Original subtitles

I loved trains as a kid, both riding on them and playing with them.

But today we're not messing around with little toys.

Oh, no, we're going extra large.

We're a nation of rail lovers,

in a typical week taking a whopping 30 million journeys across the UK

on 4,500 trains.

So, to find out how everything's kept on track,

I've got access to a factory that builds the ultimate model train.

Not many people get to see that.

It's a truly astonishing feat of engineering.

Every month, across this colossal site,

skilled teams carry out 40 miles of welding...

..tighten 60,000 bolts...

..and spray on 67,000 litres of paint.

I'm Gregg Wallace...

Mind the gap!

..and I'm being uplifted...

The train at platform seven is having its sides put on.

..by the amazing construction techniques

that transform metal into a 187 tonne machine.

HE IMITATES TRAIN HORN

Meanwhile, Cherry Healey...

It's almost like looking into a planet.

..is going underground to reveal an extraordinary

tunnel-building machine.

The whole structure is vibrating.

And historian Ruth Goodman...

You just know you're on an electric train, don't you?!

..is energised by the history of electric trains.

Every week, 20 train carriages roll off the end

of these incredible production lines.

HORN WAILS

This is manufacturing on a whole new scale.

Welcome to Inside the Factory XL.

This is the Alstom Factory in Derby.

They've been making trains on this massive site

for over 140 years.

And I must admit, I'm just a little bit excited

to see how they build a train.

Yes, a whole train!

Across the 84 acre site,

2,000 people work around the clock,

blending traditional expertise with the latest

in train-building technology.

But it's not a quick job.

Each train takes up to 1,000 hours to complete.

Today, we follow production of their latest model

for the Greater Anglia Rail Company,

the Class 720 Aventura Electric Train.

Highway To Hell by ACDC

The factory is fulfilling an order for 133 of these

state-of-the-art 187 tonne five carriage monsters.

Once complete, each train could ferry more than

7,000 people a day across East Anglia

at speeds of up to 100mph,

joining the 3,000 other electric trains

on Britain's vast rail network.

It all begins with a super-sized delivery

on the biggest articulated lorry I've ever seen.

Its trailer is loaded with 24 metre long

aluminium panels, weighing in at seven tonnes.

First up on the line is logistics manager Leroy Joseph.

That is ludicrous!

Leroy, good morning. Morning, Gregg.

What bit of the train is that?

That's the underframe.

What, the floor of it?

It's underneath the floor. The floor sits on top.

So, basically, that is what the rest of the train is built on.

Yes.

There are four crates on the trailer,

each one weighs as much as a small car

and contains the exact amount of aluminium

for the underframe of one train carriage.

Two overhead cranes, controlled by highly skilled operators...

Whoa.

..lift the huge weight off the lorry.

That is not easy, is it?

Whoa.

I'm really happy that is on the floor.

Leroy, thank you very much for your time.

Thank you for yours as well. Thank you.

Our train is made up of five carriages

capable of seating a total of 490 people.

The three middle carriages include a bike storage area and toilet,

and the two at either end have drivers cabs.

The production process for all five carriages

begins with the underframe

in the ginormous 180 metre long welding shed...

Look at the size of it!

..where Alan Goss is station manager.

Alan? Hi, Gregg.

This is vast, isn't it?

It is massive.

I've seen this come off, but how do you build a train?

I mean, where do you even start?

So there's six pieces of aluminium here.

We weld this together to make one underframe.

Basically like a car chassis.

Yes. Right.

So, everything on that carriage gets clamped or stuck to this.

Exactly right. It does.

Well, this is probably the most important bit

of the whole carriage, then. Very much so.

They use aluminium because it's strong and light,

coming in at just a third of the weight of steel.

You've hollowed it out here into these little triangles.

You don't want a big plank.

You want something that's lightweight,

so we've removed most of the material inside

and created the webbing structure to give it the strength.

The 300kg panels are hoisted onto a 24 metre long bit of kit

called a jig, where 20 super strong clamps hold them firmly together.

Ready for this...

..five metre high mega machine to get to work.

This is our three-headed auto welder.

Right. It welds four planks, three joints,

at the same time.

Just sticking out here is a piece of aluminium welding wire.

We put a current through this, and it's about 15,000 degrees C.

It fuses and bonds the two aluminium plates

and the wire at the same time to create a super strong bond.

All melting together?

All melting together.

You know, I bake cakes, and pies and roast joints,

that's as far as my temperature gauge will go. Yeah.

A little bit hotter.

In fact, it's more than 60 times hotter

than the hottest setting on my oven.

Right. Can we see it working?

Yes, Gregg. Let's get some welding done.

With the push of a button...

..the auto welder fires into action.

This is an extraordinary machine.

I can feel the heat.

As it travels slowly along,

electricity is channelled down the wire to the point of the weld,

where the metal and the wire melt and fuse permanently together.

But as clever as this incredible machine is,

it still relies on the human touch.

I've got a welding operative watching the weld,

making sure that there's no problems.

