For this stop on my road trip, I was visiting the River Tyne,

and I was going to be getting very cold and wet,

but not in the way you might expect.

The Tyne was the boundary between the counties of Northumberland and Durham,

up in the north-east of England.

These days it’s more complicated,

but historically the Big River marked the border.

And while I started this video on the north side of the river,

in Northumberland,

the reason I was there is over in Durham.

In 1968, the Tyne Road Tunnel opened to the public,

with a second tunnel added in 2011.

I parked up at the tunnel headquarters, and I was there for three things:

first, so the team could show off behind-the-scenes of the tunnel.

Second, to learn about a fire suppression system that I’d never heard of before.

And third, to stand under that system while it was being tested.

So, I put on safety gear, and the first stop was the control room.

-Come in. -Oh, blimey.

-This is the control room. -You have a proper mission control here.

That’s David, he’s the operations manager.

And his team were watching more than

200 cameras inside the tunnels,

helped by an automatic system that detects if anything’s out of place.

We’ve got the vehicle coming in here, in the northbound tunnel.

We’ll wait for one to come through. -Okay.

-Nice blue truck there. -Yep, big truck.

-Right back round. -Yeah.

And then it will come along to here.

Oh, so it’s always…

And we follow the vehicle all the way along.

As soon as it starts to leave one camera, it joins the next one.

Yeah. It will go all the way along to the very end

and it comes back round on the second row.

Right!

The two tunnels are very different in construction:

the first was dug by hand and by machine

15 metres between the top of the tunnel and the river bed.

The second is an immersed tube, constructed on land,

sunk down into a trench, sealed up and drained.

Then the trench is filled in and covered in a lot of rocks.

There he is.

Approximately two and a half, three minutes to get through the tunnel.

Most of the time, of course,

it’s all quiet in the control room.

But that control room

is there for a reason.

We approximately have between 7 to 15 breakdowns a month.

-Okay. -But then at the weekend we might have

a drunken person trying to walk through the tunnel.

We have animals trying to get through the tunnel.

It can be vast and varied.

That’s more often than I’d think.

So we have a target time of ten minutes to try and get that breakdown out.

At rush hour, there’s a calculation that for every minute that the tunnel’s closed,

that’s one mile of traffic jam outside.

Right.

And every time you have to hit the…

I assume there is a button which I’m not allowed to point my camera at somewhere,

that is the emergency stop.

-Have a look here. -Oh, okay.

I actually was allowed to point my cameras at the safety systems,

but I did agree to let the Tunnels team look at this video before it goes out,

and if you see anything blurred or marked as removed, that is for security.

They don’t have any editorial control over the words I’m using

or the story I’m telling, though.

There were big emergency buttons on that screen,

three of them all labelled

“STOP”, and Jack, controller on shift, said that hopefully

they never have to use them.

-We tend not to press the big red ones. -No!

If you do, something’s gone wrong there.

-It just scares you. -(laughter)

Jack also told me about

the ventilation in the tunnel, which is gonna be important later.

There are jet fans mounted on the roof to keep the air moving,

but they’re not always needed.

What you’ll see is something called the piston effect

which when there’s quite a few vehicles in there,

it naturally draws fumes out of the tunnel.

Yeah. Okay.

Lower times of traffic, such as now or through the night,

the piston effect decreases... -Right.

...so, you rely more on the help of the fans.

Stick a pin

in that “piston effect”, we’ll come back to it.

But with the sun set and light fading,

we walked out to the tunnel itself, with a few other folks from the team in tow.

We had to cross the road, which would normally be complicated,

but they timed it well:

there were two vehicles passing through with dangerous cargo onboard,

which meant the tunnels would be closed to any other traffic

for just a couple of minutes.

Those are the dangerous vehicles that were going through.

Petrol, by the looks of them.

And they just asked…I’ve got to keep quiet while we’re walking across.

We were well outside rush hour, it was nearly 9pm,

so, that closure wasn’t gonna cause too much trouble.

And it gave us a gap to get across without slowing anyone down.

And there go the cars.

Time to go into the tunnel, the oldest of the two,

with one of the big ventilation chimneys looming in the distance.

We were starting in what’s called the Escape Gallery.

This is now hats, gloves.

-Yeah, right. -It’s a hat and glove area.

-Helmet on, helmet tightened. -Just at the back, underneath.

Got it. Thank you so much!

That’s very loud and very close.

You’ll probably feel that wind, that positive pressure.

Oh, yes.

The escape gallery is kept at positive pressure,

air constantly forced in,

because if something happens in the tunnel

and people have to get out of their cars and evacuate,

that gallery needs to have clean air no matter what.

This is the big chimney.

Oh! That’s the big chimney!

So, gloves on.

