Original subtitles

How do you re-engineer a roller-coaster

for double the thrills

and spills?

When you go over the top...

it's a 91-degree drop.

How do you design a bridge that's part building

and part sculpture,

all at the same time?

Walls become floor

and walls become ceiling,

it sort of--it twists with your imagination.

And how do you build four separate towers,

and then, join them with a garden

300 feet in the air?

There was no crane in the world big enough

to lift these pieces up by themselves.

Welcome to a world

where anything is possible.

The space where innovation and creativity collide.

Part building, part Transformer.

It's incredible.

Where the only limit

is human imagination.

Dr. Mabry: This is mind-blowing

when you think about it.

We're talking about actually living

on another planet.

Unpacking the miracles

and mysteries of construction...

This was engineering on a scale

the world had never seen.

... to ask,

How Did They Build That?

The Kistefos Sculpture Park

transformed the grounds of a Norwegian paper mill

into a stunning destination

where art and nature intertwine.

But it was separated by a river.

So, in 2014, the owners decided

to connect the two sides with a bridge.

But they wanted a bridge that could also function

as an art gallery.

Yeah, talk about multitasking.

And take it from me, multitasking is tough.

I mean, one time on this show, they asked me to walk and talk?

We were still filming when the sun came up.

It would push engineers to their limits...

There is a reason why we don't put a building

on top of bridges usually.

... involve some of the most creative architects

in the world.

The client was definitely challenged by us.

And cost $25 million.

Right away, this was a challenging, er,

and extremely complex project.

But the result is extraordinary.

I was blown away.

It still gets me every time.

So, how did they build it?

The Kistefos Sculpture Park in Norway

is a stunning 67-acre open-air gallery,

divided in two by the Randselva River.

It was the brainchild of local businessman

and philanthropist Christen Sveaas.

The Kistefos, er, Museum and Sculpture Park

was founded in the 1990s.

It's on the site where his grandfather

built a wood pulp mill

in the 1880s.

By 2014, Sveaas is running out of space

to house his collection of art and sculpture.

The collection grew, and he had a dream

to realize a museum building.

Renowned Danish architects,

the Bjarke Ingels Group,

pitch a surprising idea.

We decided to ask them if it was possible

to build a bridge instead.

This, though, won't be any old bridge

because not only will it cross the river,

joining the two sides of the park,

it will house the new museum

and be a piece of art itself.

Very quickly it became obvious to us

that it would be so visible that it would become

the biggest sculpture in the sculpture park.

Their extraordinary vision

is for a sculptural, beam-like building

that twists 90 degrees in the middle,

as it connects both riverbanks.

To succeed as a bridge, gallery, and artwork,

The Twist will need to resist floods and high water

to protect the precious art collection

whilst looking like a sculpture itself.

First, the team must figure out how to create

a workable construction site in the middle of a river

that's both storm-proof and will support the building

until it can stand on its own.

Next, they'll need to create foundations

on both banks of the river that work together,

despite one side being lower and built in a swamp

and the other is higher and built on solid rock.

Once done, they'll have to construct the bridge

doing something never done before,

as they twist it through 90 degrees.

But it will also have to be strong enough

to protect the priceless art and the visitors.

Only when they remove the temporary supports

will they know

if they've gotten their calculations right.

Finally, they need to cover the exterior

in a bespoke cladding

that matches the complicated contours

and fit a huge viewing window that curves and twists.

We were all blown away by the proposal,

and, er, I think the decision was, er, was quick

and it was decisive,

and there was, erm, an excitement

to realize this building.

It's December 2017,

and as the team prepares to start,

they're given an end date

and it's one that is fixed in stone.

We got an opening date

from, er, Christen Sveaas.

He had invited all his friends

for the grand opening,

18 months from starting the foundations.

On the guest list, the Queen of Norway

and the Crown Prince of Denmark.

So, with no time to lose, they get going,

constructing the landing pads for the bridge.

There are, though, a couple of problems.

The south side of the construction site,

it's like a swampy area.

