Original subtitles

We are surrounded

by extraordinary feats of engineering.

Constantly pushing the boundaries of what's possible.

Without engineering, there'd be no modern world.

Gigantic cities,

amazing infrastructure, and ingenious inventions.

Engineering is the key to turn dreams into reality.

To reach these dizzying Heights,

today's technology relies on breakthroughs made

by ancient engineers.

It's mind boggling how they did this.

How did early civilizations build

on such a scale?

They raised the bar for construction in a way

that no one thought possible.

The sheer engineering ability,

which is in itself impressive.

By defying the known laws of physics,

and daring to dream big,

they constructed wonders of the world

from gigantic pyramids,

to awe inspiring temples,

and mighty fortresses.

All with the simplest of tools.

You know, imagine the skills people would have needed

to build like this.

Now, it's possible to unearth the secrets

of the first engineers.

They managed to construct edifices

that have survived the ravages of time.

And reveal how their genius laid

the foundations for everything we build today.

(dramatic music)

The wheel and the road.

Put together, perhaps the greatest engineering development

of all time.

Roads have enabled humans to move at speed,

enabled connectivity.

It's hard to imagine civilization without roads.

Today, the planet is alive

with the sound of rubber on tarmac.

1.2 billion cars, motorbikes, vans, trucks,

and juggernauts move us from place to place

on the millions of miles of road

that crisscross the continents.

The road has been an extremely important part

of the development of the human race.

It's one of the triumphs of engineering,

allowing freedom of movement.

Roads have enabled humans to move materials across land

that otherwise would not have been possible.

Running through icy wastes,

Amazon jungles, mountain passes, and deep ravines,

roads shaped the development of human society.

The design of the cities was centered around the car.

Roads are vital for the way we live,

and they've changed how we live.

But this global system

didn't emerge fully formed.

The first secrets of road and transport technology

were cracked thousands of years ago in the ancient world.

(footsteps)

One early civilization's engineers have gone down

in history as the greatest road builders of all time.

Constructing a 50,000 mile network threaded across Europe,

the Middle East, and North Africa.

It was not only very vast, it was also very efficient.

You can get the troops

to their designated places very quickly.

Their technological know-how

and engineering prowess was second to none.

The Romans.

Roman road building produces a network

of communication that is not just important for the Romans,

but that's going to endure for centuries thereafter.

Roman expertise and skills

would inspire generations of architects and civil engineers.

They had an incredible understanding

of structural engineering that we still build on today.

It's embedded in everything that we do

as modern civil engineers.

They developed groundbreaking techniques

to construct new types of roads, bridges, and tunnels.

Without the roads there wouldn't have been a Roman empire.

But Roman engineering skills didn't appear

out of nowhere.

The story of roads begins much earlier

at the very dawn of civilization.

Long before avenues, streets, boulevards, and autobahns,

early humans relied on simple paths.

The easiest way for people and animals to move

through the landscape.

But sometimes this proved difficult

due to natural obstacles lying in the way.

Marshy land, boggy land, potentially treacherous land.

It's not new for people to want to cross things

that they shouldn't cross.

Could an important discovery reveal

how ancient engineers found one solution to this problem?

The Avalon Marshes in the west of England.

A distinctive landscape formed over the centuries

by the extraction of peat for fuel.

And preserved within this marshland,

a 6,000 year old secret.

In 1970 while clearing out a ditch,

one peat cutter stumbled across the remains

of a mysterious wooden structure.

Tree ring dating revealed it had been built

and laid in 3806 BC.

That's the wonderful thing about dendrochronology,

tree ring dating, is that you can get yourself back

to the exact winter in the past when that timber was felled.

The structure had survived

because peat forms in waterlogged soils.

With little or no access to oxygen,

bacteria are unable to fully decompose organic matter.

The well-preserved wooden remains are an example

of early engineering ingenuity.

An entire stretch of prehistoric trackway.

Archeologists named it the Sweet track

after the peat digger who found it.

The Sweet track is an amazingly neat solution

to a particular problem,

which is how do you get from one place to another

whilst crossing a marsh?

This remarkable find turned out to be one

of the earliest road like structures in the world.

