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Today
on "Impossible engineering,"
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the Rion-Antirion bridge...
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A colossal structure built in
the heart of an earthquake zone.
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Spanning 2 miles
across open water,
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it took revolutionary
engineering...
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...and a look back at some
hard lessons from the past...
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The energy release was massive,
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and now the specimen has
just catastrophically failed.
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...To make
the impossible... Possible.
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Captions by vitac
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captions paid for by
Discovery communications
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August 2004,
the Rion-Antirion bridge
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opens to traffic
for the first time.
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It's an engineering masterpiece
of the modern age.
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This massive structure
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spans almost 2 miles across
the Gulf of Corinth in Greece.
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It boasts the longest
fully suspended deck
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and deepest foundation piers
of any bridge on earth.
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For chief engineer
Panayotis Papanikolas,
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it was the project
of a lifetime...
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...but for centuries,
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building a bridge across the
Gulf of Corinth was just a dream
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due to a long list
of environmental challenges.
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But wind isn't the only threat
to the bridge.
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The two land masses on either
side of the Gulf of Corinth
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are constantly drifting apart.
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This, along with frequent
earthquakes, high winds,
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and deep water meant that
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building a bridge across the
Gulf would be a daunting task...
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...but the need for a safe
crossing was desperate.
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The perilous waters
of the Gulf of Corinth
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often made ferry crossings
impossible
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and cut the peninsula off
from important services.
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So in the 1990s,
the government embarked
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on one of the most ambitious
engineering projects
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in modern history.
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The first challenge
was to design a bridge
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that could span
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the almost 2-mile gap
across the Gulf of Corinth.
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The distance was too great
for a single-span bridge,
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so engineers has to build
support towers in water
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that's over 200 feet deep.
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To overcome
the water-depth issue,
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Panayotis
and his fellow engineers
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would need to look
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to history's great engineering
innovations for the solution.
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Building in water
has always been a challenge.
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Early builders relied on
conveniently placed rocks
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for the foundation
of their structures.
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Fine for lighthouses,
useless for bridge building.
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Creating artificial islands
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was time-consuming and
impractical in deep water.
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In the 19th century, pressurized
structures called case-ins
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were developed to create
underwater building sites.
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But they were difficult
to build...
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And dangerous.
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Fortunately,
in the 20th century,
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a new technique was
on the horizon.
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In the 1940s,
engineer guy Maunsell
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came up with a solution
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that finally conquered the
challenge of building at sea.
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Professor Luke Bisby is heading
far out into the English channel
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to see the remains
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of Guy Maunsell's bold creation
firsthand.
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Maunsell's influence
on contemporary engineering
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I don't think
really can be overstated.
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This was really the first time
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that this had ever been
attempted,
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and so it was really quite
a daring feat of engineering.
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Maunsell's innovation
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was triggered
by the second world war.
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It became clear the river thames
was a prime target
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for German bombers
during the war.
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The Germans wanted
to destroy London's docks
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and lay mines
to disrupt allied shipping.
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So Maunsell came up
with a radical new design
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for off-shore sea defense...
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...naval forts consisting of two
80-foot high concrete towers
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each containing four floors
of accommodations
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topped with a gun deck.
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But the ingenious part
of Maunsell's design
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wasn't the layout of the fort...
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It was how it would
be constructed
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and deployed at sea.
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Knock John here was towed out
3 to 6 miles
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from where
it was constructed on land,
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and then it was sunk in place
exactly where you see it.
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Maunsell designed
the bases of his forts
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as huge hollow concrete barges.
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Despite their enormous weight,
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they had enough buoyancy
to float.
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Maunsell built the forts
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on top of these
large concrete barges
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and then calculated how large
the barges needed to be
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in order to hold
the weight of the fort
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so they could be taken out
and then sunk in place.
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The massive
4-1/2 ton concrete forts
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were constructed in a dry dock,
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then towed out to sea with
a 100-man crew already on board.
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When they had it in
the place where they wanted it,
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they essentially just pulled out
a stopcock at one end
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and let the water flow in.
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As the water was flowing in,
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the barge started to list
in the water.
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Eventually, the nose dipped
under the water.
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All 100 men were hanging on
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as the fort was sinking
at 35 degrees.
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Despite the rough submersion,
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Maunsell's groundbreaking design
worked perfectly.
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The bottom of the barge
basically filled up with water,
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and eventually the entire barge
sunk to the bottom
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and flattened out.
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Maunsell's forts
helped British forces shoot down
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22 enemy aircraft
and 30 flying bombs.
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They protected London
from attack
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and made engineering history.
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The influence of this
type of construction you can see
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in all different facets
of engineering today.
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You can see it in the
off-shore-oil-and-gas industry
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with oil platforms.
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You can see it being used as
foundations for wind turbines.
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And, of course,
you can see it being used
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as a way of placing foundations
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for large bridge structures
around the world.
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But the most impressive use
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of Maunsell's revolutionary
floating concrete design
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is at the Rion-Antirion bridge.
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The Rion-Antirion bridge
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spans an incredible 2 miles
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across the deep waters
of the Gulf of Corinth.
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To support
this massive structure,
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engineers used principles
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first exploited by Guy Maunsell
in the 1940s
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and super-sized them.
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In 1998, construction begins
on 4 enormous pier foundations.
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Each one is larger
than a football field
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and weighs almost 80,000 tons.
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The hollow pier footings
are built in a dry dock
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just as guy Maunsell did
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but on a scale
he couldn't have imagined.