On the other side,

rocks at six, seven metre higher level.

Building on a rock, you pour concrete,

you make a flat surface, and you're good to go.

But building on a soft or marshy land

means you either have to stabilize the soil

or go down deeper until you hit bedrock.

That's where piles come in.

They pierce through the soil

until they get to something solid

and embed in that.

They also need a temporary construction platform

in the middle of the river,

and that brings its own set of challenges.

There's a lot of protected fish

and mussels in the river.

One species, the freshwater pearl mussel,

is critically endangered,

so any disruption to its habitat

could be catastrophic.

There is a chance of getting a lot of material

into the river,

which can cause, er, damage

both to the mussels

and also the migration areas for the fish.

The solution?

Relocate the colony of mussels downstream,

and then, complete the works before the fish migrate.

We had the marine biologists,

er, diving all summer, 2017,

to relocate these 200 mussels.

They live for 200 years

and must be the adventure of their lifetime,

moving half a mile down the river.

Wildlife secured,

attention turns to building the bridge

and gallery.

We needed some kind of supporting structure,

so we decided to build this temporary bridge

to be able to build the bridge on top of it.

The temporary structure must be strong enough

to support the bridgeworks on top,

and simple enough, it can be removed afterwards.

The interim bridge was designed to be dismantled

to make sure that the flow in the river

was not obstructed, er, later on.

And then, just as it's being fitted...

They called from the sluices

and said the snow is melting in the mountains,

and we had a lot of water here.

For two days, the river breaks its banks

and surges across the sculpture park.

The building site was underwater.

The worst-case scenario would have been

that the temporary platform was destroyed,

taken by the river.

That would have put the project back

at least six months, probably a year.

While the finished gallery is designed

to survive a once-in-a-hundred-year flood,

the temporary supports aren't.

But miraculously, when the flood waters subside,

they're still standing.

Everybody was happy about that nothing happened.

It took a couple of days, but we were pretty fast

up and going again.

The team now turns to the steel frame

at the heart of the radical 90-degree twist.

The building is made out of perfect rectangles,

and then, er, the first part of the gallery is straight,

and then, it turns

through the twisted gallery,

and then, goes straight again.

A specialist manufacturer in Poland

wins the contract to produce the frame.

Failure is not an option.

They tested it in the workshop,

pre-assembled,

to see if everything would fit

when it was, er, delivered from Poland to Norway.

The steel producer will be looking

for any discrepancies that would make it

rather expensive to fix at site.

Once everything is good to fit,

the steel components make the 800-mile journey

north to Norway.

Then we started reassembling them here

on top of the temporary structure.

We assembled larger pieces next to the building,

and then, lifted them onto place,

and then, bolted them to the previous structure.

It was the most beautiful structural system

I've ever seen.

Fantastic.

Two months later, with all the elements

bolted together, it's time to see

if the radical twisting frame will stay standing

when the temporary supports are removed.

I think it was one of my most stressful days,

er, ever.

Starting from the outside in,

the temporary support columns

are removed one by one.

But as they reach the middle,

their worst nightmare comes true.

The frame starts to sag.

Is it wrong calculations?

Is it wrong installation?

Why is this happening?

In Norway, the team behind

a radical bridge-cum-art gallery

that spans a river with a 90-degree twist

has just discovered the frame

won't support itself, midway across.

It was exactly what not should happen.

And we were in a period

where, time-wise,

we were extremely, er, under pressure.

Investigations reveal

the bolts that hold the frame together

are the problem.

The bolts deformed

just a tiny, tiny bit, er,

and that was enough to make it sag.

We jacked the bridge back up,

and then, welded some of the connections together,

and that effectively stopped the movement.

It adds four weeks onto an already tight schedule,

but the additional joints will have a long-term benefit.

It's a stronger structure now

than it was supposed to be,

and that feels good.

Which means the frame's exterior

can be clad in anodized aluminium

while the gallery's interior

makes an ingenious use of an altogether,

more everyday material.

