
An underground cathedral protecting Tokyo from floods - pseudolus
http://www.bbc.com/future/story/20181129-the-underground-cathedral-protecting-tokyo-from-floods
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240dl
I took a trip to this place when I was in Tokyo last spring; here are my
pictures for the curious:

[http://www.lucashayas.com/journal/2018/11/18/maoudc](http://www.lucashayas.com/journal/2018/11/18/maoudc)

It cost about 80 bucks all told and was a bit of an ordeal to organize (you
need a fluent Japanese speaker), but was definitely an experience. It was a
little disappointing in how limited our tour was. I get the sense that they've
narrowed down the area you can wander since opening. Still, I've explored
storm drains in the US quite a bit and this was a whole different level.

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pseudolus
Your pictures are stunning. The entire facility has quite a sci-fi aspect to
it. Did you actually run into any hornets? :)

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240dl
Thanks! Didn't see any scary hornets sadly. The whole structure is totally
sci-fi, even inspiring a level in Mirror's Edge.

You might also enjoy some of my other drain exploration shots from stateside:

[http://www.lucashayas.com/journal/2015/3/31/minolta-
af-s](http://www.lucashayas.com/journal/2015/3/31/minolta-af-s)

[http://www.lucashayas.com/journal/2014/1/19/understructure](http://www.lucashayas.com/journal/2014/1/19/understructure)

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tareqak
What's cool to me is not only the planning and engineering involved in
creating these sorts of responses, but ability to accumulate the funds, the
political will, and the discipline to see it all go through start to finish.

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RobLach
Read about Chicago’s Tunnel and Reservoir plan.

It’s a 60 year underground water infrastructure plan that’s been miraculously
more or less on schedule and budget.

[https://en.m.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan](https://en.m.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan)

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OldHand2018
The Chicago system is about 2 orders of magnitude larger (someone might want
to check my pre-coffee morning math), but a very big distinction is that
Chicago stores the overflow water in outdoor, open-air reservoirs, not
underground storage tanks.

I agree that it is rather impressive for a long-running American construction
project to be on-time and on-budget, but keep in mind that most of the project
has been tunneling through very consistent bedrock with nothing in the way.
Also, the McCook Reservoir mentioned in the wikipedia article as 13x10^9
liters is a former limestone quarry that they purchased and then connected to
the system. The wikipedia article says it will be expanded to 38x10^9 liters
by 2029. That's true... but what is really going on is that all they've done
is sign a contract to buy the quarry on the other side of the highway once the
stone company is done with it, perhaps around 2026 or so. Only then will they
do any construction to connect it to the system. Don't get me wrong, it's a
very smart move. But it's not an 11-year long project for which they have to
maintain a schedule and budget.

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Hoasi
This is quite magnificent, some pictures here:
[https://ja.wikipedia.org/wiki/首都圏外郭放水路](https://ja.wikipedia.org/wiki/首都圏外郭放水路)

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nja
wow, those pictures bring to mind the film depiction of the mines of moria in
terms of scale and regularity

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bdamm
It's big, but I haven't seen any information about how the capacity of the
system compares to the capacity of the rivers feeding into it to generate
water. Would the system survive a Harvey-type event? Or is it meant to deal
more with seasonal fluctuations to prevent runoff causing flooding? 100 tons
per second doesn't seem like a lot to me, compared to runoff that can be
generated during spring thunderstorms. It's impressive and no doubt Tokyo will
benefit from the infrastructure, but really the main chamber does not look
much larger than a dig for a large skyscraper.

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240dl
In addition to the main chamber there are several pits that also store lots of
water. Here's a photo I took on the tour that might show it better:
[https://static1.squarespace.com/static/5265796de4b0bacb22141...](https://static1.squarespace.com/static/5265796de4b0bacb221414bc/t/5bf1a9784ae237221b19d406/1542564238049/Metropolitan+Area+Outer+Underground+Discharge+Channel+3.jpg?format=1000w)

Unfortunately I don't remember the tour specifics well enough to confirm the
exact use case of the system.

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kweks
From what I remember (and similar to other designs), the pits take the brunt
of the flash flooding, before releasing into the chamber. The reservoir can
hold the water for as long as required before dispatching it.

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jurip
Helsinki doesn't need flood protection, but we have a large (~25000 cubic
meters) underground lake right in the center of the city for heat management:
[https://gizmodo.com/helsinki-built-an-underground-lake-to-
co...](https://gizmodo.com/helsinki-built-an-underground-lake-to-cool-its-
building-1631985837)

The local energy company is also converting some artificial caves, originally
dug for oil storage, to similar use:
[https://www.helen.fi/en/news/2018/Gigantic-cavern-heat-
stora...](https://www.helen.fi/en/news/2018/Gigantic-cavern-heat-storage-
facility-to-be-implemented-in-Mustikkamaa/).

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Nux
Pretty awesome!

Reminds me of the cisterns underneath Istanbul (Constantinopolis), built by
the romans.

[https://en.m.wikipedia.org/wiki/Basilica_Cistern](https://en.m.wikipedia.org/wiki/Basilica_Cistern)

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kweks
There's a few things similar in Paris as well. Most dense cities with little
natural run off have them.
[http://ninjito.com/2009-07-19](http://ninjito.com/2009-07-19)

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crochi
I love this level on Mirrors Edge

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cdkee
Came here to post this. Now I know where they got their inspiration! Though,
ironically enough, I always got the vibe that that city from the first game
was more like Singapore.

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Apocryphon
Now that’s what you call a GeoFront.

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Joakal
Any pictures of it flooded?

I searched and could only find pictures of it empty.

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kweks
The ones we visited in Paris have 50cm thick solid steel doors and submarine
hatch style wheels to wind them shut.

I would anticipate that even just the air pressure that is expelled during a
surge is probably enough to cause serious damage to people.

On the scale of G-cans, it's hard to know if it would be more dangerous or
less dangerous..

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audiometry
Last week we tried to book a ticket for a visit next month. (They have a
strict schedule). Unfortunately seems tours suspended until March 2019.

