Original subtitles

Today on "Impossible engineering,"

the Shanghai Maglev... The fastest passenger train

on the planet, with a top operating speed

of 268 miles per hour.

The Maglev is faster than the formula one car.

It is flying along.

A train that defies the most basic laws of motion.

The thing that's different and very unique

about the Maglev is the fact that it floats.

It took centuries of innovation

and experimentation...

Wow, it looks like something out of the future.

To make the impossible possible.

Captions by vitac www.Vitac.Com

captions paid for by Discovery communications

China is a country on the rise.

Its largest and wealthiest city, Shanghai,

attracts people from all over the world

with its ambition.

As Shanghai's population increases,

so does its demand for space.

The city faces heavy traffic jams

and congestion on a daily basis.

Shanghai is busy.

Cars, as well as buildings,

fight for space on the ground.

It can be very difficult to move around.

By the beginning of the 21st century,

Shanghai streets were at maximum capacity.

A heavily congested eight-Lane highway

was the city's only link

to the Pudong international airport.

To get to the airport by car,

it takes 45 minutes.

You really need something to cut through the city

to get to the airport without stopping

and without encountering any other vehicles.

I, like most people in this city,

don't have time to sit in traffic.

China's solution...

The Shanghai Maglev, or transrapid...

A cutting-edge,

high-speed train, the fastest in the world.

The thing that's different and very unique

about the Maglev is the fact that it floats.

It hasn't got any wheels.

It floats across the guideway all the way to the airport.

Now the Maglev is just about to pull out of the station.

When it's at its top speed,

it'll be moving at 431 kilometers an hour.

That is just beyond belief, incredible.

To design a passenger train

capable of reaching 268 miles per hour,

the Maglev's engineering team had to toss out

many of the design features

we've come to associate with trains.

First, their train wouldn't have an engine.

Huh?

Then they would do away with one of engineering's

most fundamental inventions... The wheel.

Finally, they would defy the most basic laws of motion.

Ow!

Ooh!

Wow! Ooh!

But before engineers could design

their futuristic train with no engine or wheels,

they had to figure out a way to fit it

into the already overcrowded streets of Shanghai.

Shanghai is one of

the most heavily populated cities in the world,

and the population is increasing.

Now, building the infrastructure it needs is very challenging

just because there is no space.

Like all the buildings around here,

the only place really to build is to go up.

Chicago is one of the world's busiest cities.

The logistical challenge of moving around its inhabitants

is a daunting task...

But the city's early planners came up with an idea

over 100 years ago that still keeps the city moving today.

In the late 19th century,

Chicago is one of the fastest-growing cities,

if not the fastest-growing city in the world.

In the 1840s,

shortly after the city was established,

we had roughly about 4,000 people.

And by 1900, we've got over a million and a half.

Our city is rapidly expanding.

It's almost the Shanghai of the late 19th century.

So, how did engineers

and planners deal with the need

to transport the city's growing population

without clogging the busy city streets even further?

So this is the solution that was developed,

to elevate the city's rail lines above the street traffic.

Although it's not cheap to do this type of infrastructure,

it is cheaper, of course, than building subways.

Work began on Chicago's train in 1892...

But building tracks 30 feet above

the city streets was not welcomed by everybody.

Third-floor apartment tenants

now had to keep their curtains closed if they wanted privacy,

and young women were warned to be careful

of roving, railborne Peeping Toms.

Nevertheless, the system was a big hit for most.

It was lovingly nicknamed the "I," short for elevated.

We're here at Quincy.

This "I" station has been restored,

and it gives us a sense of what commuters would have seen

in the late 1890s.

And the basic concept of moving people in and out of the city

at a different level

than street level has not changed since then.

Elevating the city's train

was a solution so successful

that, more than 120 years later,

the "I" is still transporting

a half-million passengers each day.

The growth of the "I"

and the growth of Chicago are synonymous.

The boom of population

in the late 19th century follows right along

with the growth of this transit system.

And I don't think, without the "I," we would have had

this great, vibrant American city that we have today.

Engineers of the Shanghai Maglev

are taking Chicago's idea

of an elevated passenger train...

Ooh!

That was fast.