When you do a twisted building

where the floor becomes the wall

and the wall becomes the ceiling,

you often end up with three different materials.

And we wanted everything to be seamlessly the same.

So for the interior finishes,

we ended up, er, with an eight-centimetre wide,

er, cheap plank, a standard that you could find

in any hardware shop, er, in the world.

To create the 90-degree twist,

the planks are fitted onto joists

that have been calibrated to curve with the frame.

We did the 3D modelling

of the internal cladding in the bridge.

That is not something we would usually do,

but the carpenters at site

could see the benefits

of having some pre-made wooden joist

that was easily to assemble at site.

Creating the twist from a series

of progressively rotating rectangles

is what makes the design so clever.

But when it comes to the windows

that will flood the midsection with light,

the same trick won't work.

The only thing in the building

that's not straight

is the glass

in the middle that twists.

So this warped surface in glass

is something that could be done

by very few producers of glass

in Europe and a few in China.

It takes six weeks of precise fitting

to ensure the curved panels perfectly align.

When those were installed

and glued in place, I was happy.

In 2019,

18 months after work started on the foundations,

by the skin of its teeth,

the ground-breaking bridge-cum-gallery

has its royal opening.

We were pushing the craftsmen,

er, out the basement door on the north side

while the dignitaries were on the south side

having their speeches.

Two of the first people to enter The Twist

at the inaugural opening

was the Crown Prince of Denmark

and the Queen of Norway.

The finished building is a stunning hybrid

that serves as a museum,

sculpture,

and bridge,

whose twisting geometry creates

three distinct gallery spaces,

including a light-filled panorama

overlooking the river and historic mill.

You can see the slowly flowing water by,

and then, you see the dramatic twist.

Every angle, every place you stand, it's unique.

In my opinion, this is the most beautiful

piece of architecture in Norway.

The priceless collection of art has a new home,

while the sculpture park has a fitting new addition.

What I'm most proud of here

is, of course, the sculptural effect

it has sitting in the forest.

Mission accomplished.

How do you transform

a rickety old wooden roller-coaster

into a state-of-the-art ride

that'll satisfy modern thrill seekers?

Well, it's a job that's gonna have

its ups and downs.

And then, more ups and downs.

Followed by a 206-foot drop

straight down that'll have you screaming

your head off.

Coasters have been with us

since the late 1800s.

The first one in the US was Coney Island's

six-mile-an-hour switchback railway.

Since those early days,

they've gotten much longer

and much, much faster.

By the '50s, they're pushing 60 miles per hour.

And with the debut of tubular steel in 1959,

twists and turns get tighter

and steeper.

By 1975, coasters are even pulling full 360s.

But as the new millennium approaches,

at Busch Gardens Park in Florida,

preparations are underway for a coaster

they hope will outdo them all.

Gwazi was one of the longest

wooden roller-coasters in the world.

It sprawled across eight acres.

Riders really loved the raw wooden rattle

and the relentless negative G pops.

These negative Gs, a momentary feeling

of being lifted out of your seat,

are part of the thrill that draws crowds

to the legendary wooden ride for 16 years.

But by 2015,

Gwazi's beginning to show its age.

Florida's climate is brutal.

You've got relentless UV,

80% humidity.

There's tropical rain and hurricanes.

The Florida climate really took a toll

on, um, the wooden structure

and the wooden track.

The park decides to close Gwazi

before it gets dangerous.

But now, they need a new ride that can cut it

against bigger and faster competition.

We knew this needed to be an incredible ride,

a statement piece.

There's a lot of competition

in the Florida market.

You've got to have

the world's something

or the state's something.

You have to break limits.

Rather than start from scratch,

they decide to completely reimagine Gwazi.

We opted to keep the framework

that was there, essentially,

because it still makes a very cool,

classic looking coaster

with all that wooden structure that's underneath it.

To create what's known in the trade as a hybrid,

where they take Gwazi's old wooden structure

and add other materials to turn it

into a state-of-the-art modern ride,

they bring in R-M-C,

a company that specializes in doing just that.

