state-of-the-art

antenna tower capable of transmitting 62 miles away.

Construction begins in 2008,

but before Skytree can even rise above the ground,

its designers face a seemingly impossible problem.

Where we are now used to be part of Tokyo bay.

The land I'm walking on was underwater.

So what that means is the soil around here is extremely soft.

And, for engineers, this presents a big challenge,

especially when you do something of that height

in a place that has earthquakes and typhoons.

It's going to want to push the building.

So that building needs to be firmly anchored into the ground.

If you don't get the foundations right,

then that's a recipe for disaster.

With this colossus exerting over 75,000 tons of force,

how can you ensure it will remain

standing on unstable soil during an earthquake?

To accomplish the impossible,

engineers must look to the past.

Hmm?

It might be far from perfect,

but soft ground has rarely scared away history's engineers.

Oh, forget it.

Olé!

In fact, some of the world's most famous cities

had been built on swamps and marshes.

Bravo.

I'm getting wet.

In New Orleans, the ground is so soggy,

the city famously had

to build their cemeteries above ground.

Ah, that's better.

And Berlin is criss-crossed

by a constantly changing 40-mile network

of pink pipes used to pump the ground

free of water.

Whew.

Ah, wunderbar.

Architectural historian Jen Masengarb

is exploring San Francisco

to find out how the 1848 gold rush

ultimately sparked an engineering revolution.

To serve this booming bay area,

architects constructed the monumental

new ferry building.

It weighs about 150 million pounds,

which translates to about 75,000 tons.

Not only does it stand in a seismic zone,

the building's 245-foot tower

and extreme weight both rest on 180 feet of bay mud,

creating near impossible building conditions.

So those tasked with designing a new ferry building

really had to think about innovative solutions

in order for the building to be successful.

To support this grand architectural design

on unstable grounds, engineer Howard Holmes

had to look beyond traditional methods

and dig deep.

I've got some wet sand, which is the same kind of sand

that's here underneath the ocean,

and this wooden plank is to help us

see that concrete mat

the entire building is sitting on.

And these nails are those wooden piles

that are driven down to the sand.

In a typical building, you might use only as many piles

as you would need to support the building.

So let's see fit that works.

I can put quite a bit of load on this,

but we're in a seismic zone.

You can see that I can turn this sideways pretty easily.

So wiggle, wiggle, wiggle.

But to survive earthquakes,

the new ferry building needed something more.

So, here's my new demonstration with lots of piles.

Wow. Not only can I not push it in very much,

but when I try to wiggle it side to side, I really can't.

And the secret of this stability

is due to the friction.

Friction is created around

the surface area of each of these piles,

and more piles equals more surface area.

And because it's much more stable like this,

any earthquake load,

all of those forces are just going to be absorbed

by all the piles,

making the rest of the building much more secure.

Brilliant.

Over 5,000 wooden piles

extend deep into San Francisco's semi-fluid Sandy mud.

These support the structure's 111 concrete piers.

It's a foundation with three parts,

which you can see here.

A reinforced concrete mat under the whole building,

then concrete piers,

then wooden pilings driven down into the mud.

Those wood pilings are about 80 feet in length.

Underneath the tower, there are 345 piles alone.

Completed in 1898, the new ferry building

continues to defy sinking sand to this day

and anything else that nature throws at it.

This design has withstood

the earthquakes of 1906 and 1989,

both of which caused massive damage

throughout San Francisco.

The building has proven itself

through its innovative engineering.

At the over 2,000-foot-high Tokyo Skytree,

engineers take Holmes' revolutionary method

into the 21st century.

To stabilize it, workers drive 131 concrete piles

into the soft ground.

But the building's record-breaking height

adds a further problem.

To compensate for this, Skytree needs a unique system.

Its 75,000 tons of force

is exerted onto a tripod-shaped base.

160 feet below the surface,

three clusters of 4-foot-thick walls use friction

with the surrounding soil to increase horizontal rigidity.

Three 160-foot wall piles connect each cluster

with added knuckles acting as spikes,

further increasing friction.

Combined with the column piles,

the towers foundations act like a tree's roots,

bracing the superstructure

for even the most extreme of conditions.

But to complete the world's largest free-standing tower,

engineers must look to the past...

It's a brilliantly simple solution

and sparked a renaissance in skyscraper construction.

...To make the impossible possible.

Soaring over 2,000 feet,

the Tokyo Skytree is the tallest free-standing

tower on the planet.

More than six times higher than London's big Ben

and twice the height of its predecessor,

the Tokyo tower,

Skytree is changing the face of Japan's capital.

But as high-rise architect David Malott reveals,

building to this height in this highly congested city

poses a unique challenge.

