It's amusing to me watching devs talk about the breakneck pace of AI and LLMS, AGI all that sorts of stuff, what that wild future will give us - when there are far, far more difficult problems that lie directly in front of us, mainly getting public infrastructure projects done in normal spans of time, or hell, getting them done at all.
Kind of - the art of fortune telling plays a big part in things
It's not needed now, but we think that it will be needed in the future
It's needed now, but we don't know if we will use it in the future
How MUCH will it be needed in the future
Will there be a future technology that makes this investment unnecessary, or even obselete before the project ever completes
For the latter, a big argument of "No need to invest in commuter trains" argument was "self driving cars are 'just around the corner' and they will make mass transit a quaint thing of the past" was used to deny investment in trains.
If empirical observation is 'technical', then keen eyes can spot the grifters before they can be elected or corrupt the already-elected. Then we just need the will to permanently deter them.
What indication do you have that the construction time for tunnel 3 is due to corruption or even that it's taking longer than necessary? It seems like a very large engineering project; sometimes those take time.
That is true. In fact it relates to one of current America's greatest truths: coordination problems here are much more difficult than many technological problems. This is what makes many of those "oh so you take those autonomous vehicles, put them on a track for efficiency reasons, then link them together so they can transport more people, and voila! you have a train!" comments ring hollow.
Building a train requires coordination. Building an autonomous vehicle requires technological innovation and convincing a few people at the top levels of government. The specifics matter (and the Abundance guys have done a great job summarizing them) but it's due to an entrenchment of certain styles of laws.
So the answer to "why do Americans build self-driving cars to ease transport when Europeans just built subway systems?" is "we do these things not because they are hard, but because they're actually much easier than the other thing you find easy".
You have to deal with directly affecting real estate owners, potentially 100s of thousands of different ones in NYC. Not to mention 100s of years of underground infra and all the different companies that own that stuff without cutting service to anyone. It's insanely difficult and I'm not sure I understand why you think it wouldn't be.
You're missing what I'm saying. I'm poking fun at devs that think AGI will magically solve all our problems - they have no idea just how insanely complicated physical infrastructure is.
They need to do a post-apocalyptic movie with a scene set in Fresno with unfinished CA HSR viaducts hulking in the background against a polluted orange sky.
If you ever want to put the cost of something into context, remember that Mark Zuckerberg spent $77 billion on the Metaverse.
I went looking for an article I read a decade ago about the challenges of supplying water to NYC and maintaining the aging infrastructure. Part of the "race" to build new capacity is so they can actually turn off some of this supply for extended periods to repair it. Millions of gallons of water leaks or is just unaccounted for every day.
I didn't find it but this [1] kind of goes into it.
And since you can't turn the water off (generally), you need to do repairs in fairly extreme environments and use materials that don't corrode over very long periods of time. IIRC some pump or valve infrastructure was made out of manganese bronze for this purpose.
Mark's money is sucked up from the entire world, whereas NYC's money is picked from the pockets of NYC residents, obviously I'd prefer one over the other given I live in NYC
Still a bit more to go. Hopefully they offer some tours of the final phase before it’s flooded and no longer accessible for decades.
> The Bronx and Manhattan already receive water from it, and the final phase — extending service to Brooklyn and Queens — is expected to be completed by 2032.
So many questions ... which probably have been asked on prior HN threads ...
I wonder why 800 feet underground: Is that necessary to pass beneath all other infrastructure (to prevent flooding it?)? Remain beneath waterline to create negative pressure and reduce leaking? ?
Also, what is the general mathematical relationship between depth, rock pressure / weight, and energy required to drill? That is, what is the proportion of energy required to drill beneath 800 feet of material compared to drilling beneath 400 feet?
I don't know about New York in particular, but Chicago water engineering seems a related topic.
Here you do deep tunnels to avoid the surface, in ways another poster said; everything is easier when nothing is in the way.
For the mathematical difference, 400 feet below sea level and 800 feet below are almost exactly the same: difficulties are water getting in to your pit, but the machines that work on rock, work on rock at the same speed regardless of depth, so the difference between 400 feet and 800 feet is best described as 400 feet difference. A big issue here is that they do not drill; they hammer. Pounding base pylons into bedrock causes dramatic rhythms in the surrounding 500m, but that's to deal with the bedrock, not depth.