But how had it been built?

The Sweet track is a very clever design.

Very simple kind of X shape,

pegs would have been put down with planks going across,

leading through this swampy area.

It was a simple

but brilliant engineering breakthrough.

One that would change the world.

As they've grown, roads have completely reshaped human life.

In the last hundred years,

the globe has experienced massive environmental

and economic change,

and road construction has had to keep pace

with ever growing numbers of vehicles.

With over four million miles,

the United States has built

the world's largest road network.

Super highways stretching from city to city,

state to state, coast to coast.

But solid roads have been around a lot longer

than first thought, and one discovery

from the ancient world would rewrite

the story of the rise of the road.

(thundering)

It was discovered in the unlikeliest of places.

Built by a civilization

that seemingly didn't need roads at all,

as it had command of a mighty river.

Around 5,000 years ago,

the ancient Egyptians established their extraordinary

and enduring civilization.

Famous for great advances in every area of human endeavor,

from the arts to science, technology to religion,

their accomplishments include great monuments,

pyramids, temples, and artworks.

Egyptian civilization developed along the river Nile.

It was the super highway running through Egypt.

It gave Egypt life.

It basically joins up every single

inhabited place in Egypt.

With all its towns built

along the Nile's banks,

the river was Egypt obvious means of transport.

The Egyptions used ships for pretty much everything,

so food and drink was transported by boat certainly.

Building stone was transported by boat.

People used ferries on a regular basis.

For many years,

experts thought this was a civilization

that simply had no need of roads,

but that was about to change.

In the mid nineties,

while mapping out a region 43 miles southwest

of modern Cairo,

two American geologists made an amazing discovery.

They stumbled across a series of stone slabs

that seemed out of place.

For miles around, there was nothing but empty desert.

Further studies revealed these were paving stones.

Although much of its length had disappeared over time,

the archeologists realized they discovered a massive road,

seven and a half miles long.

Pottery fragments found nearby proved it had been built

between 2600 and 2200 BC,

making it the oldest known paved road anywhere in the world.

Incredibly, it had been constructed long before

the wheel was first used in ancient Egypt.

Yeah the road's an exciting discovery

because this paved road is a thousand years

before we think the wheel is really introduced

into Egypt on chariots,

so why would they need a paved road?

What was being transported along that road?

Answers seem to lie with a nearby quarry.

The reason why they went to all the effort

of building this road was because the stone

from the quarry was a particularly exotic sort,

you couldn't find anywhere else in Egypt.

The basalt stone quarried at Widan-El-Faras

was pulled along the road to the ancient Lake Moeris,

seven and a half miles away.

There it was placed on barges and transported up the Nile

to the pyramid construction sites.

Yeah, the road's an exciting discovery,

because it really helped us to build the picture

on how things like the great pyramid were built.

As the sands of time have reclaimed the land,

the road today appears to lead nowhere,

ending abruptly in the middle of the desert.

Building a paved route through such an inhospitable place

was a daunting task for ancient engineers.

And even today, road construction

through desert terrain remains challenging.

(dramatic music)

The Empty Quarter in the Middle East,

largest sand desert in the world.

Covering an area of around 250,000 square miles.

In days gone by, only the hardiest of travelers

would attempt a crossing.

It has stood for centuries as a natural barrier

between the kingdom of Saudi Arabia

and the Sultanate of Oman.

Despite the extreme terrain,

the two countries were determined

to create their first transport link,

but engineering this desert freeway would prove every bit

as difficult as crossing it on foot or camel.

The temperatures vary from over 50 degrees during the day,

all the way down to one degree at night.

You're building on sand,

and that sand moves all of the time.

Some of these sand dunes are 80 meters high,

and so you're building a road through a desert,

the ground is moving beneath you.

Overall, 170 million cubic yards of sand

was cleared for construction.

Hundreds of workers took three years

to complete the project.

Now open, this freeway has transformed

what was once an arduous journey

to a relatively brief drive.

The modern technology used here,

wasn't available to ancient engineers.

That didn't stop early civilizations

building large road systems of their own.

But for early roads to become truly effective,

a major engineering breakthrough was needed.

