All language subtitles for Superstructures Engineering Marvels Series 1 4of6 Tallest Building 1080p

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narrator: This tower
is a pinnacle of
modern engineering.

It's more than
half a mile high.

Benjamin: This has never been
done at this scale before,
anywhere in the world.

Narrator: Dubai's
burj khalifa is the
world's tallest building.

Weighing in at more than half
a million tons, the desert
skyscraper contains enough

steel to stretch a quarter
of the way around the world.

But without a revolutionary
internal structure,
it wouldn't even stand up.

Bill: You couldn't take
what had been done on other
buildings and just enlarge

them, it doesn't work.

Narrator: It's so daring
that during construction,
designers tore up their plans

and upped the ambition.

Bill: We were able to go
much higher than we started,

and they kept on
getting taller and taller.

Narrator: Today, it's
the tower against which
all others are judged.

Bill: Every time I come here
it's like, I'm, I'm actually
in awe of what we did.

Benjamin: Much of what is
incredibly innovative about
the burj khalifa, you will

never see at the building
itself, because it's all
hidden away behind the façade.

Narrator: The only
way to find out how
this superstructure

became reality, is
to take it apart and

uncover its
engineering secrets.

(theme music plays).

The burj khalifa is an
unbelievable 2,717 feet tall.

This mega tower was
designed as the center piece,

for a new global city.

Suze: The development
of the uae was reliant
on its oil wealth.

But as this diminishes,
they need to future
proof themselves.

And so what they're
doing is making the area
a destination to visit,

for entirely different reasons.

Who wouldn't want to say that
they've visited the tallest
building in the world?

Narrator: Dubai's central
location makes it an
ideal spot to attract

tourists from both
europe and asia.

But it's also one of the
most unsuitable places on
earth to build sky scrapers.

Thanks to the
unforgiving conditions
of the arabian desert.

Suze: Dubai is one of
the toughest places
to build anything.

Let alone the tallest
building in the world.

It's extremely hot,
and it's extremely dry.

Narrator: Back in 2003,

when the burj was
first dreamt up, this
part of dubai was little

more than just sand.

To bring this
ambitious project to life,

a team of the world's best
engineers is assembled.

Led by skyscraper
expert, bill baker.

Bill: Whenever you start a
project in a new location,

you need to find out what
are you gonna be sitting on,

are you on sand, are you
on rock, are you on clay?

Narrator: When bill
and his team investigate
the site for the tower,

they drill hundreds of feet
down into the ground.

Their results could
not have been worse.

Bill: What we found
what was down there
was a sedimentary rock,

so it's a rock.
It's not like a strong
lime stone or granite.

The rock is called
calcisiltite, so to
take that word apart,

calcia is like seashells, so a
silt means a dust like particle.

So it's called seashell dust.

Narrator: The tower is
in serious trouble, before
construction even begins.

Suze: A building of
this size will weigh a huge
amount and will also require

extremely solid foundations.

These are difficult
to achieve when
you're digging down into

a sandy environment,

because there's no bedrock
to lock that building into.

Benjamin: As time passes,
the building could settle,

which is to say
one part of the
building starts to sink,

and in that case you have
a very serious problem.

Houses can settle,
you can go back into a
settling house and jack it up.

You cannot jack up the
world's tallest building and
simultaneously one of the

world's heaviest buildings.

Narrator: Without solid
foundations, buildings
can't support themselves.

Italy's famous
leaning tower of pisa

was built on top of
weak sandy soil with measly

10 foot foundations.

It didn't stand a chance.

Chicago's
monadnock building,

sits atop swampy,
soft ground.

It's sunk by 21 inches
since it was built in 1891.

And in less than a
decade the millennium tower
in san francisco,

has sunk by 18 inches
and worse still,

it's tilting north west
by more than a foot,

cracking dangerously.

Benjamin: The burj khalifa
is incredibly heavy.

The base of the building
actually carries the weight
of the building itself.

