Original subtitles

Narrator: Stretching over two miles

Across the saint lawrence river...

This is canada's newest and toughest structure...

The samuel-de-champlain bridge.

With three months to go before it opens,

Engineers are in a race against time to finish construction.

Maiholt: The clock is ticking.

We're now in the final push.

Narrator: What technologies make it strong enough

To handle 60 million vehicles a year,

And how does its design beat extreme winter weather?

We unlock the engineering secrets that make this structure

The most advanced bridge in north america,

From its aerodynamic profile that stands up

To the strongest winds to a skeleton forged

From super-strong corrosion-resistant materials,

To reveal what it takes to build the ultimate super bridge.

-- Captions by vitac -- www.Vitac.Com

Captions paid for by discovery communications

♪

Montreal, canada.

The nation's second-largest city is a major hub

For business and commerce.

Montreal's success depends on its big bridges

Spanning the saint lawrence river.

They must move people and goods between the city

And throughout the rest of canada and the u.S.

To meet this need,

Montreal opened the first champlain bridge

Over the saint lawrence river in 1962.

The designers expected it to last for a century.

But within 30 years, the bridge started to crumble.

Now, after five decades in service,

It needs around-the-clock monitoring

And costly maintenance.

Alex szemenyei is part of the team

Tasked with keeping the old bridge operational

Until the new one is complete.

To get an idea of how much these repairs

Have cost over the past few years,

Since 2014, approximately $300 million

Has been invested into the bridge.

So we're looking at approximately $50 million

To $60 million a year being put into the bridge

Just to ensure that it stays strong

And it stays standing until the new bridge opens.

Narrator: Along the length of the the bridge,

Flaked concrete exposes rusted rebar beneath.

Engineers call this damage spalling.

With the original bridge crumbling apart,

The city is in dire need of a replacement

To keep up with the economic demand of the region.

But building and maintaining big bridges in this part of

North america is a huge engineering challenge.

Over the course of 12 months,

Montreal's climate fluctuates wildly.

In summer, temperatures can soar to a sweltering 95 degrees.

In winter, the air pressure can plummet to minus-22 degrees.

Fast-moving ice floes overtake the saint lawrence river

And freezing winds batter the city.

To keep this metropolis connected and moving

Through any kind of weather,

Engineers in montreal are building this --

...The samuel-de-champlain bridge.

It spans over two miles...

And costs over $3 billion.

♪

The bridge is designed using innovative technology

Built into its mighty structure

To stand up to everything mother nature throws at it.

Ingenious cables keep massive chunks of ice

From crashing onto cars and pedestrians below,

A deck structure that remains rock-solid

Against the strongest winds, expanding joints stop the bridge

From cracking as the temperature changes,

An ingenious drainage system

Flushes away corrosive salty water

Before it can destroy concrete and steel.

All these elements combine to make

The new samuel-de-champlain the ultimate bridge.

Construction began on the bridge in 2015.

First, engineers installed 37 sets of pillars

Called piers on land and into the saint lawrence riverbed

To create a base for the structure.

Next, they laid a steel platform on top of the piers.

Then they used giant floating cranes

To place 9,600 concrete deck slabs.

Today, this elite team works around the clock

To ensure the bridge will be completed on time

For its grand opening.

Once finished, this vital roadway must be able

To carry 60 million vehicles

And $15 billion worth of cargo each year,

Stay open 24/7 in all types of weather...

...And survive for at least 125 years --

The life span the canadian government specifies

For new critical bridges.

Chief engineer guy maiholt leads the team

In charge of the herculean task of building

This superstructure.

Maiholt: There's daily stresses on us, the entire team,

To do whatever we can to get the bridge open in time.

Narrator: The stakes for guy and his team couldn't be higher

Because the cause of the damage isn't going away any time soon.

In order to keep the roads clear,

Montreal uses a crucial chemical to keep their roads ice-free.