(upbeat music)

A deceptively simple invention that would change everything.

The wheel.

It enabled the creation of vehicles

from simple wagons to fine carriages,

and chariots of war.

Producing power, and keeping time.

Giving rise to grueling challenges and safe landings.

Creating excitement, making us scream to go faster.

Bringing movement for all.

And even the chance to explore new planets.

So when did the wheel roll onto the human stage,

and who invented it?

In 2002, archeologists were excavating the ruins

of ancient pile dwellings.

Houses built on stilts, located in marshland

near the city of Ljubljana, Slovenia.

The team unearthed a wooden cartwheel.

It was made of ash and its axle of oak.

Archeologists knew right away it must be ancient,

but radiocarbon dating revealed that it was in fact

over 5,000 years old,

making this the oldest wheel yet discovered.

Here is a breakthrough moment in the history of the world

that really does hold an important key

in terms of the story of human evolution.

The wheel was the breakthrough

that allowed roads to come into their own.

Beginning with simple carts,

this technology was life-changing.

And rather than what you can carry in a basket

on your back, all of a sudden you've got

the opportunity with this technology to move that much more.

The invention of the wheel drove

an explosion in transportation.

Over time, carts got bigger.

Carriages and wagons were developed,

capable of carrying heavier loads,

and moving goods and people further than ever before.

This simplest of all inventions

has led to a world that moves at a relentless speed.

Today, road transport operates on a gigantic scale.

Around 335 million commercial vehicles,

vans, lorries, buses, and trucks operate across the globe,

delivering everything and anything, wherever it needs to go.

And possibly the longest delivery route in the world

can be found in Australia.

Highway One stretches 9,000 miles,

and circumnavigates the entire country.

Some of the biggest monster vehicles carry goods

along this massive road.

Trucks reaching over 175 feet long with around 100 wheels.

They're known as road trains.

They can do that because the roads are flat and empty,

and they don't have to stop or start very often

for hundreds of miles, you know, straight roads.

But when it comes to straight roads,

one ancient civilization springs to mind.

Their transport network was built

upon breakthroughs made in earlier centuries.

With the wheel in place, and stone roads tried and tested,

Roman engineers had all the building blocks.

They brought them together to conquer and control

the biggest empire the world had yet seen.

Extending across 5 million square kilometers of Europe,

North Africa, and the Middle East.

At its peak, Rome ruled over 50 million people,

nearly a fifth of the world's population,

and they simply couldn't have done it without roads.

Very hard to talk about roads and the origins of roads,

without talking about the Romans.

But what were the engineering secrets

that made Roman road buildings so revolutionary?

Roman engineers began building roads in 312 BC,

the first running from Rome to Capua,

near present day Naples.

It was named the Appian Way.

The Appian Way was Rome's first major road.

It was their highway down into south Italy.

The Romans developed new engineering techniques

to construct this ancient super highway.

Once an ideal path was cleared, a trench was built,

filled in with sand and boulders

to create a solid foundation,

followed by a layer of gravel compacted with clay or mortar.

On the surface, a layer of paving stones angled

to allow the water to drain off to the side.

This was a road unlike any seen before.

It's as technologically advanced a road

as you're likely to see.

It's got elements of everything we would do

in a road today.

They had drainage systems, they had impermeable layers,

they had crushed stone, dressed stone,

the whole shooting match.

The Appian Way connected Rome

with nearby cities and regions, extending control.

But this was only the beginning.

Rome's generals soon realized

the advantages good roads offered.

A paved road with 40,000 Legionnaires coming at you

would be incredibly intimidating.

And it was Roman soldiers

who built much of the network.

When you look at the list of different skills

that were available in the Roman army, it's a long list,

and included in that were experts surveyors,

engineers, and construction workers.

Roads were constructed on a vast scale,

enabling Rome's further expansion.

Having dominated the whole of Italy,

the Roman imperial ambition grows greater.

Colonizing neighbor after neighbor,

after neighbor, after neighbor.

Between 200 BC and 14 AD,

Roman armies invaded most of Western Europe,

Greece, and the Balkans, the Middle East,

and North Africa, all linked by newly constructed roads.