Which means that the bottom
is carrying all the weight of
the entire building above it.

This has never been done
at this scale before,
anywhere in the world.

Narrator: Once complete,
it will weigh more than
half a million tons.

With no solid bedrock
to anchor it into,

bill and his
team are forced to rethink.

The solution they come
up with is ingenious.

The burj sits atop a
gigantic 12 foot of concrete,

which is sunk 24 feet
below the surface.

It covers a massive
80,000 square feet,

the same as
28 and a half tennis courts.

It's known as a raft
foundation, because it
floats in the soft ground,

cleverly spreading the
colossal weight of the tower
across a large surface area.

Roma: Now, if you think
about it, if you're out in
the summer walking on grass,

and you've got
stiletto heels on and

we all know that the heels
are gonna dig straight in and

you kind of want to
fall over backwards.

But if you had a flat
trainer on instead,
that doesn't happen.

And the reason is,
that your weight is
being nicely distributed and

spread across a larger area,
so the pressure is lower.

Whereas in a stiletto
there's lots of weight on
a very concentrated point.

Narrator: The raft
foundation spreads the
weight incredibly well.

But the raft itself has
to be kept in position.

Any shift sideways and the
tower could start to lift,

and eventually topple.

The raft is secured
by 194 concrete piles.

Each are five feet
in diameter, and reach
more than a 164 feet down

through the soft ground.

But unlike traditional piles
they never reach solid ground.

Instead, they rely on friction
to hold them in place.

Andrew: Friction is a really
surprisingly strong force.

Although any one of
those foundations, which
are just going into sand,

isn't able to support
a huge amount of
force being exerted on it.

If you have
enough of those piles,

which have a tiny bit of
friction on each one,
then collectively,

they can support the enormous
weight of this building.

Narrator: Despite the deserts
best efforts to thwart them,

bill and his team lay some
truly remarkable foundations.

Bill: The building
settled very little.

Somewhere between
40 and 50 millimeters,

which is little
less than 2 inches.

So you know, my thumb
is one inch thick, okay,

and so the building
settled a little bit
less than two thumbs,

to give you an idea of how
much this building went down.

So it's a very
good foundation.

Narrator: The
engineers have overcome
the problem of the unstable

desert ground, but
they still have more than
half a mile to go vertically.

Strong foundations
aren't enough on their
own to keep the world's

tallest building standing,

just as important are
the load bearing solutions
hidden inside the tower itself.

Benjamin: We think of
sky scrapers as buildings
built out of a metal frame

with a glass curtain
wall hanging from it.

But the burj khalifa is
actually site cast concrete.

Narrator: It's the
ideal material to
construct the burj khalifa.

Dubai is known for its well-
established concrete industry.

Concrete is also incredibly
quick to build with,

thanks to the use of a
mold called a "jump form."

roma: The jump form is made
up of a series of walls that
are generally made from wood.

But then they've got lots of
hydraulic legs and arms,

which basically prop
it up to create a mold,

into which you then
pour the liquid concrete.

Then the concrete
can harden, it can set.

Narrator: Once
the concrete has set,
the mold is jacked up to

the next level and the
process begins again.

Greg: With a traditional
form work system you'll
probably be looking

at six or seven days
to do one story.

On the burj, we were
typically operating
on three days a floor.

And we even achieved two
and half days at times.

Narrator: Speed is crucial.

Even amidst concerns about
low pay and poor conditions
for the migrant workforce,

every day of construction
costs hundreds of
thousands of dollars.

The tower shoots up
at a phenomenal speed.

But as it gets taller,
construction becomes
more and more difficult.

Greg: Pumping concrete
to a height of 610 meters,

well it just
hasn't been done before.

Cause it hasn't
needed to be done.

Narrator: But it needs to
be done now, and quickly.

Every stage and every
process must be supersized.

Andrew: One of the
challenges is just getting
the construction materials

up the height
where they're required.

