I don't know much about tunneling speeds, but this seems much faster than Big Bertha in Seattle although for a much smaller volume (the tunnel is narrower) and (I'm assuming) less complex location.
Big Bertha is roughly 25x the size of boring company's tunnel borer. And, while your math it totally wrong for Big Bertha, it should be 0.5 miles/yr. But if you account for the 2 years that it wasn't running for repairs then it does end up at roughly 1.3 miles/yr.
Why not compare against a tunnel borer of the same size?
The world's fastest tunnel borer of that size was for the tunneling of the blue mountains (described here: https://www.therobbinscompany.com/the-worlds-fastest-tbm/). That was more than 25 years ago and even at it's average speed over the whole project, it was doing 1800ft 4 times faster than Boring company's "amazingly fast" borer.
If there's something special about the Boring company (unlikely) it's definitely not its boring ability. They just buy a used boring machine and they don't even have the expertise to do anything interesting with it.
They are currently building their first prototype. It seems correct that you would build a few tunnels using conventional equipment to gain experience before setting your sights on improving the state of the art, or is there something I'm missing?
You are missing something: the companies that build tunnel boring machines already have engineers who know how to make the machines looking into the problem of making their designs better. It isn't clear that there is a significant improvement available.
Rockets were a small enough niche that there were improvements possible if someone invested in them. It isn't clear if such improvements are even possible. (meaning they might be)
Right, but existing boring machine manufacturers don't have an infinite money pile to burn through, so they can't afford to try all the things that TBC will be allowed to try simply because Silicon Valley will afford them a bottomless pit of cash (until the next recession).
For the Crossrail project going under London, they used 8 machines in parallel and took 3 years to dig a total of 26 miles of 20 ft diameter tunnels.
That's a little more than 1 mile/yr, an average number that includes overhead like moving the TBMs between the different boring sites. And the cutting surface area (which multiplies linear speed to give material removal rate) is (20/14)^2 = 2.04 times bigger for Crossrail than the Boring Co. machines.
The two projects are on such opposite ends of the spectrum that it really makes them incomparable. Big Bertha was the second biggest boring machine ever built, and also in a risky location. On top of that it was built by a company with no experience in building boring machines anywhere close to its size.
Big Bertha dug under the downtown of a city with existing tunnels and utilities. The Las Vegas tunnel is mostly under parking lots with no obstructions.
While I doubt that "Las Vegas tunnel is mostly under parking lots with no obstructions" is even close to represent reality, here's what Boring Company says on the subject:
> With a typical minimum depth of 30 feet, The Boring Company tunnels are well beneath most utilities, which are typically less than 10 feet below the surface. In circumstances where a utility is located deeper, the tunnel depth is increased accordingly.
No, they interchanged miles with m, and in a weird unintuitive way at that. m isn't even standard for miles, it's standard for meters, and just before that miles was written instead of shortened - it's not just confusing it's also terribly presented. At least yr is intuitive, nothing about m is easily understood even given the context (which is why so many other people are complaining about it).
Big Bertha - 3.5 years, ~1.75 miles, 1.5 m/yr
Boring - .15 years, .35 miles, 2.33 m/yr