Original subtitles

The hardest jobs on Earth

demand the mightiest machines,

hammering foundations...

We're out there ripping and tearing all the rock out.

...scaling boulders.

It's such a rush.

...and battling rock beds.

This is where the power hits the ground.

Meet the monsters of rock.

A constant roar echoes off the coast

of Sault Ste. Marie, Michigan.

Squadrons of steel titans attack the shoreline,

hammering, crushing

and smashing their way through bedrock and concrete.

It's like playing in a big sandbox all day.

You get to play with bigger toys.

Fifty machines

moving over 900 tonnes of rock every day.

Just a constant movement of dirt. I love it.

These mechanical beasts need to be tough enough

to tackle one of the biggest,

most demanding demolition jobs in the world.

The excavator,

the jaw crusher, the trencher -

they're stripping things down to bedrock

to make way for a new lock in the St. Lawrence Seaway,

the gateway to Lake Superior, the Soo Locks.

It's hard to overstate

how important the Soo Locks are

to North American steel production.

About 78 million tonnes of cargo

pass through here each year.

We refer to the Soo Locks as the linchpin of the Great Lakes.

All of it carried by over 7,000 ships.

If ships can't follow this path through the Soo Locks,

they have to move material over land

and then downriver to the Atlantic Ocean.

costing millions,

if not billions of dollars in delays.

The old lock has outlived its usefulness.

A new lock, wide enough for the largest vessels on the lake,

is needed.

These machines are here to make sure that happens.

Shipping freighters are depending

on this project to continue their essential passage

through this waterway.

With a worksite this large, a lot of moving parts,

a lot of swinging machines...

These demolition monsters remove over

408,000 tonnes of rock before new construction can start.

But they're not throwing it all away.

A lot of this rubble will be reused during reconstruction.

All of the materials on site

are repurposed, whether it's rock or concrete,

will be ground and used for aggregate and backfill.

When it's time to tear things up,

the excavators are the heavyweights on the front lines.

Weighing in at a staggering 63 tonnes

and armed with a hydraulic hammer - or 'hoe ram' -

that pounds the rock

at a bone-rattling rate of 540 blows per minute...

...even the hardest stone is pulverized in minutes.

It'll tear down the old lock,

the old concrete, the rock that's underneath and behind.

But a giant hammer is only as good as its head,

and this one is easily the meanest weapon

in the war on rock.

This part right here helps contact the rock.

This is the chisel piece right here.

That's why they have a shape like that.

Helps you get more penetration into that rock.

When you're working with hard rock,

you need top-tier tools to cut down on wear and breakage.

The chisel, it's made of a heat-treated,

high-strength steel

that minimizes the risk of weak spots,

which will cause cracks, leading to catastrophic failure.

This is the toughest two feet in the world right here.

The excavator is designed

for rugged conditions and extreme environments.

It's driven by an engine

that delivers the horsepower of a high-performance sports car.

But in the world of rock crushing,

performance isn't measured in speed;

it's measured in brute force.

The machine's hydraulic system generates

a significant mechanical force

from its 436-horsepower high-performance engine.

That force is transmitted through pressurized fluid

to the hoe ram's hammering piston.

Although the machine's power is brutal in nature,

it does require a delicate touch.

Rock excavation on this project

is a lot like doing surgery with a sledgehammer.

So, we're out there ripping and tearing all the rock out...

...and then, when you get down to the bottom,

it turns into surgery with a large machine...

...where you're trying to take out

just a few inches of rock to get that flat foundation

to be able to pour concrete on.

The bedrock beneath the foundation of the Soo Locks

is called Jacobsville Sandstone.

It's a very thick sequence of red sedimentary rock

lying over Precambrian rock.

Engineers have gone to great lengths

to design the new passage.

So, the demolition team must do their part

to make sure everything

is dismantled carefully and efficiently for the project.

We have two active locks

that are really important

to the US economy and ship traffic,

and then we also have a lot of historical buildings

and historical structures on site.

So, we really wanted to get away from blasting.

At other sites,

there's no denying the speed and power

of high-explosive rock removal.

But the new lock is surrounded

by so much life and infrastructure,

the demolition crew must rely on their machines

to get the job done.