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Before the footings can be taken
out into the Gulf of Corinth,
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engineers need a solution
to a serious problem...
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A problem Maunsell
never had to deal with.
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The Gulf of Corinth
lies in the heart
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of one of the most active
seismic zones in the world.
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In an earthquake, the soft
seafloor would liquify
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causing the piers to sink
and the bridge to collapse.
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Unless an answer was found,
the project was over.
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The engineers came up
with a radical solution.
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00:10:01,168 --> 00:10:06,004
They would drive hundreds of
long tubes deep into the soil
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where the four piers will sit.
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This ingenious idea
stabilized the soft seafloor.
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Bridge footings are usually
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anchored directly
into the ground.
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But for the Rion-Antirion,
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they were placed on top
of a 10-foot layer of gravel.
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This allowed the footings
to shift with the earth
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during an earthquake.
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With a solution
to the earthquake problem,
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the engineers are now ready
to begin
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one of the most audacious parts
of the build...
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...maneuvering
the half-constructed piers
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into the Gulf.
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Engineers continued to build up
the massive structures
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while they were still floating.
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Each layer of heavy concrete
that was added
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sunk the pier further down,
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pushing it closer
to its final resting place
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200 feet below on the seafloor.
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The end result was four enormous
hollow foundation piers.
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They're the first
of their kind...
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A series of massive
concrete underwater caverns.
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The pier footings
for the Rion-Antirion
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can survive an earthquake,
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but what about its nearly
2-mile long suspended deck?
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The builders of this massive
structure will need to produce
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even more
impossible engineering.
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The Rion-Antirion
bridge in Greece
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is a modern engineering marvel.
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Over 11 million cubic feet
of concrete,
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00:12:45,532 --> 00:12:51,336
more than 100,000 tons of steel,
and 39 miles of cabling
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make up the longest fully
suspended cable-stayed bridge
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on the planet.
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Panayotis Papanikolas
and his fellow engineers
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had to overcome
a long list of obstacles
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before their dream
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of a bridge spanning
the Gulf of Corinth
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could be realized.
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The Gulf of Corinth
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is one of the busiest
trade routes in Europe.
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Its shipping lanes
cannot be disrupted.
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To design a bridge
capable of spanning this gap
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without interfering
with shipping,
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engineers would need to turn
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to the great innovators
of the past for inspiration.
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00:13:51,964 --> 00:13:55,200
It was the romans who first
engineered solid Bridges
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00:13:55,202 --> 00:14:00,138
using stone and a simple but
revolutionary shape... the arch.
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00:14:01,974 --> 00:14:04,375
However, the wider the gap,
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00:14:04,377 --> 00:14:10,748
the more arches were needed and
the heavier the bridge became.
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00:14:12,685 --> 00:14:15,820
For hundreds of years, inca
communities in the high andes
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crossed gorges using
suspended wooden walkways.
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00:14:20,093 --> 00:14:23,294
It's said that 16th-century
Spanish conquistadors
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00:14:23,296 --> 00:14:26,297
arriving in Peru
looked in amazement and fear
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00:14:26,299 --> 00:14:29,033
at the swaying Bridges
that could break at any moment.
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00:14:34,840 --> 00:14:38,009
It wasn't until 1826
that a brilliant engineer
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00:14:38,011 --> 00:14:41,379
utilized new building materials
and a new approach
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00:14:41,381 --> 00:14:43,982
to change the bridge game
forever.
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00:14:51,624 --> 00:14:53,258
The Menai suspension bridge
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is the ultimate achievement
of Thomas telford...
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00:14:56,129 --> 00:14:58,897
One of britain's finest
civil engineers.
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00:15:01,133 --> 00:15:03,101
Telford was
an accomplished engineer.
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00:15:03,103 --> 00:15:04,369
Of course, at this stage,
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00:15:04,371 --> 00:15:06,671
he had designed canals
and roads and Bridges.
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00:15:06,673 --> 00:15:09,240
He had never built anything
on this scale before,
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00:15:09,242 --> 00:15:12,310
and so, this bridge was to be
really his greatest challenge.
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00:15:12,312 --> 00:15:16,481
The Menai strait
separates mainland Wales
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from the island of Anglesey.
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00:15:18,785 --> 00:15:22,854
Centuries ago, bridging it
would have been impossible.
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00:15:22,856 --> 00:15:26,424
A traditional Roman arch design
would not only be enormous,
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00:15:26,426 --> 00:15:29,994
it would block the passage of
tall ships along the waterway.
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00:15:29,996 --> 00:15:32,196
Imagine this
as being the strait here,
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00:15:32,198 --> 00:15:34,666
and these are the valley walls
on either side of the strait.
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00:15:34,668 --> 00:15:37,068
Basically,
you cut your bits into shape,
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00:15:37,070 --> 00:15:39,938
and you then have to gradually
build your arch,
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00:15:39,940 --> 00:15:44,075
adding the bits of the arch
as you go.
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00:15:44,077 --> 00:15:47,578
And if you imagine that as now
being the completed arch...
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00:15:47,580 --> 00:15:49,147
And we have our load
coming along here...
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00:15:49,149 --> 00:15:51,950
You can see that the compression
forces that come from that car
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00:15:51,952 --> 00:15:54,852
flow down through the various
sections of the arch
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00:15:54,854 --> 00:15:57,855
and into the abutments
on either side of the valley.