So we're on ground level,

but imagine you're
trying to pump concrete
up dozens of story's.

Narrator: It takes
about a minute to pump
concrete up 50 feet.

So to get to the upper
levels of the burj khalifa,

it will be in the
pipes for more
than half an hour,

which is a big problem.

Roma: It can start to harden,

and that would be really,
really bad for the pumps.

It would essentially
cause the pumps to fail.

Narrator: If the
pumps fail, construction
will grind to a halt.

To prevent a catastrophe,

engineers must
create an entirely
new type of concrete.

Roma: So they can add
what we call add mixtures.

So they're little chemicals
that we mix into the concrete
to change its properties,

to make sure that the concrete
you're using is liquid enough
and kind of plastic enough,

that it can actually be
pumped to those heights
before it hardens.

Narrator: After
weeks of testing the
perfect mix is made.

But it still isn't enough
to get the concrete
where it's needed.

To avoid it hardening too
quickly in the searing desert
heat, the concrete must be

made with ice, and
only pumped at night.

The most powerful pumps
on earth are brought to
dubai to do the heavy lifting.

Bill: They used this amazing
pump called a putzmeister,

great name for a concrete pump.

Putzmeister was able to
actually, in one single lift,
pump the concrete from the

base of the building all
the way up to 600 meters.

Narrator: Pumping concrete to
a height of nearly 2000 feet,

sets a new world record.

The first of many
for the burj khalifa.

At the center now stands
a hexagonal concrete core.

Inside the concrete are
enough steel reinforcement
bars to reach a quarter of

the way around the planet.

But the burj's
unparalleled height, once
again presents a problem.

Bill: This concrete shaft
core by itself is too slender
to go to such great heights.

Narrator: Without
a helping hand, it
could not stand up.

Bill: You couldn't
take what had been done
on other buildings and

just enlarge them, okay.

Just like you can't take
a small animal and make
them the size of an elephant,

you know, it doesn't work.

We had to come up with a
different structural system
with different solutions,

a different system.

Narrator: Bill's new
system is inspired by
centuries old cathedrals,

where the main building
is supported by buttresses.

The burj khalifa has
three such buttresses,

which wrap around
the central core.

Their ingenious positioning
helps them dissipate the
loading forces away

from the core and
spread them over the full
area of the foundation slab.

It's the first time this
configuration has ever
been used on a skyscraper.

Roma: If the huge load
coming down the center of
the tower wasn't spread out

in the way that it is,

the amount of stress going
onto the ground would
have been much, much higher.

Narrator: With the supportive
buttresses taking shape,

and with the problem of the
concrete solved, the burj flies
ever higher.

But the taller it gets,
the more dangerous it
becomes for the workers.

Narrator: Steel cages are
used to transport people
to the highest levels.

And as soon as a
level is complete,

a fence is
erected along the edge.

Tragically, at least
three contractors die
during construction.

Today, workers still
have to brave the extreme
heights to do their jobs.

Bashar: We are 11-1-0-9, we
are above the armani entrance.

We have a task of cleaning
this part of the façade.

Narrator: It takes
three months to wash the
building from top to bottom.

And it's all done by hand.

Bashar: We
have 36 spider-men, that goes
outside to clean our windows.

And honestly, you need
to have nerves of steel
to be able to go outside.

Narrator:
Thankfully for these men,

climbing extraordinary
heights is in their blood.

Because they have come
all the way from nepal.

Bashar: Where else
other than the nepal,
where we have the himalayas,

to bring our rope access
technicians from.

Every time I meet with
them and I'll tell them,
"how do you feel today?"

"just another day,
sir, you know.
Just another day."

narrator: Each man
is attached to the
building by three ropes and

the conditions are
carefully monitored.

Bashar: Today, it
is extremely windy.

We are now at roughly
19 knots and we normally see
the whole operation as well.

Narrator: With the
wind picking up, the
men are in real danger.

Looking its best,
is a full time job.