The engineers at Tokyo Skytree had to put a tower

that's twice as high as Tokyo tower on a piece of land

that's only a quarter of that size.

The proportions of a super-tall tower are crucial.

If a structure is more that five times higher

than it's narrowest base dimension,

it can become unstable in the wind.

But Skytree's ratio is a daunting nine to one.

It's one thing to build tall and wide,

and it's a much more challenging thing

to build tall and slender.

So how do you build a super slim record-breaking tower

on such a confined plot of land?

Engineers have always been able to build short and fat,

and after a while, they mastered tall and fat.

Whoa.

But building tall and thin has often been a problem.

- Are you sure? - Go for it.

Ireland's highest round tower is an amazing feat...

I told you. Perfect.

...but isn't exactly straight.

Aah!

The first St. mark's campanile in Venice

certainly looked the part... Mama Mia.

...But the impact of the weather

and the weight of its five mighty bells led to disaster.

We're going to need a new tower.

Engineers had to return to the drawing board.

During the 1920s,

Chicago became synonymous with skyscrapers.

By the '60s, with space increasingly at a premium,

developers wanted to build even higher.

But traditional bulky construction methods

were stifling their ambition.

However, in 1968,

engineer Fazlur Khan came up with a game-changing solution.

All right. Thanks.

And architect Jayshree shah

is here to get a bird's-eye view of it.

This is the ground-breaking building

that Khan was working on.

Over 1,100 feet high,

the Hancock center was the first skyscraper in Chicago

to reach 100 floors.

But this impressive building sits on

a footprint 27% smaller

than the city's second-tallest skyscraper

from that time, the chase tower.

So how does the Hancock center continue to stand

in the face of Chicago's legendary wind?

Just take a look at this skyscraper-shaped tower.

If I push on it just a little bit,

like a lateral force similar to the wind,

you can see how much it bends.

Now, if I push even more,

you can see how it begins to twist.

Oh, geez. All right. I broke it.

But the simple addition

of 45-degree cross braces changes everything.

You can see how much stiffer it is.

When I push against the building now,

it's not bending or twisting as it did before.

Called braced tubing,

Khan used this technique

to reduce the horizontal loads on the building.

As the winds pushed against the building,

their force now transferred down the diagonals

to the base of the structure,

easing the load on the building's vertical columns.

Fazlur Khan's braced-tube design sparked a renaissance

in skyscraper construction.

Engineers at Tokyo Skytree are drawing

on Fazlur Khan's genius braced-tube design

to create a record-breaking super slim structure

that dwarfs the city.

In an area renowned for typhoons,

building a tower almost double the height of the Hancock center

on a footprint 51% smaller

requires both brains and brawn.

The 37,000-piece steel framework consists of three layers

with thousands of triangular trusses.

Immensely strong, this steel curtain can resist

wind gusts approaching 250 miles per hour.

As well as defying the odds,

its designers have also created

a shape that makes Skytree totally unique.

But to brace for more daunting challenges,

the Skytree team must turn to the past

and reach for the stars...

It was a beautifully simple concept that ultimately

helped push our exploration out into space.

...To produce more impossible engineering.

At over 2,000 feet,

the Tokyo Skytree is the world's tallest free-standing tower,

and, with it, architect Tetsuo Tsuchiya

is redefining Tokyo's skyline.

People can see this tower, and also we can see the city.

So I think it's a really great viewpoint

to really understand the city of Tokyo.

But as high-rise architect David Malott reveals,

building to this dramatic height here

means engineers must conquer

a seemingly impossible problem.

Japan is part of what we call the ring of fire,

so it's one of the most

active seismic zones in the world.

So earthquakes are a part of daily life here in Tokyo.

It's a very big challenge for us to control the swaying

and the movement of this tower.

So the engineers of Skytree

were tasked to build not only

the world's tallest television tower,

they had to put it in what is probably the world's

most dangerous location.

In a country that endures

around 1,500 earthquakes a year,

how do you ensure a super tall tower

will remain standing?

To overcome this challenge,

engineers find inspiration

in an unlikely innovation from the past.

Launch commenced.

Lift-off. We have lift-off.

Space historian Amy Shira-Teitel

is in Florida,

at the home of one of history's most awe-inspiring endeavors.

This rocket is just so big.

It's so great.

Since the 1960s, Kennedy space center

was the launch pad for NASA's epic Apollo space missions.

This is really amazing to be standing here.

This is launch pad 39b.

This is where the Apollo 10 crew launched

and went all the way to the moon to orbit before coming home.

At the moment of launch,

the five f1 engines together

produced more power than 85 hoover dams.

