Eurotunnel question?

[Asherline]

Why is it deep underwater and not above the water like a bridge? Cannot find any explanation online

It’s tunnelled under the sea bed, tunnelling is a lot cheaper than driving the hundreds of support piles you would need for a bridge. And I imagine a bridge would disrupt the boat traffic

@FelicityBeedle so why don't other bridges go under water and not on top? Your right stopping boats, but other bridges halt traffic and raise to let them through, why not go under ?

It’s the physics of the bridge. They can only get so long without becoming unstable. Most bridges rely on a combination of forces to keep them in place - think of a suspension bridge: the suspension only works if the bridge is a certain length for the cables to support and stabilise it, and the cables are hung from massive pillars. Other types of bridges rely on different distributions of forces depending on the size and type of the bridge - but beyond a certain size they all need some kind of supporting force from below or above to make the bridge stable.

It’s cheaper to build a small bridge compared to a small tunnel. But cheaper and easier to build a long tunnel than a long bridge.

@irresistibleoverwhelm that actually makes it sound so obvious!
Thank you

It’s possible to spend quite a few happy hours hopping around the pages on different types of bridges on Wikipedia!

Interestingly the longest bridges in the world all tend to be in China where labour is cheap, they have a command economy in infrastructure and they stockpile a lot raw industrial materials like steel. They’re also quite recent builds.

The outlay required to build an infrastructure project like that is huge - you’d probably not get a Western government to undertake that kind of project and it wouldn’t be profitable or financially feasible for a private company to take on either. The company that built Eurotunel was constantly beset by financial problems and project overrrun, and if I recall correctly had to be restructured several times to avoid collapse.

It’s an interesting subject!

@irresistibleoverwhelm now i understand it but more will keep investigating. It is really interesting but was constantly too complicated for me. Was it a 50/50 English and French prodject. Wouldn't have ever though it could be an independant project to me it would have to be international government thing

It was privately financed, though by both French and English companies iirc!

It was a joint project between the British and French. There is more about how the tunnel operates here:

en.wikipedia.org/wiki/Getlink

It's actually a private company. The legalities of how the international border works are governed by the treaty of Canterbury.

The Channel is 26 miles across and the busiest shipping lane in the world. A bridge would be like putting a road across a runway at Heathrow.

There's more about the shipping lane here -

www.marineinsight.com/marine-navigation/the-strait-of-dover-the-busiest-shipping-route-in-the-world/

Thanks for the links. Will have another good research now. It's so hard to understand do projects on a large scale get privately funded these days ? At that if that company goes bust or decides to stop people using the tunnel our whole country could be affected

The tunnel was started in the 80s. Margaret Thatcher wasn't keen on massive public spending. See also another big Kent infrastructure project, the QE2 Bridge - en.wikipedia.org/wiki/Dartford_Crossing

I would say @irresistibleoverwhelm covered this quite well. The Chinese can do government funded projects like this, but in general, no, most other places would use private or a mixture of public/private. For example, Hinkley Point, although that's perhaps how not to do it - www.theguardian.com/news/2017/dec/21/hinkley-point-c-dreadful-deal-behind-worlds-most-expensive-power-plant

Getlink/Eurotunnel did go bankrupt a few years ago. I think if it can't be refinanced there's a provision in the treaty of Canterbury for the company to be replaced by another entity chosen by the British and French governments. I am pretty sure it's all covered by that. It's too strategically important for it not to be governed by international law.

Capitalism means that private companies own the means of production. As the revenue generation here is passenger/freight traffic, Get Link is not going to stop people using the tunnel.

If you're interested in how things work, take a look at another treaty, the treaty of le touquet, which allows the British and French to carry out border checks at the point of departure. In other words, you go through the French border in St Pancras/Ebbsfleet/Folkestone and the British one in Coquelles/Lille/Gare du nord. This is brilliant from a customer and practicality perspective, you drive off the train and straight onto the motorway, or leave the train at the gare du nord and are out in minutes, but Brexit made things a bit tricky.

The geography of Dover/Folkestone doesn't make it possible for large holding areas to be built there. That's why there's a massive lorry park up the road in Ashford.

The whole county and road system in Kent is funnelled towards the channel and it is brilliant to have a crossing that isn't weather dependent.

Strikes or storms mean Stack or Brock on the M20 which is miserable. That's another reason a bridge isn't practical. You need a constant movement of traffic otherwise things get difficult very quickly.

You have made some great points which I never knew before. I've never heard of these treaty's before so have been helped so much today with some basic understanding, but goes so deep for me to follow. I hope to get there a bit at a time because I want to understand. This is why Brexit should have never been a public vote in my eyes, because most people don't understand what is involved, me included

The Channel is one of the busiest waterways in the world, with a rising bridge it would need to be open for shipping to pass through most of the time.

Bridges get closed in bad weather. Another reason tunnels are better.

(I remember the tunnel meeting in the middle. I was at Primary school)