Original subtitles

[narrator] In Denmark,

this elite team of engineers is embarking on an epic endeavor.

They're building a colossal two-and-a-half-mile-long bridge

to connect Scandinavia to mainland Europe

like never before.

It's not every day you build a bridge like this.

Constructed from nearly 30,000 tons of steel

and more than 3.5 million cubic feet of concrete...

We can't afford any mistakes.

...to build this megaproject, the team must work

at precarious heights...

If somebody went over the side of the bridge, it would be very

difficult to come back from that.

...and battle extreme temperatures.

No room for error. No, definitely.

This gigantic bridge ranks in a league

of ambitious new engineering wonders

that are bigger, faster, taller,

and more advanced than anything ever constructed before.

This is the inside story of the extraordinary challenge

of building these giants.

Denmark, in Northern Europe.

The country is made up of 444 islands

that straddle the North and Baltic seas.

Danes rely on a network of mega bridges to get around.

One of the most important is the Storstrom Bridge.

It carries traffic and trains and links the islands of

Falster to Zealand,

home to Denmark's capital city, Copenhagen.

The Storstrom Bridge was a marvel of engineering when it

was built in 1937.

But it doesn't match up to the demands of modern travel.

The bridge's north end has two sharp curves

where it meets land.

Trains must slow down to just 50 miles per hour

to cross it safely.

The road has a 31-mile-per-hour speed limit and is too narrow

to handle the ever increasing volumes of traffic.

The bridge is beginning to crumble after 90 years of wind,

rain, and snow.

Now, a team of engineers is attempting to build

a new bridge to replace the old one.

This superhighway will carry pedestrians,

cars, and the latest generation of high-speed trains.

It will be part of a wider infrastructure upgrade

between Denmark and Germany,

The Fehmarnbelt project, the world's longest

immersed underwater tunnel

that will slash journey times between Scandinavia

and mainland Europe.

Constructing this mega bridge over the choppy,

ice-cold and bustling shipping lane here will be

a unique challenge.

Their target is to complete the bridge

within just eight years to open in the spring of 2026.

Failure to meet this deadline will have disastrous

consequences for the budget

of this 400-million-dollar project.

The pressure is on design manager Barbara Macaulay

to deliver the bridge on time.

Storstrom in Danish means "big current," and building that

in this environment

with the currents, the winds, the ice-cold winters,

it is an overwhelming task.

The new Storstrom Bridge will be an epic feat of engineering.

It will stretch almost two and a half miles.

44 piers resting on the seabed rise out of the water.

The central tower, known as a pylon, soars 335 feet

into the air.

36 steel cable stays connect the central pylon

to the bridge deck below.

The deck supports two high-speed railway lines,

a two-lane road, and a combined pedestrian

walkway and cycleway.

Constructing this new bridge won't be easy.

The bridge must be both long to span the Storstrom Strait

and tall to allow cargo vessels to pass underneath.

To cross the Storstrom Strait, engineers must first sink

the giant foundations that support the 44 piers.

A skilled team of engineers make each one at

a purpose-built workshop on site.

First, they cast the base plate in concrete.

Next, they build a hollow concrete tower at the center,

which will stand six-and-a-half feet above sea level.

Each foundation block measures around 65-by-65 feet.

They must sit within just two inches of pre-designated spots

on the seabed.

This is how they'll do it.

First, engineers must excavate holes underwater

at the 44 pier sites.

They fill each hole with 3,300 tons of gravel to level

off the seabed.

Next, a special barge floats

each of the pier foundation blocks into the channel.

Each weighs 2,750 tons.

A huge catamaran crane lifts

and then lowers the foundation blocks onto the seabed

to sit exactly on the gravel pads.

A special heavy-duty barge will then sink the supersized

13,200-ton foundation for the main pylon.

Engineers must place the foundations

with absolute precision.

Trains will cross the bridge at 124 miles an hour.

A misalignment could shake the train, damage the track,

or make the ride unsafe.