Made all the harder,
by the extreme height
and challenging conditions.

Bashar: 31, 32, (inaudible).

Narrator: 22 knots is
over 25 miles per hour.

Strong enough to send
the ropes and equipment
flying into the glass.

Bashar: It is extremely
windy; we have to stop now.

We're calling them back in.

Narrator: The wind isn't
just a danger for the workers,

it could also shake
the entire building apart,

were it not for some
very clever engineering.

By 2007, three years
after breaking ground,

the burj khalifa
is well on its way
to becoming the tallest

building in the world.

It's already taller than
the empire state building,

and there are tens
of story's to go.

But the taller it gets,
the more danger it's in.

Here in the arabian desert,

epic sand storms
are a constant threat.

The high winds bring with
them thick clouds of red sand,

causing havoc on the roads
and shutting the airports.

Such apocalyptic
storms are rare.

But in summer, dubai
is often hit by strong
north westerly winds.

They can reach speeds of
more than 50 miles per
hour and pose a serious

danger to the burj.

Suze: Wind is gonna be a
problem for any tall building.

But when a building
is this tall, it's
an even bigger issue.

Andrew: The classic shape
of a skyscraper is a huge,

well basically,
rectangular face and

that is an absolute
disaster from an
aerodynamic perspective.

Bill: When the wind
pushes against any building
that's of a constant dimension

from top to bottom,
it will create these
things called vortexes,

little swirls in the
air that come off one side
and the other.

Evans: As those vortexes
get generated, they create
low pressure regions.

Which push on the building,
or suck on the building.

And if you don't design
the building right, those
forces can cause the building

to sway and shake.

Narrator: In 1940, wind
hitting the flat face of the

tacoma narrows
suspension bridge,

cause vortex shedding,

contributing to its
spectacular downfall,

just months after it opened.

And in 1965, high winds
destroy three cooling towers
at a power plant in England.

To prevent a
similar disaster in
dubai, chief engineer,

bill baker, tested the mega
towers design extensively,

before any
building work began.

Bill: So we went
in the wind tunnel,

we got the test data and
the data was not good at all.

The building was
moving too much, the
forces were too large.

Narrator: The team
had to do something
to reduce the sway.

Benjamin: Tall
buildings have, for much
of the twentieth century,

used a very basic mechanism
to deal with building sway.

Which is, you have a
very tall weight hoisted
at the top of the building,

that sits in a kind of sling,

and is designed to
counterbalance any
movement of the building.

Narrator: It's called a
mass damper and is the
system used by taipei 101,

the previous
holder of the tallest
building in the world.

Benjamin: So, if the building
begins to sway a little
bit too much to the east,

the counterbalance
will move to the west,

in order to help the
building stay righted.

It doesn't keep the
building from swaying,

but it keeps it
from swaying too much.

Narrator: Taipei 101's
damper works well.

In 2015 it swung into
action during a typhoon
that brought with it winds

of 115 miles per hour.

But its protection
comes at a price.

Suze: The mass damper
in the taipei 101
building takes up six floors.

They simply didn't
want to waste that kind of
space in the burj khalifa.

So they've cleverly
designed it to avoid the need.

Narrator: Bill came up
with an unconventional idea,

that both tamed
the forces of the wind

and removed the need
for a giant damper
in one fell swoop.

Bill: The way we
addressed the problem here,
was to reduce the forces.

What we did is, we
reshaped the building.

Andrew: When you look
at the burj, the first
thing you see is not a

traditionally shaped skyscraper.

It's got a very
unusual cross section and
as you move up the burj that

cross section changes.

It rotates, it changes size.

Narrator: The tower takes
its shape from a desert lily
with three petals giving

it a unique wide
shaped footprint.

It gets narrower as it rises,

and it spirals around.

So no single face
runs its entire height.

Evans: It's almost like,

lots of different
height skyscrapers
all fused together.