As you go down, one at a time, it’s not very far, this one.

Yeah.

The next stop was down a ladder into an area

that the public definitely aren’t allowed into: the service gallery.

You’ll probably hear a few vehicles rumbling over our heads...

-Yeah. -...but this is absolutely amazing.

This is underneath the road deck. -Oh!

-And you can see… -Oh...

...I’m six foot five, so you can kind of work the distance out.

Yeah.

But you can hear the rumbling, especially when you get the trucks coming through.

That’s going over our heads.

Supporting stanchions either side of the tunnel.

-Yeah. -And this is the void.

On the side were four big pipes:

two for drainage, and two for firefighting.

The one down below, the smaller one, is the mist system line.

-Mm-hm. -The mist system…

Oh right, yeah. But that’s not the same as the fire main?

That’s not the same as the fire main. It’s two different systems.

One for when the firefighters turn up and need to plug-in.

-Yeah. -And one for the automatic system.

-For us, yes. -Yeah.

The Mist System was the real reason I was there.

When I put a call out for video ideas for this series,

the Tyne Tunnels folks got in touch

asking if I wanted to look behind the scenes

and see their fire suppression system, the first of its kind in Britain.

And they suggested that I might want to stand underneath it

when they were doing a test. (laughs)

So,I had that to look forward to!

Also, the new person on camera there is Barry

who’s worked at the Tyne Tunnels for 27 years.

He wasn’t actually wearing a mic

because he was just going to be behind the camera,

but turns out he was great.

He had a lot of interesting things to say, and he said

he was okay to appear now and then.

Now, when they’re gonna turn the mist system on,

these are the valves that turn on.

He did take the box off to show those valves.

To lock it off for maintenance,

you have to turn the valve handle at the bottom right,

and if you do that, you can’t put the red box back on.

You have to have that in that position before…

If you accidentally left it locked out…

-This won’t go on. -Right.

And then you’d know that it’s not working.

You’d know there’s a problem. -Yep.

It also alarms in the control room... -Right, okay.

-...as well, so there’s lots of fallbacks. -Okay! Yeah, that’s fair enough.

The air in the service gallery was clean.

I was expecting to be able to taste petrol fumes, but no:

air is forced in, just like the escape gallery,

which, by the way, wasn’t part of the original construction.

-The escape gallery was put on later on. -Right.

Because of the Mont Blanc tunnel disaster.

In 1999, a truck carrying flour and margarine

caught fire in a tunnel under Mont Blanc on the French-Italian border.

Flour is highly combustible, margarine is basically oil.

The fire burned for days,

39 people died in the heat and smoke, and that disaster

prompted safety upgrades to tunnels around the world:

cameras, ventilation, fire suppression systems,

proper co-ordination and control,

even closing the tunnel to other traffic

for the couple of minutes that those petrol tankers were passing through.

There’s a saying that safety regulations are written in blood.

And while you can never prevent every risk,

you can certainly make a difference.

We walked along the tunnel for quite a while,

past the lowest point where any water would drain into a sump

to be pumped back up and out.

And then Barry led us into one of the crawlspaces

to where the fresh air was being pumped in from the other chimney.

(groans)

Well, I’m now old enough that I make “ugh” noises while I’m doing that, that’s fun.

Oh, I can feel the fresh air from that!

That’s what makes it nice and fresh in here.

Right.

(clanking)

-Do you want to come in? -Absolutely!

Come on then.

It’s really difficult to explain what that feels like.

It is a literal breath of fresh air in a place that was pretty fresh anyway,

but it’s sudden cold, outdoor air coming...

Oh my word! Alright.

So, that is the duct that’s bringing all the air in.

Yes, yes.

Wow.

(helmet hit) Ow!

And that’s why we have the helmets!

(laughter)

There was some clambering up ladders made of rungs that were just set into the wall.

I feel like a bloody six-foot-five mole!

Oh, wow.

That is a long way up.

-We’re not going up there now. -We are definitely not going up that.

Good heavens.

So that’s right to the top of the chimney?

Yeah. That’s right to the top.

Then it was back down,

through the service gallery, up to the escape gallery

which does run all the way along, obviously.

We’d just gone underneath instead.

There’s a lot of mind-your-head signs here.

Oop-ah!

And watch your head coming here, ’cos it’s pretty bad.

Yep.

There were two lanes of live traffic right next to us

as we headed back out the tunnel and into the night,

having made it to the historic county of Durham.

These days, the whole area on both sides is called Tyne and Wear,

but I’m going by historical definitions,

and the equipment for the mist system, the thing I’m there to see:

that’s in Durham.

And to get there, we had to cross the road again.

So we’ve got red lights there and the traffic has stopped.

