You mention "cheap tunnel boring" - maybe that is the keystone of Musk's plan that will change the paradigm... With a little knowledge of tunnel boring I fail to see how to disrupt its crazy complexity, especially in urban environments whose density extends underground already: in my neighborhood (La Défense business district) a whole new station is being build wholly under existing construction and interconnected to existing subterranean works, without any disruption - insanely good engineering and insanely expensive.

If you could bore 4x the tunnels, you'd need a capacity of 4 people per car to match peak BART. And... hey, that describes pretty much every car in existence. But using the BART comparison: recent estimates [1] put each additional mile of BART track at over $1 billion. So if it really costs $10MM/mile for the Boring Co, you could bore 32x the tunnels and beat BART capacity by a factor of two assuming even single occupancy vehicles, at about a third of the cost.

[1]: https://sf.curbed.com/2018/6/18/17464616/bay-area-subway-tra...

Even the Waterloo & City Line, the most unloved of all lines, manages 3.5k/hr over 260 days (16M/year, 5 day week).

The BART is a particularly poor example. There are _tram_ systems (ie partially-segregated rail) which do better than once every five minutes.

There is no universe where an SUV holding 4 people is more space efficient than a Skytrain car.

While this was demonstrated with a SUV there’s no reason why this can’t be used for a larger van carrying 6-12 people and tied to a carpool service. 12 people hurtling down this each second is pretty decent capacity, especially multiplied by many tunnels that do an even better job at getting people to the last mile.

It’s a platform, not just a Tesla-mover.

Except universes where a train doesn't pick you up at your house, drive you to the front door at work, take you to your kid's school after work, then take you to drop the kid off at karate practice, then take you directly to the grocery, then back to karate practice, then home but allowing you rapidly move your vehicle through a congested city thereby reducing surface congestion making overall travel conditions more efficient and reducing the need for car parks at public transportation stop for people that live in suburbs.

And how expensive was it to build the train? If you can build 3x the tunnels for AVs as you can train tunnels and trains for the same price, actual throughput dollar-for-dollar in infra spend would be much better with Boring Co tunnels.

Update with data: it cost $2 billion to build 50 miles of Skytrain. Apparently this prototype Boring Co tunnel cost $10 million per mile. That's a 4x cost advantage for Boring Co mile-for-mile, and I imagine they'll try to strengthen that advantage even further; after all, that's their whole company's purpose: cheap, efficient boring.

..and? A car also doesn't carry 500 people.

Factor in cost advantages of the tunnel — 4x cheaper mile-for-mile for the prototype, it seems like? — and the same dollars spent on Boring Co tunnels could actually move a lot more people than Skytrain: you can build 4x the tunnels, moving nearly 1300 people instead of 500.

Even if SUVs can only match the fastest average Skytrain line (50mph), that's still fairly competitive even at the current cost per mile of a Boring Co tunnel. Assuming they can bring cost down further (which is the goal of the company), they could still end up beating trains in terms of people moved per dollar spent.

Listen, I'm not saying it'll happen. But the dismissiveness here reminds me of the "Model 3 will never cost less to build than the price to sell it!!!!!" or "Tesla will never make more than 1000 cars per week!!!" or cash crunch or etc hysteria. I guess Elon attracts that by constantly missing deadlines, but he often still delivers; he just delivers a year or so late.

You're fond of throwing in a lot of utterly implausible figures to support your argument here

This plan is like when a city widens a highway but doesn't touch other parts of the road network? What happens? It just moves the choke point somewhere else in the network.

Almost all assumtions in the discussion start directly in the tunnel, and sometimes at the elevator. Almost no one thinks about: how will cars get into that thing from the road, how the cars will get out of that thing onto the road.

The fact is that a 500 capacity train running at 75-100s headways destroys this system capacitywise.

Musk has a long, long way to go before he shows that this idea of his is better than the 1986 era technology at the core of Vancouver's system.

This is like that linked tweet: all assertion, no data. What are you using to estimate the theoretical throughput of a Boring Co tunnel system vs Skytrain? Let's debate that. Right now it's all just thin air.

Assumptions I'm willing to believe, and thus make me interested in this prototype's viability:

1. Cars need less space in between them. 5-10s gaps seem more than reasonable based on highway driving. This seems especially true since these are operated autonomously in highly controlled environments, meaning we might need even less distance between cars than free-wheeling, human-operated highway driving.

2. Most train stops are useless for most people — maybe 3x stops per ride on average? Having only one stop per ride would dramatically improve average speed, since a smaller percentage would be spent slowing down, speeding up, or waiting at a station.

3. Smaller tunnels are cheaper to dig, meaning dollar-for-dollar you can build more of them to make up any remaining capacity difference.

And we also assume that all cars can enter and exit the system with no delays.

It'll be a miracle if it reaches bus capacity, much less train/subway capacity: https://www.thoughtco.com/passenger-capacity-of-transit-2798...

Basic geometry.