Name: 土木工学。クラッシュコースエンジニアリング #2 (Civil Engineering: Crash Course Engineering #2)
Uploaded: 2021-01-14T08:09:33.000Z
Duration: 8 min 46 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

基礎受動態

The building you were were born in, the one
where you work, and every road you've ever traveled,
and every bridge you've ever crossed –

they're all the creations of civil engineers.

Civil engineering is one of the most ancient
types of engineering, focused on structures
and buildings of all kinds.

And it's the accomplishments of civil engineering
that our world is built on.

Society wouldn't be the same without them.

If you want to think like a civil engineer,
imagine that you've just discovered an island

– a place that no other human had ever seen
or set foot on.

Like any good explorer, you check out this
mysterious island, to see what it has to offer,
as well as what it lacks.

Is there food available?
And if so, where does it grow?

What about the water supply?
What's the weather like?

Is the terrain easy enough to travel over?

Let's say that after answering all of these
questions, you decide that the island is habitable.

So, what if you tried to build a city there?

What kinds of structures would you need?
How would you build them?

And would it matter what order you build them in?
How do you plan an entire city?

Well, before you rush into anything, you should
take a moment to learn a thing or two from the
civil engineers that came before us.

We've been using some kind of civil engineering
for most of our history.

We've built shelters to protect ourselves
from the weather and used tree trunks as
makeshift bridges to cross rivers.

Our earliest ancestors probably weren't doing
any calculations, but they were using engineering
to find solutions to their problems.

And we can find one of the world's first
notable civil engineers about 5,000 years
ago in Egypt.

This is where we meet Imhotep, the planner
of the first Egyptian pyramid.

He was a government official, a sage, and
even eventually worshipped as the Egyptian
god of medicine.

And to that already impressive resume,
we can add the title “chief of works”, or what
we'd call him, “engineer.”

Imhotep helped oversee the building of the
Step Pyramid of Saqqara, constructed in the
27th century BCE.

The limestone-based pyramid was about as tall
as a modern 18-story building, at around 60 meters,
or 200 feet high.

And its design and construction helped pave
the way for other great civil engineering marvels
like the Great Pyramid of Giza.

This was where we really saw the first two
fields of civil engineering come together: structural
engineering and construction engineering.

Both are similar, but structural engineering
focuses more on the design and framework
of structures,

while construction engineering is more involved
with actually building the structure.

We're going to need to use both of these
disciplines if we're to have any hope of
creating a city on our island.

Let's suppose we use Imhotep's blueprints
and build a few pyramids here.

After that, let's move on to something that
we'll definitely need: a public water supply.

For this, we can find inspiration in Mesopotamia
around the year 691 BCE.

This was where the Aqueduct of Jerwan, one
of the world's first notable public water works,
was built by Assyrian engineers.

It was made of millions of stones to carry
water from the mountains to the city of Nineveh.

Since having water will be crucial to our
city, we'll want a public water supply, too,

and a more modern aqueduct system of
pipes and tunnels to carry water to homes
and buildings.

If you want to learn how to actually map out
your future community, you have to learn from
Hippodamus of Miletus.

He lived in Greece around 460 BCE, and can
be called the father of city planning.

Much of what we know about him comes from
Aristotle's work, known as Politics.

Aristotle thought Hippodamus was weird,
because he wore his hair long and wore flashy
jewelry with cheap clothes.

But even Aristotle would agree that Hippodamus
was also extremely influential.

Many aspects of urban design that we
now take for granted –

like rectangular city blocks and straight streets with
avenues at right angles – can all be attributed to him.

In fact, this layout is often known as the Hippodamian
plan, and it also involves dividing up cities into different
parts for different purposes.

This was very different from previous designs in
his day, which often involved streets that curved,
twisted, or ran into dead ends.

So, let this be a lesson for your island community:
If you're gonna build a city, you need a plan.

And if you don't plan ahead in civil
engineering projects, you could end up
with things in all the wrong places.

After all, you don't want farms and crops
near sewage treatment plants, or schools next
to a noisy airport.