[Barbara] There's absolutely no room for errors.

The whole team is under enormous pressure.

Construction begins in 2018.

First, workers excavate the seabed.

They dig 44 holes for each foundation and fill them with

gravel to create a level surface.

Next, it's time to install the 44 pier foundation blocks.

It will take workers anywhere between six and 24 hours to set

each pier foundation into place.

The biggest variable is the weather.

Any change in wind speed could cause a giant concrete pier

to sway dangerously as the crane lifts it from the barge.

Placing these large elements in the middle

of the sea

in waves and currents.

And with this really tight tolerance of five centimeters,

it's quite nerve-wracking.

The team moves the first huge pier foundation.

The workers use massive motorized trailers to carry

the huge chunks of concrete and steel onto a waiting barge.

Tugs drag the barge into the Storstrom Strait

to where a special floating crane is waiting.

The crane maintains a precise position above the target

deployment area.

The team attaches the crane's arms to the pier foundation

ahead of the lift.

The sea is calm and winds are light.

For now.

Two pairs of huge winches lift the block into the air.

A tug pulls the barge away from the crane.

The winches reverse direction to lower the block

below the water.

The block descends 23 feet to the seabed

and hits its mark.

Over the next 40 months, engineers install the remaining

43 foundation blocks.

Now comes the toughest challenge.

At the center of the bridge will be a pylon,

standing 335 feet tall, five times the height

of the surrounding piers.

But it will need a supersized foundation to support

its towering height and massive weight.

Engineers in Denmark are racing to complete

the two-and-a-half-mile-long new Storstrom Bridge.

It's a crucial part of a wider transportation plan to link

mainland Germany to Scandinavia.

A team of specialized workers make the pylon foundation

in a purpose-built fabrication yard right next to

the Storstrom Strait.

They cut 1,045 tons of steel rebar

and pour nearly 177 thousand cubic feet

of concrete to make the structure.

The finished foundation stands seven stories high and weighs

a staggering 13,000 tons.

The barge and crane the team use to position

the 44 pier foundations

are too small to place this megastructure.

The engineer's solution is to attach a supersized,

square-shaped buoyancy aid to the top of the foundation.

This huge red steel structure has a pair of air tanks

on each side.

They allow the engineers to sink the foundation.

Engineers roll the giant structure onto a special

semi-submersible barge.

Tugs pull the barge to the middle of

the Storstrom Strait.

Once the barge is positioned above the drop zone,

engineers pump water into its ballast tanks,

and the deck slowly descends beneath the sea.

The giant water wings on the pylon foundation keep

the huge block of concrete and steel afloat

as it detaches from the sinking barge.

Next comes the most challenging part of the operation.

The team must place the mega foundation block

precisely on the sea floor.

The engineers deploy a special team of divers.

Divers go down and check that it's in the right location

and also that there's no gaps underneath any of the corners.

The divers signal that the block's position is good.

The team opens the valves

on the foundation block's water wings

and fills them with water.

The block descends slowly and makes contact with

the sea floor.

A team of workers places the bridge's 44 piers

on top of their foundation blocks.

Another team pours 60,000 cubic feet of concrete

into steel frames

to build the bridge's 335-foot-tall central pylon.

First stage of the mighty build is complete.

Next, the engineers must construct and install

the huge bridge deck

that will carry high-speed trains between Scandinavia

and Central Europe.

Now, the engineers are ready to install the girders.

These are the bridge's supersized sections of deck

that will carry trains, road traffic, and pedestrians.

These girders are absolutely massive.

Each element is 25 meters wide, 73 meters long,

and weighs 4,000 tons.

This is how Barbara and her team will do it.

First, the team constructs 44 giant girders in a special

factory next to the bridge.

Then, engineers load a finished girder onto a barge.

Tugboats tow it into position between two piers.

Special lifting towers on each pier

connect to four lifting arms on each girder.

The towers lift the girder 85 feet above the water.

Engineers secure it to the pier with steel and concrete.

