Original subtitles

Narrator: This time on "impossible engineering:"

Extreme railroads"...

Penetrating the great wilderness,

Facing nature head on...

This is really wild terrain.

There's a more than 400-foot drop,

And there's no escaping it.

Narrator: With the solutions...

Like generations of moormen before him,

He looked to the ground beneath his feet.

Narrator: That make the impossible possible.

Dickrell: This has got to be one of the most hard-fought pieces

Of railway engineering on the planet.

This is magnificent! I love it.

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Captions by vitac... www.Vitac.Com

Captions paid for by discovery communications

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Narrator: Across the world, towns and cities

Are often separated by vast wilderness.

Inhospitable landscapes, punishing terrain,

And extreme weather can make crossing these divides

Seem impossible.

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But trains stop at nothing,

Tackling previously uncharted territory

With some of the most adventurous railroads

On the planet.

Overcoming the world's wilderness

Poses uniquely difficult challenges

For even the most pioneering of railroad engineers.

Potts: Wilderness like this would stop any train in its tracks.

This is an incredible feat of engineering.

Mahoney: So, this is the start of the real climb

Around one of those tight curves.

This is real mountain railroading.

Newland: It's bleak. It's isolated.

It is utterly treeless.

How can you build a railway here?

What would you build it out of?

Narrator: And it's one such seemingly impossible challenge

That faced engineers in north america

In the late 1800s.

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Promontory summit, utah, is in the heart of the west.

It's an empty desert landscape, with few signs of civilization,

As engineer dan dickrell is finding out.

Gosh, there's really nothing out here.

If you've never driven across the western united states,

There's these vast tracts of nothingness.

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Narrator: This particular barren stretch

Hosted perhaps the most significant moment

In the history of the north american railroad.

[ Bell clanging ]

Since the inception of railroads,

Engineers had dreamed of building

A line that would connect america's east and west,

And in 1869, that was about to become a reality.

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Dickrell: Oh, this is a really cool moment.

So, I'm riding on the jupiter,

Which is an exact replica of the steam locomotive

That would have been here

When the two railroads met from east to west.

For the first time, you could ride from one end

Of the continent to the other.

I can't describe to you how cool this is,

Because this is a beautiful reproduction.

It's in pristine condition.

It weighs 60 tons... about 10 african elephants.

It burns all of its fuel in about 30 miles,

Which is not a lot.

It goes about 25 miles an hour.

2,000 gallons of water to make the steam.

[ Train whistle blows ]

It's a huge-but-beautiful machine.

[ Train whistle blows ]

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Hmm.

Well, here it is.

This is the golden spike.

This is the location where the two lines met and were united.

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Narrator: But the circuitous mountain route

Added 42 miles to the trip.

The more direct alternative route, however,

Presented some seemingly insurmountable challenges.

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Dickrell: This is the great salt lake.

It is a mind-blowing sight when you're here.

It's so massive. It's so vast.

You can't see the other side.

The sky and the water blends together.

It's incredibly bright out here.

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Narrator: This phenomenal watery wilderness would present

The railroads' engineers with an enormous task.

Dickrell: Standing in this spot, it's easy to imagine

What those engineers felt so long ago,

Trying to figure out how are they gonna cross

This vast body of water.

It seems almost impossible.

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Narrator: But in 1902, engineers defied the odds

And made a plan to build across the 1,700 square miles

Of exceptionally hostile landscape.

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It's not even a bad day, and it's really choppy out here.

The water is six times saltier than ocean water.

It makes for a really dense and powerful wave.

As an engineer, when you want to build something,

You have to take into consideration the environment,

And this is probably one of the most aggressive environments

That you could build anything, right?

Extremely salty water, high humidity,

High heat in the desert.

It's not a very hospitable place

For something that's supposed to last for a long time.

So I wouldn't want to build anything out here at all.

Narrator: The monumental solution engineers came up with

Was the lucin cutoff.

For a year and a half, 3,000 men

Grafted two earth-and-rock- filled embankments together,

Bridged in the middle by an immense wooden trestle.