Busch Gardens, er, approached us,

wanting the tallest, fastest,

and steepest hybrid coaster.

That was our starting point with Gwazi.

This is Gwazi's rebirth as Iron Gwazi.

Double the height, 25 miles per hour faster,

and with a new drop that dives beyond vertical.

It will totally transform Gwazi

into the fastest and steepest hybrid

timber-and-steel coaster in the world.

It won't just compete with rivals,

but outstrip the competition entirely.

But getting there won't be without its challenges,

the first of which will be working out

just how much of the old timber frame

can be saved.

Then, they'll need to marry that with a new steel track

to deliver the speeds and inclines needed

for a white-knuckle experience.

They'll need to design and construct

a new terrifying climb and fall,

which somehow will have to go beyond a vertical drop.

And all the while, they'll need some way

to keep the cars fixed to the track,

keeping riders safe,

even if they feel they're anything but.

People expect a modern ride to be extreme.

But the more you push it, the less room there is

for even the tiniest imperfection.

And with Gwazi, they really wanna push it

to the limit.

August 2018,

and in Tampa, Florida,

the team turning the wooden Gwazi coaster

into a state-of-the-art wood-and-steel hybrid

is working out just how much

of the old timber frame

is strong enough to cope with the stresses and strains

of a much bigger and faster ride.

In the wooden roller-coaster world,

you're using southern yellow pine.

We'll run all that timber

through an analysis software

that puts loads from the train into it,

puts loads from the weather into it,

to see at what point

that particular member would start to fail.

They would come out there

and literally go through, mark things,

tag things, flag things, and then, they would start

to tear out the things that weren't gonna work.

Surveying over a hundred thousand cubic feet

of timber is a slow and painstaking process.

If there's any indications that it's gonna be an issue,

even in five years' time, we take care of it.

There was definitely more wood to be removed

than we originally anticipated.

By early 2019,

the team's ready to start the rebuild.

And the frame needs to be much, much stronger,

because they want the new tracks to be made of steel.

Steel, in general, is more than ten times

the strength of wood.

And so, it gives us the chance

to re-envision these rides into something very modern.

Not only is steel heavier than wood,

but the way it behaves is simply not the same.

Wood and steel behave completely differently

when you put weight or pressure on them.

You've got wood, which twists and swells,

depending on the weather,

and a much stiffer steel track,

which doesn't behave that way,

so it adds additional stresses on the timber.

The team adds over 30,000 cubic feet

of new timber to the frame,

but even that won't be strong enough.

So, they build a complex system of steel supports

to ensure Iron Gwazi can handle the new track.

We had to provide buttressing,

erm, through pipe column members,

and those steel pipes are braced to each other as well.

And that is to keep the wood

from exceeding its maximum allowable stresses.

Although the team are saving

what they can of the old ride,

they also have to extend it

to create what will be the climb and fall

for the fastest and steepest

hybrid coaster drop in the world.

When you go over the top, it's a 91-degree drop,

which means you go with a drop and you're actually slightly

coming back on yourself as you go down.

Most coasters drop 60 to 80 degrees,

which is pretty steep.

90 degrees is straight-down a cliff free fall.

Iron Gwazi's is 91 degrees,

which means you can't even see the track in front of you.

How crazy is that?

Pretty crazy, especially if they can work out

how to get the trains 206 feet in the air,

twice the current height.

We knew we couldn't just piggyback structure off

of this old lift hill that was a hundred foot tall.

We're going over 200 feet.

To extend it to more than double its old height

requires an engineering technique

more often used in bridge-building.

Look at a lot of bridges

and you'll see triangular trusses

because they are incredibly strong.

Any forces applied on a corner

get transferred to the two sides,

whereas a square would deform.

Which, face it, is the last thing you want

when a coaster train is passing over

at 76 miles per hour.

After months of careful design,

it takes 12 weeks to prefabricate

the 360,000 pounds of steel frame

in a factory in Idaho.

And once it gets to site, they get to work fitting it.