In this huge temporary factory, a team of 120 people

work around the clock to make the girders.

First, specialized fabricators cut and connect 468 tons of

steel rods, known as rebars, to make the girder's skeleton.

Next, they install huge V-shaped supports.

Workers then pour nearly 57,000 cubic feet of concrete

into the girder's frame.

It takes this team two months to make one complete

240-foot-long girder.

A pair of mighty hydraulic pistons pull the 4,000 ton

girder out from the fabrication shed.

And onto motorized trailers.

These roll the girder onto a barge.

Tugboats haul the barge and its cargo to the first pair of

piers in the Storstrom Strait.

The installation of the first girder begins.

Precision is key.

One wrong move and the girder will collide with the pier.

There's absolutely no room for errors because, I mean,

worst case, you can imagine one of these girder elements ending

up in the harbor.

Next, workers use cables to attach the girder to

the lifting towers on top of the piers.

The first lift of the girder is just

nerve-wracking.

Lifting an element this size

so high in the air with such tight tolerances with lifting

equipment that we haven't tried before, it's a mad task.

Two pairs of winches on the towers turn in unison.

The girder lifts up off the barge.

The lifting towers raise the girder section into the air

at a speed of six-and-a-half feet per hour.

It takes 12 hours to lift it into its final position.

Next, a team of engineers must secure the girder to the pier.

They fit a rebar frame between the two giant structures

and fill it with concrete.

After 12 hours of work, the first girder installation

is complete.

Over the next two years, the team makes

hauls,

floats,

and lifts the remaining 43 girders.

The bridge deck is in place.

The next challenge for the engineers is how to hold up

this giant span for the next 120 years.

In Denmark, engineers are six years into the build of

the country's newest mega bridge.

The new Storstrom Bridge stretches two-and-a-half miles

between the islands of Zealand and Falster.

The Storstrom Strait is a busy shipping route for vessels in

the Western Baltic.

Container ships weighing as much as 7,700 tons must be able

to pass under the bridge quickly and safely,

and the bridge must be tough enough to withstand an impact

from a fully laden cargo ship.

The ship impact is a real risk to the structure.

You can't afford a superstructure collapse.

The engineers of the new Storstrom Bridge build in

critical safety features to prevent a catastrophe.

First, they fit a T-shaped metal joint called a shear key

to the top of each of the 44 piers.

The shear keys transfer the force of a major impact

from the pier to the bridge deck.

This helps the piers absorb the shock of a collision

with a container ship.

Next, the designers of the bridge make the girders

on either side of the pylon extra wide.

Each girder spans 525 feet

to give even the largest container ships

enough clearance to pass underneath.

The pair of super-long central girders weighs 8,800 tons.

The girders are too heavy to support their own weight.

So, engineers use 145-foot-tall temporary piers to hold them up

while they complete the next stage

of this mega building project.

Engineers run a total of 36 hollow casing tubes from

the bridge deck to the central pylon.

The longest tubes measure nearly 530 feet.

Next, they thread a total of 3,000 steel cables through

the casing tubes and fix them at both ends.

Then, engineers tension each strand individually

until they're the correct tightness.

Finally, the engineers can remove the temporary piers.

Ilona Hall oversees this critical cable installation.

Welcome to my office.

Outside in the elements, room with a view.

Ilona's team must complete the task within four months

for the project to stay on track.

It's very important that the stay cables are installed

at exactly correctly.

There's very tight tolerances on the loads, the lengths,

and the positioning of the stay cables relative to

the pylon and the deck. It's got to be perfect.

A lot of lives depend on this bridge being

structurally sound.

The team works for three days to install 36 hollow tubes.

Now it's time to fit the 3,000 steel cables.

Workers fasten one end of a cable to a guide.

Then a special pulley hauls the cable through the hollow

casing up to where it meets the pylon.

A special crew secures the cable to an anchor point.

Up here, workers perch on a tiny platform exposed

to the elements.

