Elon Musk Unveils Boring Co's First Tunnel

I thought it was obvious this would quickly become an expensive express option. It's not going to fix traffic for the masses, it's going to fix it for the rich.

Sure it’s not density of subway but more tunnels will partially offset lower capacity. This is about lowering tunnel & ‘station’ construction by ~2 orders of magnitude. There’s also lots of room underground to build vs surface, so little constraint there.

Lowering cost is Elon’s demonstrated strength (SpaceX rockets and Tesla batteries), so gotta factor that in. Small tunnels cost way less than subway tunnels, not factoring in improvements in boring ops. It’s all about shaving off 2x here and 5x there across the whole system to make it cheap enough to get benefits.

Lower cost let’s you open up new routes to lower density areas. Means cars can get off the road from those areas which would otherwise contribute to traffic.

This is like going from mainframes to personal computers - enabled by lower cost, more people can have access.

LA metro has a tough job in their hands with handling their traffic and is likely behind this. It’s not trying to be or marketed as a direct substitution for subway, it’s another option that happens to compare favorably but be implemented in a different way and by different parties.

Alternative comparison is to freeway which has 1 car every 2 seconds, and this claims 1 car a second on main path.

Well even if it weren't higher capacity, it has other advantages -- no parking/leaving the car, potentially no ticket gates or waiting for a train... etc.

Trying new ideas isn't a waste of everyone's time, it's research.

It is not, per general EU regulations no 'single bore' tunnel can be longer than 1km (0.62miles0. Tunnels that are longer than that, either have to be double tunnels, with escape doors between them, or one large tunnel and an emergency smaller one.

This looks the size of a emergency tunnel. Still, the cost of building it seems pretty low. Boring Co could build two side by side, (one for each direction) and have emergency hatches between them.

I'm not sure what you're purporting to show other than two people disagreeing with each other, without providing evidence... Sure, an individual subway car has "more capacity," but does a subway system have more capacity? For example, I rarely see BART trains come within five minutes of each other. A tunnel that allows cars within 10 seconds of each other could provide more capacity than a tunnel with higher-density trains spaced further apart. Average density across the tunnel system could be higher (aka more throughout) with autonomous vehicles even if individual transport units have lower density (SUVs instead of train cars).

Off the top of my head, here are issues train cars face with managing density that autonomous vehicles wouldn't face:

1. Needing to stop at stations where few people are getting on or off, meaning that trains behind you must be at least (MAX_SPEED * STOP_TIME) behind you. With cheap tunnel boring + AVs, you can quickly and cheaply build tunnel branches that skip exits, so individual cars need less space between them (you branch off to exit; no need for extra rails or switching technology, since it's built into the cars).

2. Entrance/exit from the train car: with trains, any jerk can run in as the doors are closing, preventing the train from leaving, backing up the trains behind you and leaving a huge gap with trains in front of you. With AVs, you're already in the car.

3. Trains have fairly long stopping distances, increasing the distance needed between trains for safe operation. Some quick Googling indicated that an 8-car passenger train traveling at 80mph can take over a mile to come to a complete stop — it's hard to imagine a car with such long braking distances. That puts a pretty hard lower bound on how densely you can pack an ordinary subway tunnel.

Maybe I'm totally wrong, but it would be more useful to give actual data and evidence than knee-jerk shutdowns. It's not obvious to me, a non-train-engineer (like many on this site!), that the dismissive tweet is particularly meaningful.