Original subtitles

[Narrator] Construction.

Heavy machinery. Tight schedules.

Millions at stake.

What could go wrong?

Everything.

Whether it's faulty equipment, poor design, human error

or just bad luck...

These are...

Construction Fails.

In this episode...

Highway overpasses...

They look like they could stand forever...

But all that trucking take its toll.

Slip sliding away...

...when the ground is no longer solid...

...everything goes downhill.

The Broadway Bridge that refused to take a final curtain call...

Construction tires. When axles fail...

...tires go rogue...

And stuff gets broken.

There are 100 million kilometres of roadway in the world.

They're the arteries of commerce.

And the blood that flows through these arteries

is carried on trucks.

Day and night, truck drivers deliver goods

from the shop down the road...

...to the furthest reaches of civilization.

No nation has more new highways and overpasses

than the Peoples' Republic of China.

But when all those highway overpasses wear out,

watch out.

Heyuan City, Guangdong Province June 2015.

An overpass collapses.

One person is killed.

Four are injured.

Wuxi City, Jiangsu Province October 2019

The evening rush hour.

An overpass drops.

Three cars are crushed.

Three people are killed.

So, what went wrong?

China is renowned for its break-neck pace

of construction.

But the speed at which infrastructure is constructed

has led to some failures small and large.

Baoding City, Hebei Province

August 2018.

A heat wave causes the road to buckle.

And then explode...

Neither the driver nor the passenger on this scooter

was injured.

It's likely the paving was completed before

the road bed had time to settle.

The bigger the machine, the bigger the problem.

Road collapses are not isolated to China.

Oklahoma City, USA

May 2016.

A highway overpass collapses.

But this incident was caused by a truck

colliding with the bridge...

not travelling over it.

Unfortunately, China is the overpass collapse capital

of the world.

The problems are magnified by the use

of inferior construction material.

China uses more concrete than the rest of the world combined.

But not all that concrete is top-grade.

Concrete is a mixture of cement paste and aggregate.

Too much of either can result in substandard concrete

that is brittle.

Compounding matters is the style of the bridge.

The bridge that collapsed in Wuxi was a box girder design

with three spans.

Four piers were holding three segments of bridge.

Two of those support piers were single-column.

The structural integrity of a single column

depends on an even distribution of weight...

...on both sides of the bridge.

It gets worse.

The trucking industry in China is extremely competitive

with low margins.

According to news reports, shipping companies

routinely load trucks beyond their cargo capacity.

A preliminary investigation showed the collapse

had been caused by overloaded trucks.

As many 100 trucks crossed the bridge every day.

Trucks travelling on one side often carried

more than double their load limit.

Meanwhile, the returning trucks driving on the other side

of the bridge were empty.

Experts believe the continuous passage of overloaded trucks

driving on one side of the bridge

caused lateral instability in the structure.

The single column piers collapsed.

Overloaded vehicles and poor bridge design.

It was a killer combination.

The Chinese government still grapples

with the problem of overloading.

New regulations and higher fines

have failed to reduce the incidents.

According to the Chinese government's own research,

one out of ten short haul cargo trucks are overloaded.

Between 2006 and 2015, about 60 percent

of major incidents were a direct result

of overloaded trucks.

As long as trucks are too heavy,

and construction standards are poor,

China's roadways are going to keep failing...

and falling.

When you build a home it's a good idea

to scope out the surroundings.

Are you putting stakes down near water?

Are there trees on the property?

And most importantly, is your house on a hill?

These are just some of the critical factors

that can save you - or sink you -

in the event of a landslide.

A landslide is a massive downhill movement of the earth.

A destructive combination of water, soil,

rock and gravity.

It's a force that can literally move mountains.

A layer of earth breaks loose

and forms an unstoppable avalanche

that can topple anything in its path.

Shoving buildings and vehicles along a road to ruin

or burying them under a mountain of debris.

Water is the major culprit.

On an incline, friction holds things in place.

But when the ground liquefies it lubricates a slick layer

of mud which acts like a ramp.

A slippery slope where everything slides downhill.

And there goes the neighbourhood.

Most of the time, landslides are a natural disaster

triggered by another natural disaster.

Torrential rains loosen the soil -

and the ground crumbles under the weight of a structure.

Raging floodwaters ravage river banks and retaining walls,

then carry anything in its trajectory downstream.

An earthquake shakes up the ground,

then crumples whatever is sitting on the surface.

Even after the storm has passed,

the banks and shores remain unstable...

and dangerous.

But sometimes people bring landslides

down on themselves.

Deforestation uproots the trees that anchor the ground in place.

Hillside irrigation over-soaks the soil.

And sometimes it's just dumb planning.

Like building on the side of a hill with a history

of landslides or an area that's prone

to flooding or tremors.

Landslides can lie in wait for eons or ambush in an instant.

Causing loss of life, destruction of property

and billions in damages.

Populations seem largely defenseless

against this force of nature.

But there are ways to defend your property

against the assault...

...and minimize the chances of being swept away.

Plant mature trees around your home.

The root systems dig deep and hold the ground in place.

Rocks and retaining walls can slow the flow

and trap rolling debris.

Reroute the water so you won't be carried downstream.

Drain water from the slopes.

Build terraced steps around your house

to reduce the angle of the slope.

Drilling giant bolts into the rockface

can actually hold the hill in place.

One government study concluded that,

"the effects of landslides on people and structures

can be lessened by total avoidance

of landslide hazard areas".

In other words, if you really don't want to be

caught in a landslide.... live somewhere else.

Or you could take your chances.

Then, it's all downhill from here.

The advent of the wheel over 5000 years ago

marked a turning point in the human journey.