While controlled explosives

have been used when absolutely necessary,

the bulk of the work has been handed over to the machines.

The advantage of using

a lot of these excavators is

you can put a lot of different machines

in a lot of different areas and do it a lot safer.

The Ojibwe First Nations peoples

were the first to negotiate

the six-and-a-half meter change in elevation

between Lake Superior, Michigan and Lake Huron.

As trade increased in the area,

larger and larger boats became more common,

and moving them across the lakes became more difficult.

And ultimately, it leads to the construction

of the lock, in 1853,

to facilitate the transportation and voyage.

The Soo Locks officially opened in 1855

and have been operating and improving ever since.

This current demolition

is just another phase in their evolution.

But before the demolition started,

this entire area was underwater.

So, to bring the machines in,

they had to come up with a way to get the water out

and keep it out.

The solution, cofferdams.

A cofferdam is basically a giant waterproof wall

that you build in the water.

These temporary barriers hold the water back,

so that the site can be made safe and the work can continue.

Two cofferdams were initially installed

at either end of the lock.

But as the site grew, more of these barriers were needed

to keep the water out so demolition could continue.

Pumps remove 181 million litres of water.

The cofferdams make demolition possible

in the most impossible locations.

But the work of pumping that much water out

and managing the overall water level of the site

is the key to the system.

Keeping a dry workplace is a constant battle.

All the water gets pumped out

to the St. Mary's River or Lake Superior.

In total, we have about three miles of pipe

and 16 different pumps collectively pushing water,

four feet a second, out to the other side of the cofferdam.

Right now, we're pumping about 2,200 gallons per minute,

which is about 3.1 million gallons per day.

That's more water than four Olympic-sized

swimming pools a day.

With the water held back,

another mechanical beast gets to work.

one with an endless appetite for rock.

It can eat bedrock, dirt, concrete, limestone.

Pretty much anything that it'll eat,

besides metal, she'll eat it.

The rock crusher is massive.

It can pulverize the material at a punishing rate

of 550 tonnes per hour.

In a 12-hour workday, that's roughly the weight

of 3,000 monster trucks.

Right now, you got the excavator loading the crusher.

It's coming down the chute here,

down the feeder box, into the grizzly bars.

The grizzly bars are a simple sorting system.

Smaller pieces fall through the gaps

of impact-resistant metal grates,

onto a conveyor belt, where they're easily ejected.

The large rocks rumble across the vibrating feeder box

and grizzly bars,

and then fall into the enormous jaws of the crusher.

Inside, rocks are smashed

between a fixed and moving plate.

The moving steel plate crushes the rocks repeatedly

as they fall through the narrow opening,

reducing the boulders to mere fragments

as small as ten centimetres.

The rock's just going to get smaller until the size we need.

You know, it's just going to go down to the jaws,

start getting popped all the way down

to the size that we got it set at.

All that rock smashing has a mesmerizing effect

on the people who work these machines,

who have a passion for what these mechanical monsters

can do each day.

I've been running equipment in dirt for 12 years now.

I just fell in love with it and I knew

this is what I wanted to do for the rest of my life.

Part of the crushed material

is being used to fill in the old lock,

while the rest will act as a windbreak for ships.

Being able to keep the material on site, crush it,

and reuse it is a big benefit.

Repurposing the rock eliminates the need

to truck and ferry tonnes of material off the work site.

It's a great way to be more efficient

when your timelines are tight

and the eyes of the community are watching.

Following the rock crusher's assault,

a new machine rolls into action.

Enter the trencher,

a surface mining titan that hungers for only one thing...

...grinding up rock.

And its weapon of choice is a ferocious, gnarly-toothed barrel

that can chew up over 100 kilometres of rock

in a 12-hour workday.

This colossus demands respect.

This machine shakes very violently.

It's not an easy ride.

It feels like you're riding a bull all day.

The trencher or surface miner,

is a 100-tonne behemoth of rock-ripping action.

We're gonna rev up. Once we up to speed,

we're going to drop the boom and...

...we're tearing up some earth.

We're excavating all this rock down

to get the rock all flattened out for a new foundation.

So, using a big drumhead allows us to flatten that out

and get that prepped and ready for concrete.

