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...

Harlem, New York; an explosive situation

creates a mystery for emergency workers to solve.

Fast moving flood water....

Turns into a disaster for this bridge.

Skyscrapers...

Creating space out of thin air...

When they fail - it's a disaster.

When they fail before they're even built?

That's jaw-dropping....

And the Glasgow tower -

It can't seem to get anything right...

Shortly after 9 AM on March 12th, 2014,

the local gas supplier in East Harlem, New York City

received a call about a possible gas leak...

They dispatched a crew to investigate...

But before they arrived at the scene...

There was a huge bang,

and flames seen shooting into the air.

Two buildings exploded and caught fire.

As smoke poured from the rubble,

250 firefighters responded to the frenzied scene.

The violent explosion damaged nearby buildings...

Shattered glass onto sidewalks for blocks...

And sent tremors felt more than a mile away.

Hours after the blast,

firefighters were still dousing the flames.

So, what went wrong?

Gas leaks must be fixed fast;

left unattended they can cause explosions.

In a confined space like a home or business,

the gas will mix with the air,

increasing the pressure of the space.

Then if the lights or a switch are turned on,

creating a spark,

that can ignite the gas and cause an explosion.

Infrastructure can be another culprit.

Underground pipes - covering cities

are a major source of gas leaks.

The gas usually travels through the soil

and dissipates into the air.

During winter, the soil is hardened by frost,

which traps the gas and causes pockets to form.

But when the frost thaws, it can be released.

And vintage buildings can be quite brittle.

So, even a room-sized natural gas explosion

could trigger the collapse of an older masonry structure.

It just breaks into small pieces,

leaving piles of debris behind.

When there is an explosion, pressure builds up

very suddenly in all directions

and expands in the direction of the walls and ceiling.

The ceiling, the floor of the apartment above,

can blow out from the force

acting in the opposite direction of gravity.

When the floor and sideways supports are lost,

nothing is holding up the building,

so the construction fails.

That may explain the building's collapse,

but what caused the explosion in the first place?

Newer gas mains are usually made

of either more flexible plastic or coated steel,

which inhibits corrosion.

The destroyed buildings were served by a main,

made of plastic and cast-iron.

The rigidity of cast-iron pipes

makes them susceptible to stresses,

including pounding from construction

and vehicle traffic above.

Was traffic to blame

or was it the city department of transport?

Several road repairs had been done in the area,

just days before the blast.

The gas company claimed the department had been informed

of roads near the buildings needing repair multiple times

over many years...

Including the week before the incident...

and that their delays fixing them

had caused problems that led to the explosion.

There was even a sinkhole from a broken water main

in front of the buildings on the day the buildings blew up.

In the end, The National Transportation Safety Board

resolved that the gas explosion had two causes.

The first was a defective pipe joint that allowed gas to leak.

In 2011 a new building had been connected

to the gas main serving the collapsed buildings -

and the two plastic gas lines were not correctly joined.

But the explosion might not have happened at all

if New York City had repaired the large hole

in a nearby sewer main -

which it had known about for 8 years.

Robotic cameras show a lack of maintenance

and repair work on the sewer main resulted in a large hole.

Over time, the hole expanded and allowed soil to flow through,

causing the pipes to sag,

overstressing the defective joint

and cracking it open.

The combination of these two circumstances

caused the explosion.

Though out of sight, underground maintenance

should not be out of mind,

it's just as important as building maintenance

to the preservation and safety of a structure.

The Waiho River Bridge on New Zealand's Westland

crosses the river that runs through

the Franz Josef Glacier valley.

The bridge carries locals across the water

and connects hikers to the 12-km glacier

that feeds the river.

Or it did.

Until March 26, 2019.

Floodwaters, violently snapped the bridge pier

on its northern bank,

ripping the rest of the steel and concrete structure

out of the riverbed and tossing it downstream.

The island was no stranger to heavy rainfall

and annual flooding.

But the bridge was secure - they thought.

The steel-pile piers that held up the spans

were drilled 15 metres into solid bedrock.

And the bridge had undergone protection maintenance

to bolster its foundation just two weeks

prior to the collapse.

So, what went wrong?

Rivers are the world's bloodline,

nourishing the land and powering the cities.

But that immense power and destructive current

can turn against you.

Surging at 3-metres per second,

the force of fast moving floodwaters

can cause the same devastation as a Category 4 hurricane.