Rivers (e.g. Mississipi) work with much smaller gradient of just 0.01% [1], while with your assumption it would be 0.25%, so 25x.
Maybe instead it needs to pass under the rivers [2: cross-section] surrounding New-York, which may be much deeper, especially when it comes closer to the bay passing Queens and Brooklyn [2: map]
> I'd guess the reason for the 800 ft is because the reservoir it'll draw from is near sea level.
I believe Tunnel #3 connects to the Catskill Aqueduct[1], which draws from the Schoharie and Ashokan reservoirs. Both are at least a few hundred feet above sea level (the Ashokan is about 600 feet above, since it was formed by flooding a valley in the Catskills).
But I have no idea why they dug it so deep, given that! Maybe to give themselves an (extremely) ample buffer for any future infrastructure in Manhattan.
The tunnel is a pipe, as long as the tunnel and exit end is lower than the entrance end, water will flow without pumps. Unlike an aquaduct, it doesn't need to be on a continual downward gradient from one end to the other.
> Also, what is the general mathematical relationship between depth, rock pressure / weight, and energy required to drill?
There isn't any. It completely depends on the local geology.
Liquids are easy because there are no lateral load transfers, and the structures have to bear the weight of the entire water column above them. But with soil you get lateral load transfer, so the pressure on the tunnel is not easily relatable to its depth.
That's also why you can have mines that are kilometers deep, yet with tunnels held by wooden beams.
That depends on the rock type. In london, most things are clay, so not actually that solid (ie it needs shoring up immediately, and will collapse without supports, hence the travelling shield)
manhattan schist appears to be reasonably hard (not granite, but also no clay)
My immediate thought is at what point does desalination tech + clean energy reach the crossover where building a 60 mile tunnel over 60 years not make sense?
It feels like very soon, and coastal cities can stop relying on hinterland reservoirs for water.
Probably never. The tunnels cost a lot to build but, once built run almost for free - they're powered by gravity and will keep running for close to a century before major maintained is needed.
Yeah that makes sense but if growth dictates another tunnel... And it takes another 60 years, your capital expense starts to look a lot like an operating expense. Not to mention one of the big stated purposes of this tunnel is actually to facilitate maintenance of the other tunnels. There is probably more operation cost hidden here than seems obvious.
Capital vs operating is a big factor here. The tunnels operations & maintenance cost is probably far lower than a desalinization plant that could produce an equivalent volume of potable water.
> Desalination will be a West Coast thing. The East Coast has abundant fresh water.
It's not entirely accurate to say that the West Coast doesn't have enough fresh water. Oregon and Washington have a lot of rain, and many groundwater resources.
California kneecaps itself with perpetual deeded water rights and mismanagement/closure/lack of improvement to reservoirs and related infrastructure. There's a long history of this kind of stuff in the state (see the watering LA desert, the Salton Sea experiment, and many others).
Readit News
There typically are no technical solutions to rhose.
It's not needed now, but we think that it will be needed in the future
It's needed now, but we don't know if we will use it in the future
How MUCH will it be needed in the future
Will there be a future technology that makes this investment unnecessary, or even obselete before the project ever completes
For the latter, a big argument of "No need to invest in commuter trains" argument was "self driving cars are 'just around the corner' and they will make mass transit a quaint thing of the past" was used to deny investment in trains.
Not that they can't, but they won't.
The corruption and graft run so deep you would have to literally murder a lot of people to get that to happen.
Building a train requires coordination. Building an autonomous vehicle requires technological innovation and convincing a few people at the top levels of government. The specifics matter (and the Abundance guys have done a great job summarizing them) but it's due to an entrenchment of certain styles of laws.
So the answer to "why do Americans build self-driving cars to ease transport when Europeans just built subway systems?" is "we do these things not because they are hard, but because they're actually much easier than the other thing you find easy".
Deleted Comment
https://www.nyc.gov/assets/dep/downloads/pdf/water/drinking-...
https://old.reddit.com/r/nyc/comments/in5lm7/cross_section_s...
