trainmew

> Not sure where you're getting that info. I just looked up NFPA 130 and it specifically calls for multiple types of insulation (for cables as well as concrete and steel) as well as automated water sprinkler systems, and even standpipes for firefighters.

You're moving the goalpost and earlier insinuated that tunnels for subways require lining and other fire suppression systems. They do not. The automated sprinklers are needed for stations, but not the tunnel itself. Same for standpipes.

The insulation for cables are a given, because you will need it for ALL tunnels. Not just HV cables, but ALL cables, including fibre and low-voltage cables.

Thus, no difference.

> Tesla doesn't use LIDAR but they do use ultrasonic sensors. Tesla's existing autopilot systems works just fine on completely dark, unlit roads. I don't see why these skates would be any different.

Does Tesla's existing autopilot system using LIDAR/ultrasonic cameras have automated collision protection that does so without having to communicate with the other cars behind it traveling at 120mph to 150mph? No. You will need to modify the system to do this, and you will need to add the mesh network to the tunnels, among other things I described.

> Even with fibre and low voltage power for access points (if even needed), you're still leagues away from the cost and complexity of a full tracked third-rail system.

Agreed. Tracks and third rail are not cheap, comparative to not using them at all.

> I'm not sure what you mean. Flexibility is cheaper. Being able to use a tunnel that is 500 feet long at a 10% grade is cheaper than having to build a tunnel that is 1500 feet long at 3% grade.

How? If the total length of the overall tunnel is the same, the cost of materials are not substantially different.

> You seem to be really hung up on the ability of the skates to know where they are. I'm not sure why.

Because the claim is that the tunnels are nothing more than concrete and some lighting. I'm pointing out instances that will require more things in these tunnels.

> You've never heard of a mesh network? Even if AP are needed, it's still considerably less wiring than a full third rail setup and still poses no fire risk.

Yes, I know mesh networks. This is how many trains now communicate with each other. Third rail has some fire risk (incredible odds, however, and likely means maintenance regime is not good), and I agree that if they are removed that removes the fire hazard entirely. However, these skates carry batteries, hundreds of them and operating at significantly high speeds. I'm pointing out that these batteries can and will catch fire too, especially if the self-driving component of the skates fail. It is a more credible risk (but cheaper, sure) and more likely to happen more frequently given that the self-driving component is not perfect and relies on cameras (even LIDAR ones) than third rail catching fire.

> You're really overestimating the amount of engineering work needed to be done.

I'm really not. I work on those automated subway systems in Asia that has automated platform gates for those subways to stop at, and the amount of engineering and safety assurance work to ensure those trains actually align themselves correctly is a lot. Why do you think those platform gates have emergency egress doors all over? Have you ever noticed those trains stopping, then creeping to ensure they're aligned right? Those issues are not there not because they're easy, but because substantial man-hours of work have been done to ensure they are safe.

> The concerns you're raising are already solved. The 'magic' of this system isn't in the self-driving vehicles part at all, as that's already being done with automated transport systems the world over. The 'magic' is in the tunnel construction itself.

And I'm pointing out that there's no magic in the tunnel construction. By the time you have added those safety redundancies you end up with something very close to a subway system, just with smaller carriages running on batteries.

Yes, I know that. That now means you need a way for the skates to communicate with each other and maintain a safe distance from each other before they collide and obviously slower speeds. That bare concrete tunnel is now longer bare since you will need communication access points, fibre cables for redundancy, etc.

> Standard subway systems have to have much more in regards to fire suppression than just ventilation. The entire tunnel has to be protected from fire damage with insulation, some tunnels have sprinkler systems, etc. These wouldn't be needed in the dugout tunnel.

No they don't. There's no insulation for underground tunnels for subways; just steel liners and reinforced concrete, at least according to NFPA 130. No sprinkler systems. So no difference here.

> LV vs HV

Yes, true. HV cables and other supporting systems are more expensive. So the only difference here is batteries, which are far more combustible than cables in concrete.

> LIDAR cameras

Correct me if I'm wrong, but to my knowledge, Tesla has removed LIDAR-based cameras in their lineup.

> There are also automated subway systems all over the world that don't depend on the tunnels being lit, and they don't seem to have any issue avoiding collisions.