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00:15:57,857 --> 00:15:59,590
Now, the problem
that telford faced
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00:15:59,592 --> 00:16:01,392
was that
as you're building an arch,
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00:16:01,394 --> 00:16:03,661
you would have to have
some supports down here
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00:16:03,663 --> 00:16:04,862
underneath the middle
of the arch
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00:16:04,864 --> 00:16:06,097
so that as you're building it,
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00:16:06,099 --> 00:16:07,732
the blocks don't fall
into the strait.
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00:16:07,734 --> 00:16:09,867
And that would require
some scaffolding.
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00:16:09,869 --> 00:16:12,737
And this was just not acceptable
to the admiralty at the time
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00:16:12,739 --> 00:16:15,206
because this is a very busy
shipping channel
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00:16:15,208 --> 00:16:16,975
and they required
100 feet of clearance
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00:16:16,977 --> 00:16:18,309
above the high-water mark.
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00:16:18,311 --> 00:16:20,678
And that led telford
to have to consider something
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00:16:20,680 --> 00:16:22,880
that could give him
a very long clear-span
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00:16:22,882 --> 00:16:25,550
with no supports in the water
even during construction.
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00:16:28,287 --> 00:16:30,021
Telford's solution
246
00:16:30,023 --> 00:16:33,891
was the world's first major
long-span suspension bridge.
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00:16:36,261 --> 00:16:39,897
For a suspension bridge, we need
two very strong abutments,
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00:16:39,899 --> 00:16:41,699
and then you need two towers.
249
00:16:41,701 --> 00:16:43,868
And then what you do is,
once you've built your towers,
250
00:16:43,870 --> 00:16:45,269
you take a cable
like these guys,
251
00:16:45,271 --> 00:16:47,572
and you string these
up and over the towers.
252
00:16:47,574 --> 00:16:50,775
And then you drop hanger cables
down from the main cables
253
00:16:50,777 --> 00:16:52,810
and then put your bridge deck
in place.
254
00:16:52,812 --> 00:16:54,912
And then once your bridge
is completed,
255
00:16:54,914 --> 00:16:57,815
if you have a load that comes
along... say our car here...
256
00:16:57,817 --> 00:16:59,317
It comes along,
257
00:16:59,319 --> 00:17:01,419
and now when the load gets out
near the middle of the span,
258
00:17:01,421 --> 00:17:03,788
the load from the car
then gets transferred up
259
00:17:03,790 --> 00:17:05,323
through the hanger cables
260
00:17:05,325 --> 00:17:07,692
into the main cable
up over the tower.
261
00:17:07,694 --> 00:17:08,893
The tension in that cable
262
00:17:08,895 --> 00:17:10,895
gets anchored
in these strong abutments,
263
00:17:10,897 --> 00:17:12,196
and the compression force here
264
00:17:12,198 --> 00:17:14,866
goes down into the foundations
in the bedrock.
265
00:17:14,868 --> 00:17:16,868
That's essentially how
a suspension bridge works
266
00:17:16,870 --> 00:17:18,569
like this beautiful bridge
we have here.
267
00:17:20,606 --> 00:17:22,774
Telford's suspended deck
268
00:17:22,776 --> 00:17:24,976
was a stroke
of engineering genius.
269
00:17:26,845 --> 00:17:29,147
The key advantages
of a suspension bridge
270
00:17:29,149 --> 00:17:31,416
are that you can span
long distances
271
00:17:31,418 --> 00:17:33,918
with no supports
below the bridge decks.
272
00:17:33,920 --> 00:17:37,155
So you can get very long,
clear, unsupported spans
273
00:17:37,157 --> 00:17:38,623
because all of the support
274
00:17:38,625 --> 00:17:40,792
is coming
from the suspending cables
275
00:17:40,794 --> 00:17:42,326
and the main cables
up above you.
276
00:17:42,328 --> 00:17:43,428
So below the bridge deck,
277
00:17:43,430 --> 00:17:45,063
there's absolutely
no obstructions,
278
00:17:45,065 --> 00:17:47,932
which in a strait is obviously
a very important thing.
279
00:17:59,511 --> 00:18:02,113
A suspended bridge
was the obvious solution
280
00:18:02,115 --> 00:18:04,482
for Papanikolas
and his fellow engineers
281
00:18:04,484 --> 00:18:05,817
in the Gulf of Corinth,
282
00:18:05,819 --> 00:18:08,986
but they would have to do it
on a much larger scale.
283
00:18:11,256 --> 00:18:13,524
The Rion-Antirion
would need to be
284
00:18:13,526 --> 00:18:15,460
an incredible seven times longer
285
00:18:15,462 --> 00:18:18,830
than the Menai
suspension bridge.
286
00:18:18,832 --> 00:18:22,533
Unlike the main anchored cables
of telford's suspension bridge,
287
00:18:22,535 --> 00:18:25,670
this cable-stayed design
would use individual cables
288
00:18:25,672 --> 00:18:30,341
radiating from 4 huge pylons
spaced 1,600 feet apart.
289
00:18:30,343 --> 00:18:34,278
Each cable set would support
a 40-foot section
290
00:18:34,280 --> 00:18:35,513
of the bridge's deck.
291
00:18:38,517 --> 00:18:42,720
In 2003, deck building begins.
292
00:18:42,722 --> 00:18:45,423
Each section is floated out
into the Gulf of Corinth
293
00:18:45,425 --> 00:18:48,459
and attached to either side
of a pylon until the decks meet.
294
00:18:48,461 --> 00:18:53,498
This massive operation took
more than a year to complete.