This is the point where the old, original trestle

Would have started extending out into the lake.

It was 12 miles of timber.

2 square miles of forest

Were used to make this immense wooden structure.

Narrator: In 1904, a train passed over the lake

For the first time,

Cutting the journey through utah from 10 hours to a mere 2 hours.

But, by the 1950s,

Conditions had taken their toll on the trestle bridge.

Dickrell: The pilings themselves weren't driven

That far into the lake bed,

And the lake bed in this particular lake is very soft.

So the weight of the trestle itself, as well as trains,

Would cause subsidence.

The trestle would sink.

The aggressive nature of salt infiltrating the wood

Would cause it to split and deteriorate.

Ultimately, it was decided that the trestle was to be torn down

And replaced with something stronger.

Narrator: Faced with such extreme conditions,

Engineers had to find a more robust solution.

In 1956, work began to create an epic causeway

That would carry the railroad

Across a raised stone embankment

Across the entire span of the lake.

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This is the causeway.

It stretches almost as far as the eye can see.

Tons and tons of fill rock are dumped into the lake...

Something to build a track upon.

Narrator: 75,000 tons of rock were transported daily

On six of the largest bottom- dump barges ever constructed.

Seeing workers on top of the causeway

Gives a sense of the epic scale of this work.

The size of the boulders, the elevation above the lake...

It's massive.

It's a massive structure.

Narrator: But once again, mother nature showed her hand.

Dickrell: Now, these rocks and boulders that fill the causeway

Look large, but the forces that this lake

Can bring to bear are even larger.

But it's a testament to how heavy this causeway is

And how soft and squishy the lake bed is...

It's always sinking, always subsiding.

And so it's a continual battle to replenish this structure

In a constant fight against the environment

That engineers, the rail line

Are continuing to fight, but it's tough.

It's a tough fight.

Narrator: And crucially, culverts that had been built

To allow water to flow through the causeway

Had cracked to the point they could collapse

And take the track out of service.

Due to the nature of this extreme environment,

Those culverts were folded upon each other,

They were consumed, it didn't work.

Narrator: To keep trains running, the cracked culverts were filled in.

But what happened next was unprecedented.

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Blocking the flow of water created a startling difference

In salinity, water level, and even color.

So, the engineers had to come up with a different plan,

A different solution,

That ultimately would enable the lake to breathe its water

And allow railways to move.

Narrator: In 2016, this clash with nature inspired

Another incredible feat of engineering.

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Dickrell: So, this is the brand-new bridge

That engineers hope will solve the causeway's problems

Once and for all.

The new pillars are driven 200 feet down,

Even though the lake's only 35 feet deep.

The pilings themselves are steel core

Covered in a special material

To prevent, effectively, environmental damage

Eroding and destroying the columns.

See as we pass underneath the berm here...

This allows the railway to add and remove material,

To help flow control in between the northern

And the southern parts of the lake.

The northern part's much saltier,

So the water exchanges through.

Wood couldn't make it. Concrete couldn't make it.

So hopefully this is the solution

That will solve these problems,

From a material science perspective, for the railway.

Narrator: This watery wilderness baffled engineers for decades.

But, despite the struggle, the railroad ultimately won.

This has got to be one of the most hard-fought pieces

Of railway engineering on the planet.

Nothing but respect for the people

That keep this line in service in such a tough place.

[ Train horn blows ]

Ohh, what a cool sight to watch

This actually happening on the great salt lake.

Oh, this is awesome.

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Narrator: But harsh environments come in many forms.

In new zealand's north island, for example,

Is an epic wilderness of impenetrable rainforest

And soaring volcanoes...

A terrain completely inhospitable for a new railroad.

But the innovative minds behind the main trunk line

Weren't about to take impossible for an answer.

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Narrator: In the late 1800s, engineers were trying to connect

New zealand's two major cities,

Auckland and wellington, by train.

But there was one spot on the route

Where progress reached an impossible impasse.

