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Comment by infotainment | Hacker News Reader

> The premise of the Boring company is very simple: digging smaller tunnels at scale is going to have economies of scale associated that means you can have vastly more of them for the same money.

...so instead of 1 tunnel with a train in it, we could achieve the same throughput with 10 tunnels with single occupancy vehicles. Brilliant! Cost savings achieved! I'm sure the math will just somehow work out that 10 tunnels is cheaper than 1.

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Economies of scale and learning effects are a pretty well studied phenomenon. So, yes, these are quite reasonable assumptions to make.

I'm more talking about replacing 1 massive tunnel between a handful of destinations with hundreds of tunnels going to many destinations. Why stop at 10?

I seriously doubt you can leverage economy of scale in something as labor intensive as building tunnels.

Why? They literally throw away machines that dig tunnels because they are built just for one tunnel. There's decades in between tunnels being dug for most big cities operating underground railways. A company that would be tunneling non stop could make a lot of improvements probably and get really good at it.

There is no basis whatsoever that learning effects don't apply to the business of tunneling.

Making improvements != economy of scale. Digging 10 tunnels in parallel using 10 machines and 10x the people I bet won't save you much in the grand scheme of things.

And the reason why they "throw away machines" is because most of the time those are custom built based on the project and the wear and tear is substantial.

The trick to cost saving: stack the tunnels! Exploit the 3D feature of below ground!

You know, I was thinking about how that would actually work, and I just can't imagine it being anything remotely close to efficient.

For example, if you were driving on tunnel level 26 (you had to go down there because it's rush hour and the higher levels are jammed up), wouldn't it be insanely annoying to get back to a higher level? Do we have massive spiral ramps connecting each tunnel level? What about interchanges onto other directions, do you need to be on a particular level, or do you need to spiral your way up to Level 15 West Tunnel Expressway Interconnection Point to transfer to Northeast Extended Tunnel Expressway Business Loop 2A?

Haha, you spent a lot more thought than me!

Why would every level have easy and uniform connections to every other level? They are transport connections, not destinations. And 26 levels? Why would you ever need that much capacity?

You need 26 stacked tunnels to meet the capacity of a subway line with 60 second interval, remember? (I don't think they've achieved intervals that low, but give it time)

And why would you ever stack them like a fence? Go ~2 deep, ~2 wide, and cover ~7x as many routes. Depth is more for avoiding intersections between cross-traffic than for lack of space.

What nightmare would that station look like and be to navigate

Loop has smaller but more numerous stations, because it can have smaller and more numerous stations. With trains every station along a route adds considerable delay for every passenger, exacerbated by the slow stopping speeds of rail. This is not so for pod-based transport where the stations are split off the main line. Stations are also cheaper because they can scale down to only a small subset of the though-traffic.

So.. roads. With taxies. You’ve reinvented roads without parking lots in taxies lol.

Except for all the significant differences, yes.

It’s roads in tunnels with small cars/vans going mostly point to point.

It’s just a separate road system with pods driven by a person or computer.

What are the significant differences?

Traditional surface roads in cities:

* Take surface space that can be better used for walkable densification, or are already taken by roads.

* Produce significant atmospheric and noise pollution, even from EVs.

* Conflict at cross-traffic, especially so for dense road networks like grids.

* Have to navigate around building geography, so for example can't support high speed turns.

* Conflict with pedestrians so are limited in speed and have to support frequent stopping points.

* Have no central routing and control for journeys so suffer unbounded traffic, even where additional vehicles lower capacity.

* Are hard to add to existing developments that need additional capacity.

* Don't have out-of-line stations for on- and off-boarding.

Add to this the differences you've already mentioned, like uniform taxies rather than mixed private cars, a comparative ease of automation, and being additive to existing network capacity rather than conflicting with it.

Most of that is just “tunnel vs surface” or “private vs public” ownership

It’s still just roads in tunnels with taxies.

Yes, I agreed already. Putting aside all the important differences it's the same thing.

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