Nova (1974–…): Season 45, Episode 9 - Operation Bridge Rescue - full transcript

The great North American
covered bridge,

an icon of early
engineering ingenuity.

Thousands of these uniquely
distinctive structures

once knit this land together.

But today, the few that remain
are under threat.

Abandoned, burned,

or destroyed by flash floods
and storms.

Oh, my God.

The bridge is gone.

The devastation
was absolutely total.

Now, a team of master craftsmen
and elite engineers...



Whoa, whoa, whoa, whoa!

Stop!

Battle torrential
rain and blizzards...

If this isn't
out of the floodplain,

Mother Nature is going
to take it.

Go on ahead.

To rebuild

one of the world's longest
single-span covered bridges.

I don't think we've ever jacked

anything this large
and this heavy up this high.

Let it down... whoa!

What are the engineering secrets
that enable these huge spans?

And what can we learn

from the world's oldest
covered bridges in China,



where engineers face
the same challenge...

To save these historic wonders
before they're lost forever.

We're losing more and more
of our woven arch beam bridges.

Concerned?

Yeah, very concerned.

"Operation Bridge Rescue,"

right now, on "NOVA."

Major funding for "NOVA"

is provided by the following:

In the heart
of upstate New York,

40 miles southwest
of the capital, Albany,

lies the small town of Blenheim.

Fewer than 400 people live here,

but the town once boasted
a landmark

that put it on the map...

A covered bridge with one
of the longest single spans

in the world...
The Old Blenheim Bridge.

This distinctive structure
was also one

of the last surviving
twin-lane covered bridges.

It is more than a symbol.

It is more than a structure.

It is an icon
of our cultural identity.

Covered bridges
were once a common sight

across much of North America,

with single spans
up to 360 feet.

They connected communities and
expanded the early road network.

Where timber was abundant,

craftsmen covered their bridges,

making the structures last
far longer.

You have to admire the bridges

as workmanship
of a different time.

A wooden bridge left in the open
would last nine or ten years,

because when water gets
in there,

rot sets in,
and the bridge fails.

But covered can last
indefinitely.

North America had an estimated
15,000 covered bridges.

But today, over 90% are gone.

In 2011, Hurricane Irene smashes
into the east coast of America.

It slams North Carolina,

then blasts the rural heart
of New England.

The storm reaches as far inland
as Vermont,

with flash floods destroying two
historic covered bridges here,

including the 140-year-old
Bartonsville Bridge.

Listen to that.

I don't like that at all.

There it goes.

Oh, my God!

This was the event

that also wiped out Blenheim's
cherished covered bridge...

A National Historic Landmark.

It was the heart of the town.

It was our small claim to fame.

The longest single-span wooden
covered bridge

in the world.

It was always there.

It was always something
you could depend on.

Hurricane Irene was almost
a biblical flood event.

The devastation was
absolutely total.

The area received some 15 inches
of rainfall.

Roads were washed out,
infrastructure was destroyed,

communications were
virtually eliminated.

The floodwater here
rose so high,

that it lifted the
Old Blenheim Bridge wholesale,

up off its stone abutments,

carrying it a short way
downstream,

before it was dragged
underneath a roadway

and smashed to smithereens.

When we came down
the morning after the flood,

there was pieces of the bridge,
just scattered all over here.

There was a big chunk
of the roof

that was laying up against the
other side of the guard rail.

Just... the destruction.

It was hard to believe
it was even possible.

And there was just
this empty spot

where the covered bridge used
to be.

The bridge is gone.

I felt like
I'd lost a loved one.

It felt like I had lost a friend
that I'd known my whole life.

After years of effort,

the residents of Blenheim
have secured $6.7 million

to rebuild their lost bridge,
attract tourists,

and help kick-start
the town's recovery.

Thanks to everybody
for taking the time out

to come down
to the town board meeting,

Head of the Blenheim
Recovery Committee

is Don Airey.

With that bridge,

that historic landmark
being rebuilt,

we feel that
we could almost close the door

and find some permanent closure,

although never forget,

the catastrophic day
of August 28,

when Hurricane Irene struck.

To take on the unique
engineering challenge

of rebuilding
the Old Blenheim Covered Bridge,

the town has enlisted one

of the last surviving
covered bridge craftsmen...

Stan Graton II.

Stan's a true craftsman.