Amongst the rugged, overgrown wilderness

Was the central plateau.

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Local railway expert paul mahoney

Is taking the railroad to this challenging location.

Mahoney: I'm at otorohanga railway station,

About to get the train down to raurimu.

This railway was surveyed from the north and the south.

But for 14 years, raurimu was a sticking point for engineers.

Narrator: But, in 1898, it fell to engineer robert west holmes

To conceive a plan to surmount the wild landscape.

However, it wouldn't be as simple as carving a path

Through the untamed bush of raurimu,

As heritage adviser karen astwood

Is discovering for herself.

Astwood: When engineers were trying to make a railway

Through this area, they had such a lot of trouble.

It was a real nightmare.

Coming down from the central plateau,

There's a more than 400-foot drop,

And there's no escaping it.

Narrator: Faced with a distance of just 1.2 miles

In which to negotiate the steep rise

Between the valley and the plateau,

The gradient of 1 in 15

Would be too extreme for standard locomotives.

Astwood: The only way to make it up that gradient in the train

Would be to use specialist trains,

But the cost of maintaining those

Was simply too prohibitive.

There was talk that the line might have to be rerouted.

The government didn't want that.

They'd already spent enough money on the project.

Overcoming the wilderness here

Was seen as the lesser of several evils.

Narrator: Even riding the rail link today,

The journey is a reminder of what holmes was faced with.

This was covered in a thick native forest.

It's very rugged country.

Here's the sort of forest they were working in.

Narrator: With help from technology

That holmes could only have dreamed of,

Karen is getting a bird's-eye view

Of this uncultivated landscape.

This is really exciting.

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Narrator: And from the sky, the extraordinary solution

That holmes came up with can be viewed in all its glory.

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The raurimu spiral.

Astwood: What we can see below is one of the most ambitious

And brilliant pieces of wilderness engineering

In the world.

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Here comes a train, so we're gonna be able to see

Holmes' masterpiece in its full glory.

Narrator: Following an intricate route,

The single track snakes its way around

To lengthen the line at a shallow gradient.

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The raurimu spiral is a really impressive

And complex set of elements

Which is really compactly put together.

Narrator: But holmes' masterpiece was anything but straightforward.

The spiral twists and tunnels under itself,

Up first through a giant horseshoe curve,

And then a pair of tight quarter turns,

Before winding around on itself in a complete circle

To reach the plateau.

It extends a distance of just 1.2 miles as the crow flies

To create a track over 4 miles long.

Seeing the spiral from holmes' perspective

Reveals the curves close up.

So, this is the start of the real climb

Around one of those tight curves that are 150 meters radius,

And we're on a 1 in 15 grade.

This is real mountain railroading.

They had to fit this railway to the landscape,

And it was very dense forest here,

So they couldn't actually see very far to do the surveying.

Narrator: A problem made worse by the treacherous terrain,

Which gave holmes no natural vantage points

To plot a route from above.

Mahoney: There was no way he could get to a high point

To see how the land was set out.

He had to do a lot of exploring to create a picture in his mind

Of what the terrain was like.

So this is an amazing railway-location achievement.

Narrator: These days, engineers would carry out an aerial survey

And simply take to the skies.

Astwood: All the loops and curves, even the small ones,

Are really critical,

Because they lessen the wear and tear on the trains,

And on the track, as well.

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Narrator: But mapping a route wasn't the only challenge

That had to be overcome to pull off this audacious build.

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Mahoney: So, coming out of tunnel number two,

We're, more or less, halfway 'round the spiral now.

Looking back, you can see just what rugged country this is.

Narrator: Carving a path through the impenetrable forest,

Steep ravines, and sheer cliffs had to be done by hand.

Mahoney: So, the spiral was entirely constructed by pick and shovel

And some dynamite blasting.

And this is a high rainfall area.

The workers lived in tent camps.

And it was pretty tough going.

What an achievement.

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Narrator: In 1908, the first train traveled down

The raurimu spiral...