Because if you get that weld in the wrong place,

that's going to seriously damage that aluminium.

It will just scrap the whole underframe.

Has that happened before?

No.

It has, hasn't it? No, Gregg.

Luckily for Alan, the huge auto welder does its job perfectly.

And six more aluminium stiffening panels are added,

this time by hand,

to complete the job,

creating an enormous 24 metre long 2.5 metre wide underframe.

The body of our train is made mostly from aluminium.

But how do you produce aluminium?

Cherry is on an epic mission to find out.

I've come to the foothills of Ben Nevis in Scotland.

Not, perhaps, the first place that comes to mind

when you think of metal works.

But in the UK, it's the only place to smelt aluminium.

Nestled amongst this beautiful scenery is the Lock Harbour smelter.

This 40 acre site produces 48,000 tonnes of the shiny metal every year

using a process called smelting.

To find out how they do it on such an epic scale,

I'm meeting engineer James Tangney at the factory's intake area,

where they've just taken delivery of the key ingredient.

James. Hello. How are you?

Lovely to meet you.

What is in this gigantically long train?

Aluminium oxide, which is the raw material for producing aluminium.

And there is a sample.

Um, what, you mean this pot of icing sugar?

Yes. THEY CHUCKLE

So, as we speak, it has been pumped out of these trains into the silos.

Aluminium oxide is extracted

from a red coloured rock called bauxite.

It's mined in countries across the globe,

including Australia and China,

but can't be turned straight into aluminium.

So it's first processed into the fine white powder

using industrial chemicals in specialist refineries...

..before arriving at sites like this.

So there's some serious engineering magic to turn this into aluminium.

Yes. Well, I'd like to see it.

Yeah, on we go, then.

Three of these 250 metre long trains deliver

nearly 2,000 tonnes of aluminium oxide every week.

From the rail yard,

the fine white powder is sent into one of two

300 metre long buildings called cell rooms.

Holy Moley, James, look at the size of this room!

Absolutely massive!

Yeah, and it contains 40 individual cells.

So this is where we make the aluminium.

This is the heartbeat of the whole place.

So inside each of these cells right now, there is molten aluminium?

Yes. So it's a continuous process, 24/7.

The aluminium oxide is constantly fed via overhead cranes

at a rate of three tonnes a day into each of the six metre wide cells.

Oh, my God. That's amazing.

You can feel the heat coming off.

It's a dangerous process.

The cells, heated by electricity,

operate at nearly 1,000 degrees Celsius,

and we're only able to get this close because of our air fed masks.

Within these cells, the electrolysis process happens.

I remember that from school science.

It's just a very fancy word for putting electricity

through something to separate our materials.

Aluminium oxide is made up of both aluminium and oxygen.

The aim of the game is to separate the two elements

using an electrical current.

As the aluminium oxide is fed into the cell,

it's dissolved in a liquid solvent.

Electricity is fed through the mixture

from a positively charged electrode, called an anode,

near the top of the cell

to a negatively charged electrode, called a cathode, at the bottom.

The oxygen is attracted to the anode and the aluminium to the cathode.

The whole process uses as much electricity as it takes

to power 10,000 homes.

To cope with its insatiable demand,

the factory has its own hydroelectric power station,

using water from the hills high above.

So where does the oxygen go, and where does the metal go?

So the oxygen reacts with the carbon in the anodes

to form carbon dioxide, and that is captured.

The metal is heavier as that sinks to the bottom.

Every 36 hours, the aluminium that has sunk to the bottom

of each of the 40 cells is extracted using a process called tapping.

Wow!

It's almost like looking into a planet.

A 2.3 metre long nozzle is lowered in...

Like an elephant's trunk.

That'll go down to just a few

centimetres off the bottom of the cell.

..and two and a half tons of 960 degrees Celsius

pure molten aluminium is sucked out...

It's got a little red nose.

..before being tipped into a transportation crucible.

That is absolutely amazing!

It looks like maple syrup. Right.

But obviously if you put that on your pancakes,

you probably wouldn't have a kitchen left.

The aluminium is driven to the casting area,

where 42 tonnes of the liquid metal

rushes down a series of concrete channels

towards three casting pits.

Running down it almost like a maze.

So there's three moulds there.

So the metal disperses evenly between the three moulds,

and slowly, over 70 minutes, the mode forms the final slab.

After cooling for a further 30 minutes,

the aluminium emerges as three metre long 13 tonne blocks.

That is a big slab of metal.

When you see the finished product,

especially when it comes from that fine white powder,

that's really nice to see.

The finished slabs are ready to be sent on for further production

across the UK and Europe.

This incredible metal is one of the most important materials

of our modern age,

with millions of uses, from kitchen foil

to modern passenger trains.

And what a mega process.

It's been an absolute blast, or maybe I should say "smelt".

370 miles south at the train factory in Derby,

our aluminium has been welded by machines...

..and hands.

Construction of the underframe for one carriage is now complete.

One of the factory's 75 individual cranes takes over,

before it's whisked 420 metres across the site...