Ever since the 1960s,

The city covers its roads and bridges with salt --

Over 285,000 pounds of it every year.

Salt is an effective way to melt ice,

But it destroys concrete structures.

When de-icing salts melt away snow,

They dissolve into the liquid water,

Trickling down the side of the bridge.

Over time, this salty water seeps through the concrete

And contacts the steel rebar inside.

The salt water contains chloride ions.

These react with the steel, causing it to rust and expand.

Eventually, the bridge becomes so cracked

And damaged that large chunks of it will begin to break away.

Without proper maintenance,

The bridge's steel skeleton will become so corroded,

The entire structure could collapse.

The challenge for guy and his team is to make the new

Samuel-de-champlain bridge 100% salt-proof.

To solve the problem, engineers must completely rethink

The very fabric of this bridge.

Maiholt: In planning the new bridge,

We really learn from the old bridge,

And we were quite proscriptive in the type of materials

To ensure that the bridge would perform well

Over its intended 125-year design life.

Narrator: They choose to build the skeleton of the bridge

From stainless steel rebar.

This chromium-enhanced metal is 10 times more resistant

To corrosion than traditional steel.

Marcel martineau's team encases the skeleton

In the ultimate protective concrete layer.

Engineers combine stainless steel

Rebar and corrosion-resistant concrete

To produce the bridge's 9,600 deck slabs.

Installing them onto the bridge structure takes 22 weeks.

Today, marcel's expert team races to fill the spaces

Between the slabs with more concrete.

This mix is made with less water

And is much denser than traditional concrete.

Workers use special machines to eliminate air pockets

From the concrete to guarantee its salt-proof qualities.

This section of roadway is just one small part

Of an ingenious drainage system.

The bridge's designers engineered the structure

Like a giant sink

To reduce its concrete's exposure to corrosive salt.

The shape and angle of the deck's camber directs

Water towards drains located along the edge of the roadway.

Water enters an intricate system of pipes, up to 24 inches wide,

Running along the inside of the structure to the nearest pillar.

The pipes release the salty water

Three feet above the water line.

This reduces the amount of concrete

Exposed to the corrosive solution.

Once poured, the concrete is left to cure for up

To seven days.

Workers cover the concrete to protect it from the elements

And ensure it dries at the right speed.

Once set, workers spray the entire surface

With a synthetic resin.

This waterproof membrane is part of a layered system

Specifically designed to prevent the damage salt causes.

To ensure that we won't have corrosion on this bridge,

We start with a good drainage system.

We then have a thick layer of asphalt.

We then have a waterproofing membrane.

We then have high-performance concrete,

Which is much more resistant to salt penetration,

And then we have the stainless steel rebar.

And the old bridge had none of these.

Narrator: The super bridge is now immune

To the damaging effects of road salt.

But the mega-structure must withstand more climatic extremes

To last 125 years.

What technology protects this bridge

From montreal's major temperature fluctuations?

And what is its secret

For beating the region's destructive winds?

Narrator: In montreal, canada, engineers have just three months

To prepare for the opening

Of the new samuel-de-champlain bridge.

It must be robust enough to serve the city every day

For a minimum of 125 years,

As mandated by the canadian government.

If engineers get its construction wrong,

This new bridge could suffer the same fate

As its crumbling older neighbor.

One of the biggest challenges

Facing the new bridge's engineers

Is building a structure

That can withstand montreal's extreme temperature range.

In summer, temperatures can reach up to 95 degrees.

In winter, the temperature can plummet to minus-22 degrees.

Maiholt: So you really have to look at each individual component,

Understand how it's gonna behave under the extended design life,

And then design it accordingly.

Narrator: Montreal's weather cycle will have a big impact

On the city's new bridge.

Almost all the bridge's components expand

When they heat up and shrink when they cool.

Individually, the change in size is miniscule,

But combined across a two-mile-long bridge,

It can be dramatic and catastrophic.