We say all roads lead to Rome,

and for the Roman road network this was definitely the case.

This extensive network allowed Roman troops

to quickly March to trouble spots,

even at the farthest reaches of the empire.

So you can move say from Rome to Britain

in tens of days, which is very fast by ancient standards.

This sprawling road network

would also help create vast fortunes.

The better the roads, more of them,

over longer distances,

the more material can be moved around,

the more sales, the more contracts, and the greater wealth.

The Romans even built roads

across some of the most hostile terrain.

Terrain that even today presents

a major challenge for engineers.

The mountains of Norway.

Roads here are often narrow and twisting,

thanks to the extreme landscape.

So when planners decided a new, bigger route was needed

to link Bergen in the west with Oslo in the East,

they faced a problem.

They'd have to cut straight through a mountain,

calling for the longest road tunnel in the world.

(dramatic music)

So how did engineers go about building it?

The solution came from outer space.

High tech satellites orbiting the earth.

The tunneling machines operate completely independent

from humans, so they're guided by GPS systems

that position them precisely,

even though they're below the ground.

A staggering 3 million cubic yards of rock

was excavated from the tunnel,

but construction wasn't

the only complication engineers faced.

In a tunnel taking 20 minutes to journey through,

how could they deal with driver fatigue?

One of the design solutions was having the road moving

from straight to curved, straight to curved,

to keep the driver having to move the wheel and stay alert.

Designers and psychologists experimented

with lighting levels.

They divided the tunnel into four sections,

separated by three large mountain caves.

While the main tunnel has white lights,

the caves have blue and yellow.

This was to counteract things

like claustrophobia or panic,

keeping people calm in such a long tunnel.

Using this creative blue and yellow lighting

to simulate almost like a sunrise,

and keep people calm and content in their journey.

This clever tying together

of engineering and psychology,

allowed engineers to build the impossible.

The tunnel opened in the year 2000,

having taken five years to construct.

Back in the ancient world without modern machinery,

tunneling through a mountain was almost unthinkable.

Even the Romans were forced

to compromise their famously straight roads,

but there's one other natural obstacle

that Roman engineers had no choice but to tackle head on.

Water, sometimes there's no way around it.

The classic Roman road was entirely straight,

entirely level, marching out like a set

of legionaries across the landscape,

and that does produce problems

when you encounter a river.

For centuries,

earlier civilizations had built short foot bridges,

but for Roman generals to march thousands

of Legionnaires across a river,

something much more substantial was required.

If Rome was to continue its expansion,

it was vital engineers crack this problem.

To build permanent stone bridges,

the Romans needed new technology.

The technology they use to build these bridges

is really quite something when we think about

how long ago lots of these were built.

We have some brilliant examples all over the Roman empire.

Some Roman bridges even survive to this day.

So what were the secrets of their construction?

In search of answers,

scientists analyze the chemical makeup of Roman mortar.

They discovered it was a strange concoction

of volcanic ash, lime, and water,

mixed together with volcanic rock.

Experiments show that as the volcanic ash binds

with limestone, a chemical reaction takes place.

This prevents the spread of cracks within the concrete,

making it stronger.

The resulting concrete that they made

could actually set underwater,

and that was a really special feature of Roman concrete.

With this breakthrough,

new kinds of construction became possible.

Rome's greatest engineers set to work.

Among them, Marcus Vitruvius.

So Vitruvius was one of those classic examples

of the master builder,

and he wrote this incredible series of 10 books

about how to build things.

These works have guaranteed his place

as one of the greatest architects in history.

Vitruvius says that when we design something,

any building at all, we have to consider three things:

strength, function, and beauty.

Waterproof concrete

gave Roman bridges solid foundations,

but how would Vitruvius and his engineers

build bridges strong enough to support the weight

of an entire Legion marching across?

When you put weight on something, you bend it.

And when you bend it,

the top of that piece of steel, or concrete,

or whatever it might be, is in compression,

and the bottom is in tesion.

Tension is what rips it apart.

(scream and crash)

Once again, Roman engineers improved

on an earlier design.

They created this magical structure called the arch.