Andrew: The result is,
that when the wind hits
the burj,

it reacts with different
levels in different ways.

And that means the
vortexes are different
at different heights.

So instead of having one
massive coherent vortex
that can exert a huge force,

you have lots of much
smaller ones.

Evans: And what that means,

is that these vortexes
can't really ever get a
strong grip on the building,

and do damage to it.

Narrator: When bill
returned to the wind tunnel,
the results were shocking.

And the final height
of the burj khalifa was
drastically revised.

Narrator: This
observation deck,

on floor 148 of
the burj khalifa,
is more than 1800 feet high.

Hundreds of people
flock here every day,

drawn by the building's
jaw dropping height.

But this mega skyscraper
was never supposed
to be this tall.

Ahmad: To be
the tallest, this was not
our aim at the beginning.

The aim was, doing
spectacular project.

Narrator: As the
engineers change the
shape of the building to

help counteract the wind,

they discover a
surprising side effect.

Bill: Because of the
way we tuned the building,
the way it moves,

so that it doesn't
amplify forces it
received from the wind,

we can go much
higher than we started.

It kept on getting
taller and taller.

Even after the foundations
were in and the bottom of the
building had been started.

Narrator: Changing the final
height after construction has
already begun is a bold move.

Ahmad: The tallest
building here in dubai
was only 33 floors.

So imagine where
we are now today.

So for me that, it was
literally like a dream.

Narrator: But the extra height
brings with it a new problem.

As well as the tourists that
visited, thousands of people
live and work in the burj.

The building's capacity
is 35,000 people, the
equivalent of a small city.

Andrew: One of the most
important parts of a city
is the transport network and

that's absolutely critical
if you've got a vertical
city like the burj.

Benjamin: One of
the major challenges
in this whole building,

is how do you move
people through it,
efficiently and quickly?

Narrator: Stairs
are impractical.

Although the burj has plenty
of them, nearly 3000 in fact.

Suze: When it comes to
vertical living, elevators
really are the key.

Narrator: But once again,
the tower's extreme height
means the solution isn't

as simple as it seems.

Benjamin: In the past,
the obvious solution,

when it came to thinking
about tall buildings,

was to simply make sure every
elevator went to every floor,

all throughout the building.

And that at first,
seems to make sense.

But if you've ever been in
a hotel during checkout time,
on a Saturday morning and

you were on the seventh floor
of a seven story building,

you've learnt quickly
that you will stop at
every single floor.

Your 30 second ride to
the lobby is now a three
and a half minute ride.

And that seems
like an eternity.

Now, magnify that
by 160 story's.

Narrator: To save everyone
from spending half their
day in the elevators,

engineers turned to
a solution inspired
by city commuting.

Benjamin: You have
express trains and
you have local trains.

And the express train
takes you the 90 blocks
you don't want to stop at,

and you get off and
take a local for the
last two or three blocks

that you really
intend to get to.

You can do the same
thing with elevators.

Narrator: Right in the
heart of the building,
nestled in the concrete core,

are 57 elevators.

Eight of these are express
elevators that only stop
at floors 43, 76 and 123.

The so called sky lobbies.

From here, people can take
one of the local elevators
to all the floors in between.

To make the system even
more efficient, two of the
elevators are double decker's,

so as tourists make their
way to the observation
deck on level 148,

others are riding to their
offices in the car above.

Marcel: We're in the heart of
burj khalifa at this moment.

Next to me you see one
of the biggest machines,
or the biggest machines

we have in the world,
driving a double deck elevator.

Narrator: The elevators
in the burj are some of
the fastest in the world.

Whisking people hundreds
of feet up and down,
at 22 miles per hour.

Marcel: The acceleration and
deceleration of the elevators
is controlled in detail.

The idea of the
experience is to let people
not feel the movement.

Narrator: This
phenomenal speed also
serves another purpose.

The elevators form part of
an evacuation plan that turns

conventional
wisdom on its head.