The 4.2 meter wide barrel, or drum,

is equipped with carbide-tipped steel teeth.

A carbide is a mixture of carbon

with other metal elements, often tungsten.

The addition of carbon makes a new metal significantly harder

and more wear-resistant.

In this case,

the teeth stay sharper for longer

to keep on tearing up the earth.

The teeth are designed to chew up and spit out

the hardest of rock.

They can dig a trench up to one meter deep.

On this drum, you're going to have over 150 teeth

that are grabbing the ground while this thing is rotating.

This is where the power hits the ground,

and this is what's going to turn hard rock into rubble.

Hammering rock is hard work.

But on the Soo Locks project,

their opponent is particularly stubborn.

Jacksonville Sandstone

is a difficult enemy for the surface miner.

It's a well-cemented, coarse-grained

red sandstone that will eat up lesser machines faster

than they can break the rock.

And any breakdowns

could lead to a landslide of problems.

You can tell the machine's doing good

when it's not hopping and banging super loud,

and when it really starts to

hop and bang is when you really need to change some teeth out,

when they're getting worn.

Maintaining your machines is key

to a smooth demolition operation.

These machines take a beating

in harsh, demanding, and dusty environments.

If crews aren't looking after things properly,

it can lead to safety issues,

causing downtime and major repairs.

But before the ground crew can inspect the teeth,

they need to give them a rinse.

Right now, I'm cleaning off the drum

because the tips are full of mud,

and we've got to clean them to make sure they're not broken.

Every bite takes its toll.

I'll have my ground guy

change out the teeth while I'm rotating the drum for him.

It takes some heavy-duty dentistry

to yank these rotten teeth.

Sometimes, you gotta knock it a little bit loose, so it spins,

put the prong up there...

...and it just pops right out.

Grab a new tooth,

put it there...

slide it back on...

...and it's back in. Now, you got a new, fresh tooth.

With a new set of chompers in place,

the trencher can get back to dinner

and shaking its operator right down to the bone.

I'm sitting in this machine,

running it for ten hours a day, six days a week.

It's a little hard walking some days, but it's all fine.

It's a dangerous game.

Amidst flying debris

and bone-crushing equipment, one wrong move could be disastrous.

When you put labourers,

operators, excavators, all in the same hole,

you know, there's a lot of hazard.

Our biggest motto is, you know, just watching out for,

not only yourself, but your--

you know, be your brother's keeper.

More than a century ago,

hundreds of men toiled against this rock with crude tools

and pickaxes.

Now, these colossal machines

are the ones who reshape the landscape.

Their thunderous work serves a greater purpose,

ensuring that trade continues

to flow through this crucial passage.

Water has been critical to transporting goods

for thousands of years,

and that's not going to change.

The Soo Locks will be integral to our movement

for hundreds of years to come.

These rock-crushing behemoths

have carved a path in the earth itself...

...redefining what's possible with every hammer blow.

On the rugged Nevada landscape, rock crawlers...

...machines that look like cars...

but climb like mountain goats,

unleash their raw power,

taking death-defying tumbles...

...crawling their way up 90-degree rock walls

and down heart-stopping drops,

as they push the limits of mechanical engineering.

Yeah, baby.

A rock crawler is a specialized four-wheel drive

off-road vehicle built to slowly

and very methodically tackle the most challenging terrain,

climbing boulders, steep crevasses,

or taking stomach-churning dives with ease.

Unlike race cars, where everything on the machine

is built for speed, rock crawlers are all about control.

These are precision vehicles built to maximize flexibility,

torque and grip.

Speed is our enemy and control is our friend.

Sometimes, slow is scarier than fast.

Once a year, the best of the best

travel from across North America to transform

these rocky Nevada hills

into a pro, unlimited rock crawler battleground...

...to take home a small cash prize

and the all-important bragging rights.

We are the top of the pro class, and we're running

the biggest obstacles possible.

One of the things that appeals to me

about this sport, rock crawling, is the adrenaline rush.

I've been over 153 miles an hour on skis.

I've jumped out of a plane.

I don't think there was as much adrenaline rush there

as there is actually in driving these cars.

Rock crawlers are the king of the hill.

