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Posted by zeristor 3 days ago

A train-sized tunnel is now carrying electricity under South London(www.ianvisits.co.uk)
145 points | 102 commentspage 2
mfateev 3 days ago|
That sounds like an excellent use for narrow boring company tunnels.
londons_explore 2 days ago|
Pretty sure they haven't yet achieved their cost/speed targets, else they would have easily won the contract for this tunnel.
blackhaj7 3 days ago||
Anyone know why the power cables in the image zig zag up and down?

Seems like it would require more cable than a straight line so I am guessing there is a reason for it

sokka_h2otribe 3 days ago||
Some good reasons:

-gotta hang them somehow, and in a very controlled way.

-thermal expansion, very important not to cause axial strain on a cable, which happens on tight bends.

You might think it would be enough to just have slack "somewhere" but I think you get to have many many micro adjustments when you have it across the entire length.

Why don't HV telephone lines do this?

I have no idea. Maybe because they can hang and droop more easily. I hope someone more knowledgeable gives a real answer.

matt-p 3 days ago|||
You are basically spot on. Thermal expansion (primarily) but you need it to be evenly spread for lots of boring reasons like as you mentioned axial force reduction, fatigue life, anchor load limits and so on. These tunnels just use forced air to cool the (XPLE) cables so they're not oil filled or anything. Tunnels are basically all thermally constrained.
blackhaj7 3 days ago||
Interesting, thanks!
blackhaj7 3 days ago|||
Thanks for the explanation!
7952 3 days ago|||
My guess is that the droop is just due to gravity. And it is easier to affix in fewer places. But the style of photography exaggerates the effect.
dmoy 3 days ago||
https://news.ycombinator.com/item?id=46334725

TL;DR

Camera makes it look more than it is, it's mostly just sag

If you want to see electrical with significant zig zag, open up the wall of a house that was built without very detailed plans, but still hired an electrician with a lot of prior experience being told to move stuff after the fact. They just zig zag it like crazy under the drywall, so there's an incredible amount of slack to pull wire to new and exciting unplanned locations.

blackhaj7 3 days ago||
Very interesting, thanks!
sowbug 3 days ago||
I'm looking forward to the next Amendment to the 18th Edition's conduit-fill factors.
jimnotgym 3 days ago||
So Everywhere else in Britain it is 'too expensive' to put cables underground. Just goes to show how London centric this country is.
KaiserPro 3 days ago||
Yes.

And I wish people would understand how costs work.

Pylons need space right, they also need maintenance corridors and access. Every ~360m you need a space to put a pylon[1]. Can you imagine the cost of buying 400m2 every 360 in zone 1?

what about the scaffolding when you need to re-string the cables? can you imagine how expensive that would be? what about if a lorry smacks into it? Its just not practical.

I grew up in norfolk, next to a bunch of HV pylons. No-one commented on them, because they were always there. THey are going to put some more in, and suddenly "its a blot on the land scape" and its "ecological damaging" Then its proposed that the cables are buried. apparently a 200 meter clearing 30km long is more ecologically friendly than pylons ever n hundred meters.

but thats an aside.

[1]https://www.quora.com/What-is-the-distance-between-electrici...

jimnotgym 3 days ago||
I wish that people understood how costs work? Does that count as polite conversation in London? It is about typical of how Londoners sneer at the rest of the UK.

London is the place that costs don't work. It is full of things that don't need to be there, driving up the real estate prices. The port closed decades ago, so let's move the insurance and FX markets somewhere cheaper? Let's move out the government departments too.

Modern London is all about MPs who are physically tethered to Westminster by in person voting, being surrounded by the kind of people who want direct access to MPs...

All of the companies who specialise in creaming money off real companies gravitate towards that pig trough. Today they need data centres as close as possible, so they can cream money off faster. And we now have to feed those parasites with extra power lines.

Don't lecture me on costs, while London continues to try so hard to inflate the price of the tidal mud it resides on, by sucking in the rest of the UKs wealth.

KaiserPro 3 days ago|||
> Does that count as polite conversation in London?

no, because this is mostly a logical fallacy.

> It is full of things that don't need to be there

Like what specifically? Most heavy industry moved out in the 70/80s, the port moved to essex in the 80s. The fish and meat veg moved out to canary wharf, and are going to move further out soon. what else should be taken away?

