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Comment by huebnerob | Hacker News Reader

I thought that the anemic pace of tunnel construction was more a political problem than a technological one. Either Musk has solved NIMBY-ism and red tape, or he happened to pick a convenient location free from these issues for his pilot tube.

I suppose much of politics is arguing over who’s going to pay for something, and who’s going to actually build it. With The Boring Company digging their own proving ground, these questions are moot.

Far from being a naysayer, I live in NYC, we need more tunnels dug than ever before. If this works, we'll take twenty.

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Is tunneling really the issue? The tunnel for the extension of the line 14 in Paris was completed last week, at a speed of 25 meters by day (twice as fast as expected). Yet the line won't open until at least 2020, many years after the initial deadline. Construction was stopped for more than a year because of groundwater flooding in one of the new stations, which prevented the boring machine from going through. I'm not sure the tunnel boring itself has ever been a technical challenge.

I am not sure if it does solve NIMBYism entirely. I note on the map of tunnels they would like to build there is no link between Santa Monica/UCLA/West LA and downtown LA.

I assume that is because such a tunnel would involve dealing with the city of Beverly Hills, which has historically been unenthusiastic about mass transit.

According to Elon, conventional tunneling costs "as much as $1 billion per mile," which is the biggest reason we don't have more tunnels.

How is what he doing not conventional? That's a mail-order tunnel-boring machine he's got there.

And tunneling doesn't cost 1 billion dollar a mile. One Mumbai metro line is being built at 100 million dollar per km, the cost includes everything, stations, tracks, coaches, etc. And they're using 17 tbm for this purpose.

The cost is proportional to what kind of environment you're operating in. If it's ideal terrain it'll be cheap. If it's difficult, ever changing conditions with a high risk of subsidence damage to the structures above, get ready to pay way, way more.

See the Seattle "Big Dig" project for an example of how sideways things can go if you hit an unexpected snag.

From what I’ve read so far, they are making it electric, more powerful, faster, fully automated and continuous (no switching between digging and support-building).

A modern TBM is already exactly as you describe. They rotate pre-cast sections into place, then push off of them hydraulically to advance the machine. They don't stop digging.

Innovating on the TBMs is definitely part of it; I don't know why you are concluding from a picture that it isn't? Boring smaller tunnels is also part of it.

You can read more here: https://www.boringcompany.com/faq/

I don't have an easy way to check your claims against Elon's, for example whether existing "modern" TBMs are fully electric as you claim, or run on fuel as Elon claims, and whether continuous tunneling is the norm or not.

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