When Wales Shook the World

Many people, many things have left their footprint on Wales.

Some rugby players have landed with a pretty heavy tread.

Some songs, and actors, and storytellers have left an indelible mark.

Industry has left its scars.

But the cutting edge of progress has also left behind the most memorable imprints -

civil engineering, construction. They can sound a bit dry, but this is all about brilliance, genius.

These now familiar landmarks were once pioneering projects,

driven by the spirit of innovation, full of drama.

Risks were taken, huge reputations were laid on the line.

There were setbacks, grand plans were dogged

by derailments, doubts, death and danger.

Ultimately, there was triumph, all bearing the seal, built in Wales.

For the first soaring achievement, we're going down, deep down.

I've made this trip countless times,

shuttling back and forth between my home in the borders and London.

Overground rail travel, just for a few miles heading east out of Newport,

and then suddenly...

..underground travel

into the black hole beneath the Severn Estuary,

the watery divide between Wales and England.

The Severn Tunnel. I know, it's a tunnel and there's not lot to see.

But of all the feats of 19th-century engineering,

this may well be the most dramatic. It took 13 years to build,

is 4.5 miles long when it was completed in 1886.

That made it the longest underwater tunnel in the world.

Even if it had been built without a hitch, it would have been some tale.

But this is all about what came at them unexpectedly.

A force that has to be tamed to this very day.

Today, there are other iconic crossings, over the Severn Estuary.

Almost directly beneath is the Severn Tunnel,

a project once dismissed as too risky and unpredictable,

which it very nearly was.

Building the tunnel ran into all kinds of difficulties.

It's only here today because one man risked his life to save it from total flooding.

More on Alexander Lambert in a minute.

Before the tunnel was built, there was only a long, dangerous

ferry crossing between New Passage in Gloucestershire and Portskewett in South Wales.

Freight trains had to cross further upriver, at Gloucester.

The original journey time

from London to Cardiff via Gloucester was 5.5 hours.

When the tunnel opened, it saved an hour and a quarter,

so it went down to 4.25 hours.

When the new line was built from Swindon to the tunnel,

we saved another chunk of time, which brought us down to three hours.

A tunnel is a black hole. Does that work against it?

It's a tunnel and you don't see much of it, sadly.

Therefore, it's never really had the high profile publicity

that, say, the Forth Bridge or the Golden Gate Bridge

in San Francisco has always had.

You can look at the splendour and yet,

the engineering that went into the Severn Tunnel was just as great.

It was. Great Western Railway proposed tunnelling under the Severn Estuary at the Shoots,

a relatively narrow stretch of water, but unusually deep.

The tunnel would have to be forged through contorted and ever-changing strata of rock,

200 ft below ground.

And above it, the Severn Estuary, with the highest tides in Europe.

And then there was always the notorious Severn Bore -

tides and this wave.

There was a constant danger of flooding.

Digging the tunnel started in 1873,

on the Welsh side of the estuary, here at Sudbrook.

The site has been in constant use ever since and is still

the tunnel control centre for the maintenance and monitoring teams.

Experts, every one of them, in the workings of this underworld.

The Victorian engineers started by sinking a shaft that went straight down 200 ft.

To keep the workings dry, they built a drainage shaft

that housed two engines, pumping out 300,000 gallons of water every day.

That sounds an awful lot of water, but everyone thought that the two

pumps were quite sufficient, until one day, when disaster struck.

October 18th, 1879.

The men working underground inadvertently tapped into a vast body of water stored in the rock.

Nobody had known it was there.

They called that they'd unleashed, the Great Spring,

and it would be a source of anguish for years to come.

In 24 hours, the entire works were flooded.

Miraculously, no life was lost.

The men working underground escaped with just a soaking.

But the existing two pumps had no effect at all on the spring.

300,000 gallons were nothing compared with the invading millions of gallons.

They were six years into the project, everything came to a standstill.

The Great Western Railway decided to hand over the project to a contractor.

The man appointed was Thomas Walker.

The new man in charge inspected the tunnel and found desolation.

The shafts were flooded.

Worse still, Walker was practically on his own.

The work force had left to look for jobs elsewhere.

Even with additional pumps, Walker found he couldn't get rid of the water.

He decided what he had to do was isolate the flooded section, to give the pumps a chance.

That meant sending in a diver, down the 200 ft shaft,

along the tunnel, to get to a door that would seal off the flood.

The man for this incredibly difficult challenge was one of the most famous divers of his day,

Alexander Lambert.

It was an extraordinary act of bravery.