As montreal freezes in the winter and warms in the summer,

The bridge can length by up to 10 feet over the year.

Ignoring these fluctuations could cause the bridge's deck

To buckle as it expands or crack as it contracts.

To solve this problem,

Designers incorporate gaps into the bridge deck.

The gaps are up to 63 inches wide

And sit at eight strategic places along the decks.

These allow the bridge to expand freely into the open spaces.

The gaps stop the structure from cracking,

But unfortunately, make it impossible for vehicles to pass.

The solution are these one-of-a-kind expansion joints.

They're designed to both fill the gaps

And let the bridge flex.

Intensive factory tests ensure each joint can stand up

To the extreme temperature changes throughout the year.

Today, project manager alexis lauzon

Oversees the final joint's installation.

The expansion joint is an important part of a bridge

To make sure that the bridge can move freely

Throughout the seasons.

This expansion joint will take a lot of abuse

Throughout the years.

Narrator: Alexis' crew installs expansion

Joints into all eight gaps in the bridge deck.

The sides of each joint

Attach to the ends of two road sections.

As the bridge expands or contracts, the joints,

Each 65 feet long, move along rails.

They react to the bridge's lateral and vertical movements.

Foam buffers ensure the joints metal strips

Remain evenly spaced as they move.

Spring bearings beneath the strips distribute

The load of vehicles through the bridge's concrete structure.

With three months to go before the bridge opens,

Alexis and his team are feeling the pressure.

The expansion joint that we're gonna see today

Is quite heavy and quite big.

We have a 60-meter piece that weighs around 16 tons.

The workers need to be really meticulous

Because any wrong movement could be fatal.

Narrator: A mighty crane lowers the huge 32,000-pound joint

Into position.

The team removes some steel obstructing the gap.

Then the joint slots in perfectly.

As temperature changes make it stretch and shrink,

Expansion joints will stop the bridge deck from breaking apart.

But the deck's change in shape presents

Additional engineering challenges for this team.

Six huge deck sections join to pier legs sunk

Deep into the saint lawrence riverbed.

The piers could be stressed and damaged

As the sections expand and contract.

Additionally, montreal sits in an active seismic zone.

Over the next 125 years, the city will experience

At least one major ground movement.

When it happens, there's a real risk

The bridge will sustain catastrophic damage.

If the structure were not flexible, under a seismic event,

It would transfer tremendous forces

Because the structure would be much more rigid,

Which could potentially, severely damage the piers.

♪

Narrator: Engineers install special joints to allow the deck

To slip across its legs and stop the bridge from breaking apart.

The bridge rests on these bearings.

These bearings allow the bridge to move.

Free to move and flex, the new samuel-de-champlain bridge

Is now ready to withstand extreme temperature fluctuations

And any future earthquakes.

The engineers' next challenge

Is to make sure that this mega-bridge

Can combat devastating winds

And stand firm when hit by an onslaught of deadly river ice.

♪

Narrator: In montreal, the new samuel-de-champlain bridge

Is scheduled to open in just three months.

This massive feat of engineering is expected to serve the city

For at least 125 years.

The bridge has six lanes,

Which will carry over one million vehicles each week.

But this behemoth accommodates additional modes

Of transportation, too.

On one side, a pedestrian walkway and bike path.

Down the center runs a rail line

Directly into montreal's central station.

To accommodate all these elements,

The deck is 190 feet wide.

But here, size makes you a big target

For a powerful force of nature.

Winds in the saint lawrence river valley

Can reach speeds of over 60 miles per hour.

♪

For the bridge to remain standing,

Engineers space its pier legs a mere 275 feet apart.

The short distance between legs

Reduces each deck span's overall length

And bolsters the bridge against fast-moving air

Pushing on its massive structure.

But one crucial part of the bridge

Needs a different method of support.

Bridge piers cannot obstruct the 475-foot-wide shipping canal

Running parallel to the river.

To span it, engineers must suspend

A critical 780-foot-long section of the bridge.