You're working with existing wood

and you're adding structure, you're adding a new lift hill,

so the complexity is very much like a ground up,

brand-new roller-coaster.

But you're, er, integrating a new roller-coaster

into an existing ride.

Even so, in just a month,

the team erects the 20-storey hill lift tower

which will be Iron Gwazi's pièce de résistance.

Their next challenge is creating the tracks

to go on top of it.

So, on a classic wooden coaster,

the tracks are made up of layers of timber,

which then have a thin steel strip

for the wheels to run along.

Here though, they need a system that's much stronger

to keep the trains on the tracks

when they roll and loop.

We start with, er, a flat sheet of steel,

and all of the track pieces are cut from that steel

on our plasma tables.

What we're doing is taking individual pieces

from plate, cutting out a shape,

and then, those shapes will get folded together by hand

to make the I-Box track system.

Then, a combination

of three different wheels lock onto the track,

making sure that however steep the drop,

the trains stay firmly attached.

Our track has a little lip overhanging on the inside.

So, you have the wheels called upstop wheels,

which are riding on the underside of this lip,

and they keep the train from flying off of the track.

At least, that's the plan.

First though, the steel track needs to be fitted

to the wooden structure.

And that's not straightforward in a climate like Florida's.

Florida has high humidity.

That humidity will find itself

being absorbed by the wood,

which will then swell,

and then, the steel will be baked by the sun

and it will expand,

which means that they're breathing

at different rates.

Which also means the steel tracks

could come apart from the wooden frame,

sending a train travelling at 76 miles an hour

flying off the rails.

The engineers behind a massive,

hybrid coaster in Tampa have hit a problem.

How to attach two very different materials,

steel track onto wood frame,

without them pulling apart in Florida's extreme climate?

Wooden-structure roller-coasters

are very much a living organism.

They're breathing.

And the combination of the steel track

and the wooden structure means

that they have different rates of expansion and contraction.

To compensate, they design a special bracket

called a saddle,

which allows both the wood and the steel

to move at different rates, while keeping them together.

The saddles have to be flexible to be able to move

and adjust in pretty extreme ways

to be able to support this new track.

In all, 1,300 saddles are fitted,

which just leaves more than 4,000 feet of steel track

to be securely installed and in the correct sequence.

In December 2019, the first trains arrive

and after testing, the wait is over.

On February 13th, 2022,

Iron Gwazi is ready to rock and roll.

The lift goes 45 degrees, you go up 206 feet.

It's the world's steepest incline

of any hybrid coaster.

You do this 91-degree, er, drop...

then you bank slightly to the left,

then you go up immediately into this massive

outward, banked curve.

You're flying out of your seat, you get a ton of airtime,

it's a great moment.

It just keeps going and going and going.

And it's fast all the way to the end,

just element after element, you're flying through it.

The ride was literally just relentless.

In its first year,

Iron Gwazi draws over a million riders.

Every drop, twist, and inversion,

the result of relentless testing

and precision engineering.

I immediately knew it was a success.

Just seeing people smile, seeing the reaction,

when they come into the station clapping.

The most important and fun thing about this

is watching other people enjoy these rides.

We saw smiles. And when you see people

get off the ride, eyes lit up,

you know, people high-fiving each other.

There's something special about that,

seeing other people enjoy a creation

that you and your team worked on for so long,

and poured everything into.

You know you're making memories for people.

That's a pretty special experience.

Brisbane's city leaders

wanted to persuade the Olympic committee

to let them host the 2032 games.

The question was,

how could they swing the vote in their favour?

There were a few obvious options:

take the committee to brunch and pick up the bill.

Or go with the slightly bigger gesture,

like a $2.5-billion redevelopment

that would reshape the entire city.

Not subtle, but very effective.

Originally called Meanjin

by the Turrbal people who lived there

for thousands of years,

Brisbane is Australia's third largest city,

and capital of Queensland, the Sunshine State.

Brisbane is traditionally described as a river city.

The river really dominates the whole town.