Smashing buildings to splinters,

washing out roads,

and carrying off cars and trucks like they were bath toys.

Under the surface, the churning water uproots trees

and dislodges heavy rock formations,

shooting them along the river floor like projectiles.

Bridges are designed to withstand this force of nature.

And most of them survive.

But what happened on March 26, 2019

was literally the perfect storm.

An unlikely build-up of factors that colluded

to bring down the Walho Bridge.

Over time, the Franz Josef glacier

has been gradually receding,

building up the river bed and sending sediment

and rocks downstream,

where it scours away the defensive barrier

of rock and gravel mix installed at the base of the bridge piers.

New Zealand's South Island is essentially a rainforest -

and used to heavy annual precipitation.

But this year it all seemed to come down

in one major deluge,

dropping over a metre in just 2 days.

The Waiho's water level,

which had been rising consistently

over the last decade,

swelled to record highs, cresting at over 7.5 metres.

The higher the water volume, the faster the current flows.

Debris deposits from the glacier

formed a channel on the riverbed.

That concentrated the water, funneling it at high velocity

towards the north bank.

On the day of the storm, bystanders could hear

the sharp crack of rocks slamming into the base

of the bridge.

That underwater chute was acting like a cannon,

propelling a large boulder at the northern edge of the bridge,

blasting it with the impact of a torpedo.

The pier buckled - and the rest of the bridge

gave way in quick succession.

As rain continued to pound the area,

people were trapped on both sides of the swollen river.

It took only 18 days to rebuild the Waiho River bridge.

But experts predict that as the Franz Josef glacier

continues to recede, water levels will continue to rise.

And this "once in a lifetime" accident

will certainly happen again.

Skyscrapers - when we can't go out,

we go up.

More energy efficient than sprawling suburbs,

they create living and working space out of thin air.

These imposing towers are one of the greatest marvels

of modern times.

So, when skyscrapers fail - it can be a giant disaster.

In 2006, in South Padre Island, Texas:

Developers began work on Ocean Tower:

a 134-unit condominium skyscraper

on a narrow strip of sand near the Mexican border.

They claimed it would become the finest quality tower -

built in the best location.

The pitch was perfect - but the construction was not.

Just two years after breaking ground,

the tower began to sink.

Pier supports buried more than 30 metres

underneath the clay ground began buckling,

stressing beams and columns

throughout the entire structure.

Nicknamed the "leaning tower of South Padre"

the doomed Ocean Tower never opened for business.

The ambitious 31-storey construction failed

before it was even complete.

So, what went wrong?

Part of the faulty tower had sunk,

cracking beams and columns.

This jeopardised the entire structure.

Officials claimed the garage and the tower were mistakenly

connected when built, forcing the weight down

upon the garage.

The use of expandable clay, which compresses under weight,

compounded the issue.

While the heavy tower's core sunk 36 centimetres,

the attached lighter parking lot

dropped less than half that depth.

Developers boldly claimed the skyscraper would re-emerge

from these problems "stronger and safer than ever".

Today a skyscraper is defined as having more than 40 floors

or at least 150 metres in height.

But the first skyscraper is generally considered

to be the Home Insurance Building in Chicago.

It opened in 1885 with only 10 floors.

With that, the skyscraper was born,

and the race to the top began.

To achieve great heights, a new building method

was developed that used a grid of steel beams and columns.

Strong enough to support any stresses or forces

a building might experience, including both the weight

of the floor and the building contents.

Since their creation skyscrapers have grown ever taller,

but to do so have had to face one of their biggest challenges

- the wind.

To counteract this force, most skyscrapers

are designed to move several metres in either direction,

like a swaying tree,

without damaging their structural integrity.

This is done by installing diagonally-braced steel trusses

between central elevator shafts

to create a stronger core.

Then most of the beams and columns are moved

to the outside edge of the walls to make a stiff tube.

But wind was not the issue at the beleaguered

Ocean Tower in Texas.

There the garage beams needed to be separated from the tower,

and new columns placed under the beams.

Then the foundation repaired.

However, the cost to fix the tower was just too high.

Developers chose to cut their losses...

Demolishing the $2 million-a-unit

beachfront skyscraper took more than a ton of explosives,

two-and-a-half miles of detonating cord,

and months of planning.

It took less than 20 seconds but became

the tallest reinforced concrete structure

ever to be imploded.

Paris is home to the iconic Eiffel Tower...