A rare breed

in terms of being able
to have the skill set,

the mindset, and the drive

to recreate these original icons
of early America.

Saving them, preserving them,

and in this case,
recreating them

for future generations
to appreciate.

Stan is a third-generation
timber bridge builder.

Today, he works
with his cousin J.R.,

his father, Stan, Sr.,
and his son Garrett,

passing down knowledge
and tools.

I've been in the family
business since 1976,

and we build and restore
covered bridges.

Yep.

But recreating
the Old Blenheim Bridge

will test even a builder
of Stan's pedigree.

Down!

Beautiful.

It's a massive structure.

It's going to be 36 feet high
at the peak,

226 feet long.

It's going to be right up there

with the top projects
that we've done.

There are no original blueprints
of the bridge.

Luckily for Stan,

government engineers surveyed
the structure back in 1936,

producing detailed plans.

We're duplicating the
exact design of the old bridge.

We've changed the species
of wood

from spruce to Douglas fir,

because you can't get a spruce
that big and that quality

anymore.

And we're using galvanized steel
instead of wrought iron,

and it's the only
the compromises we made.

The Old Blenheim Bridge
was built

by Nicholas Montgomery
Powers in 1855.

To construct it,

he assembled the structure
on land in Blenheim village,

while masons built
the stone abutments

next to the creek.

Between the abutments, they
installed temporary scaffolding.

The team then dismantled
the bridge

and rebuilt it, piece by piece,
on top of the scaffolding.

Once in place,
they removed the supports,

allowing the bridge to settle
onto its abutments.

But erecting bridges like this
over fast-flowing rivers

was risky.

One worker was killed building
the Old Blenheim Bridge.

It's more dangerous working
over the water.

Men were a lot hardier back then
than they are today,

I don't work as hard
as my grandfather did,

I know that.

So now they need to find
a safer technique

to build
the New Blenheim Bridge.

The solution?

Build the bridge's
two outer walls,

and one central wall,

flat on land, next to the creek,

then raise them vertically.

Brand-new concrete abutments

will elevate the bridge
higher above the creek,

protecting it
from future floods.

Once they've added the siding
and rafters,

they must move
the 100-ton structure, intact,

up onto its new abutments.

A daunting challenge.

Jerry!

Hey, Stan!
How're you doing, buddy?

But one that this man,
Jerry Matyiko, relishes.

Nice seeing you again.

Nice to see you.

He is a character,
he is a character, yep.

Known him for quite a while.

He's a great guy,
a wealth of knowledge

24 feet up, and how tall is it?

30 feet?
30 feet.

Jerry's been moving
supersize structures

for over 50 years.

Go on ahead!

He's moved over 1,000.

We move everything
from outhouses to lighthouses.

We've moved airport
terminals, smokestacks,

theaters, gymnasiums, monuments.

You name it, we've moved it.

On the island
of Martha's Vineyard,

Jerry recently relocated

the 160-year-old
Gay Head Lighthouse,

in danger of toppling
off the crumbling cliff.

To Gay Head Light!

The people were all glad
to have us there

to save the lighthouse.

It's just something sacred

to the people
on Martha's Vineyard.

But launching
a 226-foot-long, 100-ton bridge

into thin air over this creek

is an entirely new challenge
for Jerry.

This bridge
is just so much bigger

than the other covered bridges.

This is the biggest
and the tallest

and the longest ever built.

It's going to be
really something.

For this job,

one option would be to use
a giant crawler crane

to pick up the bridge
and move it over the creek.

But this could be risky.

It's got limits
on what it can lift,

at what angles.

And you know,
there are cranes that tip over.

A safer option would be
to set the bridge on tracks

and roll it
up onto the abutments.

But a tight turn could derail
this scheme.

Rolling on railroad rails
is good for going straight,

but we have to make
a sharp turn.

It's just no way you could have
rolled it on rollers.

So this is Jerry's plan.

First, they will build
a temporary roadway

across the creek.

Then he'll install eight sets
of powered hydraulic wheels

under the bridge.

These should help steer
the bridge

around the sharp turn

and drive it onto the roadway.

Once in position,

Jerry will use hydraulic jacks
to raise the bridge 25 feet.

He will then set rollers
underneath the bridge

and use hydraulic push rams

to inch the massive structure
onto the concrete abutments.

At least, that's the plan.

There's a lot of problems
that can happen.

One of the hardest parts

is going to be making the turn.