...And giving it a 21st century twist.

Engineers of the Shanghai Maglev

have taken Chicago's century-old solution

of an elevated railroad and created their own

19-mile guideway high above the city streets.

The advantage a system like this has

in already built-up urban spaces

is it's very easy to install.

It doesn't interfere

with underground services.

It doesn't interfere with existing

infrastructure at ground level, which is really good.

But building an elevated guideway

in this part of the world

came with some unique challenges.

Shanghai sits in an area of great seismic activity.

It also has weak Clay soil.

The risk of liquefaction is very high.

Liquefaction is an unusual

and dramatic phenomenon

that can occur during an earthquake,

when solid ground turns to mush.

Aah!

Physicist Andrew Steele

has prepared a simple demonstration

to show how liquefaction works.

So this water represents the groundwater.

This ground has got a very high water table,

so it's only got a thin layer

of dry soil on top of the saturated soil underneath.

So, imagine you build on this land,

you construct your beautiful city.

But you built on Sandy soil,

and you build on a fault line.

So there's the danger of an earthquake.

You can see that, as you shake it,

then the groundwater is forced up

into the top layer of the soil, and that changes its state

from that of a solid to very much behaving like a liquid,

and the buildings are just sinking straight into it.

Earthquakes are a constant threat in Shanghai.

If the ground liquefies, the Maglev's designers

had to ensure the tracks

wouldn't sink into the soft soil.

So engineers developed a technique called piling.

They built each support pier on top of a giant concrete cap.

Underneath the caps are concrete piles,

which are driven 200 feet into the ground.

If the soil near the surface liquefies,

the deep roots will hold the Maglev's track in place.

In less than nine months,

Chinese engineers constructed over 2,500 concrete columns

to support the guideway.

This would be the fastest train in the world.

But trying to get a train up to speeds

pushing 500 kilometers an hour,

designers would be faced with the problem

of wind resistance or drag.

The greater the speed, the greater the resistance.

And all this air movement has

the potential effect of slowing the train down

and wasting valuable energy.

To build a train

that can break 300 miles per hour,

engineers had to look back

to the great innovations of the past for the solution.

The earliest evidence of railroads

can be traced back to ancient Greece.

Men and animals pulled wheeled vehicles in limestone grooves.

The grooves prevented the wagons

from leaving their intended route.

Railroads were developed as a way of reducing friction.

In 1805, the English discovered that a good horse

on an ordinary road could pull a wagon weighing a ton.

But on rails, that same horse could pull

12 wagons each weighing three tons for six miles

in just two hours.

Oh.

When steam power was introduced,

continents could be crossed with ease,

transforming the modern world.

Railroads dramatically changed the way we live.

But throughout the 19th and early 20th century,

train design was at a standstill.

Train design fundamentally hadn't changed for 100 years

since this, stephenson's rocket.

You can see the classic cylindrical boiler.

We got a smokestack at the front,

and its completely snubbed, flat, unaerodynamic nose.

It would take a radical thinker

to shake things up.

And in the 1930s, england steam locomotive engineer

Nigel Gresley designed a new, sleek machine that would,

at the time, be the fastest train in the world...

The Mallard.

Everything about this locomotive is designed to go

as fast as possible.

You've got these massive wheels driving it forward.

We've got a double chimney to suck out the exhaust

as quickly as possible at high speed,

and then you've got this beautiful streamlined shape

in stark contrast to the trains that had come before.

Gresley used a wind tunnel

to develop the Mallard.

Wind tunnels had been used on planes

but never on a train before.

He made some interesting discoveries.

Andrew Steele is visiting a test center called the train rig

to see firsthand the difference

a streamlined train design can create.

This is the test track. It's 150 meters long,

and we can accelerate trains to 75 meters a second,

which is over 250 kilometers an hour.

Today we've got two different trains

that we're going to be testing.

This is a flat-nosed freight train,

which represents sort of an unaerodynamic train

as they were originally designed.

And this one here is a high-speed train.

Got this sloped nose.

We're going to see what difference that makes

to the speed the train can travel at.

And this is what we're going to be using

for the actual experiment.

These things here are light gates.

And when the train goes past this one,

it interrupts the light beam, and we can detect that time.