295
00:18:55,534 --> 00:18:59,003
Just as they had to do
for the bridge's pier footings,
296
00:18:59,005 --> 00:19:02,773
designers had to ensure the deck
could survive an earthquake
297
00:19:02,775 --> 00:19:06,344
in one of the most active
seismic zones in the world.
298
00:19:16,155 --> 00:19:18,990
Expansion joints
allow the deck to stretch
299
00:19:18,992 --> 00:19:22,827
as the two land masses on either
side slowly drift apart.
300
00:19:22,829 --> 00:19:25,296
But protecting it
against a massive earthquake
301
00:19:25,298 --> 00:19:27,965
will require
a groundbreaking new approach.
302
00:19:41,980 --> 00:19:45,183
Instead of resting
on the foundation piers,
303
00:19:45,185 --> 00:19:47,051
the deck hangs just above
304
00:19:47,053 --> 00:19:49,554
creating a single
1-1/2 mile long,
305
00:19:49,556 --> 00:19:51,756
fully suspended floating deck.
306
00:19:55,127 --> 00:19:56,928
When an earthquake strikes,
307
00:19:56,930 --> 00:20:00,498
flexibility will be key
to the bridge deck's survival.
308
00:20:00,500 --> 00:20:02,767
The piers can move
on their foundations.
309
00:20:02,769 --> 00:20:05,436
And if the deck was attached
when this happened,
310
00:20:05,438 --> 00:20:07,138
it would buckle and break.
311
00:20:07,140 --> 00:20:10,408
But it's also important
that the deck doesn't sway
312
00:20:10,410 --> 00:20:12,343
during the frequent high winds
313
00:20:12,345 --> 00:20:14,779
experienced
in the Gulf of Corinth.
314
00:20:14,781 --> 00:20:18,849
Engineers had to ensure rigidity
in normal conditions
315
00:20:18,851 --> 00:20:21,552
but flexibility in the event
of an earthquake.
316
00:20:21,554 --> 00:20:26,023
Their solution... the world's
biggest shock absorber.
317
00:20:38,403 --> 00:20:41,005
If the bridge
begins moving erratically,
318
00:20:41,007 --> 00:20:44,442
a fuse breaks, sending the
massive dampers into action.
319
00:21:04,229 --> 00:21:07,131
This quake-busting design
proved its worth
320
00:21:07,133 --> 00:21:09,600
four years after the bridge
opened
321
00:21:09,602 --> 00:21:16,274
when a 6.4-scale earthquake
hit the Rion-Antirion in 2008.
322
00:21:16,276 --> 00:21:19,143
The innovative damping system
kicked into action
323
00:21:19,145 --> 00:21:22,580
saving the bridge from disaster.
324
00:21:34,493 --> 00:21:37,194
But earthquakes
aren't the only natural forces
325
00:21:37,196 --> 00:21:39,430
that engineers
will need to overcome.
326
00:21:51,209 --> 00:21:53,411
To ensure
the Rion-Antirion's survival,
327
00:21:53,413 --> 00:21:55,379
they will need
to take a look back
328
00:21:55,381 --> 00:21:58,249
of some of history's great
engineering catastrophes.
329
00:22:11,730 --> 00:22:14,865
Designers
of the almost 2-mile long
330
00:22:14,867 --> 00:22:18,669
Rion-Antirion bridge faced
huge environmental challenges.
331
00:22:20,872 --> 00:22:23,808
In one of the most seismically
active regions in Europe,
332
00:22:23,810 --> 00:22:25,876
cutting-edge technology
was developed
333
00:22:25,878 --> 00:22:29,547
to protect the bridge
from earthquakes.
334
00:22:29,549 --> 00:22:30,848
But the bridge faces
335
00:22:30,850 --> 00:22:33,818
another equally destructive
environmental threat
336
00:22:33,820 --> 00:22:35,586
that its engineers
must overcome.
337
00:22:48,600 --> 00:22:50,968
To protect this massive
structure from wind,
338
00:22:50,970 --> 00:22:54,071
engineers will need to take
a lesson from the history books.
339
00:23:01,446 --> 00:23:04,849
When the Tacoma narrow
suspension bridge opened
340
00:23:04,851 --> 00:23:06,717
near Seattle in July 1940,
341
00:23:06,719 --> 00:23:09,453
it was thought to be at
the forefront of bridge design.
342
00:23:15,927 --> 00:23:19,730
But it wasn't long
before the bridge
343
00:23:19,732 --> 00:23:23,534
got the nickname
"galloping gertie."
344
00:23:23,536 --> 00:23:26,337
There was clearly
a very big problem.
345
00:23:26,339 --> 00:23:28,539
Just four months after opening,
346
00:23:28,541 --> 00:23:31,609
the bridge's twisting motion
became so violent,
347
00:23:31,611 --> 00:23:33,677
it suffered
a catastrophic failure...
348
00:23:37,916 --> 00:23:41,585
...crashing almost 200 feet
into the water below.
349
00:23:45,991 --> 00:23:47,525
An investigation found
350
00:23:47,527 --> 00:23:50,694
that the relatively light
40-mile-per-hour wind
351
00:23:50,696 --> 00:23:53,330
was hitting the solid edges
of the deck,
352
00:23:53,332 --> 00:23:56,667
creating an unstable oscillation
that fed off itself,
353
00:23:56,669 --> 00:23:59,770
amplifying to the point
of disaster.
354
00:23:59,772 --> 00:24:03,908
The wind conditions are far more
severe in the Gulf of Corinth.