Almost four decades after the north island main trunk line

Was first conceived...

Finally taming what had seemed

Like an insurmountable wilderness.

Over a century later, it's still considered one of new zealand's

Greatest feats of engineering.

This must have been so complex to try and lay out,

And it really is just a tribute to holmes' genius,

And also the engineers that he worked with.

It's just... it's spectacular.

Mahoney: 80 years after holmes laid out the spiral,

I was riding with the chief civil engineer of the railways,

And he'd been involved with trying to improve the route

Of the railway, really, for electrification.

And the modern engineers were still not able to improve

On george holmes' spiral location.

It's a masterly piece of engineering

That survives to this day.

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Narrator: But imagine the challenge of building

One of the earliest railroads in britain.

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In devon in the southwest of britain

Sits a huge expanse of harsh, magical, and ancient landscape.

Newland: This is dartmoor national park,

Which is just shy of 1,000 square kilometers

Of amazing wilderness.

It's full of ponies, rolling heathlands full of gorse,

And its most famous export... granite.

Narrator: And in the 1800s, that granite was in demand.

With the british industrial revolution at full steam,

Buildings were getting taller, bridges were getting larger,

And engineers were looking close to home for supply

To meet the ever-increasing demand...

As historical archaeologist cassie newland is finding out.

You can really see 'round here, that the...

The granite just sort of comes out of the ground,

It's everywhere you step, everywhere you look,

Which is why people have used this resource in this place

For thousands of years.

Narrator: Dartmoor might have been full of granite

For almost 300 million years.

But in 1820, the enormous challenge would have been

Building a transport system to get the rock to civilization.

Newland: It's bleak. It's isolated.

It is utterly treeless.

You can go from frostbite to heatstroke in a blink.

How can you build a railway here?

What would you build it out of?

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Narrator: Entrepreneur george templer decided he could defy the odds

And build a railroad to transport goods

From his quarry at haytor.

But it was the intrepid railroad engineers

He called on who would have to make his plan possible.

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Narrator: 19th-century entrepreneur george templer

Needed a way to transport vast quantities of granite

From his isolated quarry

To the building projects that needed it.

Newland: This idyllic little oasis is actually haytor quarry.

And it would have felt incredibly different

150 years ago.

We'd be surrounded by bustling men hard at work

Drilling holes and blasting with dynamite

To take vast chunks of granite out from the cliff walls.

The air would be thick with dust.

It would be completely unpleasant.

Just behind me, if you can see the log in the pond,

That log is actually the base of a derrick,

A kind of crane that would have been used with the winch

That you can see in the background

To lift these huge blocks of granite.

So, you would turn this handle.

[ Creaking ] ooh!

And it would crank a cable to lift up the arm...

Your jib arm of your crane, which is just over here.

And if you're very careful and don't fall in,

It's this huge, huge length of wood with a socket

At one end through which all your winching gear

Would pass right the way down to the base over here,

Which would fit into a metal socket in the ground

And allow you to pivot around

To lots of different points in the quarry,

Lifting the stone that's blasted off from the side

To places it can be worked

And also lifting it onto the wagons to take it away.

So, the challenge of haytor is getting the granite out.

But at 1,300 feet above sea level

With no other natural resources,

It is an impossible challenge.

Narrator: Templer had realized that building a track

Out of the quarry was the only option.

Like generations of moormen before him,

He looked to the ground beneath his feet,

And he built the railway from granite.

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Narrator: This engineering marvel born out of the ground

Is the haytor granite tramway, amazingly developed to transport

The very granite that it was made of from the quarry

To a canal for distribution.

Now, this rail here is the perfect place to see how skilled

And arduous a job it is to produce a granite railway,

Because using a chisel and a hammer,

You've got to cut this lovely, precise line

Right the way along your rail for the wagon wheels to run in.

The one good thing about having invested all that time

In creating a granite rail is, you don't then need sleepers.

The stone itself is so heavy, it holds it in place.

Now, granite is incredibly hard.