The entire structure is in compression,

and so that meant they could just use stones,

and if you pile stones up in an arch shape,

you can put a huge amount of force on it.

Bigger arches boosted

Roman construction capabilities.

This arch structure, which enables you to build up,

as well as out, of course is fundamental

to not just the construction of bridges and aqueducts,

it's also going to be important in the construction

of civic buildings, like the theaters, the amphitheaters,

and even the Colosseum in Rome.

The combination of Roman concrete

and the Roman arch made these structures incredibly robust.

An astonishing number are still in use today.

The Alcantara Bridge over the river Tagus in Spain

was built between 104 and 106 AD.

A Latin inscription on one end of the bridge

boasts of Rome's engineering prowess.

(speaks foreign language)

Which means I have built a bridge,

and it will last forever.

Very Roman, and so far so good, it's still there.

But the Romans aren't the only civilization

to have built impressive bridges.

Inspired by their Roman predecessors,

modern day engineers continue to push the boundaries.

(upbeat music)

Bridge design today is a really, really exciting thing

to do as a structural engineer.

There are so many different materials being used

at the moment.

There are so many different forms

that the bridges can take as well.

And to pick a favorite bridge,

I think I'm gonna go with the Golden Gate Bridge

in San Francisco.

The golden gate bridge was opened

to traffic in 1937.

Its main span is 4,200 feet long.

The US Navy had wanted the bridge to be painted

in blue and yellow stripes to increase its visibility,

but when the steel arrived in San Francisco,

painted in a burnt red primer,

the consulting architect decided the color

was more pleasing to the eye.

For nearly three decades,

this was the longest main suspension bridge span

in the world.

Some of the big suspension bridges

that have been done are just jaw-dropping.

The record is now held

by the Akashi Kaikyo bridge in Japan,

just under 2.48 miles long.

(upbeat music)

It stands in an earthquake prone region.

It also gets hit by some of the Earth's most severe storms.

(thunder and wind)

It's built to stand winds up to 180 miles per hour.

Piercing the sky above southern France

is the tallest bridge in the world.

The Millau Viaduct enables motorists

to take a drive through the sky,

890 feet above the Tarn Valley.

(upbeat music)

But modern engineers haven't always got it right.

Every now and again, a disaster happens

that makes engineers stop and think about

what they're doing.

July, 1940.

The Tacoma Narrows Bridge,

built in the United States of America, was open to traffic.

At that time, it was the third biggest suspension bridge

in the world.

So the Tacoma Narrows Bridge was built

in an era where bridge designers were really starting

to push the limits of what was possible,

and suspension bridges were all the rage.

At that time, the understanding of the aerodynamic effects

on these very lightweight, slender,

flexible bridges was not well understood.

The Tacoma Bridge had a fatal engineering flaw.

Shortly after its construction,

it started to buckle and sway along its length

in windy conditions.

The bridge got excited by the wind.

The frequency of the wind,

and the frequency of the bridge was similar.

And just like a tuning fork,

the bridge actually started dancing on the wind.

It soon acquired the nickname Galloping Gertie.

And just four months after opening,

on a stormy winter's day, disaster struck.

(intense dramatic music)

As it was dancing, it tore itself apart.

(crash)

It absolutely blows your mind

that this bridge was made of concrete,

because it just looks like paper flapping away.

And that was an absolute shock

in the world of engineering,

that such a sophisticated, leading structure, could fail.

With any new technology,

failure is always a possibility.

But engineers learn lessons from each mistake,

and continuously improve their designs.

A process of trial and error,

that also applied in the ancient world.

(rumbles)

The earliest wheels were just crude round lumps of wood.

Result, slow cumbersome vehicles.

The big issue with the big solid wheel

is they're really heavy.

The poor old oxen, or whatever it is pulling the cart,

has got to deal with wheels

that may weigh more than the load.

But the wheel got a major facelift

around 2000 BC.

Engineers figured out that replacing the middle portion

with spokes would retain strength

while making the wheel lighter.

The primary benefit of the spoke

is that it reduces the weight of the wheel.

The spoke enabled new types

of vehicles to emerge,

faster and leaner like the chariot.