Suze: Everyone knows
that in case of fire, you
never take the elevator and

you always take the stairs.

But the burj khalifa
is a bit different.

Narrator: One particular
elevator has an incredible
travel of 138 floors.

More than any other
elevator in any other
building in the world.

This is the burj's lifeboat.

It is encased in thick
fire resistant concrete.

And can take 26
people at a time,

safely down to the
ground in less than a minute.

Having a fail-safe
emergency plan in place,

is more important
here than anywhere.

Suze: Having the
prospect of being
stuck 160 floors up

in the air,
should anything happen,
petrifies me.

Narrator: Just next
door to the burj khalifa,
is the address tower,

a 63 story hotel and
residential skyscraper.

New year's eve 2015,
the address is engulfed in
flames hundreds of feet tall,

after an electrical
fire breaks out.

In 2017, another dubai tower,

the unfortunately
named marina torch,

has to be evacuated
after it too catches fire,

for the second time
in two years.

Hundreds of terrified
residents are forced to
flee for their lives.

Resident: They
actually came around
pounding on our door,

telling us to get out.

So that's when
we knew to leave.

Narrator: The burj is twice
as tall as the torch and can
hold thousands more people.

Evacuating them all
in the event of a fire
would take far too long.

So instead engineers
have designed the building
itself to keep people safe

for as long as possible.

Roma: They've created
what we call refuge areas.

So that means that people
can go down a few levels of
stairs, but then they're into

these encased, enclosed
rooms that, you know, smoke
can't infiltrate into them.

They've got fresh air supplies
and they're fire proof.

Narrator: These safe
havens only work if
people can reach them.

The stairwells
must be kept clear.

Today a routine test will
see if the tower's specially
designed smoke suppression

system is working properly.

Bashar: Ideally this is a fire
exit route and it needs to be
safe for whomever is using it.

Narrator: In the
event of a fire,

fresh air is pumped
into the stairwells at a
higher than normal pressure.

It creates an invisible
barrier at the thresholds,

preventing any smoke
from getting past.

Bashar: Although
we have the machine
very close to the door,

the smoke won't enter.

Narrator: Hopefully,
none of the burj khalifa's
safety equipment will ever need

to be used.

But here in the desert, the
most dangerous heat doesn't
necessarily come from fire.

Nstruction of the
burj khalifa has been

underway for three years.

The tower is now
nearly 1500 feet tall.

And a new stage
of building begins,

the installation
of the glass curtain wall.

Bill: Just like people,
in a tall building,

you need a skin to
protect it from the elements.

Here you see the
cladding of the building,
the curtain wall.

Narrator: The burj's skin is
made of glass and aluminum.

Benjamin: The individual glass
frames sit within metal frames
and are actually assembled

off site and then are brought
onto the construction site
as prefabricated systems.

Narrator: The panels
must be hung one by one.

Positioning all 2600 of them
takes two and a half years.

By September 2009,
all the burj khalifa's
cladding is firmly in place.

There is more than a million
square feet of glass.

Enough to cover a
football field, 20 times over.

But all this glass creates
a new problem for the burj.

Temperatures here
in dubai can hit more
than a sweltering 120 degrees.

Keeping cool takes
serious effort.

Especially inside a
giant glass building,
like the burj khalifa.

Bill: The surface temperature
can get quite hot.

Almost as hot as
boiling water.

Benjamin: If you think
about an all glass building,
in an incredibly hot climate,

where the sun is
shining all day long,

what you would have is
the inside of your building
would get incredibly hot,

in fact, lethally
hot within a few hours.

Narrator: But thanks to
some clever technology
within the glass itself,

the mega tower doesn't
act like a giant greenhouse.

Bill: Now when you look at
this building, it sparkles.

All that sparkle is the
solar energy that's not
going into the building.

It's being reflected off.

Benjamin: You have a
pane of glass on the interior
and a secondary pane of

glass on the exterior,
coated in metal.

The metal gives
that reflective
quality from the light.