The man-hours that go into taking out a slice of granite

Like this are incredible.

And if you think, you'd do that over 10 miles' worth of railway.

The labor is extraordinary.

The first thing you've got to do is split your rock

Into manageable chunks.

And you do that using a feather-and-tear method.

These slots here are remnants of that process.

Narrator: The ingenious feather-and-tear method is still used today,

Though made much easier with the help of modern tools,

As demonstrated by dartmoor national park employees

Lee and andy.

[ Drill whirring ]

So, what we're doing here... we're drilling a line of holes

Down the length of the granite where we want the split to be.

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Now, the next stage of the process here

Is to use the feather-and-tear tools.

Two types of tool here.

We have this metal iron chisel,

Which is the tear in the process,

And these two thinner strips of iron

Which fit down the side of it in the hole.

Once you've got this arrangement in the hole,

If you hit this on the top with a hammer,

It will force it down and force the granite sideways.

If you do that in each of the holes along the length,

Eventually, the stress will cause the granite

To split along the line we want it to.

That's not going anywhere, so that's ready for the next stage.

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Learn Thai online with BananaThai http://osdb.link/bananathai

I think that's it.

We have now successfully split the slab

Exactly where we wanted it to.

Shows it's a very effective and quick technique, really.

Narrator: This astounding feat of engineering

Is made more impressive by the speed of its construction,

Precipitated by an important commission.

So, as soon as george templer had won the contract

To build london bridge,

He had to get this railway in as quickly as possible.

The quarry opened in 1819,

And this railway was opened by 1820.

That is an astounding feat of will.

Narrator: But solving the challenge of building this railroad

Is only half of this incredible achievement.

As steam locomotives had only just been invented,

Templer used the more common engine of the day...

Good old horsepower.

The problem was how to avoid your prized equine engine

Getting crushed by a load of granite.

So, grading is always an issue for every railway.

But, here, where you've got just regular wagon wheels

Running on grooves cut in stone, it's a particular problem.

Instead of the horses pulling the wagons,

What they effectively have is the horses braking the wagons

From behind and up to 12 wagons,

Each of them carrying 3 tons of granite,

Being sort of slowly lowered down the hill on these rails.

Narrator: And bringing 40 tons of granite

To a stop on an incline is no small task.

But the solution would help to build some of britain's

Most iconic structures.

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Narrator: The engineers responsible for laying a track

That would transport granite

From templer's mountaintop quarry

Had a major problem to solve...

How to slow the wagons when horsepower alone wasn't enough.

With the dramatic inclines along the way

And tons of granite on board,

It was crucial to develop a dependable braking system.

So, you've got the horses behind, but for tricky bits

Where there's an incline or points,

You've got a man with a stick... a 12-foot pole

That he jams against the wheels as an extra brake.

The whole thing is at the absolute limit of human skill

And ingenuity.

And the reason the horses went down

Was not just to brake it, but to pull the wagons

Back up the hill from the other end.

So, it's all thanks to templer's pragmatic solutions

That the granite from the high tors can now be found

In some of our most iconic buildings...

Nelson's column, the british museum, london bridge.

And it's all down to this perfect-yet-simple railway.

Narrator: It's another tenacious solution to reach into the wilderness.

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But for some remote railroads,

It's about connecting civilizations.

Covering an area greater than western europe,

The tibetan plateau in asia

Is the largest and highest plateau on earth.

With drifting sand dunes and alpine wetlands,

Temperatures swing from a bone-chilling minus-40 degrees

In the winter

To a sweltering 86 degrees in the summer.

It's a treeless and windy wilderness.

At first, this seems like the last place on earth

For a railroad.

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But the qinghai-tibet railway has taken on this challenge.

For a century, china had dreamed of connecting

With the inaccessible region of tibet.

In 1974, work on a railroad began at xining,

Cutting across the rugged northern edge

Of the plateau east to golmud.

When engineers tried to head south to lhasa,

They encountered a seemingly impossible obstacle...