An icon that helped define the Roman empire.

Most have been lost to the ravages of time,

but one amazingly intact example turned up in 2019,

on a burial mound in Croatia.

Just under 2000 years ago,

this site lay within the Roman province of Pannonia.

The find was a sophisticated two wheeled carriage,

revealing the engineering mastery of the era.

And alongside the vehicle, intact bones.

There was a Roman chariot found buried in Eastern Croatia

that also included human remains in the site,

and the remains of horses.

It was spectacular.

Shining a light on Roman advances in vehicle design.

The chariot is hugely important.

It enables you to travel farther,

and faster, and better than any other form of transport.

The chariot's also a significant symbol.

It literally lifts you up above the people

who were walking around you.

And so to be buried with it in death,

is to prove how important you were in life.

But these vehicles weren't just status symbols

for the Roman elite.

They were first and foremost for racing.

Chariots for the Romans were something

to be used in a spectacle.

And there was only one place to go,

the Wembley stadium of ancient Rome.

The Circus Maximus.

Largest stadium in ancient Rome,

the Circus Maximus was built solely for chariot racing.

It was constructed around the sixth century BC.

At a capacity, the crowd seemingly of 250,000 people

all assembled to watch teams of charioteers racing

at high speed, with high danger.

It's one of the great, great, great sights of Rome.

The racing chariots were lightweight,

but very sturdy.

The wheel base was wider to minimize the risk

of rolling over, and smaller wheels decreased

the force on the spokes when cornering,

though this led to a more bumpy ride for the charioteer.

(upbeat music)

The Circus Maximus is basically Silverstone,

or Monte Carlo for the Romans.

Just as the ancient world sent out charioteers,

their modern day equivalents still take to the track today,

in vehicles that reach extraordinary speeds.

Drivers pit themselves against each other

in the lightest and fastest cars engineers can build,

with speeds approaching nearly 300 miles per hour.

The technology is so advanced,

some change gear quicker than the blink of a human eye.

These are the fastest vehicles on earth,

and they're made of really light material,

they have huge downforce.

They're incredibly aerodynamic.

But they only work because those aerodynamics work

with the surface below.

Just like motorsports today,

with their promise of excitement, danger,

and occasional catastrophe,

(crashing)

ancient chariot races were also an adrenaline sport.

Races were grueling.

Seven laps covering a distance of around five miles,

lasting up to 15 minutes.

Life of a Roman charioteer was a very dangerous one,

and your life expectancy was extremely short.

The final races in the Circus Maximus

were held in 549 AD, almost a millennium after they began.

By then the Roman Empire in Europe and North Africa

was falling into serious decline.

Rome was losing its grip over many

of its conquered territories.

Despite its massive road network,

the Empire had become overextended.

The Romans didn't really have the resources

to keep control of such a huge area of land.

The Roman Empire falls,

the Roman roads fall into disrepair,

and the terribly complicated system of constructing them,

maintaining them, and using them, falls away.

Romans may have stopped building roads,

but across the world,

other empires were expanding or creating their own.

China continued its period of road construction

at this time.

And the Incas began building their impressive road network

during the 15th century in South America.

But in Europe, for well over a thousand years,

no one bettered Roman road building or design.

Roman roads are still used in the middle ages.

You get a patching up, you get a repair,

you get a reuse of Roman roads,

and a reuse of the technology.

And have Roman roads left a legacy

that shapes our way of life even today?

Clues to their impact were discovered

by a team exploring satellite imagery

of modern European roads.

Satellites orbiting the earth capture images

of every part of the planet day and night,

and a recent study compared

modern Europe's nighttime illumination

with a map of the Roman road network at its peak.

(dramatic music)

So when researchers map on where modern roads are,

compared to their Roman predecessors,

they match up extraordinarily clearly.

Nearly every junction

from the ancient Roman roadmap is matched

by a splash of light in the modern era.

Evidence that modern European cities and motorways

were built upon roots laid down by the Romans.

Roman roads formed the backbone

of the continent's road systems.

The legacy of Roman territorial conquest,

Roman power, is still ingrained in our earth today.