> Today they need data centres as close as possible,

This is a cable replacement, but yeah, lets go with new datacentres in london (as we know planning is quick and simple, so they are popping up weekly....) However the key issue is that population density is now back to somewhere like it was in the 40s (https://trustforlondon.org.uk/data/population-over-time/)

So whilst power demand is largely flat, infra doesn't last for ever, so even power cables need to be replaced.

> Modern London is all about MPs who are physically tethered to Westminster by in person voting, being surrounded by the kind of people who want direct access to MPs...

Yup, all 8.9 million people that live there are entirely there to do lobbying. I to am a lobbyist.

> Don't lecture me on costs, while London continues to try so hard to inflate the price of the tidal mud it resides on, by sucking in the rest of the UKs wealth.

Well, as you've neatly avoided any mention of costs of tunnel vs pylons, its not really a lecture is it. I hope you come to peace with the general concept of london.

bboreham 3 days ago|||
FX trading has been completely online for about 20 years.
jimnotgym 3 days ago||
You would think so, wouldn't you? Then why is the FX department at my bank based in London? As a mid market client they occasionally used to send one of them out to see me. They told me all about their office and team in London...sat in front of screens. Their system aggregated the banks position onto the screen of the master trader for each currency, sat at a screen in the next office. What utter waste
tim333 3 days ago||
FX departments are in London because that's where the FX traders want to be. There's no government department telling them to be in London. It's kind of how free markets work.
docflabby 3 days ago|||
London and the south east is the UK in economic terms. Its the only those 2 regions which are net contributor to taxes

https://www.ons.gov.uk/economy/governmentpublicsectorandtaxe...

jimnotgym 3 days ago|||
It would be nice to have a similar study that corrected for

1) the amount of wealth claimed to be generated in London, that was actually just financial services sucking in money from the rest of the UK

2) The cost of all the pensioners that left London when they retired, claiming their pension and health care in a different part of the country

nephihaha 3 days ago||||
This region is by far the most heavily subsidised in the UK in reality, which is confirmed by the number of expensive infrastructure projects there such as this one.

London is effectively kept going by these infrastructure projects and so many UK government agencies and businesses being headquartered there. Even the monarchy plays a role, as a massive gravy train mostly based there. All that money keeps other businesses in London going. Every time someone pays UK taxes in any form they are supporting jobs and physical facilities based there. The BBC is another one. People throughout the UK are forced to pay a licence fee that is mostly used to produce content in and about London.

This is part of a repeating pattern. London took massive amounts of resources such as coal, metals and manufactured goods from other parts of the UK which are now in poverty. The North Sea Oil boom of the 1980s, was used to prop up the London stock market, and only a fraction of that money stayed within Scotland which was suffering industrial decline at the time. (Aberdeen has surprisingly little to show for the oil boom and is now a city in heavy decline.)

matt-p 3 days ago||
Vast majority of the civil service is outside of London these days, I suspect disproportionally so.

BBC similarly, spends the vast majority of it's money outside London. If you were from anywhere near Manchester, Glasgow or Liverpool you'd know that perfectly well.

I'm afraid governments have actually done genuine work to try and reduce dependence on London to not very much avail. Network effects rule again, why is twitter (X) bigger and more popular than blusky or whatever?

onraglanroad 3 days ago|||
That's because all the wealth of the UK is leached towards London and the SE.

Then a small bit of what is leached is paid back in taxes and you pretend that means the leeches are subsidising the actual workers.

jasoncartwright 3 days ago|||
Sounds like you are trying to compare the many hundreds of miles (thousands?) of transmission cables needed to cope with the massive geographic change of generation sources to this ~20mi cable system.

There are many examples of how the UK is London-centric. This isn't one of them.

VBprogrammer 3 days ago||
It sounds like sour grapes. London contributes nearly a third of the UKs tax income. It has a higher population than the whole of Scotland.

Not to mention that over ground wires are manifestly better in every dimension except for aesthetics.

This is a great example:

https://youtu.be/z-wQnWUhX5Y?si=qdqrpJ-zS7lh2J8Z

jimnotgym 3 days ago||
>contributes nearly a third of the UKs tax income.

Because it contains all of the financial services business that screw money out of all of the real businesses in the rest of the UK.

zeristor 3 days ago|||
Manchester is burgeoning, still someways behind London.