[Ilona] Up at the top of the pylon, we're measuring the wind

constantly so that if the gust speed exceeds our limit,

then we will stop works activities.

Time is a critical element when you're constructing.

Every day is money.

Today, the winds are light, and the team is making

rapid progress.

They thread the other end of the cable down into the girder.

Here, another team fastens it to an anchor point.

They use a super strong hydraulic jack to tension

each strand.

The jack will pull that strand tighter

to put the load into each individual strand.

The strands are parallel.

They must remain parallel at the bottom and the top.

So there's a sequence which we stress.

The team repeats the process for every strand.

Ilona checks for defects and signs off.

[Ilona] Today has gone really well.

They are very efficient

at doing all the individual components,

working together as a team, in deck, in the pylon,

outside the pylon, all working together.

Finishing the stay cables on the bridge is

an important milestone.

Putting the stay cables in is almost that last piece of

the puzzle to the bridge supporting itself.

Next comes the ultimate test for the newly installed cables.

Engineers prepare to remove the temporary piers that

support each giant girder section.

If the cables fail, the girders could

become unstable.

Repairing them would take months.

Engineers unlock the temporary piers from beneath

the girder sections,

and a special barge tows them away.

For the first time, the bridge supports

its own weight.

The operation to install the cables is a success.

Engineers in Denmark are racing to complete the new

Storstrom Bridge.

The bridge must open in 18 months' time.

The pressure is on for design manager Barbara and her team.

This huge project is obviously very costly, so the quicker

we can complete the bridge and open it, the better

for everyone.

The team's next challenge is to build the bridge deck on top

of the girders.

The deck must support three types of transportation,

two high-speed rail lines, a two-lane road,

and a combined pedestrian and bike path.

The deck of the old Storstrom Bridge measures 48 feet across.

It has two car lanes, a narrow walkway

for pedestrians, and a single low-speed

rail line.

The deck of the new Storstrom Bridge is nearly 35 feet wider

than the old bridge.

Its two car lanes are both 11 and a half feet wide,

and it has two high-speed rail lines.

It rests on the shoulders of architect Jesper Henriksen to

design a cross section this wide that can support

this extra weight.

When building a bridge with both rail and boat,

then we have different options.

Of course, the first option is, of course, to have two

independent decks.

I mean, that's like the very fast and easy way.

But on this one, we choose to have one combined deck section.

To have both rail and road combine them is, of course,

a big challenge for the engineers.

We got some massive forces that we have to get together

and down into the piers.

The load distribution across the deck of the new bridge

is uneven.

One side must support the weight of the heavy track

and the 660-ton high-speed passenger trains

that roll across it.

The other side must support the lighter road

surface and vehicle traffic.

The bridge's design must balance the two sides

to prevent a catastrophic collapse.

To fix this,

engineers design the bridge girders with a longitudinal

beam and V-shaped delta frames made from concrete and steel.

These stiffen the girder and redistribute the forces

from the heavier side of the deck.

Then, engineers abandon traditional heavy railway

ballast stones and sleepers.

Instead, they lay 1,500 concrete slab tracks.

These are much lighter.

Engineers mount rails on top.

Each is 590 feet long and weighs 11 tons.

Finally, they fix the slabs in position with concrete.

Today, design manager Marco Raimondi

inspects the delta frames

that strengthen the two critical central girders.

These delta frames essentially stiffen the box of the girder,

and they prevent the distortion when we have an unbalanced load

from the rail.

The delta frame also supports this central beam that is

running longitudinally.

On the bridge deck above, a crew installs the tracks that

will carry the high speed trains between

Germany and Scandinavia.

A regular railway uses stone ballast and sleepers

to support the track.

The advantage of these is that workers can adjust them easily.

But ballast and sleepers are too heavy to use

on the new Storstrom Bridge.

The engineer's lightweight solution is called slab track.

This is a continuous line of concrete slabs that have

special fastenings to secure the metal rails.