355
00:24:03,910 --> 00:24:07,044
The mountainous landscape
creates a funnel,
356
00:24:07,046 --> 00:24:10,214
where winds of 70 miles per hour
are common.
357
00:24:10,216 --> 00:24:13,617
The aerodynamics of the bridge
deck are a crucial element.
358
00:24:28,333 --> 00:24:31,101
The fairings safeguard the deck
359
00:24:31,103 --> 00:24:34,738
from gusts
of over 150 miles per hour,
360
00:24:34,740 --> 00:24:37,007
but the massive cables
holding up the deck
361
00:24:37,009 --> 00:24:40,611
also need to be strong enough
to survive extreme wind gusts.
362
00:24:40,613 --> 00:24:43,080
The designers
of the Rion-Antirion
363
00:24:43,082 --> 00:24:46,417
looked to an engineering marvel
created years ago
364
00:24:46,419 --> 00:24:47,885
for the solution...
365
00:24:47,887 --> 00:24:51,388
One that conquered a challenge
once thought to be impossible.
366
00:24:57,996 --> 00:25:00,631
In the second half
of the 19th century,
367
00:25:00,633 --> 00:25:02,399
the growth of New York City
368
00:25:02,401 --> 00:25:06,070
was being stunted by the limits
of the east river.
369
00:25:06,072 --> 00:25:09,240
At that time,
the only way for people
370
00:25:09,242 --> 00:25:13,210
to cross from Brooklyn
to Manhattan was by ferry.
371
00:25:13,212 --> 00:25:18,582
You see here Manhattan to my
left and Brooklyn to my right.
372
00:25:18,584 --> 00:25:22,586
At the time, you could imagine
just a river teeming with boats.
373
00:25:22,588 --> 00:25:28,192
But in 1867,
boat traffic ground to a halt.
374
00:25:28,194 --> 00:25:30,928
A cold spell actually
froze the east river over
375
00:25:30,930 --> 00:25:32,796
and essentially halted commerce
376
00:25:32,798 --> 00:25:35,566
because you could walk across
the east river
377
00:25:35,568 --> 00:25:38,836
at the time on the ice,
but you couldn't actually trade.
378
00:25:38,838 --> 00:25:42,172
So it was at that point when
voices really kind of mounted
379
00:25:42,174 --> 00:25:45,543
demanding a permanent kind of
structural connection
380
00:25:45,545 --> 00:25:48,045
between the two cities
with a bridge
381
00:25:48,047 --> 00:25:49,547
to have this lasting connection
382
00:25:49,549 --> 00:25:53,350
so that you could have reliable
transportation and trade.
383
00:25:53,352 --> 00:25:55,553
The man given the job
384
00:25:55,555 --> 00:25:58,722
was German-born engineer
John Augustus Roebling,
385
00:25:58,724 --> 00:26:02,560
and what he designed still
inspires engineers today...
386
00:26:02,562 --> 00:26:06,463
The Brooklyn bridge.
387
00:26:09,067 --> 00:26:11,635
Just the concept
of actually spanning
388
00:26:11,637 --> 00:26:14,038
over such a long distance
at such a height
389
00:26:14,040 --> 00:26:16,206
was earth-shattering.
390
00:26:16,208 --> 00:26:20,077
No bridge had been built
even close to this span.
391
00:26:20,079 --> 00:26:23,347
The Brooklyn bridge
spans over a mile.
392
00:26:23,349 --> 00:26:26,817
It was made possible
by Roebling's use
393
00:26:26,819 --> 00:26:31,655
of a revolutionary
new material... Steel.
394
00:26:31,657 --> 00:26:32,957
Just thinking
of actually building
395
00:26:32,959 --> 00:26:34,458
a bridge not of masonry
396
00:26:34,460 --> 00:26:37,661
as we'd find in kind of
traditional European style,
397
00:26:37,663 --> 00:26:40,431
but saying, "we have this new
material... steel..."
398
00:26:40,433 --> 00:26:43,467
We will build the entire deck
and the cables of steel."
399
00:26:43,469 --> 00:26:45,502
This is an absolute
engineering marvel.
400
00:26:45,504 --> 00:26:48,472
Steel is stronger, lighter,
401
00:26:48,474 --> 00:26:50,574
and more flexible than iron.
402
00:26:50,576 --> 00:26:53,077
Roebling used this new material
403
00:26:53,079 --> 00:26:57,081
for the bridge's four
massive suspension cables.
404
00:26:57,083 --> 00:27:01,051
He bundled hundreds of parallel
steel wires together,
405
00:27:01,053 --> 00:27:04,455
creating super-strong
and super-safe cables.
406
00:27:07,392 --> 00:27:09,293
Engineer Adrian Brugger
407
00:27:09,295 --> 00:27:13,530
demonstrates just how much safer
Roebling's design is
408
00:27:13,532 --> 00:27:17,468
at Columbia university's
engineering testing lab.
409
00:27:17,470 --> 00:27:21,538
This cable is made up
of actually independent
410
00:27:21,540 --> 00:27:24,174
and small 5-millimeter
circular wires.
411
00:27:24,176 --> 00:27:26,410
In this case,
there's 9,000 wires.
412
00:27:26,412 --> 00:27:29,713
Those wires are then grouped
into what we call strands.
413
00:27:29,715 --> 00:27:32,816
You actually take those and you
compact those into the cable.
414
00:27:32,818 --> 00:27:35,986
This is kind of a huge leap from
the technology we had before.