You come out to one of these events

and you will see these teams do the impossible

with these vehicles.

The courses are tight. It's a game of inches.

Precision driving requires precision tools,

and the most critical tools

in the rock crawler's kit are its tires.

These are the hands and feet of the rock crawler.

This is what has to reach out and grab that rock,

wrap around the rock, pull you up the rock,

or hold you from dropping off a cliff.

DR. EL-SAYEGH: Rock crawling demands grip.

These machines are navigating

depth-defying angles

that no other vehicle could even attempt.

They need tires made from a special compound.

The rubber has to be extremely soft,

allowing the tires to bend

and stretch with the jagged rock surface.

This is a competition compound,

so it's a softer durometer rubber

than what you typically have on your car.

You can't actually flex the rubber

on your passenger car tire; you can flex this one,

and what that does is it really helps grab the rocks.

It's not only the rubber that makes these tires super grippy;

it also comes down to the tire pressure.

Just like the tires on your car,

the crawler's tires need pressure to hold their shape,

roll, and absorb any bumps in the road.

The PSI - or pounds per square inch -

is just a fancy way of saying how hard

the air is pushing against the rubber of the tire.

For an average car, tires run at about 35 psi.

The crawler's tires are dropped down to six psi.

That's pillowy soft, so they can hug the rock.

If the tire is inflated too much,

you're basically just gonna spin on that rock.

I've got enough pressure in the tire

that it's still holding the car up

and low enough pressure that it's wrapping around

and grabbing that rock.

When the rocks bite back,

these tires decide if they'll continue the climb to glory

or slide to defeat.

Tire placement is key.

And one wrong step,

either a penalty or you're done for the weekend.

For these tires to do their important part,

they need heavy-duty support.

Trying to stop a one-tonne vehicle on a dime

is a challenge.

But when that dime is on the edge of a cliff,

it also needs a mighty brake system.

This vehicle is equipped

with your traditional braking system...

Yeah, baby.

...but it also has what we call cutting brakes in our sport.

This allows me to control the brakes independently,

from corner to corner.

Most modern cars have four-wheel disc brakes

for maximum stopping power. When you step on the brake,

the pedal makes every wheel stop at the same time.

But cutting brakes are totally different.

The cutting brake system lets the driver control

each wheel's brake independently.

By locking just one wheel, the other three

can keep pushing forward, allowing the crawler

to spin around that point.

It's the same move an NBA point guard uses

when pivoting on the court.

Two massive levers control the cutting brakes.

There's one for each side of the rock crawler.

The levers are really easy to manipulate.

Push them forward to control the front wheels.

Beautiful, beautiful.

Or pull them back to control the back ones.

Use them one at a time or in combinations.

Beautiful, yep, just like that.

Yeah, baby.

The result is a tremendously tight turning radius

that can be created around any tire.

And if the rock crawler does get stuck in a tight position,

you could lock two or even three tires,

depending on the situation.

The power to lock individual wheels at will

helps the drivers stay safe

while making split-second decisions

about the direction they're traveling.

The braking capacity is phenomenal.

You get on rocks and you're in a precarious position

and, you know,

you're teetering on whether or not you're going to roll over

or actually make the obstacle,

and when you actually make that obstacle,

it's such a rush.

With all the complexity

involved in the braking system,

the drivers need to depend

on the car's three-speed automatic transmission.

An automatic transmission is vital.

The driver can't be wasting time and energy shifting gears

with everything else that's happening.

They're busy with brakes, systems, and steering.

Managing the gears by hand would be too difficult

and ultimately costly,

especially if they make mistakes.

In the wild world of rock crawling,

things can go sideways in a heartbeat.

Falling down is one hazard of many -

engine fires and machine failures,

drivers get pinched, trapped, or knocked out,

and there's the constant risk of violent rollovers.

The danger is real.

The driver needs to be kept safe in the vehicle.

And so, you've got all these gussets

and braces that are providing safety.

There's bars in the door that, you know,

keep rocks from coming in.

In our sport, safety is primary concern.

It starts with our fire suit.

We have a five-point racing harness,

so I buckle that up, cinch it tight, it locks me into my seat.

Rock crawlers are way more rough and tumble

than your average off-road vehicle.