Then, a fraction of a second later,

it'll go past this light gate, interrupts this beam,

and by measuring the difference between two times,

we know this distance here,

so we can work out exactly how fast it's going.

The model trains are fired

using giant rubber catapults.

So I was just applying some tension to the track now,

and that's pulling the train back into the firing position.

I'm almost as tense as the train is.

Okay.

So just... Here goes.

Ooh!

That was fast.

Ooh!

And believe it or not,

that was a sort of slow test run.

So now that we've done that test run,

the key thing is to find out the readings that we got

from these light meters.

We've got two readings here.

At the first set of light gates,

it was doing about 36 meters per second.

But then, by the time the second set of light gates,

just a couple of meters later, it's only doing 34 1/2 meters

a second, so you can see it's lost some speed,

the aerodynamic drag has kicked in

and slowed the train down.

In the short distance between gates,

the flat-nosed train loses around 5% of its speed.

Next to be tested is the sloping-nosed model.

Ready, aim, and fire.

Phew!

Wow.

Oh.

The sloping-nosed model's speed reduces by only 2%

between the light gates.

Phew!

So these numbers, they're quite subtly different.

But when you scale it up to a full-sized train

and you're looking to propel it constantly down the track,

this can translate into a big change of efficiency.

A fact

Nigel Gresley discovered while designing the Mallard

and exploited brilliantly.

Gresley's engineering really was

a complete step change.

Although we'd used aerodynamics in planes

and hydrodynamics was known about in boats,

this was the first time

those principles had been applied to a train.

And that is what enabled the Mallard

to travel at 126 miles per hour.

In 1938, the Mallard set the record

for the fastest steam train on rails,

a record which still stands today.

The designers of the Shanghai Maglev

have learned from the breakthroughs

made by the Mallard and created a train

that travels at speeds that innovator Nigel Gresley

would have thought to be impossible.

In one test run, it exceeded 300 miles per hour...

Almost three times what the Mallard was capable of.

You can see it has a very sleek,

streamlined design

with a very smooth, sloping nose.

Also the train wraps itself around the guideway

which reduces turbulence that might otherwise be generated

between the train and the track.

But to build

the fastest passenger train on the planet,

engineers would need more than just an aerodynamic design,

so they drew inspiration

from a decades-old engineering experiment...

They combined the principle of the hovercraft

and a jet engine,

and they smashed the rail speed record.

...To create their own impossible engineering.

The Shanghai Maglev

is the fastest passenger train on the planet.

It travels at an astonishing top operating speed

of 268 miles per hour.

The train has transformed travel

between downtown Shanghai and Pudong airport.

The Maglev runs

all the way from here to Pudong airport,

which is a 34-kilometer journey in that direction.

Now if I was to get the Metro,

it would take me over an hour.

If I got a cab, it would take me 40 minutes or so.

But if I got the Maglev, which I like to do,

it takes me only seven minutes.

But the development

of the futuristic Maglev took decades of experimentation

before it reached its incredible 21st century performance levels.

Created in Germany,

the first passenger-carrying prototype,

the transrapid Maglev system, was unveiled

in 1971.

It traveled at speeds

where little consideration to aerodynamics was necessary.

But as experiments continued

and speeds rapidly increased,

the train car design that now graces

Shanghai's elevated track took shape.

However, increased speed

means increased engineering challenges.

The Maglev going to the airport

and the Maglev coming from the airport

pass each other at incredible speeds,

potentially a combined speed of over

860 kilometers per hour.

And this could cause a potential problem.

However sleek the design,

any object passing another at speed

creates a change in pressure between them.

Lower pressure, as the trains are together,

followed by a return to a higher pressure once they've passed.

This could potentially cause stresses to the cabin walls.

So maglevs have been engineered

with an aluminium composite shell,

light, but at the same time, strong and stiff enough

to support the pressure

acting on the structure by high-speed traveling.

But there were other design elements

that the Maglev's engineers had to consider

if they wanted their train to achieve record-breaking speeds.

It's not just the wind

that provides friction on the train.

One of the biggest losses of energy

that occurs in a traditional train

is produced by the friction

between the wheels and the track.