It's going to be a hard time.

But there's
another dangerous threat

to this ambitious plan.

This is definitely
in the floodway.

Any snowpack during the winter

is going to end up melting
and coming down.

And if we do not get this
out of this floodway

before spring,

it will end up in pieces
like the original bridge.

That means Stan and Jerry
have just nine months

to build the New Blenheim Bridge

and move it into place

before spring meltwater
floods the worksite.

The first step of the build

is to assemble
the bridge's skeleton

from over 6,000 timber beams.

It is a massive jigsaw puzzle.

All the members are numbered,

I for interior, N for north,
S for south.

And we really need to be careful

not to use up the wrong one
in the wrong spot.

Just like the old bridge,

the secret to the
New Blenheim Bridge's huge span

is her three vertical walls,
called trusses.

These will be built
with a slight arch, or camber,

for increased strength.

Each truss will be made up

of dozens
of interconnecting triangles.

These distribute the weight
of traffic

throughout the structure.

The taller interior truss

makes the bridge
a rare two-lane crossing.

Within this truss,

a vast, triple-laminated arch
will add even more strength.

78 separate timbers will make up
the base of the three trusses.

It's critical the joints between
these timbers hold strong,

so they will use
an ingenious sawtooth joint

to lock the beams together.

Those sawtooth joints work
like a ratchet.

It's probably the strongest
actual wood joint

that you can come up with.

The team uses power tools

to cut the teeth
of the sawtooth joint,

but then,
they use traditional tools

to finish the joint,

just as Nicholas Powers did
for the original bridge.

They must cut each tooth
with extreme precision.

An ill-fitting joint could fail

and cause the bridge
to collapse.

We need a nice tight-fitting
joint.

This is where all the tension is
in the bridge,

so most of the structure
of the bridge

boils down to these joints here.

They use ten
galvanized steel bolts

to lock each saw-tooth joint
together.

200 years ago,
when iron was more expensive,

bridge builders would often use
wooden dowels,

known as tree nails or trunnels,

driven through the timbers
to secure them.

After five months cutting

and hauling more than 63 tons
of timber,

Stan completes
the first two trusses

of the New Blenheim Bridge...
Yup!

One exterior truss,

and the taller central truss
that will form the peaked roof.

But the clock is ticking.

It's now November,

and the team has
just four months

until their worksite
is likely to flood.

We're a month and a half
behind where we wanted to be.

We've got a critical path,

because of the spring floods,
the snowmelt.

It's starting to worry me
a little bit.

We've got to have this
out of this riverbed

and up onto the abutments.

To keep the build moving,
their next challenge:

use two cranes to raise
each truss up vertically.

But there's a problem.

The trusses are so long,

that if each crane pulls
at just a single point,

the timber will flex
and could snap.

To guard against this,

Stan will rig each crane
to pick up the truss

at two separate points,

and underneath, he'll add
extra towers of wooden blocks,

called cribs.

This spreads the load,
supports the truss,

and reduces flexing as it rises.

At least, that's the theory.

Every bit of that
needs to be supported.

If it isn't supported correctly,

you would snap it in half.

Okay, we're going to bring it up
until we get movement.

We're gonna go slow, guys.

A pair of slings connects
the cranes

to the central truss.

Both cranes are gonna boom up
and hold their load.

Crane supervisor Woody gears up
for the first big lift.

Okay, guys, here we go.

Yep, coming up!

Watch for movement.

We have to watch it,

that it doesn't slide towards us
or away from us.

So we have to keep the cranes

so that they're picking
straight up.

Cable up.

Looking good.

But just as the truss
approaches vertical...

Stop, stop!

It starts to slide
off its supports.

Whoa, whoa!

Stop!

The wooden support towers shift,

leaving the truss
barely supported.

Just the weight of the bridge.

It's trying to slide out
as you're lifting up.

Could slide out entirely
if we don't fix it.

Stan's team rushes
to rebuild the towers.

Yep, down!

With the supports shored up,
they restart the lift.

Woody!

Okay, both cranes, cable up.

Cable up easy.

Disaster narrowly averted,

the central truss is vertical.

Beautiful!

What are we doing next, Stan?

Got to use this cheap labor
while you got it.

Jerry bought me a couple
of cigars, actually.

Doing a major pick like this,
kind of relaxes you.

Okay, both cranes, cable up.

The team races to reset
the cranes

and lift the first outer truss.