Red lights there and the traffic has stopped.

So, this traffic lane is actually open right now.

But we know that this is all safe because someone is blocking all the traffic

on a rolling roadblock.

There was a tunnel patrol vehicle coming through for the evening maintenance,

travelling slowly and straddling both lanes southbound,

which meant there was a big gap for us to walk across.

Northbound, I think we delayed two cars by about one minute?

Sorry if that was you.

Control’s put the red lights on, stopped the traffic.

-Yep. -Make that pause. Monitor through CCTV.

We know where the gap is. -Yep.

On the radio to us, safe to cross the road.

-Yep. -Release the traffic straight away,

get everybody moving again. -And away they go.

It’s as efficient as that.

Then, into the South Extract Building, which has pumps, maintenance supplies,

some of the backup power, and the water tank for the mist system.

200 tonnes of water, ready to go.

And we’ll see that in just a moment.

Here’s some audio of me in the shower.

(water running, surprised "huh")

I had a new razor, and that was my first time shaving with it.

I didn't take video, ’cos I was in the shower.

I’ve been using disposable razors all my life, because

that’s what I started with, and I never thought to change that.

I thought razor burn was just an inevitable part of shaving,

but it's a design flaw.

Most modern razors flex a bit and bend slightly, so

the angle’s a bit wrong,

and it feels like you have to push harder.

The manufacturers use workarounds, like lubrication strips and

double or triple or septuple blades, but the root cause

is that the razor flexes.

Henson Shaving sent me over their razor.

It’s made by aerospace engineers, built to very precise tolerances,

and machined out of aluminium, so it's solid.

First time using it, first time ever using a razor like it,

it was as good as the disposables.

After a few shaves, when I got used to it,

it was better.

I’m getting less razor burn, and

I’m not buying expensive disposables that I just throw away.

And I assumed Henson was going to be some subscription lock-in thing, but

no: the blades are the international standard double-edge ones.

If you want to use a different brand of blade, you can.

Henson just make a very solid, very good razor

that will last a long time.

If you scan the QR code, or follow the link in the description,

you can buy one, and they’ll also add in

a hundred free blades, which will last most people years.

Enough dallying around: the South Extract Building,

and the mist system’s water tank.

-Oh, that is the tank just there. -That’s the tank there.

Because people could get hit with it.

It’s so big.

There’s a nice life ring there. -There’s a life ring!

Oh, I like the life ring.

-Yeah, because someone could fall in. -Absolutely.

And they might not know how to swim.

I mean, hopefully if they’re here, they do.

Well, look at the height of it.

(laughter)

Just to be clear, that was a joke!

They do not have pool parties in the water tank!

It’s very cold, dark, deep mains water.

And because that tank has to be kept filled at all times,

it has a float valve, and…

look, there is an alternative term for a float valve,

and we’re all just going to have to agree

not to laugh at the next few seconds of this video, okay?

We’re all gonna be professional.

-Oh. -So, the water comes in…

That’s just a ballcock for your cistern. -That’s a ballcock.

-It’s a ballcock. -That’s the same as you find in a toilet.

It’s the biggest ballcock you’ve probably ever seen in your life.

(laughter)

Don’t, don’t...just don’t.

It’s just a height measurer.

When that drops, this valve opens.

-Absolutely. -Yeah.

When the mist system’s activated, they turn on three fire zones:

the one the fire’s in and one either side

for a total of about 75 metres.

And for that, the mist system uses 2,000 litres of water per minute,

which is a lot, but not as much as sprinklers or a deluge system.

It’s designed to suppress a fire, give people time to get out,

and give emergency services time to arrive.

And to pump that water…

How much…oh! (pump humming)

I thought the pump had just started there.

-That’s your jockey pump. -That’s the little one, yeah.

The jockey pump

keeps everything at a safe pressure, ready to go.

It’s meant to fire up regularly.

For a moment, I thought the system had actually been activated,

but, no, that would have been much louder.

There’s a pipe from the tank…

2,000 litres of water a minute through a single filter,

or about a bathtub every six seconds.

That’s a good filter.

And then thirty-three pumps.

Those aren’t for different parts of the system.

When that thing fires off,

all of those pumps are ready to run.

That’s not 140 PSI.

They’re using metric units, 140 bar.

Mains water pressure, the stuff that comes out of your tap, is maybe three or four.

140 bar is what you get out of a pressure washer,

the ones that blast walls and driveways clean,

except those pressure washers use 10 or 20 litres a minute

instead of 2,000.

And it runs to destruction, because the alternative is a fire.

Right.

Tonight, they were testing

Fire Zone 4 northbound,

which conveniently for me was also in County Durham,

just a little way into the tunnel.

This was scheduled maintenance and it was all gonna happen very quickly.