..to be prepped for painting.

Meeting me in the blast facility is Graham Welch.

Graham. Hi, Gregg.

There you go. Look at this.

Now it's in this dark, quiet room,

it really gives you a sense of the scale.

It's mammoth.

Right, what are we doing in here?

We shot-blast the surface to abrade it.

You rough it up? We rough it up, yeah.

Otherwise, on this shiny surface, the paint won't bond to it.

How do you do that?

This is the shot-blast media.

It's actually stainless steel.

But this is soft. How does that rough up that?

Cos it's impacted at massive pressure

through this robotic arm behind us, if you'd like to pick that up.

Right. And we can operate it manually

to demonstrate how it works.

Really? Right. What have I got to do?

That's it.

Now pull the joystick towards you.

Ah!

Wow!

That's scary.

That is... Ha-ha!

Whoa.

The robot is capable of firing 500g a second

of the stainless steel pellets against the aluminium

at speeds of up to 500mph.

Ah!

That was brilliant.

It's a little bit Star Wars, isn't it? It is.

HE IMITATES MACHINE

Once we're safely out of the chamber,

it's time to fire up the Death Star.

The robot arm travels back and forth,

blasting the shiny metal, roughing it up,

and leaving it perfectly prepped for painting.

The underframe is probably the most important part of our train carriage

because many other components will be attached to it,

including the walls, known as side panels.

Three panels, varying in length from 4.3 to 9.3 metres,

are attached along either side.

Just like our underframe, the six side panels have been shot-blasted

and are travelling inside one of the factory's

seven 28 metre long paint booths.

First they're sprayed with a resin based sealer to prevent corrosion,

then primed with a liquid plastic coating

to ensure a smooth finish,

ready for the water-based white top coat.

Oh, that's the side panels of your train!

These are our side panels.

Is that just for me, or do you honestly spray those by hand?

We do spray them manually, yes.

Why do you not put that in front of a machine?

Because there's this low volume, they're all painted manually.

You call these tons of metal and all this engineering low volume?

Yes. Compared to automotive, for instance.

Each train requires 780 litres of paint,

about 24 times more than a typical car.

You're not going to let me have a go at that, are you?

No, we've got a gun behind here that you can have a look at.

You can control the amount of paint and the amount of compressed air.

Are you frightened that I'd mess it up?

There's a possibility.

And that's too expensive to mess up.

HE LAUGHS

It's not like slinging a chocolate bar away, is it? No.

It takes two people just 40 minutes to spray on two coats of white

and another 50 minutes for the sections of black and grey

that form our trains unique livery.

33 hours after entering the blast chamber,

six shiny side panels emerge.

The exact number needed for one train carriage.

Now, that looks fantastic!

Now, that actually looks like a train.

It does. It's a beautiful finish.

I am very surprised you do it manually.

We've got guys working here who have been here over 40 years,

who used to paint these trains with a brush.

Brilliant. Who knows?

I might be sitting on this carriage one day.

Mate, that was fabulous.

Our gleaming carriage walls are now ready

for the next stage of production.

We are making an electric train,

which is cleaner, quieter,

and more environmentally friendly than diesel.

But this technology is surprisingly old.

Ruth is tunnelling into the history of the electric train.

On a typical day, nearly five million rail journeys

are made in the UK,

on a total of 4,500 trains

running on 20,000 miles of track.

But did you know that the world's oldest surviving electric railway

is right here in the UK?

Today, more than a third of our rail network is electrified.

Perhaps surprisingly, it was here in the seaside town of Brighton

where this revolution began.

This is the Volks Electric Railway,

the electrifying grandfather

of the modern electric train.

In use since 1883,

it still runs along the seafront.

I'm meeting station manager Phil Lucas

to learn how it all started.

Hello, Phil! Hi, Ruth.

My goodness. This is gorgeous. Isn't it?

It's an extraordinary thing to be still running.

Yeah. Would you like to come on board and go for a ride?

Ooh, I'd love to. Come on, then.

I do like a railway.

BELL TRILLS

You just know you're on an electric train, don't you?

Yeah. There's no denying. It's got to whir, it builds up.

So how on earth did the first electric railway in Britain

end up in Brighton?

Well, it's all because of a gentleman called Magnus Volk.

This is him. Oh, very distinguished.

Yeah. Now, he lived in Brighton,

but he was fascinated from a very early age by electricity.

In the 1870s, Volk was the first person on the South Coast

to install electric lights in his house

at a time when electricity was barely in use anywhere.

Streets were lit by gas lamps,

and steam trains powered by coal.

But in Germany, an engineer by the name of Werner von Siemens

had come up with a brand-new kind of train.

First exhibited at the Berlin Industrial Exposition in 1879,

his electric-powered prototype was a huge success.

And it wasn't long before it caught the attention of Volk.

He was fascinated by the technology that Siemens was using.

Gosh, this little tiny engine. Incredible, isn't it?

Siemens's revolutionary train was propelled by a simple motor

powered by electricity running through the rails,

much like many of today's trains.