First, workers lay 1,500 slabs along the length of

the bridge deck.

Next, they use rollers to install 590 foot long sections

of steel rails.

32 clamps on each slab track lock the rails into place.

Finally, the workers use concrete to bond the slabs

to the bridge.

[Marco] It's an operation that requires extreme care.

The rail has to be positioned within one centimeters, both in

plan and in elevation from the nominal alignment.

Fixing a misaligned slab will be time consuming and could

delay the opening of the bridge.

No room for error. No, definitely.

Marco inspects the final length of slab track to make

sure all the blocks are lined up correctly

before they're concreted into place.

[Marco] The final completion of the rail is the end of

a very long process.

It feels definitely as a great achievement.

We're ready to go.

Engineers in Denmark are racing to complete

the new Storstrom Bridge.

The megastructure must withstand at least 120 years

of punishing Baltic winters.

Almost half a mile to the east is a reminder of what could

happen if they fail.

The old Storstrom Bridge opened in 1937.

An inspection in 2011 revealed significant damage

to its concrete and steel components.

It now requires regular monitoring and costly

maintenance to ensure it's safe.

Chief Project Manager Mette Thyregod is part of the team

tasked with keeping the old bridge operational until

the new one is complete.

[Mette] So, what you see here is the stalactites underneath

the concrete, and that says water coming through

the concrete, the bridge deck, which means that

the waterproofing is no longer working.

And this particular concrete is very sensitive to water

and salt coming through.

It both causes cracks in the concrete, but also causes

corrosion of the rebars.

At this point, you are past repairing, so it really needs

a new bridge.

The new Storstrom Bridge needs a defense against

a twin threat --

freezing water that expands inside gaps,

and rock salt spread on the roadway

to keep it ice-free.

These will corrode the steel rebar and damage the concrete

of the new bridge.

The challenge for the engineers building the new bridge is how

to make it 100% waterproof.

It falls to Andreas Hensen to ensure the whole bridge deck is

completely weather-sealed.

This is extremely important because this is

one of the main factors of the long-term durability

of a structure like this.

We have to be sure that no water comes inside.

The bridge's roadway covers an area of over one million

square feet, the same footprint as 12 standard-sized

city blocks.

Andreas' team needs a quick but 100% effective way

to waterproof an area this large.

Workers spray 220 tons of this yellow-colored membrane across

every square inch of the road surface.

Once dry, they then apply a second layer,

220 tons of this white-colored membrane.

They complete the waterproofing with a coat

of this red bonding material.

The process takes seven months to complete.

A team of road builders then lays asphalt

over the three waterproof layers.

It's critical for the bridge's future health

that every square inch is sealed.

Even the smallest hole in the waterproofing will allow

salty water to contact the concrete and steel below.

He uses a special machine that passes an electrical current

through the road surface to detect tiny pinholes

in the waterproofing.

The surface must be completely dry for the readings

to be accurate. But it's snowing heavily.

It has to be dry because we're using an electrical current

to run through the waterproofing.

So now, first, we have to remove the snow and the ice.

We're doing that with compressed air

with a special air lance that we're using.

The machine makes a sound if it detects a hole

on the surface.

Good news, the machine remains silent.

The testing is complete and we're sure that no water

will come inside the concrete.

So the bridge can remain in function for the next

120 years, and that's fantastic for us.

A vehicle or train fire near the huge central pylon could

pose a danger to the integrity of the bridge

and the safety of the people using it.

The steel cables that support the bridge deck could degrade

rapidly if exposed to extreme heat.

[Ilona] If steel gets heated, it loses its tensile strength,

so the cables will elongate, they will lose their strength

to hold up the bridge.

Ilona descends the equivalent of 12 stories to the base of

the central pylon to inspect the system designed to combat

a dangerous fire on the deck.

Just 30 feet below sea level is this

two-and-a-half-ton mega-pump.

In the event of a fire, the pump pushes nearly 1,600

gallons of seawater a minute up to hydrants on the deck,

to hoses that spray water under the cables to keep them cool

and prevent them from losing their strength.