Now, we should also take a page from the Ancient
Romans.

They were some of the greatest engineers of the past,
with roads, tunnels, bridges, and plenty of aqueducts
and water supplies throughout their lands.

Their works are great examples of the third
field of civil engineering: transportation.

Good infrastructure will let you use as much of the
island as you can, for example, roads that run over hills
and valleys, and bridges for crossing lakes and rivers.

Part of what made Romans so prolific in their
city designs was the clever use of their environment.

They mixed lime, small rocks, and volcanic
ash to make their own form of concrete,

which allowed them to build impressive structures
like the Pantheon and the Colosseum.

Since I don't see many volcanoes on our island, we should stick with a more modern kind of concrete, like the one patented in early 19th century England by Joseph Aspdin.

He used finely ground stone and clay to make
what he called “Portland cement” because of its
resemblance to the limestone of Portland, England.

But there are few better lessons in the importance
of building materials than the Eddystone Lighthouse.

The tale of this structure begins at England's
Eddystone Rocks in the late 17th century.

And like most great engineering stories, it
started with a problem: The rocks, off the coast
of Cornwall, were causing lots of shipwrecks.

Henry Winstanley was a painter, builder and
merchant who lost two ships on these rocks.

It was octagonal, made of wood, and lasted
for a few years until a storm came through
and destroyed it.

But another builder soon constructed a second
lighthouse, also made of wood.

This one lasted for around 50 years, but was then
burned to the ground from the spark of a candle,

a reminder of how susceptible wooden
structures are to fire.

It became apparent that the wood wasn't
working for this lighthouse, so a new generation
of engineers had to do something different.

Instead of wood, he began building a lighthouse in
1756 made from hydraulic lime, a type of concrete
that sets under water.

This allowed for his lighthouse to last for more than 120
years, until 1877, when it was dismantled because the
rocks beneath the tower were beginning to destabilize.

But Smeaton's success in meeting this
challenge set the stage for using cement and
concrete in structural building.

Smeaton is actually the first to label himself
as a “civil engineer”.

And ever since, engineers have had him
to thank for separating the civilian side of
engineering from the military side.

We'll also want to thank him for the lighthouse
we're going to build on the south side of our
island to warn travelers of the dangerous reef.

So up to this point, we have a pretty good
start to our island city.

We've planned it out with public water supplies,
roads and bridges, a lighthouse, and other buildings.

But we're missing something very important:
sanitation.

Some form of sanitation has been used since
ancient times.

But a more modern form of environmental engineering
began when Sir Joseph William Bazalgette designed a
sewer network for central London.

His network helped relieve the city of its
cholera epidemic by treating the water and
cleansing the polluted River Thames,

which took nearly 20 years to complete,
and he was eventually knighted for his work.

This all led to the continued practice of treating
drinking water and sewage, which will be crucial
to maintaining public health on our island.

There are still more things that civil engineering
can do for our city, like the construction of dams and
canals, which falls under hydraulic engineering.

And then there's working with the rock and soil of the
Earth so our structures are built on the right foundation,
which is the work of geotechnical engineers.

So the idea of creating a city from an empty
patch of wilderness shows you how many problems

present themselves, and how different kinds
of civil engineering can solve those problems.

We've achieved civilizations – whole societies
– because of civil engineering.

We'll go into more detail in future episodes
that will give you an even better idea of the work
behind civil engineering.

But this is just enough to give you
– if you will – a solid foundation.

Today we learned all about many of the facets of civil
engineering, including structural and construction
engineering, city planning, transportation, and sanitation.

Next time, we'll explore the mechanical side of
engineering, including its history and the types of
work that you might do as mechanical engineer.

Thanks for watching and I'll see you then.

Crash Course Engineering is produced in association
with PBS Digital Studios.

You can head over to their channel to check
out a playlist of their amazing shows, like

The Art Assignment, Deep Look, and It's
Okay to Be Smart.

Crash Course is a Complexly production and this
episode of was filmed in the Doctor Cheryl C. Kinney
Studio with the help of these wonderful people.