Underground housing, underground businesses, etc. Would that be better for the environment + possibly save on energy costs? Also possibly safer in certain scenarios like tornadoes etc.
Potential issues that immediately come to mind are ventilation, earthquakes, and flooding. But it’s not like underground dwellings/basements/etc. aren’t a thing, so maybe those issues have been addressed in ways I’m not familiar with.
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.
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.
If we’re just talking pure theoreticals built on a tabula rasa, okay then. Like you said, everything can be hand waved away.
This should answer all of your questions and then some
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?
how do you replace viaducts? Would that need demolishing buildings on top?
Afaik you build buildings on raised foundations and the viaduct decks span the gap between buildings creating a raised “ground floor” above the actual dirt. They eventually do wear out given enough loading cycles accumulating fatigue in the metal reinforcement, but can last a hell of a long time if you keep heavy vehicles off of them.
In an ideal world the viaduct top is for pedestrians or bicycles only, and there’s enough space underneath for logistics to supply businesses from loading docks at their basement. Overhead LRTs would be a natural pair with viaducts since you can just build the LRT piers to put their load path into the viaduct columns (which you also engineer to be larger.) that way you can separate all traffic types by verticality instead of all sharing the same grade.
The big benefit there is the viaduct deck doesn’t fatigue hardly at all. Maybe emergency vehicles allowed up on the deck? Otherwise it’s just bicycles or pedestrian traffic.