Safety gear is a must.

Window nets keep arms inside vehicles,

helmets mitigate head and neck injuries,

and easily accessible fire extinguishers

are within grasp when needed.

Rocks make for a harsh landing.

So, these rigs are built to take a beating.

They stand on the shoulders of fighting giants,

the 4x4 heroes of World War II.

Popularized by soldiers

and civilians after the war,

the love of these rugged vehicles led to off-road clubs

and the eventual development of the rock crawling sport.

The sport of rock crawling was just people

pushing the limits of those vehicles,

and they kept getting stripped down,

the Jeeps kept getting body panels cut off of them.

What started with factory models

quickly evolved into customized machines

in pursuit of conquering bigger and scarier obstacles.

Less weight reduced

the stress on the engine and gave them more manoeuvrability.

Every pound saved was a little bit more performance.

This thing's designed to go over on top and back onto its wheels

and still be able to drive.

But drivers have to be prepared for everything

because epic accidents are inevitable.

When I first built this car,

I rolled this vehicle off of a 25-foot cliff,

rolled multiple times,

but because of all of my safety gear,

I didn't break any bones,

I was completely safe.

Disaster lurks around every boulder.

Drivers need a second set of eyes on the ground

to help them crawl to the finish line.

Beautiful.

Mind the rear.

Yep, there you go.

Start curling a little on the front now.

Go ahead. Don't get crazy.

He's telling me how close we are to obstacles...

Hey, go driver front. Go driver front.

...whether or not I need him to help me with extra traction...

I got you. Come on.

Work the rear. Go.

Yep.

...how much time we have left.

Two and a half minutes. We got it.

He works really hard.

I'll tell you when. Keep coming. Just keep coming.

He's depending on me, and I'm depending on him out there.

Spotting is not for the faint of heart.

These daredevils stand within feet of these monster machines,

leaping from rock to rock, risking trips or falls,

as they dodge and chase the rig around the course.

Any distraction, any slip could be fatal

and not just for the driver.

In Cedar City, Utah, we were competing,

it was a little pop over, much like this,

where I positioned myself,

I didn't think the car was going to do anything.

And then, right as John came over the ledge,

it hit and it rocked the car over and hit me.

It basically folded me in half

and I went back and I landed right on my head.

If I hadn't been wearing a helmet,

it would have killed me. It was bad. It was bad.

We're trusting each other with each other's,

basically, lives sometimes.

It's truly a driver-spotter.

It's not just a one man show. It's a team out there.

Getting behind the wheel

of a Pro Unlimited rock crawler takes guts.

But don't be fooled,

these bodies are built tough,

ready to take some huge tumbles and keep on kicking.

This is all steel structure,

and it's inch and a half diameter 120 wall tubing.

It's as strong as it needs to be

to keep the driver safe and make the car function.

The key to the rock crawler's strength

is the humble triangle.

Triangles are exceptionally strong

because of their ability to spread force across their shape.

When a triangle does get hit,

that force is dispersed along its sides.

That's perfect for a rock crawler.

It takes such a beating while it's running the course.

Basically, the more triangles we have,

the stronger the design is.

So, when the rock crawler rolls over or falls backwards,

the frame can absorb the force of that impact.

You know, you want it to take the impact

and still be safe.

You're basically inside a full roll cage.

While the triangle

keeps these machines in one piece,

it's their specialized suspension that steals the show.

This is how rock crawlers

prove they're the ultimate terrain masters.

These machines handle all those hard knocks

thanks to the unique structure of the suspension.

Inside each shock cylinder,

oil and nitrogen gas

are separated by a free-floating piston.

The oil helps absorb impact and dissipate heat,

providing a smoother ride.

As the shaft moves into the cylinder,

reducing the length of the shock,

the nitrogen is compressed,

supporting the rock crawler's weight.

When the suspension flexes,

the shaft travels in and out of the shock body,

changing the pressure of the nitrogen as needed.

The crawler has incredible travel,

which is basically the maximum distance

that the front or rear suspension

can compress to absorb impact.

More travel allows the suspension

to better handle bumps and twists,

preventing the crawler from bottoming out.

Travel is the maximum expansion or lift

you can get out of the shock.