30 cables attached to a pair of

550-foot-tall towers bear the load.

This leaves the waterway

Underneath the bridge unobstructed by piers.

But suspending sections of bridge deck from cables

Makes them vulnerable to strong winds.

♪

The structure of some bridges forces air faster

Over the top of their deck than underneath it.

This creates an area of high pressure beneath the bridge.

Just like an aircraft wing, the deck lifts up,

Stressing the bridge's joints, and damaging its deck.

Every time the wind blows,

There's a risk the new champlain bridge will suffer damage.

Maiholt: The bridge in the montreal environment

Has to be aerodynamically stable in order to ensure

That the bridge will not oscillate

Unexpectedly under intense winds.

Narrator: Engineers deploy an innovative solution

To eliminate the danger.

They design gaps in the deck

Between the bridge's road decks and rail line.

These gaps vent and disrupt the fast-moving air,

Preventing high pressure from lifting the bridge

And damaging its deck.

On paper, the bridge looks ready to withstand

The dangers created by strong winds.

But wind presents another engineering challenge

For a cable-stay bridge.

As history proves, build a bridge that's too flexible,

And wind will tear it apart.

November 1940.

Tacoma narrows bridge, washington state.

Four months after opening, 40-mile-per-hour winds

Cause the bridge to twist and sway.

The movements became so violent the bridge collapsed.

The cause was a scientific phenomena

Called aeroelastic flutter.

Suspension bridges twist fast-moving air

Into mini whirlwinds that pull at the bridge deck.

The shape and weight of most bridges

Means these vortices cause only a slight movement.

But the shape of the tacoma narrows bridges

Contained a critical flaw.

Due to its narrow, lightweight deck,

The vortices caused greater movement.

Sustained winds made the bridge wobble and oscillate.

The twisting eventually became so violent...

That the bridge collapsed.

To make sure the new champlain bridge

Doesn't suffer the same fate,

Engineers submitted the bridge to every possible wind condition

Before construction even began.

Maiholt: You cannot really predict

How well the bridge will be performing

Until you undergo some very intensive wind modeling.

Engineers enlisted the help of aerodynamics expert

Dr. Peter king.

His team at western university, ontario,

Built a scaled-down bridge model,

Costing nearly $53,000.

♪

They tested it in a wind tunnel to predict how the full-scale

New champlain bridge would behave.

King: The model is a complete dynamic replica of the bridge.

So it has the right mass properties,

The right stiffness properties,

And replicates all of the dynamic motions of the bridge.

Narrator: The model withstands simulated wind speeds of up to

112 miles an hour coming from different directions.

To further improve the bridge's aerodynamics,

Engineers modify the sides of the back span.

This is the part of the suspended bridge

That counterbalances the section

Crossing the shipping canal parallel to the river.

They hope this will stop the bridge

From shaking itself apart.

King: Here in the main span, we have a solid pedestrian barrier

On the leading and trailing edges.

Whereas in the back span, it's completely open

And allows the wind to go straight through.

Narrator: Together, the different barriers will disrupt the wind flow

Over the bridge and reduce the pull on the deck.

The bridge is engineered to beat the wind.

But there is still more mother nature can throw its way.

How will the bridge defend itself

From concrete-smashing ice floes?

And what secret technology stops ice

From falling onto the bridge and crushing the cars below?

♪

Narrator: In montreal, the new samuel-de-champlain bridge

Opens in just a few months' time.

It must be ready to serve the city every day for 125 years,

The minimum life span the canadian government specifies

For new critical infrastructure.

Workers battle freezing temperatures

To get the bridge finished on time.

On our goal to open the bridge in June, the clock is ticking.

We're now in the final push.

Narrator: The super bridge must survive over a century

Of brutal canadian winters

And the yearly onslaught of powerful ice floes.

Montreal is subject to winter freezing

Where the temperatures can go down to minus-40.