415
00:27:35,988 --> 00:27:37,454
Because before what we had
416
00:27:37,456 --> 00:27:39,590
was more or less
serialized systems,
417
00:27:39,592 --> 00:27:41,458
such as chains
or these large I-bars.
418
00:27:41,460 --> 00:27:43,293
Where if one
of these I-bars failed,
419
00:27:43,295 --> 00:27:45,963
then generally that meant that
the entire bridge failed.
420
00:27:45,965 --> 00:27:49,900
If one of these wires happens
to be bad or has a crack in it,
421
00:27:49,902 --> 00:27:55,339
then the entire cable still
has 8,999 other intact wires.
422
00:27:55,341 --> 00:27:59,777
Adrian compares the system
used on the Brooklyn bridge
423
00:27:59,779 --> 00:28:03,747
to those that came before it
using a giant universal tester.
424
00:28:03,749 --> 00:28:06,016
And more or less,
a universal testing machine
425
00:28:06,018 --> 00:28:09,620
just means that it's a machine
that is built to crush things
426
00:28:09,622 --> 00:28:11,055
and rip them apart.
427
00:28:11,057 --> 00:28:13,257
First to be tested...
A solid steel bar.
428
00:28:13,259 --> 00:28:15,025
This would be very similar
429
00:28:15,027 --> 00:28:17,094
to what you would have
on an old bridge...
430
00:28:17,096 --> 00:28:19,496
Pre-Brooklyn bridge for example.
431
00:28:19,498 --> 00:28:23,467
The steel bar has been
weakened at a specific point
432
00:28:23,469 --> 00:28:26,403
and will be stretched
under massive tension
433
00:28:26,405 --> 00:28:28,338
to simulate a bridge failure.
434
00:28:28,340 --> 00:28:33,043
So, we expect this bar to fail
at around a good 200 tons.
435
00:28:40,518 --> 00:28:42,486
Right now, you can see
that the necking
436
00:28:42,488 --> 00:28:45,289
is starting at about a quarter
up from the reduced section,
437
00:28:45,291 --> 00:28:47,157
so exactly where we wanted it.
438
00:28:47,159 --> 00:28:48,726
And it'll become more
and more pronounced
439
00:28:48,728 --> 00:28:50,260
kind of as we see it now.
440
00:28:57,102 --> 00:28:59,136
The energy release was massive,
441
00:28:59,138 --> 00:29:02,706
and now the specimen has
just catastrophically failed.
442
00:29:02,708 --> 00:29:04,041
It's broken.
443
00:29:04,043 --> 00:29:06,744
Such an explosive
failure could result
444
00:29:06,746 --> 00:29:08,879
in the collapse
of a whole bridge
445
00:29:08,881 --> 00:29:12,416
as tragically happened
with Silver bridge in Ohio,
446
00:29:12,418 --> 00:29:14,785
causing the loss
of dozens of lives.
447
00:29:17,689 --> 00:29:21,358
Next, Adrian tests
Roebling's steel cable design.
448
00:29:23,194 --> 00:29:26,730
As it's stretched,
he subjects it to extreme heat
449
00:29:26,732 --> 00:29:28,899
to weaken it simulating a fail.
450
00:29:31,803 --> 00:29:35,005
So, we are seeing this cascading
failure right now.
451
00:29:35,007 --> 00:29:36,406
You can see each wire
452
00:29:36,408 --> 00:29:38,976
is actually breaking one
after another.
453
00:29:38,978 --> 00:29:41,745
It's not just this one
catastrophic failure
454
00:29:41,747 --> 00:29:45,149
but rather this cascade.
455
00:29:45,151 --> 00:29:47,618
When the cable starts to fail,
456
00:29:47,620 --> 00:29:49,953
the remaining wires
take up the load.
457
00:29:49,955 --> 00:29:51,555
Even if all the wires fail,
458
00:29:51,557 --> 00:29:56,226
the energy released is gradual
rather than one huge explosion.
459
00:29:59,831 --> 00:30:02,299
So, what you saw there was,
you know, exactly why
460
00:30:02,301 --> 00:30:04,868
the suspension bridge wires
are such a great solution.
461
00:30:04,870 --> 00:30:06,703
But you can see
that you didn't have
462
00:30:06,705 --> 00:30:10,641
this one catastrophic explosion
and just failure of the member
463
00:30:10,643 --> 00:30:13,210
but rather each one
of these wires actually broke.
464
00:30:13,212 --> 00:30:17,114
Steel technology
enabled John Roebling
465
00:30:17,116 --> 00:30:21,185
to design what was at the time
the world's longest
466
00:30:21,187 --> 00:30:24,788
and strongest bridge
and an engineering masterpiece.
467
00:30:24,790 --> 00:30:28,158
This bridge would eclipse
468
00:30:28,160 --> 00:30:30,928
every other structure
in the entire americas.
469
00:30:30,930 --> 00:30:33,030
It would be the tallest
structure anywhere.
470
00:30:33,032 --> 00:30:35,265
So just a person actually
standing on the tower
471
00:30:35,267 --> 00:30:36,733
would be on essentially
472
00:30:36,735 --> 00:30:39,136
the first skyscraper
in the United States.
473
00:30:45,844 --> 00:30:48,879
The designers
of the Rion-Antirion bridge
474
00:30:48,881 --> 00:30:51,682
will need to super-size
the revolutionary ideas
475
00:30:51,684 --> 00:30:54,451
of John Roebling
and the Brooklyn bridge...