It became the highlight of the show,

carrying more than 86,000 passengers in just four months.

Magnus thought, there's potential here, and in 1883 he opened

the UK's first electric railway.

Oh, this must have been really quite a shock.

People by that point had had a generation of steam power,

and then suddenly, I mean, there's no engine.

It's like black magic. It's just this strange contraption.

I've actually got a quote... OK. ..from when we opened.

"People looked with alarm at the idea of an electric railway.

"It was said that the end of the world was coming.

"One minister in a place of worship in Brighton

"advised his congregation not to go near this latest

"invention of the devil."

Not everyone was scared of this devilish contraption.

50 miles north in Victorian London,

the electric railway was about to have a seismic impact

on the big smoke.

London Transport Museum's Matt Brosnan picks up the story.

Matt, how lovely to see you. Hello, Ruth. How are you?

So, um, when Volk's railway got going, the London Underground

had already been in existence for 20 years, hadn't it?

That's right, yeah. 1863 was when the first segment opened.

It had been running successfully, but used steam engines to power it.

You would often have situations

where people would be slightly overcome by the fumes

and have to be escorted off the trains because it was, you know,

so smoky and poorly ventilated.

The problems also continued above ground.

The underground rail network was expanding rapidly,

with 85 stations and 140 miles of track laid by the end of 1884.

The way it was constructed was really, really disruptive.

It used a method called cut and cover,

basically digging a trench in the ground, laying track,

building a brick archway over the top, and then laying topsoil.

That must have been really popular. The initial novelty had worn off.

So when it came to constructing London's next new train line,

one rail company took a gamble and decided to go electric...

..this time in deep underground tube tunnels,

an idea that would never have been possible with smoky steam engines.

In 1890, the world's first tube line running electric trains was opened.

Now, this is an interesting looking beast, isn't it?

It certainly is. It's the very first electric train

that ever ran on the London Underground.

That's really very quickly following on from Volks.

You know, one of the reasons why deep level tube lines

were actually possible was because of this kind of

experimental technology.

The new trains ferried passengers cleanly and speedily

across the capital.

The success of the first electric line led to the construction

of a sprawling network,

much of which is now the London Underground.

And it wasn't long before the world followed suit,

with subways and metros helping to transform cities

into global powerhouses.

It may seem a world away from that quaint seaside railway,

but the technology truly changed the world.

Humble cities became giant metropolises.

And our own London Underground carries millions of people per day.

Back in Derby...

The super sized scale of our electric train

means everything takes time,

and it's a way off carrying passengers yet.

We're already five days into production...

..but the six side panels

for one of our carriages have been spray painted,

and after travelling through the shot-blaster,

so has the under frame.

So it's time for the parts to be sent here...

..to this cavernous 22,000 square metre building,

which houses the two assembly lines that build our train.

Stretching the length of one and a half football pitches,

200 people work across 16 specialist teams,

putting together the five separate carriages

that will form our train.

The unenviable task of keeping everything on track

falls to Greg Moss.

Greg. Gregg! Am I allowed up?

You are. Right, go on, talk me through this

because there is a lot happening.

So the first thing to say is this is upside down.

So we build the train on this stage the wrong way up.

Cos all of these parts here

are much, much, much easier to fit downwards.

The seats are on the other side?

The seats are on the other side, correct. Right, OK.

All right. What's next?

So, next, we're going to fit the bolster.

What's a bolster?

This is the piece of kit that attaches the train to the wheels.

Another of the factory's powerful cranes makes short work

of hoisting the 615kg bolster into place.

Sits firmly in position on the train,

and then the wheels pivot around it.

The wheels fit on the bolster.

Correct, yes.

The wheels fit around that sticky-up thing in the middle.

44 12 centimetre long steel bolts attach a bolster

to each end of the underframe.

Two giant gantry cranes capable of lifting 20 tonnes

carefully turn the whole underframe the right way up,

and enough carpet to kit out a small house is laid...

..before it's sent onto the second halt on the assembly line,

where, for the first time, I come face-to-face

with another vital part of any train carriage.

Oh, the roof! Correct.

What's holding it up, just that crane? Yeah.

Just a big yellow jib.

With this towering supporting structure,

the largest part of one of our train carriages

can finally be joined together.

The 7.8 tonne aluminium underframe,

made up of more than 1,000 different components,

the six side panels,

now with 18 double-glazed toughened glass windows

and the vast 24 metre long

4.5 tonne roof

constructed in a similar way to the underframe.

So we've got the roof, we've got the ceiling.

That looks fantastic.

And the side panel's going on now. Is that why we're here?

That's our next job.

Shall we, then? Yes, let's.

Each side panel can weigh up to 860kg.

I don't want them scratching my paintwork.

Look at that. That's a very cool thing.

Oh, wow! It's coming out here.

It is. Ha-ha!

Isn't that an extraordinary thing?

I would never have imagined that.

Along the top and bottom are 48 holes,

which must be perfectly aligned...