Toronto boasts the CN Tower - one of the tallest

free-standing structures in the world.

And then there's Glasgow, Scotland...

Well, that city would probably rather be known

for anything other than it's infamous Glasgow Tower,

part of the city's Science Centre complex.

The $15 million dollar Glasgow tower was supposed to be

the city's answer to the Eiffel Tower.

This unique 127 metre tall steel and glass structure,

was the first in the world to fully rotate 360 degrees.

The tower's opening got off to a rocky start.

June 2001,

even opening day was a flop...

It closed early when doors failed on the elevators:

they were too heavy, and the system overheated!

The tower finally opened four months later...

but that too was short lived.

By February 2002 - two bearings

in the rotating base mechanism had sunk...

And the tower closed again.

The calamities continued for years:

In January 2005 ten people were trapped for hours

in the elevator after a cable snapped,

triggering the emergency brakes.

Fire crews had to cut through exterior panels

to get in to the tower and free the group

from 50 metres up.

This triggered an inquiry which led to the complete redesign

of the heavy elevators during a four-year shut down.

The lighter lifts put less strain on the mechanisms,

however, three days after reopening in 2014,

a cable short circuited, sending smoke belching

from the base.

What was meant to be a tower of strength

became an expensive white elephant,

riddled with problems and constantly shut down.

So, what went wrong?

The tower resembles an aircraft wing on end

and is mounted on a reinforced-concrete base

comprised of a roller bearing turntable.

The idea was that the tower would turn 360 degrees,

stabilising itself by turning into the prevailing wind.

For the entire structure to be able to fully rotate,

it does not directly connect to its foundation.

The tower rests in a 20 metre deep hole

like a pencil in a jar.

While the whole 460-tonne vertical load

rests on just a 65-centimetre-diameter

thrust bearing.

Thrust bearings, are bearing balls

supported in a ring.

The ring supporting the Glasgow tower

contains 24 rubber-sprung roller bearings.

The tower's only contact with the foundation

is through the thrust bearings.

This is what allows it to rotate into the wind.

But a few months after opening,

engineers discovered the tower had sunk

by around 15 millimetres.

Two bearings had become compressed and one had sunk.

To fix the problem the tower had to shut again -

this time, for almost a year and a half.

The ball-bearing problem continued

to dog the tower for years,

causing numerous lengthy closures.

But it wasn't just the design that was an issue;

it was the location itself.

Initially, the tower was planned to be built

in Glasgow's city centre.

But it was moved to the river bank.

Instead of being protected by the other city buildings

while rotating,

the 127 metre tall tower was now exposed

to the full force of nature.

And though most of the tower's problems

are now resolved...

it no longer rotates while visitors are inside...

they're only allowed to go up the tower

if winds don't exceed 40 kilometres per hour...

and it's closed from October to March every year.

Just because they're operating construction equipment...

And just because they're wearing construction gear...

Doesn't make them construction workers.

But it does make them hilarious.

In an attempt to get that dirt on the truck

this worker is using three simple machines.

The Wheel.

The Ramp.

And his brain.

Two of them work perfectly.

When you work on a construction crew

it's important to compliment one another's skillsets.

At this rate the project will be done...

never.

These guys are converting this neighbourhood park

into a Water Park.

They've already built their first ride.

It's called the Slip 'N Soak.

This attraction is called the Water Bronco.

He's mounted up.

Now let's see if he can stay on for...

Never mind.

This Water Park also features the very first

outdoor bidet.

Building sites can really make you hungry -

But construction worker sandwich is no one's first choice.

Here's an explosive way to get your colleagues' attention...

These construction workers decided to use a forklift

to get that load of bricks off the flatbed.

Unfortunately, that's not a forklift.

And there's no way they're construction workers.

This excavator operator is loading the truck

with imaginary dirt.

And at the end of the week he'll be collecting

an imaginary pay cheque.

This guy is fabricating a wall...

And an insurance scam.

These dedicated workers are putting a fresh coat of paint

on a fresh coat of snow.

Tomorrow they get to do it again.

Not sure what kind of fumes are coming out of that machine,

but this worker sure seems to be enjoying it.

Even after staggering into traffic a couple of times

he's not giving up his gas-powered bong.

Two guys. One saw.

One stick.

By the time they're done they'll be ready to retire.

All these workers showed up for their shift

expecting to build something.

But all they ended up making...

Were fools of themselves.

♪ ♪