476
00:30:54,453 --> 00:30:55,552
This type of oscillation
477
00:30:55,554 --> 00:30:57,454
would be very worrying
to the designers.
478
00:30:57,456 --> 00:31:00,624
The structure could collapse due
to oscillations such as this.
479
00:31:00,626 --> 00:31:05,095
...And create even
more impossible engineering.
480
00:31:18,309 --> 00:31:21,078
180 feet
above the Gulf of Corinth,
481
00:31:21,080 --> 00:31:23,280
cutting-edge suspension
technology
482
00:31:23,282 --> 00:31:26,316
inspired by Brooklyn-bridge
designer John Roebling
483
00:31:26,318 --> 00:31:28,852
keeps the ultra-modern
Rion-Antirion bridge
484
00:31:28,854 --> 00:31:30,520
from crashing into the water.
485
00:31:50,942 --> 00:31:53,777
But unlike New York City,
near-hurricane force winds
486
00:31:53,779 --> 00:31:55,779
are common
in the Gulf of Corinth,
487
00:31:55,781 --> 00:31:58,482
putting a great deal of stress
on the cables.
488
00:32:04,422 --> 00:32:07,758
At a wind-tunnel facility,
professor Luke Bisby
489
00:32:07,760 --> 00:32:11,061
demonstrates just how
destructive wind can be.
490
00:32:13,531 --> 00:32:15,165
All right, so,
we're gonna start it up,
491
00:32:15,167 --> 00:32:16,366
and we'll see what happens.
492
00:32:21,339 --> 00:32:23,507
If this was a cable
in a real bridge,
493
00:32:23,509 --> 00:32:24,775
this type of oscillation
494
00:32:24,777 --> 00:32:26,910
would be very worrying
to the designers
495
00:32:26,912 --> 00:32:28,345
because what this would mean
496
00:32:28,347 --> 00:32:30,380
is that the metal
that forms the cable
497
00:32:30,382 --> 00:32:32,950
would be being stressed
repeatedly back and forth.
498
00:32:32,952 --> 00:32:35,819
And eventually in a metal cable,
that can lead to fatigue,
499
00:32:35,821 --> 00:32:37,054
which can cause cracking
500
00:32:37,056 --> 00:32:39,222
and, hence, potentially failure
of the structure.
501
00:32:39,224 --> 00:32:40,857
So the structure could collapse
502
00:32:40,859 --> 00:32:42,759
due to oscillations
such as this.
503
00:32:42,761 --> 00:32:45,896
When wind strikes
a cylindrical structure
504
00:32:45,898 --> 00:32:47,798
like a cable, it separates,
505
00:32:47,800 --> 00:32:49,700
then rejoins on the other side,
506
00:32:49,702 --> 00:32:52,102
causing the structure
to oscillate...
507
00:32:52,104 --> 00:32:55,372
A phenomenon
known as vortex shedding.
508
00:32:57,942 --> 00:33:01,144
Vortex shedding has been
responsible for the collapse
509
00:33:01,146 --> 00:33:04,014
of several chimneys and towers
over the years.
510
00:33:06,784 --> 00:33:10,187
In 1957, British scientist
Christopher Kit Scruton
511
00:33:10,189 --> 00:33:14,291
discovered that adding a simple
fin to a cylindrical structure
512
00:33:14,293 --> 00:33:16,426
would break up the wind vortices
513
00:33:16,428 --> 00:33:20,330
reducing the vibrations
that could lead to a collapse.
514
00:33:20,332 --> 00:33:23,333
He called the fin
a helical strake.
515
00:33:33,611 --> 00:33:37,347
Just seeing a little bit of
vibration here... not too much.
516
00:33:37,349 --> 00:33:39,649
This is really incredible
that this simple spiral
517
00:33:39,651 --> 00:33:41,318
can completely prevent
the motion
518
00:33:41,320 --> 00:33:43,120
of this simulated bridge cable.
519
00:33:43,122 --> 00:33:44,554
With the helical strake,
520
00:33:44,556 --> 00:33:46,723
we get this disruption
of the flow pattern,
521
00:33:46,725 --> 00:33:48,125
we introduce some turbulence,
522
00:33:48,127 --> 00:33:50,093
and both the formation
of the vortices
523
00:33:50,095 --> 00:33:52,496
and the vibration of the cable
both stop.
524
00:33:52,498 --> 00:33:54,798
The helical strake
seems to be working.
525
00:33:54,800 --> 00:33:58,135
Since >>>Kit Scruton
invented the helical strake
526
00:33:58,137 --> 00:33:59,503
back in the '50s and '60s,
527
00:33:59,505 --> 00:34:02,172
it's been applied to tens
of thousands of structures
528
00:34:02,174 --> 00:34:04,341
and chimneys and Bridges
around the world
529
00:34:04,343 --> 00:34:07,010
and has really saved them from
potential catastrophic collapse
530
00:34:07,012 --> 00:34:07,944
due to wind effects.
531
00:34:12,683 --> 00:34:15,152
Helical strakes are integrated
532
00:34:15,154 --> 00:34:17,754
into all of the nearly 40 miles
of cabling
533
00:34:17,756 --> 00:34:19,423
on the Rion-Antirion bridge.
534
00:34:21,492 --> 00:34:24,394
This, combined with
spoiler-like deck fairings,
535
00:34:24,396 --> 00:34:27,464
makes this bridge
one of the safest on earth.
536
00:34:38,009 --> 00:34:40,577
But a bridge
can't just be functional...
537
00:34:40,579 --> 00:34:42,045
It has to be beautiful.