Lambert was working in the pitch-black,

struggling through a tunnel littered with overturned skips.

At any point, he could have ripped his hose and cut off his air supply.

But that same hose was holding him back.

He couldn't reach the door.

So, Lambert went back down, with a brand-new piece of subaqua equipment.

The latest version of the rebreather, recently designed by the inventor, Henry Fleus.

The rebreather allowed the diver to be self-contained,

but it had only ever been tested to a depth of 18 feet.

Fleuss made the first attempt with it, here in the Severn Tunnel.

But it was too much for him, and when he resurfaced,

he swore that he would not go back down for anyone.

So, down went Alexander Lambert again.

This time, he did manage to close the door.

Thanks to Lambert, the tunnel workings were soon clear, and work could at last resume.

But more disasters followed.

In 1883, a tidal wave swept up the estuary.

Water poured into the workers' houses,

the boilers and down the shaft, filling everything below.

This time, one life was lost.

The works were in a worse state than they had ever been.

Once again, they pumped out the water.

Once again, work resumed.

The Great Spring continued to force its way through.

By 1885, it had been sealed off by drawing it into a side tunnel.

At last, the final section of the tunnel was completed

and it was close to opening.

Tunnel expert David Abenheimer

is impressed by the scale of the work that once went on here.

At its peak, Walker had 3,000 men working for him on the tunnel.

The logistics of that were such that he formed,

founded the village of Sudbrook at this end of the tunnel,

just to provide accommodation for workmen and their families.

He didn't just provide housing, he provided a post office, telegraph,

a Mission Hall, a school,

and he was very good in terms of providing for his workforce.

In the autumn of 1885, Thomas Walker left for South America on a different project,

exhausted, glad to leave this one behind him.

He wasn't gone long. Within weeks, he received a telegram.

The Great Spring was back. Sealed off, it was exerting

such a force on the tunnel that bricks were beginning to shatter.

Pieces were flying out of the wall and water was pouring through the gaps.

Walker and Hawkshaw realised that the only real answer

was to divert the Great Spring once and for all.

This giant pumping station was built.

The new building housed six massive Cornish beam engines that would pump

the spring water from a catchment point underground to the surface.

The six engines were beasts.

Fed by eight boilers, they worked solidly round the clock.

Nothing like them had ever been built anywhere in the world.

The Great Spring had finally met its match.

The culvert takes the spring water to a catchment point

where the water is pumped all the way up those 200 ft to the surface.

The original Cornish beam engines were replaced in the 1960s by these electric pumps.

And on they go, just like the old engines, constantly pumping away,

keeping the tunnel operational.

Most of the water now gets pumped into the Severn Estuary.

Welsh Water does take off a certain amount.

With the Great Spring tamed at last, the tunnel was ready to open.

It happened on 1st September, 1886, with no great ceremony.

Perhaps nobody wanted to celebrate too soon.

The story of the tunnel was to have a happy ending.

Over 120 years later, it is in use as much as ever,

the most important section of all the railway lines that connect Wales and England.

Should we applaud the tunnel because it's still very much a working project?

I think so. I think, what makes us applaud it is the fact that it took

100 years for it to be surpassed by something like the Channel Tunnel.

It stayed one of the longest tunnels, and the longest railway tunnel in the country for 100 years.

-You're Welsh, does it have a special place for you?

-Absolutely.

If you don't keep the Severn Tunnel open,

and if the pumps fail and it gets flooded...

..England gets cut off from civilisation.

There it is, the tunnel, a little black hole on the edge of Wales.

There's something about this place, something chilling.

All the major characters of its construction were dead within six years of its completion.

They say it's haunted, but there is something far less chilling.

There's not much to see from here or from the train, but down there it is an absolute masterpiece,

and the spirit of Hawkshaw, Lambert and Walker lives on.

For the next feat of engineering, I'm going from the depths of South Wales upwards to North East Wales...

..and back further in time to the year of the Battle of Trafalgar

to 1805 when this opened.

Even when set against what can be built today with steel and concrete, it stands its ground.

When it was first built, it set new global standards for length and height.

But never mind the records, this is simply stunning,

a combination of stone, metal and water, man-made elegance straddling a beautiful valley,

a masterpiece, and not just for its majesty,

but also because this was an early expression of a daring new spirit.

This is the Pontcysyllte Aqueduct soaring over the River Dee in North Wales.

When it was built just over 200 years ago, it was like no other structure on earth.

It broke records, and people came from all over the world to admire it.

