Comment on Would it be better to just have a lot of society be underground?
grue@lemmy.world 4 days ago
Everything you think would be good about underground would be more easily and cheaply accomplished by building aboveground buildings that connect. (Or said another way, by effectively raising ground level to roof level without the expense of digging.)
effectively raising ground level
I can’t say I follow what this means. Moving everything we have at ground level up? I understand that this kind of thing has happened historically but only in periods where we barely built a couple of stories high.
I’m looking out over the Tokyo skyline right now and there’s every level of building. How do you get everyone to agree on the one right height?
Consider the following scenarios:
You start with a hill, then dig down into it and build a building such that it has a flat green (vegetated) roof at the original ground level.
You start with flat ground, build the same building on top of it, then mound dirt up around the sides to form a hill.
Two methods to the same result, right?
But now, imagine that instead of one building, you’ve got an entire city worth of buildings like that bunched up touching each other (no roads between them, just interior corridors). With scenario #1, you’ve still got to do a bunch of excavation for each and every building. But with scenario #2, you only need to do earth-moving around the perimeter of the city (if you even bother). Still the same result, but now method #2 is much, much cheaper.
I’m looking out over the Tokyo skyline right now and there’s every level of building. How do you get everyone to agree on the one right height?
This is a very hypothetical thread, so that’s the kind of issue that could just be hand-waved away as part of the initial premise. But if you want a real answer, that’s easy: “zoning codes.” Cities have absolutely no trouble exercising their authority to regulate building height.
Both of your scenarios seem to start with an empty landscape. When I heard “move the ground level up” I took that to mean that we are starting with an existing cityscape that has a ground level, and everything must be elevated.
It were just talking purely theoreticals built on a tabula rasa, okay then. Like you said, everything can be hand waved away.
I’ve actually been there. Like I said, it’s a gallery with little depth and does not answer how this would be applied to modern architecture n any kind of scale.
The city burned down which allowed these sweeping changes to happen. The minimum height is set by preventing yearly flooding due to heavy rains and strong tides since the area was filled in tidelands. The maximum was set by the rest of the city and its Hills. This is an engineering problem so you solve it the way an engineer would.
The way you would do this for a modern city is by first considering geography and your design requirements. “How much do we need to raise it and why?” If you only need to fit utilities in there and nothing else your necessary lift isn’t that high. Maybe a few meters. If you want to also cram cars or trains down there so you can build to viaduct top lighter by mandating no cars, and to make it a walkable city, you can set a higher requirement. You’re basically building a bridge that spans the entire city and the same calculus works for a viaduct city as it does for designing a bridge. Your biggest expenses are regrading, foundations, redoing drainage, and routing utilities into the viaduct passageways and abandoning existing utilities in the ground from the old city. That’s all if you can avoid eminent domain or conflicts with property owners.
All of this is obviously way easier to do with a newly built city from day 0, or a city that burned down. The reason it happened in Seattle is because residents were sick of yearly flooding and they needed to rebuild with fireproof materials anyways. So why not solve both?
iocase@lemmy.zip 4 days ago
The irony is if you designed a city with viaducts, the savings on ground disturbance and the extension in life for utilities (now high and dry instead of rotting in the dirt and corroding, being hit by fiber-seeking backhoes) pays for the viaduct system itself even if it costs tens of billions for a city.
When your domestic water system now lasts a century instead of 40 years, and leaks can be spotted and repaired from a catwalk, the savings compound over that same century. Apply that to power, gas, heating, cooling, telecom… Plus they stop hitting each other any time you need to dig more than a foot. Now telecom will stop hitting water lines when they go to repair broken fiber that was hit by a new construction excavating a foundation.
A 40 year buried power lifespan that cost $5 billion to install for a city means each year you need to replace 1/40th or your power cables and would annually spend 1/40th of $5 billion, or 125 million.
Those same cables in a utilities rack within a city viaduct system might last 2-3X as long since they’re dry, don’t move with frost heave, don’t experience being driven over by fully loaded semis, aren’t at risk of being hit while repairing something else…
iocase@lemmy.zip 4 days ago
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