It’d be super, smashing, great! for the cities to be far better connected together across the Pennines.

walthamstow 3 days ago|||
You're lucky to have us mate. London is the only thing going for this country. We should be betting /more/ on London.
immibis 3 days ago|||
On the flip side, that's mostly because London takes all their wealth and crowds out wealth generation
walthamstow 3 days ago|||
People move to where the jobs are. That's how most English towns came to exist in the first place in the industrial revolution.

We're ~30 years into a new information/digital revolution and London is a world centre of it. There's plenty of wealth generation happening. People are welcome to sit and wait for it to come to them if they want.

jimnotgym 3 days ago||
Can you give me some examples of wealth generation from London?. You can exclude the massive amount of Financial Services that they shout about so much, that is just a way of skimming wealth of real businesses.
walthamstow 3 days ago||
Seeing as you're already here, why don't you go to the last HN hiring page and search for London, then you can apply your special criteria about what's a real business and what isn't.
nephihaha 3 days ago|||
The UK is run as a city state for London's behalf.

The odd thing is that it makes fun of all those coal mining and oil producing areas whose wealth it has been only too happy to steal. A sort of internal colonialism.

7952 3 days ago|||
Well they are put underground sometimes when there is a sound reason to do so. But mostly there is not a good reason to do so across hundreds of miles of agricultural land.
nkmnz 3 days ago|||
What are the costs of an underground cable in the cities you’re considering, expressed as:

1. Cost per kWh transmitted?

2. Cost per person served?

3. Cost per pound of GDP generated?

Please provide this for London and the other locations you have in mind.

ra 3 days ago||
I know what you're saying, but maybe there is a tipping point when the economics is worth it.

Cool to see cycling down there - much safer than on the roads above.

nephihaha 3 days ago|
"In total, the £1 billion London Power Tunnels 2 (LPT2) project, which began in 2019, spans 32.5km across seven South London boroughs from Wimbledon to Hurst."

In spite of devolution and the so called "levelling up" programme for other parts of the UK, London obviously continues to be heavily subsidised by the rest of the UK.

EmbarrassedFuel 3 days ago||
"London obviously continues to be heavily subsidised by the rest of the UK"

This is a farcical comment. Were you being sarcastic? The tax revenue from London massively subsidises the rest of the UK. The investment happens in London because you can guarantee it will make a return, and quickly.

nephihaha 3 days ago|||
The real reason London is rich at all is because it was a trading depot with the continent. It made money from goods leaving England, and entering England. Later on, like Paris, it became wealthy off running an overseas empire, and when that empire vanished it turned to nearer territories.

London has centuries worth of investment from everywhere else based on that. That money has stayed there, and money is spent constantly on infrastructure which helps it make more money. Contrast this with Liverpool, Cardiff or Belfast which suffered decades of decline for various reasons and a fraction of the investment.

If the capital had been moved to Liverpool back at some point in the Middle Ages, then that would have remained a wealthy city instead of becoming a basket case in the eighties. The presence of the civil service and government alone would have kept Merseyside wealthy, and would have made it a huge tourist centre. Bigger than now, and even that was mostly to do with the Beatles.

By the way, the state funded Wembley refit cost more than the construction of the Scottish Parliament. Guess which one got all the negative press?

nephihaha 3 days ago|||
Let me put this another way. If I got given a very well paid civil service job, I would end up paying a lot of tax in return. And if someone paid for my house to be renovated and build the best utility and transport connections, then the value of it would go up.

And if mass media continued to promote my area continually then the value of my home would also go up. I would get given higher wages to cope with the increased cost of living there. We would get more tourists visiting my area, and firms and non-doms would set up there because of the positive image.

Much like London.

hshdhdhj4444 3 days ago||
You’re only explaining potential reasons why London is generating higher value.

Which is still implicitly accepting the fact that London does create more value that then goes to the rest of the UK rather than the reverse.

barnabee 2 days ago||
I don't see how this follows.

London is a net contributor of tax revenue to the rest of the UK, which presumably goes towards, for example, the 17 (non-London) power grid improvement projects listed at https://www.nationalgrid.com/the-great-grid-upgrade/where-it..., among other things.

The UK is often too London centric, but this project doesn't seem like evidence of it.