And with up to a foot-and-a-half of lift,

this rock crawler can absorb a lot.

The suspension travel on these is incredible.

These shocks are a 16-inch travel shock on the front,

an 18-inch travel shock on the rear.

By the time you bring one up a couple inches

and bring the other one down 16 inches, boy,

these things are completely flexed sideways to one another.

You can suck the suspension down,

so you can keep a low centre of gravity.

You can also loosen it, so you can get extension on one side,

allowing the tires to grab the rock at some really wild angles.

Like you see right here,

the rear shock is completely compressed,

so it can't go up any farther. And if we come over and see

the other shock on the driver's side, it's completely extended.

When I'm in this position,

I want the car to be as stable as possible.

So, if you're looking at the chassis right now,

this chassis is almost completely flat to gravity.

So, this car is extremely stable.

It may look crazy, but I'm in complete control of this car.

Rock crawlers are evolution on wheels -

part beast, part machine,

and an engineering marvel from front to back.

Well, this is our passion.

When it all hits,

when you are on the right line, when you're on the right rock,

and when that thing wraps around it,

and it just pulls you right up the obstacle,

it all feels perfect. It's like hitting a home run.

In the desolate foothills of Nevada,

these monsters of rock use the latest science

to challenge the laws of gravity.

Under the weight of heavy freight,

in what seems like an endless stream of passenger trains,

Sweden's 15,000 kilometres of railway lines

take a daily beating.

All that action has an impact at track level.

That's where you'll find Sweden's

rolling railway repair fleet.

They are the biggest, the most powerful ones.

I would say they are

the mightiest ones that can be built.

These machines suck up the bad...

...mix in the new...

...and then shake, rattle, and roll the material...

...remaking the railway bed.

Whether carrying freight or people,

trains are heavy and put constant pressure on the tracks.

And traveling along these tracks over and over causes wear,

deformation, and movement of the rails.

If the foundation of the rails

isn't properly maintained on a regular schedule,

it can be disastrous.

It all starts with the RailVac...

...a giant vacuum that sucks up rock...

...also known as ballast, the foundation of a railway bed.

But when ballast rocks wear out, they've got to be replaced.

When the ballast starting to get like this,

then it's really, really bad.

You see, this is not correct.

This is very bad. It's like dirt inside here.

Ballast is usually made of crushed granite and limestone.

They help absorb the shocks and keep the track dry

and the train running smoothly.

Good ballast is larger rock with rough ridges,

allowing the material to connect together more tightly,

which makes it more stable on the tracks.

Bad ballast is smaller, smoother,

and unstable because it separates too easily.

Every time a train rushes over the tracks,

the ballast beneath gets more and more worn.

The longer it's used,

the rounder and smoother it will become.

Eventually, the ballast will be so worn,

it can't hold the position of the tracks

or the weight of the trains anymore.

Bad ballast leads to unstable rails...

...and that could spell disaster,

potentially shutting down a line for repairs, or worse,

causing a derailment.

It's hard to imagine a more specialized

rock guzzling machine.

The RailVac is the length of a Boeing 737,

and it devours everything in its path.

It's got more power than a lot of vacuum cleaners together.

So, it's definitely one of a kind machine.

The purpose of the RailVac is to vacuum.

It sucks up all the old ballast,

the soil, the mud, any debris,

cleaning up the tracks to get them ready

for fresh new material to be laid down.

There's a flexible nozzle

at the end of the suction arm that can snake under rail ties

to clean up years of buildup.

It's much more versatile

and a lot less disruptive and safer

than using something like an excavator or doing it by hand.

Think self-propelled shop vac.

Then, supersize it, delivering a rock-sucking 700 horsepower.

It's a lot of power.

You don't want to get your hands in the nozzle,

for sure, I can tell you that.

You don't want to get your hands in the nozzle,

When Sweden needs to remake its rail beds,

it rolls out the RailVac to remove railway ballast

at an incredible rate - 40 cubic meters per hour.

Like a tornado inside a container

that causes the air to flow through the machine,

sucking up the ballast and all the bad materials.

There's no human driver aboard this machine.

Instead, the human walks beside it,

controlling its operation via joystick.

But rather than watching over video,

the operator can see the work in real life.