Okay, both cranes, go.

38, 39, 40.

Nothing's shifting at all.

That looks good!

Good!

Let's get her plumbed up, buddy!

Getting these two stood up
is a big milestone.

It's been six years
since I've seen these trusses.

It's just coming back to life
again.

And it's a rebirth of,
of what we lost.

With two out of three trusses
vertical,

this distinctive bridge

starts to reclaim
its rightful place

in the landscape.

Beginning in the 1800s,

each region developed
its own distinctive style

of covered bridge.

They evolved
kind of independently

in different areas.

Oregon bridges are distinctive.

They look like bridges
in Oregon, nowhere else.

Iowa has the only
flat-roofed bridges

in the country.

Pennsylvania bridges look
different from Ohio bridges.

The builders worked
from intuition,

from experience,

because there was no science
of engineering.

But the North American
covered bridge

was not the first of its kind.

Wooden covered bridges
were also built

in the medieval cities
of Central Europe.

The Chapel Bridge
in Lucerne, Switzerland,

has stood since 1333

and is the oldest surviving
wooden covered bridge in Europe.

But some of the oldest

and most spectacular timber-
covered bridges in the world

were built in the remote forests
of subtropical China.

In the southeast of the country,

visionary engineers developed

a completely unique
building technique

to link remote villages.

Professor Jack Liu

has been researching
these elaborate structures

for 22 years.

We call this structural form

the woven arch beam bridge.

A single log can't cross
a 20- or 30-meter-wide river.

So we combined them to form
an architectural structure.

But unlike
American covered bridges,

the Chinese did not use trusses.

Instead, they developed
a very different system

of interwoven beams
to create an arch.

Engineers wove one span
of three beams

with a second span
of five beams.

They used simple mortise
and tenon joints

to connect the beams together.

They added extra cross supports
and a bridge deck.

Finally, they built
a timber structure on top

to protect the arch beams

and provide shelter
from the wind and rain.

The roof protects the timbers,

but it also provides a place

where villagers can meet
and relax.

Also in some places,
the bridges house markets

and form the center
of village life.

Or they provide space
for people to worship.

We see that there is
a small shrine

inside each covered bridge.

But these bridges do have
an engineering Achilles' heel.

If the woven timber beams do not
have a heavy building on top,

the entire structure is at risk.

Gravity alone holds
the woven timbers in place.

Forces pushing upwards
from beneath the structure,

such as wind and floodwater,

can loosen
the mortise and tenon joints,

eventually tearing
the beams apart.

To combat these forces,

early bridge builders added
ever more weight on top,

to lock the beams down tighter.

It's critical

that the weight compresses
the arch structure.

The building above is vital
to the arch below.

They work together
in perfect harmony.

The more heavily tiled,

the more massive the stone
flooring, the stronger

the woven arch beam bridge
became.

But today,

these exquisite wonders
are under threat,

just like
their American counterparts.

In 2016, three historic
Chinese covered bridges

were washed away
by Typhoon Meranti.

We're losing more and more
of our woven arch beam bridges.

So this is a major problem
in this region.

The battle is underway

to repair and rebuild
these iconic crossings

before their engineering secrets
are lost for good,

in both the East and the West.

So, you guys good?

But time is the enemy.

In upstate New York,
Stan races the clock

to reconstruct
the Blenheim covered bridge

before spring meltwater
floods the worksite.

One more?

It's taken six months
of arduous work

to assemble and raise
the bridge's three trusses.

Perfect!

These will form the skeleton

of its unusual
two-lane crossing.

It's exciting,
watching it happen again.

Words don't describe it.

Really excited
to have this done.

All three trusses are stood now.

Their next task,

before they attempt to raise the
bridge to its final location,

is to install its outer walls
and rafters.

The town hopes to incorporate
part of the old bridge

into the new, creating
a link through time.

It'll be like taking
a little bit

of the bridge's soul

and, and putting it
into the new bridge.

But this will not be easy.

This is where we've got
the stored material

of the old covered bridge.

We'll do some digging
and see what we can find.

It's hard to look at,
a little bit.

A little hard to look at.

There's an old sawtooth joint.

Oh, yeah.

This probably speaks
to the power of that water,

being able to break it up
like a toothpick.

That's a rafter!

All right,
so that's a candidate.

Okay, that's... Four and a half.

Three and seven eighths.