Yes, I know. And those trains communicate via access points placed on the tracks, each of which are run with fibre and power cables. Now that bare tunnel is no longer bare.

> incline

Sure, it's more flexible. It still doesn't address the claim that this will help make those tunnels cheaper.

> It's cheaper.

Not convinced.

> expensive train stuff

Sure, I'll concede it can be cheaper than subways when you remove the tracks, HV power supply, third rail, wayside equipment, stations and just stick to concrete.

I still don't think they're significantly more expensive.

> A string (even a long one) of high-intensity LED lights doesn't require much electricity. The costs of lighting the tunnel is probably one of the least costly parts of this whole project.

Maybe. You will still need redundant power supply and redundant illumination points if you're planning to use the self-driving tech with cameras.

> then it won't be difficult to have the vehicles talk to each other (or a centralized hub)

So then you will need a way for those cars to talk to each other, and typically that means you will need wayside APs to carry that traffic. Now that tunnel is not just bare concrete and some lighting elements, you will need to lay fibre cables, power cables, and put up those boxes somewhere for communication. And oh, you might want to have calibration points on the tunnel floor so that the skates themselves know where they are, to normalize their position and report back true accurate positioning.

> The vehicles being able to know how to get to the station and open their doors is probably not really a concern. This is already done in automated subway systems all over the world. It's not hard to have the vehicle be smart enough to drive to a specific 'dock' and then look for a specific trigger to know when to open its doors. Hell, my $100 roomba can park itself in a similar manner.

You underestimate the amount of engineering work needed to do this safely and proving that it's safe. Are the lifts open lifts where the skates drive on and open up their doors? If so, that "marker" will need to be substantially big to allow for overshoot/undershoot and still be safe to open their doors (think, pinching, trapping, etc).

If so, the lifts will need to be substantially big to allow for a number of these skates to ascend and pick up/drop off passengers.

> fire suppression systems

The article clearly states the tunnels with have a tunnel ventilation system, which is standard fire suppression strategy for underground tunnels for subways.

> electrical systems

They're already laying power cables for the tunnel lighting system which is presumably for their autonomous driving system with cameras, which now has a single dependency on their tunnel lighting system.

The rest, sure, I agree can be cheaper comparatively to a subway tunnel.

> steep inclines/sharper angles

Why would you want steep inclines (more than 5% standard for metros) if you're already underground and use lifts to ascend? The electric skates will still have a kinematic envelope that the tunnel has to adhere to, especially if they're for standing passengers. I don't see how this differs substantially from subway tunnels to allow steeper inclines/sharper angles.

I don't quite see the purpose of illuminating the entire tunnel unless they're using their autonomous driving tech which uses a camera. If so, they've just put a single point of failure on their lighting systems.

How will the skates know that the one in front of it has broken down and need to be pushed? Especially when it's operating at 120mph?

I don't get it. How does this improve on the underground subway? I'm unconvinced that making the tunnels smaller means that the construction costs will be significantly cheaper and faster. Further, the electric skates make no sense from an operational or RAMS perspective:

1. They're smaller so you need a lot of them, which means wear and tear = possibility of failure is higher;

2. They're inefficient in terms of energy use (gotta charge those batteries first) vs third rail that supplies continuous redundant power;

3. How are the electric skates driven? Autonomous? If they're relying on cameras to do autonomous driving, any disruption in the tunnel lighting will kill them all dead.

4. Lighting those tunnels continuously will not be cheap.

5. If the electric skates are driven independently, how will others behind know if one has broken down in front?

6. How do you maintain headway if the electric skates don't know positions of those in front of them? How do you make sure they don't collide if all you have is a camera?

7. Emphasis on average speed is weird, no passenger actually cares about the average speed of the carriages carrying them, only the frequency between those carriages that they can get onto to get to their final destination.

8. How do those electric skates know they've reached their destination and open the doors for passengers to get off? The illustration shows tightly packed electric skates. Do they travel up the loop lifts and then exit? How will these loop lifts be operated?

This doesn't seem any different from a regular subway, only smaller tunnels, and smaller carriages carrying passengers, without any rail and other wayside equipment. Why not a battery-electric bus?