But it took the invention of the tire in the 19th century

to smooth out the ride.

Especially when you're hauling heavy loads

to and from the construction site.

Whether it's a dump truck or an excavator,

tires for construction vehicles are engineered

to support massive loads over all sorts of terrain.

Thousands of kilograms, rolling on layers

of rubber and steel, designed for strength and staying power.

The contact patch is where the rubber meets the road.

The tread optimizes traction and fuel economy.

Steel belts and radial chords add structure and stability.

The shock absorbing sidewall gives the tire the flex it needs

for braking and turning.

The high tensile bead wire grips the tire onto the rim.

All tires are built to be roadworthy and reliable.

But sometimes they blow it.

Usually it's because the last tire change wasn't done right

and fasteners like wheel studs break off

or the nuts fall off.

Many trucks have dual tires.

A wheel can drop off and go its own way

without anybody noticing...

...until somebody gets hit.

Sometimes rogue tires will travel in packs.

This truck unleashes a tag team.

But only one lands a blow.

Correction. Two for two.

But all it takes is one tire and a bad bounce,

and you might get caught on the rebound.

Not satisfied with knocking this rider

off his pins once, the tire bounces off...

...and then boomerangs back, weaving through traffic

to bowl him over a second time.

Tires are under a lot of pressure -

anywhere from 240 to 690 kilopascal.

And whether it's under-inflating the tire,

over-inflating the tire, overloading the vehicle

or overheating the rubber, tires can blow themselves

right off the truck.

An eruption of air

literally knocked the wind out of this guy.

And if you're too close to a tire when it explodes...

It can knock you off your feet...

or into the next world.

Truck tires can weigh in at over 50 kilos.

And when they catapult off the asphalt

at 100 kilometres per hour

they can become deadly missiles.

Sailing through the air and zeroing in on your windshield.

So keep your eyes peeled.

A wayward tire could come rolling along -

or flying along - when you least expect it.

And if you don't dodge that rubber bullet...

That tire might flatten you.

Bridges.

They carry things from one side to the other.

Some carry us.

Some carry our stuff.

Some carry it all.

But bridges are more than just connections.

They literally make cities.

In Hungary, bridges connect Buda to Pest.

Bridges unite countries...

...like the eight kilometer Oresund Bridge

that links Denmark with Sweden.

And when a bridge stands for long enough,

it becomes an icon.

An emblem of the city.

Like San Francisco...

Or London...

Or Brooklyn.

But when a bridge has reached the end of its useful life,

it becomes a road to nowhere.

Missouri, USA

April 2019

Cars and trucks take a last trip over the old Route 47 bridge.

For decades a key crossing point on the Missouri River.

But when authorities decided it had to go,

the traffic stopped...

...and so did the bridge.

The locals were happy to see the old bridge

go out with a bang.

[crowd cheers]

But sometimes a doomed bridge fails to cooperate.

Little Rock, Arkansas October 2016.

The city had a new Broadway Bridge

to North Little Rock.

And it needed to get rid of its old one,

the old Broadway Bridge.

The Broadway Bridge was what's called a through arch bridge.

In a through arch bridge, the bases of the arch

are below the bridge deck and the top of the arch

rises through and above the deck.

The deck runs through the arch and high tension cables

suspend the deck from the upper portion of the arch.

But the old bridge didn't agree on the timing.

So what went wrong?

Controlled demolition is an effective means

of reducing bridges to rubble in mere seconds.

Whether you're in Pennsylvania

blowing up the Hulton Webster bridge...

Or in Jilin Province, China

blowing up the old Nanhu Bridge.

Controlled demolition takes months of planning

and preparation.

Structural engineers identify the key support areas.

That's where the explosive charges will go.

The blasts are coordinated in a precise pattern

that will break the bonds.

At least that's the idea.

But bridges aren't like buildings.

They're strong everywhere.

They need to be.

There are built-in technical redundancies.

If one element fails, another takes the stress...

at least long enough to evacuate the bridge.

The Arkansas Highway and Transportation Department

determined that nothing went wrong exactly,

the bridge only weakened, it did not fall.

With the bridge collapsed in on itself,

the authorities concocted a hasty Plan B.

The demolition team called in a crane on a barge

and two tug boats to help finish the job.

Five hours and eight tugs later, the bridge went down.

There are those that can and those that can't

and those that really shouldn't even try.

Because being handy takes more than good hands.

You also need a functioning brain.

Which raises the question: D-I-WHY did you think

you could do it yourself?

Here's a safety tip.

Before starting any electrical work

always remember to first turn off the power at the source.

There you go.

And always remember to secure your ladder

with a tie line.

Because you never know what can happen.

Now you know.

A ramp is what's known as a "simple machine".

But apparently still too complicated for some.

It's impolite to drop by unannounced.

Once you've got a water leak,

anything can come through the ceiling.

Or anybody.

Now that the new floor is complete...

...they can get to work on the skylight.

This store offers an array of stylish clothing,

a foosball table and an escape room.

If it's any consolation, he probably won't remember

the whole embarrassing event.

This lightweight contender takes a swing.

And lands a jaw-breaking knock-out.

In this tug of war between nature and technology

the truck eventually triumphs - uprooting the stubborn tree.

But victory comes with collateral damage.

Instead of putting the door hinges on the outside

of the bathroom this DIYer's next project

will be to yank out the sink.

Installing these fixtures poses quite a challenge.

Now it's only half the challenge.

This is either going to work or it's not.

When he regains consciousness he's going to realize it didn't.

Even the simplest task takes skills and smarts.

And if you don't have both

you can do way more harm than good.

So the next time you have a hankering to do it yourself...

Please don't.

♪ ♪