We found one rafter
that was amazingly intact.

So this'd be the piece

that we can actually put
into the bridge

just where it was in 1855.

It'd be part of their closure,
I think.

It's like a phoenix, you know.

It's destroyed,
and then it's rebirthed now.

Feels like a small part
of the old bridge is back.

It means a lot.

Just a month remains to complete
and move the bridge

out of the floodway.

But as they battle to fit
the final rafters,

winter bites.

Three consecutive snowstorms
pummel Blenheim.

We've received over 50 inches
of new snowfall

in the past two weeks.

Concerned?
Yeah, very concerned.

The snow not only
slows the build,

but also increases the risk
of a catastrophic spring flood.

Trees trap the snow
in terms of shading,

uh, the terrain traps the snow.

And we've got three, four feet
of snowpack

that has to get somewhere.

And where it's going to go?

To the Schoharie Creek.

As temperatures rise
and the snow melts,

floodwater could soon consume
the worksite

and destroy
all the team's hard work.

That would be
the worst-case scenario.

The gun is loaded.

We have no other choice

but accelerate
the lifting of the bridge

onto the abutments
as soon as possible.

It's only when a covered bridge

is high enough
above the floodplain,

and carefully maintained,
that it will last.

There's one in America

that has survived everything
nature has thrown at it.

Just an hour northwest
of Blenheim

stands the Hyde Hall Bridge.

This is the oldest surviving
covered bridge in America

and has endured
almost two centuries

of wind, rain, and snow.

The first generations of bridges

would have been replaced
as traffic became heavier.

Very few of that early layer
are still in existence.

Built in 1825,

the Hyde Hall Bridge
is still standing,

her original trusses protected

by her carefully maintained roof
and siding.

In China, the oldest surviving
woven-beam covered bridge

is hidden in the remote
1,000-year-old village

of Yueshan...

"the Village of the Moon
and Mountain."

The Rulong Dragon Bridge
is almost 400 years old.

It's an engineering mystery
how this exquisite structure

has survived not only
four centuries of typhoons,

but also devastating
earthquakes.

Professor Liu investigates
the bridge's secrets.

The bridge is asymmetrical,
but also very beautiful.

So, this is a very,
very special bridge.

How has the Rulong Bridge
survived for so long?

A clue lies hidden high up
in the roof of the structure...

Hundreds of complex brackets,
called "dougong."

They're not just decoration.

They're also
a kind of shock absorber.

This test simulates
an earthquake

and shows how the dougong
absorb the forces

and help stabilize
the heavy tiled roof.

The intricate brackets
help legendary buildings,

like the Rulong Bridge,
roll with the punches.

A dougong looks quite simple,
but it's not easy to make.

Only a few masters know
how to make dougong.

Today, Master Wu is putting
the finishing touches

to a brand-new bridge.

Once complete,
the 143-foot-long Tunfu Bridge

will be China's longest
single-span covered bridge.

And just like
its historic counterparts,

it has an extraordinarily
complex system of dougong

to make it earthquake-proof.

Master Wu assembles
individual dougong

to form sets of brackets.

He uses bamboo nails
to join them together.

In ancient times,
there were no iron nails,

only bamboo nails.

The bamboo nail fits in here

and will not rot
for hundreds of years.

They are very strong.

The dougong are slightly loose,

allowing the roof
to absorb movement.

This skilled craftsmanship

should help Master Wu's
new woven-beam bridge

survive nature's wrath
for generations to come.

But back in upstate New York,

the future of
the new Blenheim covered bridge

hangs precariously
in the balance.

It's now March.

As temperatures rise,

torrential rain hits
the worksite,

and the dense snowpack melts
in the hills to form streams.

This deluge runs
into the Schoharie Creek,

causing water levels to rise.

The rise is much higher
than we want

and could imperil the bridge.

Thus, the big push to get
the bridge on the abutments.

Whoa!

As the creek expands,

water creeps ever closer
to the bridge,

just as the team faces
the most complex stage

of this operation.

They must now move
the New Blenheim Bridge

off the flooding creek bank
up onto its abutments.

This move is
a two-stage operation.

Stage one involves
steering the bridge on wheels

around the sharp turn
and onto a temporary roadway

that the team has erected
over the creek.

It's taken nine weeks to build
the temporary roadway

from steel girders
and heavy timber beams.

