From an urban planning perspective, there are some caveats to your points:
A new downtown would make a subway very easy and cheap to build, you could cut and cover instead of tunnelling
Cut-and-cover will make shallow underground tunnels cheaper to construct in almost all cases irrespective of building in an old city center or as part of building a new city center from scratch. In fact, older pre-WW2 cities are almost ideal for cut-and-cover because the tunnels can follow the street grid, yielding a tunnel which will be near to already-built destinations, while minimizing costly curves.
Probably the worst scenario for cut-and-cover is when the surface street has unnecessary curves and detours (eg American suburban arterials). So either the tunnel follows the curve and becomes weirdly farther from major destinations, or it’s built in segments using cut-and-cover where possible and digging for the rest.
Cheeeaaap land for huge offices, roads, and even houses
At least in America, where agricultural land at the edges of metropolitan areas is still cheap, the last 70 years do not suggest huge roads, huge offices, and huge house lead to a utopia. Instead, we just get car-dependency and sprawl, as well as dead shopping malls. The benefits of this accrued to the prior generations, who wheeled-and-dealed in speculative suburban house flipping, and saddled cities with sprawling infrastructure that the existing tax base cannot afford.
Green field is just so cheap.
It is, until it isn’t. Greenfield development “would be short term appealing but still expensive when it comes to building everything”. It’s a rare case in America where post-WW2 greenfield housing or commercial developments pay sufficient tax to maintain the municipal services those developments require.
someguy3@lemmy.world 1 month ago
There a huge difference between cut and cover in a green field, vs cut and cover in an existing downtown. Huge. That’s if you can even do it in an existing downtown because of the road alignment and existing underground utilities. It’s really unlikely you can do cut and cover in an existing city and that’s the whole problem. Greenfield you can do with side slope instead of shoring, one story deep instead of two because you can plan out exits to not interfere with an existing road, and no conflicts with traffic/utilities/buildings/noise mitigation to snarl everything up. And when you get out of the planned core you can run it on the surface and still grade separate crossing, which is cheap.
So that means you’re not in an existing town.
I’m sorry but this is really twisting what I said. I didn’t say huge roads, I simply said roads (although I can see how that can be misread).
Huge (tall) offices are the whole point, you relocate big offices and lots of jobs. With easy access to subways. That does not mean car dependency. It’s actually the other way around, a bunch of short rise offices quickly become too far away from a subway line.
Nor did I say huge houses, I simply said houses. I could include apartments in there too.
Car dependency depends on the city design, it’s not inherent to the existence of offices and roads. And the whole point of a designed city of what you can get the space for cheap subways. I didn’t mention bike paths yet but those too, without having to cram them into an existing road system. Notice I said bike paths and not bike lanes. The existing road system is the thorn in the way of subway, transit, trains, and bike paths. Trying to cram all this into existing road system is the extremely expensive part.
I’m sorry but I think this is more twisting. This is not simply housing or a business park on the edge of an existing city which is car dependency sprawl style. I’m suggesting a new city. You know the downtown, the midtown, the uptown, and yes some degree of suburb houses is probably always going to exist but I’m not suggesting huge houses.
Yeah you really seem to think I’m demanding sprawl when I’m not. I’m actually interested in the exact opposite. I don’t know if your twisting is intentional or not but it’s at the point that I think I’m going to end this conversation. It’s really far from my original question anyway.