Wow!

..with fastenings on the underframe and roof.

The train at platform seven is having its sides put on.

What amazes me is how precisely you can manoeuvre it

once it's been suspended.

It has to be absolutely exact.

Hydraulically-powered platforms rise up from the factory floor,

giving the workforce access to fix the huge panel in place.

How are they holding it in position?

So it's something called Huck bolts.

Got two parts to it.

That part goes over that part,

and there's a special machine which pulls those together,

locks it in place, and it never comes off the train ever again.

Well, I suppose it's got to be secure.

It can't work lose.

Once it's there, it's there.

Huck bolts create irreversible fixtures,

similar to rivets,

specially designed not to come loose when the train vibrates.

What carriage is this?

That's the trailer car, just has passengers on.

So that goes somewhere in the middle, right?

Exactly in the middle, in fact.

Is that right, is that the middle carriage? Very in the middle.

Exactly in the middle. How about that?

I've got an eye for these things.

Over the next three hours, five more side panels are craned in

and bolted on...

..and eight steel structural supports

to add extra strength around the door openings.

Then two huge sections called intermedia ends

are attached to both ends,

which will allow passengers to walk through this middle carriage.

With all five carriages being worked on in parallel,

our train is really coming together.

Two of the five carriages that make up our finished train

will have drivers' cabs added to one end.

But these cabs aren't made out of aluminium

like the rest of the train,

they're made of something entirely different.

Cherry's finding out how they start life.

Just a few hundred metres from the train factory

is a firm called Datum.

Away from the welding

and bolt tightening of the main assembly line,

this place is an oasis of calm.

You only get one chance to make a great first impression.

So what does it take to make a train look tiptop?

Well, it's a dedicated team of skilled tradespeople

producing cabs 24 hours a day.

Showing me how to make the perfect train visage

is managing director David Taylor.

David, hello. Nice to meet you.

I have never seen anything like this.

Is this how the front of a train starts its life?

It is indeed.

They look like huge jelly moulds.

The shell for every one of our trains cabs

is painstakingly constructed by hand

inside one of the factory's three reusable monster moulds.

So what are they doing?

Callum and Jamie here are just applying the first layer

of glass reinforced plastic.

What is glass reinforced plastic?

This is a fibreglass material made with phenolic resin infused in it.

Phenolic resin is the plastic element

of what the glass reinforced plastic is.

I would have thought that the front of a train was metal.

A popular misconception,

but this material is a very easy material to manipulate

into quite complicated shapes.

And it doesn't get much more complicated

than the shape of our cab -

a sleek, curved structure designed for its aerodynamics and aesthetics.

Why do you start with that liquid plastic?

The only reason we start with that is so that we get a smooth exterior

on the finished cab, and that's good for painting.

Calum and Jamie quietly apply two 0.1 millimetres thick coats

of plastic resin using nylon bristle brushes.

Then the glass element of our glass reinforced plastic cab is added,

which comes into the factory as thin fibre sheets.

Little strands of glass fibre that are all layered

in 360 degree format, giving strength in all directions.

We'll then wet this out with resin.

We literally paint it on to the fibreglass,

and the fibreglass will soak it up.

Is it a bit like papier-mache at school?

It's quite like it, yes.

The combination of layered individual glass strands

and plastic resin produces an incredibly

strong finished structure.

I can see how this, layered, could give some real strength.

Yeah. Put five or six layers on,

it'll give you a thickness of around about six millimetres.

After all six layers of glass fibre have been applied,

the mould glides into a huge oven

where it's baked at 85 degrees Celsius for three hours.

Inside, the heat penetrates the resin,

causing it to cure and harden.

Once it's out of the oven and out of the mould,

the shape of our cab is revealed.

That's mind-blowing.

It's incredibly smooth.

They've just made the front of a train.

There's not a hammer, there's not a screw,

and one day, this will take people all over the country.

Yes, correct.

But before it can be attached to a carriage,

things get a bit noisier...

SAW WHIRS

..in the trimming room,

where a specialist team uses heavy-duty machining tools

to cut out the side windows and remove the rough and sharp edges.

There it is. It looks much neater.

So is that it? Is that a perfect cab?

No, not yet.

Got any money on you?

All right. There we go. OK, so we need to check and make sure

there's no voids in there.

So we literally... TAPPING

Tapping all the way. You really do this? Yes.

And we're looking to hear differences in the sound.

What happens if you didn't bother doing the coin test?

Potentially, you could have an undersurface defect showing,

which obviously we don't want.

So it might look and feel a bit silly,

but it's really quite important.

It's a very important part of the job.

Tap test passed...

..any small indents are filled...

..before the cab is sanded, creating a smooth surface ready for painting.

Just like at the main factory,

it gets two coats of primer, followed by gloss top coats.

The cab is then bolted onto a steel frame which,

as well as extra strength,

provides fastenings ready to be attached to its carriage.

Then lights are fitted...

There she is.

..and it's complete.

In all her glory.

It's gorgeous.