Today, Pontcysyllte serves the tourist trade,

catering for leisure barges on the Llangollen Canal.

But the aqueduct was built for a different purpose.

When work started in 1795, Britain was in the grip of canal mania.

A time when 1,000 miles

of new waterway was completed in just 20 years.

Canals were the arteries of the Industrial Revolution.

The Pontcysyllte Aqueduct was built as part of the Ellesmere Canal project,

a 68-mile waterway network that would take Wales's mineral riches down into the Shropshire lowlands.

The canal started on the Cheshire Plain.

'In the Vale of Llangollen, it had to cross the River Dee.'

This is the landscape they had to cross.

Picturesque for us, but for a canal builder, full of challenges.

The biggest obstacle they had to overcome the broad, deep Dee valley itself.

Pontcysyllte translates as "the bridge that connects,"

and that's exactly what it does, striding across the valley.

In the numbers game, and in construction they always count,

the following are revolutionary dimensions.

The aqueduct is 126 ft high and 1007 ft long.

It consists of 18 pillars that carry a cast iron trough that is 11 ft wide,

wide enough, just for one canal boat to cross at a time and a toepath.

The engineer appointed to oversee the project was William Jessop.

Jessop was the most famous canal builder in Britain

and he was well known for his modesty and his generous nature.

The appointment of the resident engineer was, however,

a more surprising choice.

This was a 36-year-old Scot called Thomas Telford

who had considerably less experience in building canals.

But Telford was gifted and ambitious and this was his big chance.

He was born to a shepherd, he was lucky enough to get an education.

He worked as an apprentice stone mason in Scotland, but was one of those people with get up and go.

When Telford got the job, as a young man on Ellesmere Canal,

he wrote was very excitedly to his friend in Scotland,

"I am engaged in the most noble enterprise in this country. It will be a great and wonderful thing."

He was terribly excited in being part of this whole new world that was transforming Britain.

This was the opportunity. 1793 was a boom year, canals being built

all over Britain and this wasn't really the greatest at all.

The thing that made this great was Pontcysyllte,

nothing like that had ever been seen before and it made his name.

Canals nowadays are enjoyed at a more leisurely pace.

What were they in those days?

The canals were the motorways of the age.

Somebody did a calculation -

if you want to carry goods and you put them on a packhorse,

it could carry something like an eighth of a ton.

The best you could do with a horse and cart

on a really good road was about half a ton.

Put the horse in front of a canal boat and it could move 30 tonnes.

It was a huge increase in efficiency.

It is fair to say that without the canals to move goods around,

and particularly coal, we would not have had the Industrial Revolution in Britain.

Telford was appointed engineer to the canal in 1793.

The problem of how to cross the vast Dee Valley was still unresolved.

At one point, it was agreed the aqueduct should cross the valley at a much lower level

and barges would have to go up and down through a series of locks.

But Telford saw flaws in the plan and ruled it out.

Anyway, he had in mind something far bolder.

This was the era of the picturesque.

What man added had to enhance the landscape.

What made Telford's design even more daring

was its use of a new material still in its infancy...

..cast iron.

Its lines now look so classically clean and simple.

Just how radical was this?

Very radical, because the earlier aqueducts in Britain

had been very low and squat.

The waterproofing in them was a great mass of puddled clay,

that's clay been treddled by navvies walking on it.

So an enormous, heavy structure

which couldn't reach the heights of the aqueduct here.

So they were thinking of building a much lower structure until they got the ideas sorted out.

-A lot of those ideas, did they revolve around cast iron?

-Yes.

In the age of Merthyr Tydfil, as the world centre of iron smelting,

these huge fuel furnaces could actually produce enormous masses

of cast-iron which could be used to build a large structure like this.

It's so light that they could achieve these very high structures for the first time.

Cast iron, how did it compare with what had been used before?

It is extremely light compared to Roman aqueducts like Pont du Gard

in southern France, which is about as high as this.

But the stone sides of that are 4 ft thick.

Here, with cast-iron we only needed plates which are an inch thick

on either side, so it gives you some idea of the huge saving

-in weight that cast iron enabled.

-So we have this trough, 1,000 ft long.

Did they have to do anything to stop it leaking?

This was an example of one of the first uses of iron cement, but it was specialised cement because

it was mixed with boiling ox blood, Welsh flannel and iron filings!

That compressed together and...

formed a watertight bond, and that's held and not really leaked significantly in 200 years.

There must have been some trepidation on Telford's part.

