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Comment by pastor_bob | Hacker News Reader

Much of the London tube doesn't have AC. Talk about lack of planning. Pretty sure all lines of the NYC Subway had ac 25+ years ago and they're notorious for drawing out project timelines.

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Little consolation when you're waiting 15 minutes for the R train on the sweltering platform, ugh.

But yeah – sadly London's system used to be pretty cool, but the clay interior has acted like a battery, slowly absorbing the heat, and it simply can't absorb any more. It's a massive engineering problem (and oversight).

Great article on the why here: https://www.ianvisits.co.uk/articles/cooling-the-tube-engine...

To be fair, that’s been a work in progress for years, and some lines do have AC. It’s not like they haven’t been planning for it at all.

IIRC a big difficulty is that the tunnels are extremely narrow, so it’s just difficult to get any extra equipment in there. (I wouldn’t have thought that’s insurmountable, though, so there’s probably more to it than that.)

The lines without AC were constructed (mostly) in the 19th century. It's not possible to fit AC.

Alternative ways to cool the trains have been under investigation for decades, but there isn't an obvious solution.

They didn’t need AC in 19h century. The ground itself was cool and kept people comfortable.

200 years of constant usage has heated up the surrounding bedrock.

Space in the deep tube tunnels is really tight[0] (making it tricky to fit on-train air con radiators) and there's insufficient air circulation in the to clear the extra heat emissions in any case. They're working on both, but (unlike the shallower cut-and-cover lines and the NY Subway, both of which have saner tunnel sizes) it's decidedly non-trivial.

[0]: https://commons.m.wikimedia.org/wiki/File:Why_London_Undergr...

but many trains without lack if space, like DLR, are also without AC

Yeah, that's true. Expect that will change with the next set of new trains, as with the newish S Stock on the subsurface lines. Not all mainline trains have AC either, though I think it's been nearly universal on new trains from the 90s onwards.

Thankfully the Elizabeth line, opened this year, has AC. Both in trains and stations (at least the new build ones).

Small steps…

There was a competition to see if anyone could solve the problem

http://news.bbc.co.uk/1/hi/magazine/3069037.stm

Its much harder on the tube, as where do you dump the hot air? Back into the tunnel? London's clay has basically baked around the tube and is a really good insulator. Its not a particularly easy problem to solve.

You vent it to the surface, at least that's what NYC does.

These tunnels are much deeper.

The trains running in tunnels of similar construction to NYC have AC.

NYC is also a much warmer summer city than London.

The tube is for the dirty working class, AC is for the elite. A few weak people dying in London is no big deal - that's how life in London always worked.

Everyone in London uses the Tube. What are you on about?

What are YOU on about? Have you seen the queen, BoJo or any really rich person on the tube?

I've seen several wealthy celebrities, yes.

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