So you've got a super sleek cab and even stronger steel frame.

Is that now ready for all the bells and whistles that go inside?

This will go off. They will fit the windscreen,

the cabs driver's desk, etc.

I'm never going to look at a train in the same way again.

After 200 hours of calm and painstaking layering,

sanding and painting,

the cab makes the short hop to the main factory.

At our 84 acre cathedral to train production...

..the first stop for the 1.7 tonne glass reinforced plastic cabs

is the originally titled Cab Shop.

Here, a team of 24 installs seven and a half miles of cabling

and 1,300 other components which will allow the driver

to operate our train.

Project engineer Holly Evans is at the helm.

Holly. Oh, hi, Gregg. Hello.

That is unmistakably a front of a train.

What are you working on now?

We're fitting one of the most important parts of the train, Gregg,

and that's the train horn.

And that's the... HE IMITATES TRAIN HORN

SHE IMITATES TRAIN HORN

Yours is better.

So the shorter one here is the high tone, and that's a G flat.

The longer one is the low tone, and that's a E flat.

It's to make it distinguishable from a car horn, for example,

so that people know when they hear the noise,

it's definitely a train.

Come on, what are we going to do?

My box there, yeah? Yeah, that's your box there.

So lift it in.

Line up the hole. I'm in, I'm in. You're in, you're in.

Each horn is attached simply with a nut and bolt.

Oh, God.

Fiddly with gloves on. It is.

If you hold it, I'll get it on quite far.

That's it. Teamwork, teamwork, Holly.

Well, that's the theory, anyway.

If I get this wrong, and it's only your one that works,

the train might only go... IMITATES TRAIN HORN

Well, then they'll know it's Gregg's special train.

What actually powers these?

We've got an air supply that's coming from inside the train

through these pipes, comes out the front,

and that's what makes the noise.

HE IMITATES TRAIN HORN

SHE IMITATES TRAIN HORN

I'll get it eventually.

With our horns firmly in place, a huge 1.8 by 1.7 metre

windscreen is craned in

and attached with 24 bolts,

while inside, the driver's control panel is installed.

So here we are. This is an almost finished cab.

It looks like a simulator.

There's a serious amount of stuff going on in here.

Yeah, a lot of controls.

If I'm the train driver, how do I actually start the train?

You grab hold of that handle, pull that towards you,

and that's your accelerator.

And if you push it away from you,

that's like you brake.

I can even see where my horn blows.

Is it just like a myth that there's a dead man's hand?

On this particular train, we actually have a dead man's pedal.

So what happens? Does the driver have to keep their foot

permanently on that pedal?

Yeah. So, the idea is that it knows that the driver is still there,

still alive and still operating the train.

It's pretty much the cab done.

I think I'm stuck down here.

The first of our train's two cabs is fully fitted out.

So it's attached to the front of the carriage

that will become the front of our train...

..with eight large steel bolts.

That's the driver nice and warm.

But what about the passengers?

That's great, that's the doors.

As a passenger, that's probably the one thing on the train

that I always use, right?

Yeah. This is what we call the door leaf.

And these guys are very expertly

craning this into position right now.

Each of the five carriages on our train

has four pairs of passenger doors,

two on either side.

They're expertly guided into place with pneumatic powered

glass suction cups,

bolted into position at the top

and attached to a guide rail at the bottom.

These particular doors have a rather ingenious safety feature.

This is what we call a sliding plug door.

So they slide down the side of the train to open and close.

But the final action of closing is controlled by a door pillar,

which runs the full height of the door

and twists at the last moment to plug the door in

so it sits level with the side of the train.

And the same action that plugs that door in

also engages a locking mechanism in the top of the door,

and that prevents it from opening once the train's moving.

That's extraordinary, isn't it?

It is. It's an extraordinary bit of kit.

Fitting all four sets of these clever doors

takes four people 12 hours.

Elsewhere on the line,

more expert teams are busy installing luggage racks

and USB charging points.

Our train is destined to run on the Great Eastern Mainline

through East Anglia, a route in use since 1862.

Now, it's rare that we build a completely new railway,

but Cherry has special access to just that.

To the west of London, near the Chiltern Hills,

they're 18 months into the construction

of the brand-new HS2 railway line.

This is one of Europe's largest infrastructure projects.

Designed to ferry millions of passengers every year.

And one of the biggest parts is building two ten-mile long tunnels

straight through the hills behind me.

But before I venture inside the tunnel...

..I'm heading to the massive on-site concrete plant...

..where they're constructing the 4x2 metre slabs that will line

the tunnel, preventing it from collapsing.

Production is overseen by manager David Andrews.

David, lovely to meet you. How are you doing?

You're making segments that are going to go into the tunnel?

Yeah, that's correct. Where do you begin?

The guys will move the mould into the concreting chamber,

the automatic cover will come across onto the mould,

and then the doors will shut,

they'll be ready to start concreting.

Every day, 49 steel moulds travel along a conveyor into a chamber

where they're filled... Wahey! There we go!