Potentially related:
Discussing Waterworks, Stanley Greenberg's Photos of NY's Hidden Water System [video] - https://news.ycombinator.com/item?id=46416871 - December 2025
(Tunnel 3 will deliver 1B gallons/day and has a 200-300 year expected service life)
I went looking for an article I read a decade ago about the challenges of supplying water to NYC and maintaining the aging infrastructure. Part of the "race" to build new capacity is so they can actually turn off some of this supply for extended periods to repair it. Millions of gallons of water leaks or is just unaccounted for every day.
I didn't find it but this [1] kind of goes into it.
And since you can't turn the water off (generally), you need to do repairs in fairly extreme environments and use materials that don't corrode over very long periods of time. IIRC some pump or valve infrastructure was made out of manganese bronze for this purpose.
[1]: https://nysfocus.com/2024/11/27/new-york-water-leaks-drought
I'll never be a billionaire, but I'll also never spend $77 billion with so little to show for it.
> The Bronx and Manhattan already receive water from it, and the final phase — extending service to Brooklyn and Queens — is expected to be completed by 2032.
I wonder why 800 feet underground: Is that necessary to pass beneath all other infrastructure (to prevent flooding it?)? Remain beneath waterline to create negative pressure and reduce leaking? ?
Also, what is the general mathematical relationship between depth, rock pressure / weight, and energy required to drill? That is, what is the proportion of energy required to drill beneath 800 feet of material compared to drilling beneath 400 feet?
...
Here you do deep tunnels to avoid the surface, in ways another poster said; everything is easier when nothing is in the way.
For the mathematical difference, 400 feet below sea level and 800 feet below are almost exactly the same: difficulties are water getting in to your pit, but the machines that work on rock, work on rock at the same speed regardless of depth, so the difference between 400 feet and 800 feet is best described as 400 feet difference. A big issue here is that they do not drill; they hammer. Pounding base pylons into bedrock causes dramatic rhythms in the surrounding 500m, but that's to deal with the bedrock, not depth.
What? I've never heard this. Everything I've read says pylons go into drilled holes.
This thing will probably be operating hundreds of years from now. What a project.
I'd guess the reason for the 800 ft is because the reservoir it'll draw from is near sea level.
Maybe instead it needs to pass under the rivers [2: cross-section] surrounding New-York, which may be much deeper, especially when it comes closer to the bay passing Queens and Brooklyn [2: map]
1. https://en.wikipedia.org/wiki/Mississippi_River
2. https://gordonsurbanmorphology.wordpress.com/2014/10/26/wate...
I believe Tunnel #3 connects to the Catskill Aqueduct[1], which draws from the Schoharie and Ashokan reservoirs. Both are at least a few hundred feet above sea level (the Ashokan is about 600 feet above, since it was formed by flooding a valley in the Catskills).
But I have no idea why they dug it so deep, given that! Maybe to give themselves an (extremely) ample buffer for any future infrastructure in Manhattan.
There isn't any. It completely depends on the local geology.
Liquids are easy because there are no lateral load transfers, and the structures have to bear the weight of the entire water column above them. But with soil you get lateral load transfer, so the pressure on the tunnel is not easily relatable to its depth.
That's also why you can have mines that are kilometers deep, yet with tunnels held by wooden beams.
That depends on the rock type. In london, most things are clay, so not actually that solid (ie it needs shoring up immediately, and will collapse without supports, hence the travelling shield)
manhattan schist appears to be reasonably hard (not granite, but also no clay)
It feels like very soon, and coastal cities can stop relying on hinterland reservoirs for water.
There are Roman aqueducts in continuous operation for two millenia.
It's not entirely accurate to say that the West Coast doesn't have enough fresh water. Oregon and Washington have a lot of rain, and many groundwater resources.
California kneecaps itself with perpetual deeded water rights and mismanagement/closure/lack of improvement to reservoirs and related infrastructure. There's a long history of this kind of stuff in the state (see the watering LA desert, the Salton Sea experiment, and many others).
This was only a 60 year project because of politics.