Everything is now set

for heavy-move maestro
Jerry Matyiko

to prepare the bridge
for its journey.

That's if he can get
his equipment onto site.

Whoa, hat down, hat down.

Positioning these wheels
can get a little bit tricky.

And the river's up, so
that'll delay us even more.

Come on.

Whoa!

Free!

Jerry works with his son Gabe.

Sweet!

This has been pretty much
my dad's baby,

but I'm here for the move.

It's pretty awesome.

Finally, it's go time.

We're ready.

All right, Dad, come on ahead.

The front and rear
hydraulic wheels

are powered by diesel engines.

But it's elbow grease
that powers the steering.

Chains run
between the wheel sets.

Cranking the chains pulls
the wheels left or right.

P.J.! P.J.!

Tighten up.

24-year-old P.J. is in charge

of steering
the massive structure.

All right, go to the next one,
go to the back.

One wrong move could end
in disaster.

That's good.

You got to make sure

everything's tight, everything
is in perfect lined order.

Nothing can be off,

because one fraction of an inch
could potentially kill somebody.

Just as they get going,
they hit a problem.

The bridge is so heavy

that it sinks
into the waterlogged creek bank.

That gravel is screwing me up,
it's loose.

Now, I've gotta get off
of this soft gravel.

Fortunately, Jerry's got a plan.

Hold up!

All stop.

Dig out a little bit, Gabriel.

Clean out a little bit.

They lay down wooden boards
to help the wheels grip

and drive the bridge
out of the hole.

Don't need no more.

All right, move ahead, let's go.

But they immediately hit
the next obstacle.

Somehow, they have
to turn the bridge

to line up with the roadway.

We gotta get
into a really hard turn,

a 90-degree turn.

Just about as hard
as you can, as you can go.

And the harder we get
into the turn,

the more you gotta keep those
dollies heading

in the right direction
and in sync with each other.

So you got the dollies
in the front

aiming straight
towards the bridge

and the dollies in the back
going at a 90-degree angle.

Stop! Stop!

Stop. Everybody stop.

You should be heading
right there.

Dad, I can't turn anymore.

It'll fall off the embankment.

Gabe has run out of road
to turn...

And the clock is ticking.

With creek levels rising
rapidly,

they scramble to widen the
roadway near the front wheels.

All right.

Everybody ahead... go.

Nice and slow, moving ahead.

All right, let down!

But the loose rubble
underneath the roadway

is close to collapsing.

Let down... whoa!

Stop! Stop!

Keep going

and the bridge could slide
into the river.

I opened up the dollies,

and there's inches
to spare here.

At this angle,
there's simply not enough space

to get the front wheels
onto the temporary roadway.

They're stuck.

What we're doing is,
we're actually going

to just hold this end stationary
while the back comes around.

It's gonna just basically
pivot like that.

Once we get
to where we want to be,

then we stop again,
straighten everything up,

continue across the bridge.

But making space to swing
the rear of the bridge around

won't be easy.

They need to shift tons of earth...
And fast.

We're limited

with the real estate
that we have to work with,

so it's gonna be real tight.

Go on ahead!

They slowly swing the rear
of the bridge around

to line it up with the roadway
across the creek.

Finally, with inches to spare,

everything lines up.

All right, we're gonna
move it ahead on three.

One, two, three, let's go!

We're on a roll now.

Gabriel!

We got about, oh,
maybe eight feet to go.

We want to hit it on the button.

It's kind of
a one-shot-deal scenario.

Is that it?

Little bit, give me a touch!

I think we're there.

Whoa!

Oh.
Chock it up!

After an epic battle
against the elements,

stage one of the move
is complete.

The New Blenheim Bridge sits
across the creek.

But the creek is still rising,

and stage two of the move

will expose the bridge
to even more danger,

as they raise it up 25 feet
and slide it onto the abutments.

Hi, kids!

You got the pictures
of the wheels.

There's just time
for Jerry to catch his breath

and hopefully inspire
the next generation

to look after this landmark.

It's the longest
single-span covered bridge

ever built.

These kids went through

something pretty traumatic.

And I think them seeing
this bridge rebuilt?

It feels like home again.

The new bridge is gonna be
higher than the old bridge.

The flood won't take it away.

So hopefully,
if you take care of it,

it'll last longer
than you kids will,

or your grandkids.

Without the next generation
of craftsmen,

the engineering knowledge needed

to build
these enigmatic structures

could be lost to
history, in America

and in China.