They’d be closing one lane overnight, 10pm to 5am,

creating what they call a “dead lane”.

So, 10 o’clock is about the time where traffic’s light,

least disruption to the north-east.

We can manage all the traffic in one lane.

That allows us to do cleaning works and maintenance works

whilst we keep the tunnel open.

And one lane open during the night is enough.

-Yep. -So we don’t get any traffic jams.

It’s still free flowing.

To close that one lane and make it safe for the workers overnight,

a vehicle has to go through the tunnel dropping cones all the way along,

and that’s a process that takes

ten minutes or so.

The tunnel is closed for those ten minutes,

all traffic stopped, and while that happens,

they will also have…

A fire test in, I think, Zone 4.

(chuckles)

I’m gonna be standing under it!

This was their suggestion. I didn’t come to them for this.

They suggested this.

So, we followed the maintenance vehicle into the tunnel.

It feels so odd to be walking through the tunnel.

Yeah, it’s magnificent.

And I don’t know if you can see this, but there’s your two lines there.

-Yeah. -They’re your mist system.

-Oh. -See your mist heads there?

-Yeah, okay. -So, either side.

I mean, that’s…let me just make sure I’ve got that shot.

So, both sides of your lanes are covered with separate mist lines.

So, we’re looking at the line that’s going along…

-See this here? See the head there? -Yeah.

That’s your nozzle jets.

Right, and it’s not like a sprinkler head.

It’s not like you find in a hotel or something like that.

-Very, very fine. -It’s very fine mist.

That’s really important.

The “mist” in mist system isn’t an acronym, it doesn’t stand for anything.

It isn’t an old style sprinkler that just dumps as much water as possible.

It uses superfine mist that will evaporate very, very quickly,

sucking heat out of the air and turning to water vapour,

cooling down fires and even scrubbing out some of the smoke.

And remember

those jet fans that we talked about back in the control room?

I don’t know how much the camera can pick up…

there’s sort of a gentle rotation in there?

That’s something called the piston effect.

As the vehicles come through, they’re dragging air through constantly.

Right. I feel like I can still feel that now.

There’s still a little bit of a draught, but when the trucks come through,

you’ll feel that suction of air come right the way through the tunnel.

“There’s still a little bit of a draught,”

said David.

He was right, and in hindsight, we should have remembered that.

I don’t want to lower your expectations too much, believe me,

I was about to get soaked, but the plan was to stand in the middle of Fire Zone 4,

hold there for about ten seconds, and then walk forward out of it.

Just beyond that speaker there, this is your fire zone.

One thing I’d change

if I filmed this again:

I’d stand a bit further back,

because half the mist was gonna be pushed away from me.

A single fire zone is only 25 metres long,

and that mist is very, very light.

We all forgot the piston effect would make a difference.

If I’d stood further back, or maybe not central in the road,

I could have disappeared into the mist entirely.

That said, it was still…an experience.

When it happens, I want you to look for three things:

First, just how much high-pressure water is coming out of the nozzles in the roof,

and how fast it’s moving.

Second, how light and gentle that seems, at least by comparison,

by the time it hits the ground.

And third, while it might not be obvious until you see the close-ups,

just how absolutely soaked I am in a couple of seconds.

I’d brought every camera that I could.

I handed them to various members of the team.

Rolling. Okay, folks, if everyone can roll their cameras, please?

And then I tried

to look composed.

And I think I was, at least until I was startled

by one of the loudest, most terrifying industrial noises I’ve ever heard.

So, this is what it comes down to.

There’s no microphone on me.

And to be clear, this was their suggestion.

I didn’t ask for this. I put a call out for ideas...!

(loud screeching hiss)

Good grief!

(hissing roar)

I almost managed to stay for ten seconds. Almost.

(hissing roar)

And the most startling thing about it…

is just how incredibly cold that is!

(hissing roar)

(laughter)

I felt frozen, because that’s what mist does.

It hits your skin and then your body heat evaporates it,

cooling you down and leaving space for more mist to do the same.

That’s why it’s such a good fire suppressant.

That is incredible! (hissing)

I should have stayed in there for longer.

I intended to, I thought I had!

But it was so cold and so intense that the survival parts of my brain went,

“Get out now, get warm!”

I absolutely believe that works on fires.

That may not have looked like much,

but that soaked me immediately.

Every single bit of me.

I’m so cold.

And that’s the point of it.

The point of it is it’s mist! (sighs)

Transport down there, do you want it?

Yeah, I think I should probably get in there and get dry.

I’m gonna start shivering.

Thank you very much, everybody.

(laughter)

Next time, or right now on Nebula:

I take a long walk on a dangerous beach

and meet someone with a 500-year-old job.