Narrator: These special
coatings reflect more than
70% of the sun's heat.

But the burj needs more
than just sunglasses to
help it keep its cool.

Stripping away the
layers of the burj khalifa
reveals miles of ducting,

which carry cold air
all around the tower.

Wherever you are in
the building, you are
never more than a few feet

away from an air vent.

Moving this air around
such a gargantuan skyscraper
requires some serious grunt.

So every few hundred
feet the tower has an

enormous double
decker mechanical floor,

which houses
pumps so powerful,

together they could
inflate 13 hot air
balloons in just a minute.

But the burj contains
more than 65 million
cubic feet of air.

Cooling it all requires more
machinery than even this giant
building can accommodate.

Benjamin: The solution
was to build a chiller plant.

Not just one, but two, off
site, to provide the cold
water that cools the air.

Narrator: This
building might look
like an arabic fortress,

but it is actually a
high tech cooling plant,

that supplies cold
water for air conditioning
to the burj khalifa.

250,000 gallons of
water a day pass through
these giant heat exchangers,

before being
pumped to the burj
through underground pipes.

Bashar: We receive the chilled
water temperature as low
as three degrees centigrade.

Narrator: It's
used to cool more water
inside the skyscraper's

own heat exchangers.

Bashar: This is a whole
room full of machines,

dedicated for
air conditioning.

This is the main one out of
14 we have across the building.

If we lose them, we lose
the cooling, period.

Narrator: The air
conditioning system
isn't just for comfort.

Without it, the building
will quickly heat up
to deadly temperatures.

Bashar: When the temperature
hits 15 degrees outside,

the maximum you can sustain
it is roughly two hours.

Narrator: Keeping the
tower habitable is essential.

Because it's not just
a tourist attraction,
for some lucky people,

it's home.

Cantonnet: It's more
than just a statement,

it's vertical
living at its best.

It's an engineering
masterpiece.

Narrator: The burj khalifa
has 160 habitable story's.

With more than 3
million square feet of
mixed use floor space.

Roma: There's hotels,
there's offices,
there's residential,

there's shops,
all kinds of things.

Cantonnet: Our gorgeous,
beautiful terrace.

Now tell me,
isn't this amazing!

You feel like you're
in heaven, really.

Andrew: One of the
most important parts
of a city is services.

Water, gas, electricity,
sewage and if your city's
vertical, then you've got to

move all of that stuff
vertically up and down,

to get them
where they need to be.

Narrator: Supplying a regular
city with the amenities it
needs is tricky enough,

but here at the burj,
the problem is made
much, much worse,

thanks to the inescapable
force of gravity.

Maxwell: 160 floors is
an awful lot of people and all
of those people require water.

Just living their lives
and sleeping and washing
and scrubbing their teeth.

Narrator: The tower uses
a colossal amount of water.

A quarter of a
million gallons a day.

Roma: If we were trying
to move that quantity of
water horizontally

across the ground, then that
wouldn't be that challenging.

Narrator: But
moving it upwards is.

One gallon of water
weighs around 8 pounds.

So every day, the
burj khalifa needs to
lift 1,000 tons of it.

Roma: Trying to pressurize
that water to go all the way
up in one hit, would be very,

very difficult, very
expensive and just create
too much of an energy demand.

Narrator: Hidden inside the
burj's 14 mechanical floors
are huge water storage tanks.

Mains water is fed
into the tanks at the
bottom of the building,

before being pumped
up the building in stages,

through 62 miles of pipes.

At each stage,
water is held in the
tanks until needed,

when it is gravity fed
to taps and cisterns
on the floors below.

But what goes up,
must come down.

Maxwell: In your home,
waste water, it just travels
naturally by gravity.

But in higher buildings,
you don't want it all
cascading the full height

of the building.

Enormous pressure would
be built up in the pipes.

Narrator: If waste-water
fell unchecked it would
be traveling at over

100 miles an hour by the
time it reached the ground.