The more friction there is, the more power is lost.

In a car like this, for example,

1/3 of the fuel is spent on overcoming friction.

To limit the negative effects of friction,

engineers designed the Maglev in a way

that only some of history's most daring engineers have attempted.

Physicist Andrew Steele is in

the French countryside looking for the remains of a system

that could have been just as revolutionary

as the Maglev.

So here it is, over 50 years old and covered in moss.

This is what its creators thought would be

the future of high-speed mass transit...

A single concrete rail, straddled by a train,

capable of traveling

at 422 kilometers an hour, at a time

when the speed record for a conventional train

was just half that.

So what kind of vehicle

was capable of overcoming the forces of friction

to travel over 250 miles per hour?

The answer lies in a closely guarded warehouse.

I've come to a top-secret location

somewhere outside Paris

to get a rare look at what could have been

the future of land transportation.

Hello. Good morning.

So, where's it kept?

Hidden among

an assortment of military vehicles

are the last surviving examples of an extraordinary experiment.

Wow.

So this is the A�rotrain. Yes.

It looks like something out of the future.

Designed by engineer Jean Bertin in the 1960s,

the A�rotrain 01 and 02 are the only surviving prototypes

of a system that hoped to change train travel forever.

You can see the A�rotrain doesn't have any wheels.

Now that might seem strange,

but although the wheels have been the basis

for land transport for thousands of years,

they come with a big disadvantage,

because the wheels rub against the ground.

They create friction,

and the A�rotrain tries to get around that.

Engineers and scientists have been toying with the idea

of frictionless travel for some time.

The idea is that, if you can remove

that frictional resistance to motion,

then you can make things travel faster and more efficiently.

The simplest way to do that might be

to levitate it on a cushion of air,

and that's the principle behind how a hovercraft works.

We've got our own very simple model of a hovercraft here.

It's just a cd with the top of a drinks bottle on it

and then a balloon.

Before we inject that cushion of air,

the cd only moves a very small distance across the table

when I tap it.

However, what we can do

is attach a balloon to this drinks bottle top

and see if that makes any difference

to the way that the cd moves.

So here we go.

You can see that now, with a tiny tap,

the cd moves a long way.

And just as long as the balloon has got some pressure

to force that air down underneath the cd,

then it'll keep on moving around freely.

But when the balloon runs out, of course,

the cushion of air vanishes and the cd is just as hard

to move across the table as it was before.

In here, we've got the guts of the A�rotrain.

And incredibly, there were just two regular

car engines which power massive fans.

And that blasts air downwards

to lift the train up off the ground and then inwards

to keep it centered on the track.

That means the train isn't in contact with the ground

or the track, and so that source of friction is removed,

and that means that more of the energy

from this engine up here,

the propeller, can be used to power the train

to move forwards.

It's 11 meters long, weighs 2.6 tons,

and yet the air gushing out of these nozzles

is enough to keep it floating two or three millimeters

above the track.

By 1967,

the A�rotrain was proving its potential

on the test track as the next generation

of passenger transport.

A plan to build a track

for the A�rotrain between Paris and Orl�ans...

65 miles in 35 minutes.

For A�rotrain mark 02,

Jean Bertin went all out for speed.

The A�rotrain 02

was a futuristic combo of fighter jet, race car,

train, and hovercraft.

It looks like something out of a Sci-Fi movie,

but the technology itself is actually pretty simple.

I think my favorite control

is this one that goes march� and arret.

So it's basically stop and go just by flicking a switch.

Nevertheless, it was the combination

of engineering ideas

that made Jean Bertin's A�rotrain groundbreaking.

Bertin's ideas really were revolutionary.

They combined the principle of the hovercraft and a jet engine.

This was the first time it had ever been done.

Combined, they smashed the rail speed record.

An aircraft jet engine gives initial thrust

up to speeds of around 185 miles per hour.

An additional rocket motor boosts the mph to 235.

Sadly,

Jean Bertin's dream of friction-free travel

died in the 1970s

when the French government abandoned the experiment.

But almost a half century later,

the A�rotrain has a familiar-looking cousin

over 3,000 miles away in China.

The Shanghai Maglev...