The sound of the launch was so intense,

they actually had to dump 3 million liters of water

onto the pad every minute just to dampen the sound waves

so they couldn't bounce back up and rip the rocket apart.

Just like old times. It's beautiful out there.

But achieving such an explosive lift-off

called for a lot of energy.

Almost 530,000 gallons of rocket propellant

was needed to get the over 360-foot rocket

off the ground.

Delivering all that fuel

to the rocket required umbilicals,

masses of cords and wires

running all the way up the service structure.

Attached to the rocket by spring-loaded swing arms,

it was essential the umbilicals remained in place

until the very last second

before an electrical discharge jerked them

and the swing arms back towards the launch tower.

However, the challenge was controlling

the swing arm's sudden powerful movements.

They had to make sure they wouldn't break off

from overexertion or bounce back

and hit the rocket as it left the launch pad.

Thankfully, there was one engineer working on a solution.

To address this problem,

former air force engineer Paul Taylor

worked alongside NASA.

His patent for an innovative shock absorber design

offered a breakthrough for the Apollo mission's

tricky launch procedure.

The concept Taylor came up with

was the fluid damper, or the liquid spring,

and it works something like this.

Now, imagine that this coffee press

is our fluid damper,

and it's sitting between the tower and the rocket.

You can see that when our damper is empty,

it offers very little resistance to weight

or the force of the swing arm when it's released.

But if you fill it full of fluid...

look at the magic of the green liquid...

and if you put the weight back on,

you can see it compresses much more slowly.

So what's happening is, as the plunger is pressed,

the liquid is forced through the holes.

This creates resistance, which dissipates the energy,

which makes the plunger move more slowly.

During launch, as the umbilical-laden

swing arms spring back,

the attached fluid dampers are compressed,

and the fluid inside them is forced

through holes in the piston.

This action creates friction,

which slows the arms down to zero speed

at the end of travel

and minimizes risk of damage to the tower or rocket.

In 1969, Taylor's ingenious system

proved its worth as Apollo 10 safety launched

on its pioneering mission to orbit the moon,

making its mark in space-travel history.

We are go for a mission to the moon at this time.

We have ignition sequence start.

All engines running. Launch commence.

Lift-off.

Taylor's hydraulic innovation has stood the test of time

and is still in use today,

protecting sensitive equipment

during launches to the international space station.

It was a beautifully simple concept that ultimately

helped push our exploration out into space.

But using fluid dampers to brace the world's largest tower

against earthquakes is an altogether different challenge.

To do this, the Tokyo Skytree team

must make revolutionary renovations...

...to make the impossible possible.

The Tokyo Skytree is the tallest

free-standing tower on the planet.

But at over 2,000 feet, engineer Atsuo Konishi

and his team must brace it against a potentially

devastating natural phenomenon.

To stabilize the tower,

engineers rely on fluid dampers

developed during NASA's Apollo space program

and from something closer to home.

The engineers first step

in controlling the shake of the tower

centers around an ancient earthquake-proof structure

called a Japanese pagoda.

A flexible earthquake-dampening central pole

called a shinbashira

stabilizes this tiered wooden structure.

Skytree's engineers are emulating

this ancient technology,

creating an enormous 1,200-foot concrete column

set on six giant rubber bearings.

And sandwiched between this mass

and the tower's steel structure

lies the Apollo-inspired fluid dampers.

Situated between 410 and 1,230 feet,

the series of fluid dampers control the movement

of the free-standing 11,000-ton concrete core

and the steel exoskeleton throughout a seismic event.

The different vibration cycles of the central column

and steel frame can counteract

the vibration of the entire tower.

The system is so effective,

it reduces an earthquake's vibration by 50%,

meaning Skytree will survive

Tokyo's most severe seismic activity,

the likes of which is only expected once every 1,000 years.

But as well as standing firm during a magnitude-7 quake,

this state-of-the-art communications hub

must also continue to transmit its signals.

And to do this, any vibration of the 460-foot antenna tower

must be made practically still.

So the team introduces a secondary vibration system

at the pinnacle of the tower.

The tuned mass damper contains a 45-ton concrete block

which moves like a pendulum.

During an earthquake, there is a time lag

between the vibration of the tower itself

and the movement of this concrete mass,

canceling out the vibration of the main structure,

resulting in a super stable antenna system.

It can still transmit

even during Tokyo's most extreme seismic activity.

Skytree's breakthrough engineering

has tamed one of nature's most devastating forces.

But to complete this mammoth super-tower,

the design team faces even more formidable challenges,

and they must draw on another great innovation from the past

to produce more impossible engineering.

The Tokyo Skytree is setting a new benchmark

in high-tower design.