Here he was a relatively inexperienced canal engineer,

pushing for a cast iron trough,

1,007 ft long, supported on stone pillars.

It had never been done before. Would it work?

The number of spans was set at 19,

with 18 stone piers supporting the cast iron trough.

These vast, stone piers, believe it or not, are partly hollow.

It was another of Telford's brilliant ideas and became one of his trademarks.

Solid stone piers to this height would have been too heavy.

So, for about two-thirds of the way up, they are hollow and they taper

and that's what's makes the whole thing so light and graceful.

Peter, there is a modern buzz about this place, but how different was it, say, 200 hundred years ago?

It would have been very different. This canal was built for commerce,

there were coalmines, ironworks and brickworks, slate works,

the chemical works coming in. This would have been a hive of industry activity 200 years ago.

That's why the canal had to get across the valley to reach it.

So this Scotsman says, "I will give you something very graceful to fit into this industry."

-How did that go down?

-Telford and Jessop, the senior engineers on this project, there is evidence from

their writings and the records of the day, they were very conscious

they were building a fantastic structure. It would be the tallest structure of the modern age.

They needed to build something that would be beautiful rather than just plain and ordinary.

Telford had begun his career as an apprentice stonemason

and the quality of the stonework on all his projects was notable.

The stone was just as important as his revolutionary cast-iron.

The blocks for his aqueduct were quarried nearby.

Each one of these vast blocks would have been hand-dressed on site.

This etching was made during construction.

It gives an idea of the height at which the stonemasons had to work.

From the very outset, Jessop was worried about the safety of the stonemasons.

In 1795 he wrote to Telford, "I foresee some difficulties

"that appear to me formidable.

"In the first place, I see the men giddy and terrified

"in laying stones with such depth underneath them

"with only a space of six feet wide and ten feet long to stand upon."

The men would have been working right up there,

without any scaffolding as we know it, no safety harness.

One man did fall to his death. But that, according to Telford,

was due to carelessness on his part.

That sounds a bit cavalier, but Telford WAS concerned about safety.

And you only have to compare that one single fatality with what happened, say, on the Forth Bridge

built almost 100 years later. It's thought as many as 98 men died on that project.

It's only when you're travelling across the aqueduct

that you realise quite how dangerous it must have been for the workmen.

Standing on the canal boat, on one side there's a frightening drop.

Why's there no safety rail?

One wasn't required. When this was a working canal,

you'd have had a man leading a horse on the towpath, where there IS a rail for safety.

There would have been just one person on the back of the boat.

There would've been no question of them thinking about throwing themselves off

so a safety rail wasn't needed. And iron was an expensive material, so they would have saved £100,

which would have been a lot of money then, by not installing one. And we've never needed one since.

It was all about industry. But can you give us some idea of the tourism it spawned back then?

Remember, this is 1805 when it opened.

We were at war with the French and half of Europe.

So people couldn't go on the grand tour around the Renaissance sites that they would normally do.

And so there was a kind of mini grand tour going on in Britain.

So this landed at exactly the right time to attract the attention of the well-to-do.

It had the wow factor when it was first built.

People came from all over Britain and the modern world

to look at it and marvel at it.

And I think it's still got that today, even with the age of jets and motorways.

You can still come here and stand on top of it or stand down at the river and look up at it, and be amazed

that we've got the capability to build structures like that,

that still look graceful and beautiful as well.

In all, it took ten long years to build this aqueduct.

But I think everyone involved knew they were working on something very special.

It opened with a grand fanfare on the 26th of November 1805.

Thousands of people gathered to cheer a small procession of boats

going across. Telford was here to join in the celebrations.

He didn't mind a bit of publicity.

But it must have been an incredible occasion for him to stand alongside his stream in the sky

that was about to become one of the wonders of the industrial world.

What did this lead to in the world of aqueducts?

Well, after this, people were inspired by the height and length of this.

It was the highest in the world, 126ft, when it was constructed,

and about 1,000ft long, it was also the longest.

And it remained about the highest for 200 years.

Just on a personal note, when you look at it, what do you make of it?

I think it's awesome. It's awesome to walk over,

it's very impressive, and to know that it led on to all sorts of other

highly-engineered transport structures,

pushing technology to the limits.

Pontcysyllte was built at a time of great turbulence,

of warfare and industrial revolution.

It was an age of fire and furnace and steampower,

of moving ever-faster, mass production.

There was also a more sensitive spirit to this age,

governed by an appreciation of landscape and elegance.

This was a work of genius on both fronts.

Subtitles by Red Bee Media Ltd

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