..with 8.5 tonnes of concrete.

Why are they raking the top of it?

They just level it out, scrape any excess off,

fill any grooves or holes,

and then when it comes through to the next station, the robot

can give it the once-over. Robot?

A robot uses a steel plate spinning at 177 revolutions a minute to buff

and polish the surface of the concrete, making it

perfectly smooth.

Then the mould's passed through a steam curing oven,

where they're baked at 45 degrees Celsius for six hours.

Whoa...!

They're all covered in a layer of mist and moving

really, really slowly.

The heat and steam cause a chemical reaction to take place

inside the concrete, giving it unrivalled strength.

Once out of the oven, the now hard, curved segments are lifted

from the moulds and sent outside...

Oh, my goodness me.

Look at this!

..to a whopping five acre storage site.

They are as far as the eye can see.

This is an amazing sight.

This is how you build a tunnel.

But before you start, you kind of need all these. You do, yeah.

Because you can't dig a tunnel under the earth unless you've got

something to strengthen it.

Exactly.

Seven of these curved segments make a single 10m wide tunnel ring.

Altogether, 112,000 will be used

to line the two ten-mile long tunnels.

After sitting outside for 28 days to fully dry and harden,

they are loaded onto a trailer and sent deep into the hills.

And I'm following them...

This is deep.

Very, very deep.

..to this state-of-the-art 2,000 tonne tunnel boring machine,

affectionately known as Florence.

My guide to this giant is engineer James Riley.

Welcome to Florence. Well, James, she's a beauty.

What you're on at the moment is the massive machine that's

building this amazing tunnel.

It does what it says on the tin.

One mile into the hills and 30 metres below ground,

the tunnel-boring machine is a 170-metre long behemoth.

The same length as 15 double decker buses.

Essentially a subterranean factory,

it operates 24/7 and features everything from control rooms

and walkways to toilets and even a canteen.

Floor is vibrating.

The whole structure is vibrating.

But the most important part is right at the front.

That's the cutter head.

Behind that rotating piece of metal is the ground we're excavating.

At the moment, we're rotating at roughly one and a half revolutions

a minute, and that's cutting the ground ahead of us.

This is one of the most

incredible things I've ever seen in my life.

We are 30 metres below the earth,

and this is burrowing through the soil.

It's a huge feat of engineering.

What is the tool that does the digging? So, it's the cutter head,

it's a big rotating disc with a number of tools mounted on it.

You've got cutter discs, knives, buckets scraping away,

it's then powered by these ten green motors mounted just in front of us.

The huge machine tears its way through the chalk and flint

at a rate of just 15 metres a day, creating a 10 metre wide tunnel.

I can't feel this machine moving, but it is, very slightly.

I mean, we're moving, it's only 45mm a minute,

so, you know, it's a snail's pace.

But it really is an ingenious snail.

The excavated soil and crushed rock is mixed with water to create

a slurry, making it easier to pump out of the tunnel to be used

to landscape other parts of the construction site.

This is where the slurry is taken away, out of the tunnel.

12 metres behind the cutting head,

the concrete segments that will prevent the tunnel

from collapsing are installed.

So, James, this is a really important part of making the tunnel.

This is the jigsaw puzzle that puts the tunnel together.

So can you tell me what exactly is going on? On the bottom

of the erector is the erector plate, which is the vacuum which is sucking

each segment. It positions it, and these big thrust cylinders

push it and hold it in place.

You can release the vacuum, and then it goes back to the next

segment to pick the next one up and do the same process again.

Each slab is guided into position using a remote control.

Remarkably, there's no need for bolts.

Once all seven pieces are in place, the design of the ring means

it supports itself, along with up to 180 tonnes of earth above it.

So I can see that you've completed a ring already.

How many rings can you do in a day?

Roughly seven rings a day.

It's an incredible bit of kit.

You can just keep moving, keep production going.

At this rate, Florence is expected to take three years

to complete her ten mile long journey.

Once finished, she'll have removed

a total of three million tonnes of rock,

completing this epic engineering project.

Back at the mega factory in Derby,

the doors and most of the interior

of the carriage that will become the front of our five-car electric

train have been installed. And it's come to a halt

at the penultimate stage of the assembly line

for the fitting of the electrical equipment

that will eventually get this 187 tonne beast moving.

Testing manager Craig Pollard has promised to explain

how it all works.

Craig. Hello, Gregg. Now, help me out here.

This is an electric train.

So where does the electricity come from?

The train is powered by the 25,000 volt overhead wire.

Give me a comparison.

So your house, for example, when you come to charge your mobile phone,

that's using 240 volts and this is 25,000 volts.

That's coming from overhead cables.

Yeah, that's right. So one car in every five that powers this train

is what we call a pantograph car.

The pantograph is what goes up and makes contact

with the overhead wire to pick up that voltage.

Is that like the bumper cars, when the cables hit the sparky bit

at the top? Very similar, but without the sparks.

A specialist team installs the pantograph to the roof

of the fourth carriage.