As a communications hub,

the over-2,000-foot tower

can transmit up to 62 miles away.

But, for its architect, Tetsuo Tsuchyia,

this engineering colossus stands

for so much more.

But as high-rise architect David Malott can see,

creating a bird's-eye view in a tower this high

poses tremendous technical challenges.

When you're building observation decks,

it's going to be subjected

to tremendous force from typhoons.

To offer these breathtaking views requires

one resilient material... glass.

But how do you ensure the glass

will remain in a safe state

in the face of typhoons and earthquakes?

This would have been impossible

without a chance discovery made in Paris

over 100 years ago.

Scientist Suzie Sheehy is here in Paris to discover

how the city's notoriously bad traffic

inspired a transformation of safety

in the modern world.

In 1903, driving was fast

becoming the hot new hobby among Parisians,

but, like today, the traffic

was congested and dangerous,

and accidents were commonplace.

It sparked an idea

that will go on to change the world.

Born in 1878, scientist Edouard Benedictus

studied chemistry in Germany

before setting up a laboratory in Paris,

where he made his breakthrough discovery.

Car windscreens were causing drivers serious injuries

in the case of an accident.

The windscreen would smash into shards,

which in some cases proved fatal.

Incredibly, Benedictus discovered a solution

to this concerning problem entirely by chance.

During some routine testing at his lab one day,

Benedictus accidentally knocked a glass flask off a shelf.

And, remarkably, instead of smashing

into a thousand different pieces,

it actually maintained its shape.

Examining the shattered flask

that had mysteriously remained in one piece,

Benedictus observed remnants of a liquid plastic

within the vessel

and concluded that its thin coating

held the broken glass together.

Benedictus had a brain wave.

He realized that this plastic-coated glass

had the potential to save lives.

So, this is a piece of laminated glass,

and it's like the modern evolution

of Benedictus' discovery.

It's basically just two pieces of glass

which are bonded together with a piece of plastic between,

which holds it together.

And over here I also have some pieces

of just normal sheet glass.

And this is similar to the glass that would have been used

in a car windscreen in Benedictus' time.

To see how each one reacts under impact,

a 4 1/2-pound steel ball

is set 13 feet off the ground.

First up, the normal sheet of glass.

Ready to go.

Aah!

Wow! Okay.

So this piece of glass is really smashed.

You can imagine how dangerous

one of those sharp shards of glass would be

if it came flying at your face

during a car accident.

So, instead, let's try a piece of laminated glass

and see what happens. All right.

Place my laminated glass now,

but this time I'm going to raise it up higher.

With the drop height raised to 20 feet,

will this laminated glass withstand impact?

And how will engineers employ this technology

against the fury of mother nature?

As the world's tallest free-standing tower,

the Tokyo Skytree offers stunning views of the city.

But to create a safe viewpoint at this dramatic height

that can also withstand typhoons,

engineers draw from an early 20th century

breakthrough in glass design.

Let's try a piece of laminated glass.

To test its strength, Dr. Suzie Sheehy raises

a 4 1/2-pound steel ball

to a drop height of 20 feet.

Whoa.

It actually didn't go through.

Oh, wow. Okay.

So my steel ball

managed to form a beautiful

spider web pattern on here.

And the glass has actually stayed in place,

stuck to the plastic in the middle.

Benedictus' layered glass is so resilient

because the lightweight plastic stretches when struck,

absorbing any force and offering a tear-resistant barrier.

So it's a pretty simple invention,

but it's made the roads a much safer place.

Engineers at Tokyo Skytree

are using Benedictus' ingenious layered glass

to take on Tokyo's powerful typhoons.

With two 360-degree observatories

and one of the highest skywalks in the world

incorporating a glazed floor,

each of Skytree's 1,027 panels of glass

must be super strong.

Installed from the inside

and integrated into steel curtain wall framing,

this state-of-the-art laminated glass

can withstand winds in excess of

a mind-blowing 325 feet per second.

Welcome to Tokyo Skytree Tembo galleria.

Because of the pioneering work of Benedictus,

even in the unlikely event the glass does shatter,

the panes will remain in place,

allowing around 4 1/2 million people a year

to safely experience

one of the greatest vantage points on the planet.

Completed in 2012,

this audacious architectural marvel

was constructed in under four years.

It stands as the result of ambitious planning

and testing by thousands of engineers.

By learning from the great pioneers of the past, adapting,

upscaling, and making innovations of their own,

engineers have written a new chapter

in high-rise design.

They have succeeded in making the impossible...

Possible.

Tokyo Skytree is a striking landmark.

It's really a combination of

state-of-the-art Japanese construction technology,

and also the very old Japanese wisdom

of creating very tall towers.

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