> "Still, the $10 million is orders of magnitude lower than a typical subway project, Musk said."
Umm, and the capacity of these tunnels is also orders of magnitude lower than a subway. It would also be a lot harder to use and available to far fewer people. This entire idea should be laughed out of existence, but despite everything, Musk still gets fawning coverage for any crazy idea he spouts.
Maintenance will be impossible. Breakdowns of any sort would go from being annoyances to a few to being catastrophic failures for the system. Even if the tunnels never degraded, even if no car ever had a flat tire in the middle of the tunnel, and even if you could actually achieve 150mph (which would be extremely unpleasant for the passengers anyway), you couldn't physically fit enough cars through the tunnel to compare to real transit system. Given that this thing requires rigging something up to your vehicle, the onload and offload points would immediately become major bottlenecks to any serious throughput even if you could cram them in bumper to bumper.
How so? Maintenance happens all the times in subways. In Montreal they do it during 4 hours each nights. In ours, they close everything down, thus we can no longer use it, but if we had multiple smaller one, we certainly could close one at a time and lower the perturbation. They could still close them all, theses tunnels aren't meant to be the only ways to drive either, even the biggest highways are closed from time to time to maintains them.
> you couldn't physically fit enough cars through the tunnel to compare to real transit system
That's seriously so weird to see that kind of comment on Hacker News. Never heard of horizontal scaling? There's more than a ways to increase capacity and the size of the unit sure is one, but the number of units is another one. It's like saying Google is impossible because you could never fit that many website on a single core, yeah luckily we can just add cores.
> Given that this thing requires rigging something up to your vehicle, the onload and offload points would immediately become major bottlenecks to any serious throughput even if you could cram them in bumper to bumper.
Then they'll come back to the skate system, which would fix the tire issue at the same time (and many others).
My SO is a soils engineer/geo-physicist, so I know a bit about the issues at play, mostly over dinner conversations. When it comes to large infrastructure projects like these, the problems are multitude and all very individual, especially in such a geologically active zone as the LA Basin [0]. Though Musk et al. should be congratulated for the incredible achievement of even trying to pursue this idea, proper study is always required. Honestly, I've no idea about the studies that they have undertaken. But in such a place like the LA basin, I'd imagine that they have taken such measures; it would be insane to do so otherwise.
When it comes to horizontal scaling, without a proper geologic survey of the bedrock, water table, oil-wells, soil dynamics, and all the many other factors, simply multiplying the structures on top of each other can only be described as a deliberate attempt to endanger the lives of all people concerned (riders, construction crew, etc). The surveys must be made with deep consideration and respect to the laws of physics and the local environment. Brady, of Practical Engineering on YouTube has a wonderful channel that goes into some depth about large scale civil engineering [1] that is well worth a binge.
That said, with proper study of the effects and dynamics of increased removal of soil and bedrock, horizontal scaling is of course a perfectly good solution to increasing ridership.
> My SO is a soils engineer/geo-physicist, so I know a bit about the issues at play
what's this? PhD by association?
I came to Bay Area from Japan, I was surprised to hear that high buildings are not a thing here because of earthquakes. For comparison, in Japan there are about 2000 earthquakes that person can feel every year. And somehow monorail/high-speed trains/tunnels/skyscrapers are everywhere. Lazy engineering and crumbling infrastructure which stayed same for decades.
>> My SO is a soils engineer/geo-physicist, so I know a bit about the issues at play
>what's this? PhD by association?
I mean, I did day that I only know a bit about it.
That said, there are differences in the dynamics of the soil between Japan and California; each situation is unique. When it comes to earthquakes, Japan typically has deeper earthquakes due to the subduction zone that it sits above and the earthquakes are compressional(very roughly), while in CA, the earthquakes tend to be shallower along the San Andreas and more strike-slip (again, very roughly) up to 30km down involving mostly the crust. In general, one should not expect that buildings in two different seismic zones should be similar.
I haven't read much to suggest that the Bay Area's lack of tall buildings is the result of earthquake fears or "lazy engineering". Besides the fact that SF's tallest building, the Salesforce Tower, started construction in 2013, SF historically has had tall buildings, before and after the great earthquake. SF's and the rest of the Bay Area's lack of tall buildings seems to be a result of local dictate, in the same way that Kyoto lacks tall buildings. Similarly, it would be foolish/overly simplistic to blame the Bay Area's housing shortage on "lazy home builders".
> Umm, and the capacity of these tunnels is also orders of magnitude lower than a subway.
Even assuming that capacity/dollar is actually worse than subways, they can still be economically superior, for the same reason solar+battery is beating nuclear. The ability to incrementally build capacity relatively quickly and with relatively low, incremental costs beats any system that requires billions of initial investment and only comes online in the timescale of decades.
And I really don't think that capacity/dollar will be worse than subways, assuming that he intends to build off-ramps for leaving the system, as alluded to in the stream. Simply removing the need to stop at every exit greatly improves capacity, and while the capacity of an individual tunnel is still much worse than a single subway tunnel, they can just build more.
> Maintenance will be impossible. Breakdowns of any sort would go from being annoyances to a few to being catastrophic failures for the system. Even if the tunnels never degraded, even if no car ever had a flat tire in the middle of the tunnel, and even if you could actually achieve 150mph (which would be extremely unpleasant for the passengers anyway), you couldn't physically fit enough cars through the tunnel to compare to real transit system.
You seem to be assuming a single tunnel per direction. Assume 20 instead. Suddenly a car failing in the tunnel turns from a catastrophic failure into one that causes some traffic to have to take a little extra time as they back their way to the closest cross-tunnel, and a relatively minor loss of capacity until a recovery vehicle can come pull the broken one out.
And as Musk said like a dozen times in the stream, he intends to match a real transit system not by increasing capacity per tunnel, but by starting building tunnels and then not stopping until there are no more traffic issues. Since he gets to expand in three dimensions, he can just stack them on top of each other.
> Given that this thing requires rigging something up to your vehicle, the onload and offload points would immediately become major bottlenecks to any serious throughput even if you could cram them in bumper to bumper.
Their demo had the "subway wheels" deploy automatically, while in the elevator. For high-throughput exits, they probably need to bite the bullet and just build off-ramps.
> You seem to be assuming a single tunnel per direction. Assume 20 instead.
I think this is the really important part. Think of it like a computer bus - do you want a single channel able to move a lot of data at once but with potential bottlenecks as various systems fight to talk to each other, or lots of channels able to move medium amounts of data without bottlenecking one component while favouring another?
When one channel is at capacity you move to the next, with further redundancy to spare.
They left out basically every expense from that number (they noted it was unclear if labor was even included in that number), and did construction in a single city with a fawning council (legal expenses are massive on infrastructure projects).
Umm, and the capacity of these tunnels is also orders of magnitude lower than a subway. It would also be a lot harder to use and available to far fewer people. This entire idea should be laughed out of existence, but despite everything, Musk still gets fawning coverage for any crazy idea he spouts.
Maintenance will be impossible. Breakdowns of any sort would go from being annoyances to a few to being catastrophic failures for the system. Even if the tunnels never degraded, even if no car ever had a flat tire in the middle of the tunnel, and even if you could actually achieve 150mph (which would be extremely unpleasant for the passengers anyway), you couldn't physically fit enough cars through the tunnel to compare to real transit system. Given that this thing requires rigging something up to your vehicle, the onload and offload points would immediately become major bottlenecks to any serious throughput even if you could cram them in bumper to bumper.