538
00:34:42,047 --> 00:34:43,547
So once again, engineers
539
00:34:43,549 --> 00:34:46,716
will look to the innovations
of the past for inspiration.
540
00:35:11,042 --> 00:35:14,511
The Rion-Antirion
bridge in Greece
541
00:35:14,513 --> 00:35:17,547
is a wonder
of the engineering world.
542
00:35:17,549 --> 00:35:19,950
Its designers
not only had to ensure
543
00:35:19,952 --> 00:35:22,752
it could survive earthquakes
and high winds,
544
00:35:22,754 --> 00:35:24,387
but they were also forced
to construct it
545
00:35:24,389 --> 00:35:28,258
in extremely deep water
on unstable soil.
546
00:35:28,260 --> 00:35:32,329
Underwater, the bridge may be
an enormous mass of concrete,
547
00:35:32,331 --> 00:35:36,333
but above water,
it has to be elegant
548
00:35:36,335 --> 00:35:42,339
and add to the Greek landscape
around it... not scar it.
549
00:35:42,341 --> 00:35:46,776
Finding the right balance
between strength and beauty
550
00:35:46,778 --> 00:35:52,682
was quite a challenge
for the engineering team...
551
00:35:52,684 --> 00:35:55,085
A challenge that
may have been insurmountable
552
00:35:55,087 --> 00:35:58,188
had it not been for the great
innovators of the past.
553
00:36:04,428 --> 00:36:08,632
In 1928, renowned Swiss
civil engineer Robert maillart
554
00:36:08,634 --> 00:36:10,667
won a competition
to design a bridge
555
00:36:10,669 --> 00:36:12,502
that would link two remote towns
556
00:36:12,504 --> 00:36:16,706
300 feet above the salgina
valley in Switzerland.
557
00:36:30,688 --> 00:36:34,324
The result...
The salginatobel bridge.
558
00:36:37,929 --> 00:36:40,897
Designated an international
engineering landmark,
559
00:36:40,899 --> 00:36:43,266
maillart's bridge
proved to the world
560
00:36:43,268 --> 00:36:46,703
that concrete could be both
practical and beautiful.
561
00:36:53,578 --> 00:36:56,646
Engineer urs meyer
has been a lifelong fan
562
00:36:56,648 --> 00:36:58,381
of the iconic structure,
563
00:36:58,383 --> 00:37:02,419
but he's about to see it from
an entirely new perspective.
564
00:38:07,685 --> 00:38:11,855
Building a bridge in this remote
part of eastern Switzerland
565
00:38:11,857 --> 00:38:13,690
required great ingenuity.
566
00:38:34,445 --> 00:38:36,780
Concrete is strong
in compression,
567
00:38:36,782 --> 00:38:39,115
but reinforcing it
with steel bars
568
00:38:39,117 --> 00:38:41,117
also gives it strength
in tension,
569
00:38:41,119 --> 00:38:45,021
allowing it to be manipulated
into almost any shape.
570
00:38:45,023 --> 00:38:49,092
Maillart designed an elegant
three-pinned hollow box arch
571
00:38:49,094 --> 00:38:52,262
supported by reinforced
concrete columns.
572
00:38:52,264 --> 00:38:55,899
This made the concrete
strong enough
573
00:38:55,901 --> 00:38:58,468
to transmit the bridge loads
to the foundations
574
00:38:58,470 --> 00:39:01,938
but flexible enough
to absorb any ground movement
575
00:39:01,940 --> 00:39:04,974
that could cause dangerous
cracks to form.
576
00:39:04,976 --> 00:39:08,611
Maillart's sleek design also
used less reinforced concrete,
577
00:39:08,613 --> 00:39:11,081
making it cheaper to build.
578
00:39:11,083 --> 00:39:13,383
But there were some skeptics.
579
00:39:38,175 --> 00:39:42,112
When the salginatobel bridge
opened in August 1930,
580
00:39:42,114 --> 00:39:46,750
it was hailed an engineering
and artistic triumph,
581
00:39:46,752 --> 00:39:49,753
proving to the world
that concrete Bridges
582
00:39:49,755 --> 00:39:52,222
could be both functional
and beautiful.
583
00:40:28,492 --> 00:40:32,729
1,000 miles away in Greece,
maillart's influence can be seen
584
00:40:32,731 --> 00:40:35,832
all over
the Rion-Antirion bridge.
585
00:40:39,136 --> 00:40:41,805
The four reinforced
concrete pylons
586
00:40:41,807 --> 00:40:46,276
embody cost-saving minimalism,
flexible strength,
587
00:40:46,278 --> 00:40:48,011
and elegant design.
588
00:41:10,568 --> 00:41:15,138
780,000 tons of reinforced
concrete ensure this bridge
589
00:41:15,140 --> 00:41:18,007
could survive an earthquake
of 7 on the Richter scale.
590
00:41:44,034 --> 00:41:47,637
The Rion-Antirion bridge
has redrawn the map of Greece,
591
00:41:47,639 --> 00:41:49,739
and its designers
have rewritten the rules
592
00:41:49,741 --> 00:41:52,842
of bridge engineering forever.
593
00:42:26,744 --> 00:42:32,081
By modernizing innovations
of the past
594
00:42:32,083 --> 00:42:37,086
and making groundbreaking
discoveries of their own,
595
00:42:37,088 --> 00:42:42,158
the engineers and designers
of this incredible structure
596
00:42:42,160 --> 00:42:46,596
have succeeded in making
the impossible possible.
48864
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