This will mean that the river will freeze over.

It can freeze up to 0.9 meters thick.

This ice breaks up.

It will generate large floes of ice that will impact the piers.

Narrator: Blocks of ice can inflict critical damage

To big structures that stand in their way.

♪

The current in the saint lawrence river

Accelerates ice up to speeds of 2.5 miles per hour.

A potential floe traveling this fast

And measuring approximately 150 feet across

And three feet deep could strike the bridge

With the same force as the weight of 10 trucks...

...Cracking and severely eroding the concrete.

♪

This footage from the 1960s

Shows that ice floes on the saint lawrence river

Have always been a problem.

♪

The old bridge is covered in scars sustained

In battles with the ice.

Alex szemenyei's vigilant team must react fast

To keep the crumbling structure standing.

Szemenyei: On our piers, we actually have steel lining

Just at the water level

To ensure that when ice does hit the piers,

That the concrete itself is protected.

But over time, sometimes the steel lining disintegrates

With the water, and concrete can be affected.

Narrator: For the new samuel-de-champlain bridge to survive,

It needs the strongest concrete legs

Of any structure across the saint lawrence.

All concrete is a mix of water, sand, gravel, and cement.

Increasing the ratio of cement

To water raises the concrete's density

And makes it super tough.

Engineers then add a secret ingredient

That changes the concrete's chemistry

To make it even stronger.

♪

At the atomic level, when cement mixes with water,

The reaction creates calcium silica hydrate,

Which bonds the concrete mix together.

But the same reaction also produces other particles

That disrupt the bonds,

Forming weak points in the concrete.

When engineers add a chemical called silica fume,

It reacts with the disruptive particles,

Turning them into more calcium silica hydrate,

Making the overall structure stronger than ordinary concrete.

When construction work first began on the bridge's

Piers back in 2015,

Engineers poured the bridge's pier starters on land

And let them set until solid.

Then they used a floating installer to sink 38 bases

Into the riverbed of the mighty saint lawrence river.

Samuel-de-champlain bridge's super-strong concrete

Makes it tough enough to resist destructive ice floes.

But new challenges lay ahead.

How does this super bridge prevent falling ice

That endangers lives?

And what cutting-edge technology makes this bridge so intelligent

It knows when it needs help?

♪

Narrator: Workers in montreal race

To complete the city's new super bridge.

Yet only when all the cables have been installed

Will the bridge be ready to open.

Maiholt: Completing the cables is significant

Because the bridge at that point will be structurally completed

And the only things that will remain are finishing works.

Narrator: The pressure is on foreman jonathan simard

To finish the job.

Jonathan and his team must install special sleeves

The encase the full length of the bridge's 60 cables.

Cable sleeves protect the metal inside from ice and rain.

But in winter, some sleeve designs can create threats

That pose a danger to both traffic and pedestrians.

2014, charleston, south carolina.

The ravenel bridge closes when large chunks of ice fall

On passing cars, shattering their windshields.

Nine vehicles sustain damage.

It's the way water freezes on the bridge's cable sleeves

That creates the falling ice.

♪

Temperatures fluctuating just above

And just below freezing cause the problem.

Rain coats the sleeves in water.

When the temperature drops below 32 degrees,

The water freezes.

Temperatures rise, but not by enough for the ice

To completely melt.

New rainwater accumulates on top of the ice

And freezes when the temperature drops below 32 degrees again.

Soon, a thick layer of ice completely encases the sleeve.

The ice becomes heavier, until it breaks away...

Crashing onto the bridge deck below.

The designers of the new samuel-de-champlain bridge

Must protect its cable sleeves

From shedding dangerous large chunks of ice.

The ingenious fix is a unique design

Running the length of the cable --

A series of equally-spaced hoops.

You can see that there are circular ribs.

This is a bit different from what you would see

On most bridges.

The idea here was with these circular ribs,

It will help shed water more efficiently.

Narrator: The circular ribs are spaced at one-foot intervals.

