The Assassin (Sha ren zhe Tang Zhan)

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 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.