Across Europe, we still use the same sort of roots,

we still live in towns that were founded

or occupied by the Romans.

It took many years for Europe

to surpass the peak of Roman road building.

By the 18th century, with Europe's wealth increasing,

demand for improved transport was growing fast.

As more vehicle traffic came on the roads,

they had to be wider.

And when widening the roads,

that meant a new era of road construction had to begin.

Yet it wasn't until the latter part

of the 18th and early 19th century

that engineers created the first truly modern road.

And it was a British engineer, John McAdam,

who made the breakthrough.

He was convinced that massive stone slabs were unnecessary

to support the weight of passing carriages,

so long as the road itself could be kept dry.

McAdam actually said, "We don't need those big lumps

"of stone at the bottom."

And to compare it with the Roman technology,

I mean the Roman roads were six foot thick,

and these things was two foot thick.

His design resulted in improved roads,

built faster and at lower costs than ever before.

The technology quickly spread across Europe

with the majority of main roads

undergoing McAdamization by the end of the 19th century.

And this new road engineering came in the nick of time.

There was a new kid on the block,

about to roll off the production lines

that would change society, economics,

and civilization forever.

The ultimate freedom machine.

Horse powered transportation had been king

of the road for 5,000 years, but now it's reign was over.

There is a massive, massive change,

and one we are still living with today

with developments in the internal combustion engine.

(upbeat music)

Since the Romans, speed of travel on roads

has not changed.

It's people walking, is herding sheep,

and it's horse-drawn carts.

Along comes a car and all of the sudden,

in a period of a decade,

you've moved from nought to 10, to naught to 30.

In another couple of years, it's naught to 50.

As car production increased

throughout the 20th century, so did road building.

What the motorcar enables you to do

is to go from exactly your doorstep

to someone else's doorstep,

and that's not just for personal travel,

but that's for the movement of goods as well.

Across the world in every country,

on every continent, networks of roads became

the living veins of modern society,

reshaping cities and landscapes.

The idea of the road and the car

begin to dominate city planning,

and you have cities built around the idea

that everyone goes everywhere in a car.

What that does is to produce a demand

for ever bigger, ever longer, ever wider highways,

when every time you construct a new highway,

more people buy cars, because more people are able

to take advantage of that freedom.

The car may have made life easier,

but reliance on these metal beasts

has come at a terrible price,

(dramatic music)

as the planet chokes on the exhaust fumes cars leave

in their wake.

It has created problems for our planet through pollution,

CO2 emissions, methane emissions,

and greenhouse effect of course.

Road traffic accounts

for over 20% of global CO2 emissions,

and road construction adds to that.

Roads and cars are considered a major contributor

to global warming.

And in many places, road transport

has become an urban nightmare.

Manila in the Philippines,

and Bangalore in India,

are considered to be the worst places on the planet

for traffic congestion.

In many cities, it's now quicker to cycle than to drive.

With the world facing massive environmental damage,

engineers are now stepping up to help reinvent the wheel,

and the road.

Fleets of electric cars controlled by computers

may one day automatically select

the most efficient available routes

on roads which provide their own power supply.

One idea is that roads will become large solar panels,

so the roads themselves will absorb the sun's energy,

and then they'll put that energy

into the electric vehicles that drive on them.

But new technology may not solve

all the problems of overcrowded roads.

The future must be finding a way of continuing to travel,

continuing to trade, continuing to communicate,

but doing so leaving a less dangerous footprint.

Finding a way that doesn't cost the earth.

From the early trackways of stone-age Britons,

to the paved roads of ancient Egypt,

the road network of the Roman empire,

to modern super highways,

the road has long been the driving force of humanity.

Throughout the centuries, road engineers

have built big, dug deep, and scaled heights.

Inseparable, the road and the wheel have endured

a long journey to what they have become today.

The wheel had a rough start as a clumsy heavy contraption.

It's evolved into a fit lean machine,

transporting people further and faster

throughout the globe than ever before.

From the very beginning, human ingenuity and innovation

has overcome the greatest of obstacles.

Ancient engineering was essential in laying the groundwork,

and whatever the future holds,

it'll be engineers who keep the planet on the move.

(intense dramatic music)