Because of the cable's slanted angle, when it rains,

Water accumulates behind the ridges

And harmlessly falls on the bridge deck below.

The water freezes in chunks trapped between the ribs.

The ice sheds in smaller pieces.

So when it falls onto the bridge deck,

It's not dangerous to passing cars and pedestrians.

Finally, the sleeves are in place.

Now jonathan's team must thread through the steel cable strands.

Future maintenance crews will only have to replace

Individual damaged strands.

They will not have to switch out the entire super-heavy cable.

Engineers use winches to thread each strand one

By one up the sleeve and through to cable anchors in the tower.

They then pull the ends downwards

And secure them to the deck.

These are five times the strength of normal steel.

The strands themselves are actually doing all the work

In terms of supporting the weight of the deck structure.

Narrator: The next challenge is to tighten the cables to hold

The estimated 28 million-pound weight of the bridge's span.

What ingenious tool makes sure every cable

Is stretched to the correct tension?

And what technology makes this bridge intelligent enough

To know when it needs maintenance?

♪

Narrator: In montreal, workers race to ready the new

Samuel champlain bridge for its grand opening.

Once complete, the bridge must support over

One million vehicles every week

And serve the city for 125 years.

♪

Advanced super-strong materials and an ingenious design

Make the bridge wind-proof, ice-proof,

And flexible enough to cope

With montreal's extreme temperature variations.

But its life span depends on identifying

And repairing problems before they become critical.

Limited access to inspect the structure's interior

Is a big reason why the old champlain bridge is failing.

Engineers cannot see critical issues

Until they show up on the bridge's exterior.

By then, it's too late to solve the problem at the source.

At that point, all engineers can do is patch up the damage.

So designers are building the new bridge to have all-area

Access to avoid these past mistakes.

Hatches, walkways, and crawl spaces allow them to inspect

Every square foot of the over-two-mile-long bridge.

♪

But engineers still need help to identify potential problems

As early as possible.

Borja bailles leads a team

Tasked with making the bridge intelligent.

Borja's team installs 435 sensors

That send data 24/7 to a central monitoring station.

Alerting humans to problems early on

Is a big step to the bridge achieving its mission

Of serving montreal for 125 years.

♪

At deck level, engineers race to thread

And tension the last remaining cables.

The must tighten each of the cable's 127 strands.

Mechanics deploy a special tool to tension them one by one.

Maiholt: They put a hydraulic jack, which will pull the strand,

And then they'll stick these wedges

That will lock the strand into place.

♪

Narrator: Over the next 20 days,

The team pulls out all the stops to finish the job.

The last cable plugs in right on schedule.

♪

Two months later, at 5:00 a.M. On June 24th,

The samuel-de-champlain bridge opens.

The first vehicles roll westward over the saint lawrence

On montreal's newest and toughest crossing.

Over four years, a 1,600-strong workforce

Has poured over 3 million cubic feet of concrete,

Laid over 75,000 tons of steel, tightened 1.2 million bolts

To span the mighty saint lawrence river.

It's mission accomplished for guy and his team.

To work on a project of this magnitude is almost a dream,

Because you don't build these sort of bridges very often,

And it's gonna be there for many generations to come.

Narrator: The samuel-de-champlain bridge is tougher

And will carry more vehicles than any other bridge in canada.

Built into its mighty frame are five engineering marvels

That make it the pinnacle of bridge design.

Ribbed cable sleeves stop dangerous ice

From falling onto passing cars.

A vented design keeps the deck

Steady against the strongest winds.

Expanding joints allow the bridge to flex

When the temperature changes.

Pier legs built from super-strong concrete withstand

The force of crushing ice.

And innovative drainage gets rid of corrosive salty slush.

This is a bridge that is big,

Tough enough to survive anything mother nature throws its way,

And it's set to become a montreal icon.

The samuel-de-champlain bridge is built to be the ultimate.

♪