Nearly 350 miles of unstable terrain

With a permanently frozen layer

Below the surface known as permafrost.

Senior engineer mr. Jinchang wang

Was part of the team in charge of finding the solution.

[ Wang speaking native language ]

Interpreter: Permafrost is a mix of soil

And sand bound by ice with a temperature

That remains below zero for at least two years.

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[ Speaking native language ]

If the frozen soil is always below zero,

It will provide a solid and stable foundation

For buildings above it.

However, the surface layer can melt,

And its load-bearing capacity can decrease,

Damaging all the architecture above.

Narrator: Without solid land to lay a track on,

Engineers had to find an innovative solution.

[ Speaking native language ]

Interpreter: So, we built a bridge

Instead of laying tracks.

Narrator: This is the qingshuihe bridge.

At over 7 miles long,

It is the longest bridge over permafrost in the world.

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To make it a reality, engineers had to dig deep enough

To reach the solid base below.

[ Wang speaking native language ]

Interpreter: So, there must be four piles beneath every pillar.

The pile foundations are 20 to 30 meters deep.

Narrator: To reach those depths,

A rotary digging machine is used.

The holes are then filled with concrete.

But as heat is released by a chemical reaction

During the concrete-mixing process,

The danger is damaging the permafrost.

So the work needed to be completed

During the harsh winter months.

But to set and strengthen,

Concrete must be kept above 50 degrees,

Which means it has to be heated before it's poured.

So chemicals are added to the mixture to help speed up

The setting process and safeguard the permafrost.

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This phenomenal bridge spanned the most difficult section

Of the qinghai-tibet railway and enabled engineers

To finally complete their journey across the plateau.

[ Speaking native language ]

Interpreter: Building a railway under extreme weather conditions

On the qinghai-tibet plateau is 10 times more difficult

Than building a railway on normal, solid ground.

Narrator: It took an army of more than 600 medics

And 17 oxygen stations to support the construction team.

Reaching altitudes of over 16,400 feet

Means that oxygen is 45% lower.

[ Train horn blows ]

Today, just traveling the route gives a real sense

Of the conditions that the workers faced.

Even passengers on this highest stretch of rail

Need to have access to oxygen.

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Completed in 2006, the railroad was mainly used by tourists

Visiting the once-isolated region of tibet.

Today, it's a vital part of everyday life for the locals,

With the number of trains almost doubling in just over a decade.

But none of it would have been possible

Without the qingshuihe bridge.

Interpreter: Being part of the operation and management

Of this worldwide engineering project is my glory and my duty.

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Narrator: Permafrost might be a formidable opponent,

But around the world,

Railroads must cross many different landscapes.

And one that presents an altogether different challenge

Is a forested wilderness.

Steep inclines and dense foliage

Once stood between the california lumber industry

And its ability to meet skyrocketing demand

For building materials in the 19th century.

But the engineers behind the sugar pine railroad

At the base of the sierra nevada mountain range

Were prepared to make the impossible possible.

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Narrator: In the late 1800s, fueled by the gold rush,

The demand for timber across north america was sky-high.

Thick pine forests on the western slope

Of the central sierra nevada wilderness

Offered an abundant supply.

Horses and oxen were the usual method of transport.

But to meet demand, locomotives, with their superior power,

Began to appear.

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But getting them through thick forests was far from easy.

Engineer chris potts is at the site

Of a once-prolific logging operation.

This is the sugar pine railroad,

Located in california's sierra nevada forest.

And these surroundings are what would be typically seen

In the early logging camps.

These tracks here are actually quite modern,

Made of steel, sturdily fixed into place, and well-maintained.

The difference is that the early railroads

Would have had no such luxury.

Earlier railroads were made of the logs they milled.

The tracks would have only ever been temporary.

Narrator: Quickly-laid temporary tracks

Would weave their way through the trees.

The tracks' tight curves and makeshift nature were a recipe

For disaster for the recently introduced rod locomotives.

These huge trains were powered by pressurized steam,

With their horizontally mounted pistons

Driving only a single set of wheels.