So the Chinese are taking
a highly proactive approach...

Building huge museums
to the art and science

of covered bridge construction,

like this one in Qingyuan.

They're also teaching
the woven arch technique

in schools.

The kids really have fun
in this class.

They explore the structure
of the bridge.

This is
the most important learning,

but also the most exciting.

The number of masters
who can build these bridges

is decreasing.

There are only a few left.

If we don't pass on
these skills,

we will lose them,

and this would be a great loss
for our country.

So we must give our children
bridge-building knowledge

as early as possible.

I look at the pictures

and see the masters
who built the covered bridge.

I admire them.

I think when I grow up,

I want to be a bridge builder.

The future
of Chinese woven beam bridges

seems to be in good hands.

But in Blenheim, New York,

the future
of this covered bridge

remains balanced
on a knife-edge.

The 100-ton structure is finally
over the creek,

but not yet safely
on its abutments.

The team must race to complete
the second stage of the move.

Lifting the bridge up
onto its supports

will require 12 hydraulic jacks

to raise the structure 25 feet
into the air.

Only when the bridge reaches
its final height

can they then slide it
onto the new abutments,

out of danger
from the rising creek.

The jacks can only raise
the bridge

16 inches at a time,

so the blocks support the bridge

until the jacks are retracted

and reset for the next big push.

We got 2,000 four-foot,
6 x 6 oak blocks.

It's just
a nice big block party.

I don't think
we've ever jacked anything

this large and this heavy
up this high.

18 to 20 feet
doesn't seem that high

when you're just looking at it,
but once you get up there,

and there's water over here...
We're already about ten foot up,

so we're gonna be
about 35 foot up,

and it's kind of creepy
when you're up there.

Watch yourself!

Higher you go,
the slower it goes.

I think we're there!

The team raises the bridge
the full 25 feet,

but it won't be safe

until they slide it across
onto the abutments,

using steel beams, rollers,

and hydraulic push rams.

All right, guys.

I'm gonna start pushing...
Let me know if it does not move.

I'm ready when you are.

All right, pushing in three.

One, two, three, go.

Gabe extends the push rams.

- Moving?
- Moving!

That sounds great!

These inch the bridge
towards the abutments.

Well, we only got about another

six, seven feet to go,

and we'll be over the abutment.

Final push.

It takes three hours

to push the bridge across
to its footings.

Looking good, looking good.

We're gonna get that plumb bob
right over that X.

We don't need all them fancy
stinking lasers and all that.

We just got a plumb bob.

The big question...

Will the bridge
and the abutments line up?

This is one of the more
nerve-racking portions,

because of how crucial
the alignment is,

whether the bridge
and the abutment

are all on the same page.

'Cause I know my bridge
is right on.

It's just a matter of,
"If it doesn't fit,

it's their fault."

Four.

Three.

Two.

You want more?

Yes, yes.

I'm one up... whoa, whoa, whoa.

I'm good!

Spot on!

Now, just to lower the
bridge onto the abutments.

Touchdown.

She made it!

After almost seven years,

the Old Blenheim Bridge
is reborn,

and the community can finally
welcome back an old friend.

It's beautiful.

I can't believe it.

It looks just like
the old bridge.

You were, like, this big

the last time we went
across the bridge.

It's crazy.

Huge beams, and all my
family and friends here,

it's just amazing.

A walkway will link the crossing
to the west bank.

It's taken $6.7 million,
176 tons of timber,

and some ingenious engineering,

but one of the world's longest
single-span covered bridges

is back where it belongs.

Good afternoon, everybody.

Thank you for joining us

at the ribbon-cutting ceremony.

There you go, and...

It's kind of like a phoenix,

a phoenix rising from the ashes,
except for us it was water.

I think it represents
a new beginning.

And I hope that someday

I will be able to bring
my grandkids here.

To the bridge!

In the heart of Africa

lie two of the world's
most dangerous volcanoes.

When will they erupt again?

An international team
of scientists

plunges into the craters
of these twin giants...

Rock!

To learn their secrets,

predict future eruptions,
and save lives.

Avoid another disaster.

"Volcano on Fire"

and "Volcano on the Brink"...
Next time on "NOVA."

To order this "NOVA" program
on DVD,

visit ShopPBS
or call 1-800-PLAY-PBS.

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on Amazon Prime Video.