It will channel the electricity from the overhead cables

through wires running along the train carriages

and towards the six tonne

cast-iron wheel sets called bogies that sit

beneath the underframe.

Finally,

we've got some wheels.

What have I got on here, then?

We've got the motor, and that's what drives the train.

How many of those have we got on a train?

Cos that can't be the only one.

No, no, we've got five of these across the whole train.

And they're the brakes?

We've got the pad that's actually pressing against the face

of the wheel and that's your friction brake system.

So what's the next stage in our train, then?

So literally the next piece we're ready to do is to move the car

down and lower it down onto the bogies itself.

HORN HOOTS

That must mean something. We got a load of flashing lights.

The factory's largest overhead cranes spark into life...

Whoa. ..and carry our 28 tonne carriage...

It's a flying train.

..smoothly towards the bogies.

Extraordinary sight.

GREGG CHUCKLES

So happy it's moving away from me!

The steel bolsters I saw fitted to the bottom of the underframe

must be lined up precisely with holes in the centre

of the bogies.

If you get this wrong, that will cause a lot of damage.

You can see it just starting to pinch down now,

they're lowering it ever so slowly, just edging in.

Ooh! The bogie starts to take the weight of the car.

I thought taking a panna cotta out of a mould was a risky business!

Look at that!

You cannot get that a couple of inches wrong.

Are we docked? Yes, it looks like it. Yeah, that's it.

Absolutely.

It has taken quite a while, but we have finally got a shiny train

carriage on proper wheels. That's it.

HE IMITATES TRAIN HORN

95 passenger seats are bolted in...

..and our carriage is ready to roll off the end of the assembly line

to join the four others that will form our train.

So we've got the finished vehicle now.

We're just about to pull it out. Onto this? Onto this.

This is a traverser. I don't get it. Why put it on this?

We need to move the vehicle left to right across the yard.

So to do that, we need to traverse horizontally.

KLAXON BLARES Is it going to go now?

Is that it coming? That's it.

A powerful winch fires into action...

..and our 25 metre long carriage glides on.

Listen, I'm used to watching a train move, but not like this.

Look at that!

It's incredible, isn't it? That is crazy!

Even sounds like the train coming!

Mind the gap!

Just like our train,

the traverser is powered by overhead cables.

Amazing, isn't it? That is fantastic.

Rails in the ground guide it across the yard at a leisurely 2mph.

That's a train moving sideways.

Not many people get to see that. Absolutely not, no,

that's truly inside the factory, that is.

That's put an enormous smile on my face.

I think that is just beautiful.

I'm lucky enough to see quite a few factories, but honestly,

wow.

The assembly line produces 20 of these carriages every week...

..before they're coupled up and sent to the factory's final stop -

the test track.

That's a very impressive sight.

Brand spanking new, gleaming, it's just out the wrapper.

I want a minute to take it in, you know.

I don't suppose we're allowed inside, are we?

Yeah, go on, then.

All aboard!

Holly's doors, these are.

Come on.

There's seating for 490 passengers, with standing for 203.

It's got that new car smell about it, hasn't it?

Do you know, I know these trains,

these are the trains I ride, I know 'em.

Fully air-conditioned vehicle.

Can I go down to the cab? Take a seat into the driver's.

No way. Go on.

Yes!

Yeah!

This is very cool. Do you want to have a drive?

Seriously?!

Drive the train?! Yeah.

Have a go! Do you know what you're doing?

I think I do, cos I was in the cab with Holly.

Now, before we go off, don't forget to sound the horn.

HORN HOOTS

GREGG LAUGHS

Right, right, right, steady.

Then, if I move this back now, this is going to start moving, right?

Correct. VERY gently. No way.

Get out of here! I'm driving a train!

I am driving the train!

Craig, don't go anywhere.

Ahhhh!

Bring it back a bit. Bit more.

No, no, no, no, no, no, I don't want to go any faster!

A little bit faster. No!

You're only doing 10mph.

Get out of here!

Though this train is capable of 100mph,

with just a mile of test track...

Just going to slow it down a bit, I'm getting a bit scared.

..I think I'll stick to under 40.

I love this.

Mate!

This is incredible.

Now it's on me to bring all 187 tonnes...

Start applying the brakes.

..to a standstill.

That's pretty good.

That was one of the most amazing things I have ever done.

I'm glad you've enjoyed it.

That was absolutely brilliant.

HORN HOOTS

This service may be terminating here, but our train's real journey

is only just beginning.

From the factory in Derby,

it travels 147 miles south to a depot in Wembley,

north London, for testing.

Once complete, it'll ferry people all over Essex,

Cambridgeshire,

Suffolk and Hertfordshire,

and into London's Liverpool Street Station and back.

Each train will travel up to 132,000 miles every year,

transporting up to 7,500 people a day.

I've loved watching this thing being built, but as great

as it's been, learning about the miles of welding and seeing

the mighty cranes, the real highlight...?

Come on! What do you think?

Getting to drive a train!

Now, who can say they've done that?

That was amazing.