Its north bank is home to the city's

bustling business district,

all except for one historic riverfront neighbourhood,

Queen's Wharf.

This area is where the first wharfs

were built in 1828,

and they used to be called King's Wharfs.

It's also where European convicts arrived

in the 19th Century,

and many of Brisbane's oldest buildings,

including the Commissariat Store

built by prisoners in 1828,

still stand today.

It has a very powerful connection to the history

and the birthing stories of Brisbane.

In the 1970s, the state government

takes up home there.

But within 40 years,

they're moving on to new offices.

It was a part of the town that

didn't really have a lot going on,

but it was definitely a diamond in the rough.

So, in 2013, the government

puts the 66-acre site up for lease.

Brisbane was lacking a recent landmark development.

And there's an opportunity there with a site that made sense.

Developers DBC

want to put the city on the world tourist map

and local architects Cottee Parker

are put on design duty.

We wanted to attract

local and international visitors to Brisbane,

just on the strength of this one development alone.

That pretty much drove every single design decision

throughout the process.

Their vision for Queen's Wharf

will transform Brisbane's skyline

with a complex that includes a casino,

ballroom, and leisure resort,

including three hotels and 2,000 apartments,

all crowned by an incredible sky deck

300 feet above Brisbane.

To build it, the team will undertake the largest

inner city excavation in Queensland's history

right next to the flood-prone Brisbane River,

while somehow protecting the 11 historical buildings

on the site.

The enormous foundations must be strong enough

to support the parking garage,

entertainment hub, and four towers,

which need to be built as quickly as possible.

Then, contractors Multiplex

will take on the most daring operation of all,

the Sky Deck.

Somehow, they will have to get the enormous sections

300 feet in the air

when they're too heavy for the toughest crane.

And then, stop them from ripping the towers apart

when they're all connected.

This is development on a scale Queensland

has never seen before.

Wow, we have to now deliver this very, very large

and complicated project

in a really important part of the city.

Before anyone can lift a shovel,

the first job is demolishing the old government offices,

but making sure the surrounding historic buildings

stay standing.

There was quite a lot of engineering done

to design a complicated external bracing system

that was put into these buildings

to also protect them during the development.

It takes 18 months, but in April 2018,

with the historic buildings shored up,

contractors begin excavating for the foundation.

And the team faces a huge challenge.

In fact, two.

The excavation was

the largest excavation in Australia.

We had to dig down seven levels of basement

to get to the foundation levels.

Not only are they excavating

a 200,000-square-foot area,

but they're doing it beside the Brisbane River,

and that's a risky move.

The Brisbane River has one of the most flood-prone

flood plains in Australia.

In 2011, the flooding was so bad,

huge parts of the Central Business District

were submerged.

Any construction needs to keep the river at bay.

The way we ended up resolving this

was to use something called a diaphragm wall.

You have a special rig that can cut a vertical slot

that is then filled up with a mud called bentonite.

Bentonite basically holds back the water.

We then drop in a reinforcing cage...

and fill the wall up with concrete.

A staggering 90,000 cubic feet of concrete

and thousands of tons of steel later,

the wall is finished.

The top of the wall was probably about

five metres above the normal river level.

But will it be high enough

to deal with an extreme tidal surge?

In January 2019,

Brisbane experienced a king tide,

with the river level peaking at nine feet,

and flooding the local area.

In Brisbane, Australia,

the city centre's biggest ever construction project

is at risk of a tidal surge from the Brisbane River,

overwhelming the massive wall built to protect it.

After a tense 24 hours,

the wall does its job and holds back the water.

And by the summer of 2019, the excavations are complete.

Just in terms of sheer size and scale,

450,000 cubic metres of earth

that were excavated, that,

you know, roughly equates to about...

11 million beer kegs or something like that.

It's phenomenal.

It then takes another year

to build out the five floors of subterranean parking.

We needed something like

7,000 cars to park in this facility.

And the team turns to its next major challenge.

The heart of the project will see four towers

all connected 300 feet off the ground

by an enormous sky park.