So it is also carefully
moved in stages.

Maxwell that's managed
by sewage holding tanks.

So it drains into a tank a few
floors below and then pumped
out in a controlled way.

Narrator: And the entire
water system is soundproofed,

so residents can't
hear any machinations.

But here, their comfort
isn't the only consideration.

Ding.

But it keeps rising.

Nine months later, it
becomes the tallest man
made structure on earth,

but it still
isn't done growing.

Its crowning glory is to
be a 700 foot metal spire.

Bill: The contractor
couldn't get a crane that
high to place the spire.

So we decided to
assemble the spire down
inside the building.

Then it was launched from
inside the building, and
then came out to the top.

Narrator: With
the spire in place,

the burj is now its
full and final height.

A mind blowing 2,717 feet.

That's half a mile tall.

There is nothing on earth
anywhere close to this tall.

It's nearly twice the height
of the empire state building.

And its nearest rival,
china's shanghai tower,
which is 600 feet shorter.

But its extraordinary height
has turned it into a target.

(thunder and lightning)

bill: You might say that
the burj khalifa is the
lightning rod for dubai.

The spire gets
hit quite often.

Narrator: Dubai can be
battered by terrible storms,
and each one can potentially

bring lightning strikes.

Suze: A thunderstorm
cloud can contain a
hundred million volts.

So if just one bolt of
lightening hits a building,

it could be
immensely destructive.

Andrew: With a
building as unprecedentedly
as tall as the burj,

they didn't have the data
even to work out how many or
how large a strike to expect.

Narrator: For the burj,
lightening definitely
strikes twice.

In fact, it's been
hit more than 18 times
since it was built.

Benjamin: So the main
challenge of any tall building
is to figure out how to take

that lightening, run
it down the side of the
building without letting it

get inside the building,

without letting it
penetrate the building,

until it can
harmlessly reach the ground

and cause no problems.

Akhil: I'm not, too much
scary to go in there.

Narrator: At the top
of the spire is one of
the most sophisticated

lightening protection
systems in the world.

Today, one of the
rope access technicians is
going to check it for damage,

following a recent storm.

It takes even an experienced
climber nearly an hour to
reach the top of the spire.

Sensors on this lightening
rod anticipate when a
bolt is about to strike and

send out a stream of
charges to attract the
lightening towards the rod.

Which works well, if the
lightning strikes the top.

Suze: Because the
burj khalifa is so tall,

the lightening
doesn't just strike at the top,

it can strike anywhere
across the building.

It needs to be
lightening proof,

all around it.

Narrator: Luckily,
the tower has a hidden
trick up its sleeve.

The entire metal
exoskeleton of the
burj khalifa acts as a

faraday cage, drawing
the lightening to the
ground around the outside.

Andrew: And this faraday
cage directs that electrical
current around all the

important stuff,
the electronics,

the people
inside the skyscraper,

without damaging
anything inside.

(fireworks)

narrator: The protective
engineering has kept the
burj khalifa safe for nearly

a decade and in this time,
it has become a global icon.

Bill: The effect of
this tower is immense.

If you go out to
the lagoon next to the
building, in the evening,

every day of
the year there's
thousands of people there,

to see the building,
to see the fountains,

to see the lighting show.

It put dubai on
the world stage.

Ahmad: It started with
a dream and then a
journey of seeing that dream,

every day getting built,
high and high and high.

Narrator: From its
unshakeable foundations, to
the rock solid concrete core.

From it's
extraordinary protective skin

to the ingenious solutions
that allow it to function,

this tower is an
engineering marvel.

Cantonnet: We're still the
best, we're still the highest,
we're still staying up there.

Bill: On my way here,

walking over to the
building this morning,

I stopped to take
a picture of this
building I know so well.

I just have to, it's
just quite remarkable.

Narrator: The burj khalifa
is one of the greatest
superstructures ever built.

Captioned by cotter
captioning services.