With all the power from the engine

Concentrated in a small area, it meant poor traction

And a limited ability to climb gradients.

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This is a rod locomotive's worst nightmare.

They could only travel about 4% grades at their max,

And this right here is about 12%...

Almost three times as much as a rod locomotive

Could usually go on.

With the rough terrain, the tight curves,

And the steep grades,

Rod locomotives would have a hard time making it here.

Narrator: But it's not just the terrain

That the engineers were battling.

Potts: When the rod locomotives went down the track,

The action of the piston moving back and forth

And back and forth

Would have easily tore the tracks right out of the ground.

If locomotives were gonna make a positive impact

On the logging industry,

The rod engine would have to be completely rethought.

Narrator: And in 1877,

Entrepreneurial-logger- turned-inventor ephraim shay

Proposed a solution with the introduction

Of his radically redesigned locomotive.

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[ Bell clanging ]

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This is incredible!

I'm riding the number 10 shay,

The largest narrow-gauge shay ever built.

Standing up here, you can truly appreciate the power...

The steam, the heat of the fire,

And the pistons moving up and down.

What a feat of engineering.

Absolutely incredible.

Narrator: This is a shay lima locomotive,

And it's impressive beyond its mighty power.

Potts: At first glance, you'd be forgiven for confusing the shay

With a rod locomotive.

But, actually, it was a revolution in design.

It completely transformed the locomotives

For the logging industry.

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Wilderness like this would stop any rod train in its tracks,

But not the shay.

Narrator: In fact, the innovative design making this locomotive move

Changed the lumber industry.

So, just how did the shay

Help make the sugar pine railroad a reality?

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Narrator: Engineer chris potts is discovering

How ephraim shay's revolutionary locomotive design

Enabled the sugar pine railroad to take on the dense woods

At the base of the sierra nevada mountain range.

The key to shay's design is that, instead of using rods

To power just one set of wheels,

It uses gears to share the power between six sets of wheels.

It's a fundamental change

That transforms how a locomotive uses its power

And gives the shay its unique appearance.

This is how it works.

There are three giant pistons,

And these massive pistons work in a vertical direction.

As the power generated by the steam from that boiler

Is transferred into this gear train,

It is sent down to the bevel gears,

And these gears work with a 2:1 ratio,

Where the smaller gear spins

Twice as fast as the larger gear.

And the way it works is,

It takes that speed from the smaller gear

And transforms it into torque,

Meaning that this train can go up 14% grades...

Unheard of for trains of its age...

And can take huge loads across huge distances.

There's a bevel gear on each one of these wheels,

Essentially making it a 12-wheel drive.

Pretty cool.

Narrator: By realigning the cylinders

And gearing the power to each set of wheels,

Shay also had increased traction,

And would be far better suited

To the demands of the challenging logging landscape.

So, one of the key differences here is that this train operates

With three vertical pistons,

Meaning that it was a lot less destructive

Than the rod locomotives of its time,

Where they operated with a horizontal piston,

Meaning that it was less destructive to the tracks.

Narrator: After its introduction in 1878,

The shay locomotive was an instant success story,

Enabling these relatively small engines

To move heavy goods at low speeds through rough terrain.

Over the next 10 years,

More than 300 shays were produced,

Totally transforming the logging industry.

Potts: The shay train was perfectly equipped to brave

Even the most challenging of wilderness.

This is an incredible feat of engineering.

Just the sheer power.

I love it!

?

[ Bell clanging ]

?

Narrator: For centuries, railroads have carved paths

Through the world's most unforgiving wilderness.

?

Through exceptional creations...

It's spectacular.

You don't find this type of thing

In many places in the world.

It's rainforest-railway engineering at the world's best.

Narrator: And cutting-edge solutions...

Someday, they'll have to build a train on mars

Or the moon or whatever,

But this is about as close as that gets on earth.

Narrator: Engineers continue to succeed,

Creating impossible railroads.

Engineering versus the wilderness...

I think engineering won.

?

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