The world's fastest passenger train,

a unique engineering feat

situated in one of China's most ambitious cities.

This Maglev here is the only

high-speed Maglev in the world, and that kind of

chimes in with the ambition of Shanghai.

People come here to design daring buildings

and daring systems.

And one of the most daring of them all

is the Maglev...

Traveling at a staggering 268 miles per hour,

appearing to defy physics.

The first time I traveled in the Maglev,

we hit 400, and I thought, "oh, my goodness."

And then it continued to travel even faster.

I could not believe what I was seeing and experiencing.

And it is currently doing a top speed,

flying pretty much at 431 kilometers an hour.

And it still feels very comfortable

for the speed at which it's traveling.

The Maglev is faster than the formula one car.

It is flying along.

The Maglev's record- breaking speed is possible

because it's levitated above the track

by powerful electromagnets

instead of a hovercraft design like the French A�rotrain.

But levitating a train with magnets

would be impossible without one of science's great innovators.

Born in 1791,

Michael Faraday was the son of a blacksmith

and received little formal education,

but he would go on to revolutionize

the engineering world.

His original laboratory

still exists at London's royal institution...

I'm going to give it a little push.

Where physicist Andrew Steele

is exploring how Faraday's discoveries

made magnetic levitation possible.

Faraday's discoveries revolutionized

our understanding of the interplay

between electricity and magnetism.

And one of the things that this understanding allows us to make

is an electromagnet.

So an electromagnet is made of a coil of wire.

You then need to get the ends of those pieces of wire

and plug them into a power supply.

And, finally, to magnify the magnetic effect,

you often place a core of a material like iron

in the middle of the magnet.

Let's connect this up.

And to prove to you that that's magnetic,

you can see...

That even with this extremely simple setup,

we can actually get a piece of metal to stick to it.

Another crucial factor about electromagnets,

if you want to use them for levitation,

is that we can change their strength,

and we can do that very easily.

Just by changing the electric current

passing through this magnet,

I can turn the current down

and make the attraction much weaker.

Or I can turn the current up and make that attraction

get stronger again.

Not only can electromagnets be adjusted

and turned on or off at will,

but they're also significantly stronger than ordinary magnets.

If you want to suspend an entire train,

you're going to need a pretty powerful electromagnet.

And actually, electromagnets are pretty strong.

This little one is enough to suspend my entire body weight.

And actually,

this thing needs surprisingly little electric current.

There's less electricity flowing through this device

than there is through your hair dryer or your kettle at home.

We've got an electrical current

flowing through this electromagnet.

If we connect it to the piece of metal on my back,

then, hopefully, there should be enough strength

to hold me above the floor.

And there you have it.

On the Shanghai Maglev,

powerful electromagnets

are installed into the underside of the train cars,

allowing them to float.

Guidance magnets keep the train centered,

and support magnets pull the unit

to the underside of the track, lifting the train above.

The entire train floats,

suspended 10 millimeters below the track.

Not only does this reduce wear and tear,

but it also makes for

extremely fast, friction-free travel.

Because there's no contact

between the train and the guideway,

there is no friction, and this means that the train

can have a lifetime of up to 50 years

with minimum maintenance required.

But while designing

China's futuristic passenger train,

developers couldn't just focus on speed.

They had to ensure the Maglev

was environmentally friendly, too.

China, like all modern economies,

is worried about its carbon emission quota.

As development continues,

the demand for oil will also likely increase,

but China has a limited domestic oil supply.

With its current gas-guzzling congestion problems,

greener transport initiatives are drastically needed.

Otherwise, the city will choke.

Their environmentally friendly solution

came from one of history's great engineering innovators.

In the late 1940s,

a British engineer's groundbreaking experiment

would earn him the nickname

"the father of the Maglev."

This is a sheet of aluminium.

When I put it on the motor and switch on the magnets,

something pretty dramatic occurs.

Electrical genius Eric laithwaite

developed the first practical linear electric motor,

creating an effect he later dubbed the magnetic river.

First of all, it will levitate,

or support, an aluminium plate.

It will guide it sideways,

and it will also propel it along.

The linear motor

takes a traditional coiled electric motor and unrolls it.