Like operating a big RC car or something like that.

So, it's pretty cool.

Its belly now bulging with ballast,

this beast needs to unleash its load.

So, it travels down the track, and with the touch of a button,

a hydraulic sigh of relief can be heard.

Side hatches on the tank open up

and the old ballast tumbles out into the ditch.

We emptied out both sides,

about 40 cubic meters of dirt ballast.

The RailVac moves up the track

to continue slurping bad ballast.

The next machine in the railway restoration is arriving.

True to its name,

the ballast feeder is loaded with fresh rocks,

ready to drop them in place.

The suction machine and the ballast feeder

are not more than 5-10 meters away from each other.

To be able to be that close, with safety,

the skilledness and the trust

between the operators is very important.

The ballast feeder uses a conveyor belt system

that's surprisingly agile.

It can rotate effortlessly from side to side,

strategically placing ballast

exactly where it's needed along the tracks.

The whole floor will move

and this conveyor belt is going to drive it forward,

so we can throw stones.

The other machines, they can only, like,

throw stones straight forward.

We can throw stones 180 degrees.

That's the unique part of this ballast feeder machine.

The ballast feeder is fully automated,

and the operator can control

the flow of the ballast from the touch screen,

saving a lot of time.

There are train schedules to keep,

and delays on the line can cost millions of dollars.

Putting the ballast exactly where it needs to go

is a huge factor in keeping this operation tight.

The ballast feeder leads

a specialized train of its own.

I'm coupling together the machine,

and we're going to synchronize it with those cables,

so they can work together.

Today's rock-slinging configuration

comes with four wagons.

Altogether, it's 90 meters

of rock and roll ballast feeding action.

This is the four wagons then

because this job will require all that stone.

Out with the old, in with the new.

Upkeep like this is critical in keeping the railway on track.

Railways, as we know them, have existed since the 1700s.

These tracks were laid on the ground or on wooden roadbeds

and were prone to instability.

As trains became heavier and faster, the instability

and shifting of the track laid on the ground

becomes a huge problem with time,

and ballast is the solution.

By the 1800s, railway builders began using beds

of crushed stone or gravel to support the track

and provide stability.

The change of ballast in early days was done by a shovel

and bucket.

Then, you have to stop the traffic for a long time.

As trains evolved,

so did the technology to support them.

Manual labour was replaced by machines

specially designed for the task.

Once the ballast is laid

and the dust is settled,

a third machine comes along to shake things up.

The tamping machine may look unsettling,

but in fact, it's designed to do the opposite.

16 prongs, or tines,

plunge into the rail bed and then vibrate.

The action forces the ballast to fit more snugly.

Up close, this machine looks more like a transformer

than a maintenance vehicle, with its spider-like tamping unit.

The operator is constantly monitoring

the plunging prongs.

This 83-tonne behemoth

can tamp 700 meters of rail bed an hour.

When everything is good to go and all my...

measurements in there looks good,

we start to tamp, and we go up to first

sleeper here, and its rollers

that grab the railroad in each and lift it up

and hold it exactly right.

Now, the vibrating tamping tines

plunge deep into the ballast.

The tines squeeze together,

vibrating and shaking the ballast rocks

and allowing them to settle,

creating support for the rail lines above.

A few more squeezes for good measure ensure the voids

are completely filled with the fresh ballast.

The whole process is repeated

until the tamping machine registers

the correct ballast pressure levels beneath the rail.

They do it two or three times

when we have this much to lift,

and then, the ballast gets stiffer,

it holds up better.

Once the ballast is all tamped down,

the tamper corrects the rail alignment

to make them perfectly parallel and level.

The rails are then laid carefully over the new ballast

to ensure the trains run smoothly.

You're responsible

for the track when it's finished,

so I try to make it perfect.

If it's like this now, it's perfect.

This is how you want it to be.

All new ballast,

this is gonna hold many years forward

and gonna be more stable during winter,

during rain season, all that.

This stretch of track is refreshed,

but there is a lot more railway ahead

for these specialized machines.

It went pretty well.

We all planned to do 45 meters and we did it.

So, yeah, job well done, I would say.

And they're keeping Swedish Rail on track,

one kilometre at a time.