Ilona meets engineer Troels Fischer

to inspect the pump.

The bridge can't open to the public without this

critical safety feature fully operational.

We have this manual operation panel here.

It will then pressurize the vault and send it up

to the deck.

We have to test this once every week to just inspect by

the sensors we have down here, and then we'll also have

a camera to check whether there's leakages.

That looks fine now.

This unique firefighting system is ready for use

in the event of an emergency.

[Ilona] It's great to see the systems installed and the testing

being completed.

This is forward thinking in terms of bridge engineering.

Engineers in Denmark race to complete

the new Storstrom Bridge.

The grand opening is only four months away.

The new bridge weighs over 220,000 tons.

Each pier pushes down onto the seabed with the equivalent

force of almost three Eiffel Towers.

It is critical that every pier settles into the seabed

by the same amount.

If a pier settles too deeply, the bridge will become unstable

and could cause a train to derail.

Surveyor Jimmy Petersen and his team monitor the amount

of settlement.

If he discovers that it's too great, then engineers will need

to complete repairs that could delay the opening

of the bridge.

The geologist has made predictions for how much

the settlement on each pier area should be.

Predictions are not always accurate.

If it settles more than expected, the worst case

scenario would be that the bridge drops

into the ocean.

The designers of the new Storstrom Bridge build into it

an innovative monitoring system.

They mount a nearly 25-inch-square reflector

onto each pier.

Every six days, a GPS satellite

fires a signal at each reflector.

This plots the precise position of each pier over time.

This is the first time ever in the world that we have had

a system like this.

Jimmy clears debris from each reflector.

It's critical the surface is clean to ensure the satellite

makes an accurate reading.

Jimmy heads into the nerve center

for the monitoring system inside the bridge's girders.

He connects a special laptop to the network

to check the latest batch of readings from the satellite.

He analyzes the data.

If any pier is settled more than expected,

then engineers must push back the opening of the bridge.

We can see that there has been a settlement

of about 12 millimeters throughout the last year,

and that the settlement has stabilized.

That's exactly what we want to see.

This special monitoring system tells engineers

that the new Storstrom Bridge is sturdy

and ready to carry road and rail passengers

across the Storstrom Strait.

The new bridge must stand for at least 120 years.

The designers of the bridge commission an innovative survey

technique to document the health of the bridge

before it opens to the public.

It is the job of specialized engineer Usman Butt to create

this unique bridge's digital birth certificate.

So we're going out today to try and get the last pictures

for the 3D model.

Bridge is constructed, so we're missing the last couple

of images.

Usman flies a special camera drone.

It takes 180,000 overlapping photographs

of the exterior of the bridge.

We have a position down to an accuracy of

five centimeters.

So we really know where we are in the world, [indistinct] this.

Usman will stitch together the photos the drone takes

to create a super detailed 3D model of the bridge.

The model will document every imperfection.

Future engineers can compare this data

with their later inspections to gauge as early as possible

if the bridge needs repairs.

[Usman] At the moment, I'm taking overlapping images

in a way that we can create the 3D model.

So we need to have full coverage of the entire

structure so that we don't miss any angle for the model itself.

Back at the office, Usman adds the latest drone data

to the existing model.

He reveals the results to design manager

Barbara Macaulay.

[Usman] We can see already that we have, initially,

788 detections of different kind of cracks.

Is that the number of defects we should be concerned about?

[Usman] It's quite normal to see a lot of defects.

That doesn't mean it's critical defects.

I would say this looks harmless.

[Barbara] It's amazing.

Having this digital birth certificate, I think, gives us

the confidence there's no hidden defects.

We can always have a record of where we started and let's say

in six years or 20 years time to see if new defects

has developed.

This clean bill of health

means that the new Storstrom Bridge is ready

for its grand opening.

Soon it will carry cars and high-speed trains between

North Germany and Denmark well into the 22nd century.