Instead of spinning a rotor, what was the coil, or stator,

provides a bed that drives the object along its length.

And there you have your modern

vehicle being guided, lifted, and propelled,

all by means of the same set of coils.

Laithwaite's experiments

provided the key that unlocked the potential of the Maglev.

The builders of the transrapid Maglev system

constructed a series of stator blocks.

They are the main component of the linear motor

and act as the propulsion system for the train.

Once installed, they were tested in Germany,

and in combination with the support

and guidance magnets, enabled the Shanghai Maglev to levitate.

The train can travel over 300 miles an hour

without an on board engine.

A linear motor is embedded into the guideways.

But don't be fooled

into thinking this whole track is electrified all the time.

What is so brilliant about this system

is that only the sections of the track

on which the vehicle moves

is powered at any time.

So as it sets off, the track ahead of it is dormant,

and only the section in front of the Maglev turns on.

As soon as the Maglev has passed over the short section of track,

it turns off again,

as the job of pushing the Maglev along is taken up

by the next section of track.

And so on and so on, all the way to its destination.

But with less than six inches

between the Maglev and its guideway,

even the slightest malfunction could be catastrophic.

It is critical to maintain

an even gap between the train and the track,

no matter how many passengers are on board.

To do this, the Maglev's builders

had to create one last piece of impossible engineering.

Traveling at an astonishing

268 miles per hour

while floating on a magnetic field,

the Shanghai Maglev is the only high-speed train of its kind

operating commercially in the world.

But having a levitating train fly through Shanghai

at such high speeds comes with several engineering challenges.

There is a carriage hurtling along

at over 430 kilometers per hour.

So it is critical to control

fluctuations in the magnetic field

and maintain an even gap

between the train and the track,

no matter how many passengers are on board

or what variations there are in the load it's carrying.

With just six inches between

the Maglev and its guideway, any errors could see the train

crunch into the track.

The engineering team's solution,

as physicist Andrew Steele demonstrates,

relies on sensors constantly regulating

the current flowing through the electromagnets.

There we go.

You can see this permanent magnet

is suspended underneath this electromagnet.

Whenever the permanent magnet moves

slightly imperceptibly closer,

this little sensor on the bottom here detects that,

sends a message down to these electronics,

and tells the electromagnet to become a little bit weaker.

It turns down the current.

That allows the ball to fall away a little bit.

As it falls away, the sensor detects that again

and increases the strength of the electromagnet

and pulls the ball back towards it.

So one complication of this system

is that your feedback system always needs to be working,

and it needs to be working very fast.

You can see this ball

is spinning and wobbling a tiny bit,

and that's fine for a little demonstration like this.

But if you got a train traveling

at hundreds of kilometers an hour along the track,

you're going to need a very, very sensitive

and accurate feedback system.

The Shanghai Maglev

takes this simple concept to a whole new level.

There are 128 sensors in each section of the Maglev vehicle.

They feed back the distance between magnets and track

thousands of times a second.

Powerful computers adjust the electromagnet's current

constantly with microscopic accuracy.

This is the guideway,

and the train floats one centimeter from the guideway.

Now, that is incredible precision.

Now, there's a computer system that makes sure

that, all of the time, the train floats

at one centimeter from the guideway.

An advanced computer system

regulates the operation of the train service.

Each journey's travel time is predictable to the second.

Now, this is the ambition of the Maglev,

with computer systems

able to achieve an extremely precise service.

It's taken decades of planning,

design, and testing to create

the world's only commercially operating high-speed Maglev.

It's a unique concept that throws away the rule book

for traditional train travel

and makes high-speed journeys possible in engineless vehicles.

A system like the Maglev

points to the future of transport in our world,

incredible things to be achieved.

This shows us that we can get people moving

from "a" to "b" in short periods of time,

which is great.

By drawing on the innovations of the past,

adapting, improving them,

and making breakthroughs of their own,

the designers and engineers

of the Shanghai Maglev

have realized the dream of a super-fast train

that flies without wings

and have succeeded in making the impossible...

Possible.

It's kind of unbelievable

that there's a train that goes over 400 kilometers an hour.

It is a vision of the future,

and it's here right now.

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