But first, they need to solve a problem.

If we tried to build these towers one by one,

the project would've taken four times as long.

And on any building project,

time is money.

So, they need to build as quickly as possible.

It becomes really about mass production.

How quickly can I pour concrete?

How quickly I can get that formwork up

to pour the next level?

Even the formwork or moulds

used to pour concrete for the floors

are designed for speed.

These forms are self-supporting and jump up the tower.

We fill it with concrete and reinforcing.

It self-supports off the structure

and goes again to the next level.

Once we got into the flow of building the towers,

then it's repetition, similar floor plates,

similar locations of columns,

we were achieving as fast as four days in some cases.

With the towers roaring up,

by September 2022, the team turns its attention

to one of the greatest challenges of the project,

the Sky Deck.

The crowning glory of the composition

is the--is the Sky Deck.

It's roughly a three and a half thousand square metres

of open public space for the people of Brisbane

to celebrate and enjoy the river.

This wonderful public space, though,

is going to be 300 feet up in the air.

Building a 20 to 40-metre

spanning steel deck,

20 storeys in the air

is not something that you do every day.

Huge sections of steel are prefabricated,

and then, brought to site

where they can be assembled on the ground.

A lot of the structure could be complete

at podium level, where it's safer to do.

You're not working at height.

The problem though is that having assembled

these huge sections of the Sky Deck on the ground,

you've somehow got to get them 300 feet up in the air.

There was no crane in the world big enough

to lift these pieces up by themselves.

The team instead turns

to an amazing piece of engineering

called a strand jack.

Strand jacks are highly specialized

hydraulic lifting devices

that are used to lift or pull massive loads

with high-tension cables.

So, by using several jacks in tandem,

you can lift thousands of tons at once.

The sky decks were slid out into position.

They use high-tensile strand to lift the Sky Deck.

It is actually a jack that pulls the strand up

in very small controlled increments,

and the points which are jacked,

they're all synchronized, so that the structure,

as being lifted, never becomes out of balance.

It takes three lifts,

each lasting five to eight hours

to get the bridge sections,

weighing up to 413 tons, into place.

It's one of those things where you can't believe

it went to plan as well as it did.

There was almost no hitches

in that whole installation sequence.

The sections of deck may be in place,

but fixing them to the towers could spell disaster

if not done correctly.

One tower may move one direction

and the other tower in the opposite direction.

Which means the Sky Deck could pull the towers apart.

It required the design of some really customized joints

in order to allow these buildings to move

and prevent them locking up against each other.

Called an articulation or sliding joint,

it's designed with a system of bearings

that allows the towers and decks

to move independently of each other.

So the deck sits on top of the bearing,

but can slide backwards and forwards.

And we have to design those joints

for a large degree of movement.

On August 29th, 2024,

after construction began,

Queen's Wharf opens its doors to the public.

The first sense was of relief

more than--more than anything else.

What was once the site of the city's

first European settlers over 200 years ago,

remains its historic heart.

Only now, it's joined by a state-of-the-art complex

of 2,000 apartments,

three hotels, and a casino.

There's also more than 800,000 square feet of public park,

including the lower leisure deck,

and the gravity-defying Sky Deck,

floating 300 feet in the air.

I think the Sky Deck is a great addition to Brisbane.

It's a great public space for everyone to use.

You have the full 180-degree view,

you can see the birds... Just nothing like it.

Queen's Wharf stands proud,

an extraordinary addition to the city skyline.

It's great to see how...

it's transformed the skyline of Brisbane,

and this is not just during the daytime,

but at night-time as well,

when the facade comes alive.

We have built something special for Brisbane.

It has revitalized a part of the city.

It has absolutely put Brisbane

on the world stage as a world city.

And is ready for when Brisbane hosts

the 2032 Olympic Games.

There are not many projects you get to work on

that have that bigger impact.

It's an incredible feeling.

In a world where imagination,

innovation, and creativity

define the spaces that surround us,

How Did They Build That? shows again and again

that humankind will overcome the seemingly impossible.