7 ms·

You can't. The tunnel is cheaper because it's not for a subway. The tunnel for this 'Dugout Loop' is a simple tunnel lined with concrete and possibly some lamps

You can't. The tunnel is cheaper because it's not for a subway. The tunnel for this 'Dugout Loop' is a simple tunnel lined with concrete and possibly some lamps for lighting. That's it. It doesn't require any of the expensive things that a subway requires like tracks, electrical systems like a third rail or overhead cable, fire suppression systems, etc. The dugout tunnels can probably also be steeper and have sharper angles, which allows more possibility for routing that a subway wouldn't be able to do (vehicles on train tracks can't go up very steep inclines or take very sharp corners). Another substantial part of this is that the Dugout Loop vehicles ascend to the surface through an elevator or ramp, which allows the station platforms to be built above ground. The platforms can also be smaller (they only need to fit a couple car-sized vehicles, not an entire train). This reduces cost substantially, as building out a large underground train platform is often one of the most expensive parts of a subway build.

semi-extrinsic 8y ago
It will definitely have some sort of tracks. They've shown demos of a Model X on tracks in their demo tunnel. The project will also have to deliver on the same demands wrt. fire suppression as any other tunnel. The station building iself must be sized according to the number of people per hour, not the train length; the physical platforms that you use to step on/off trains on subways typically extend into the tunnels.
- txcwpalpha 8y ago
  >It will definitely have some sort of tracks. They've shown demos of a Model X on tracks in their demo tunnel. The website linked specifically says that it will not have tracks. The concrete itself acts as the 'guide' for the skates without needing any type of other tracks (such as traditional metal train tracks). >The project will also have to deliver on the same demands wrt. fire suppression as any other tunnel. This is also address by the website. Fire suppression isn't needed because the tunnel is made only of concrete. There is no concern about other materials (asphalt, high-voltage electrical, etc) catching on fire. >The station building iself must be sized according to the number of people per hour, not the train length; the physical platforms that you use to step on/off trains on subways typically extend into the tunnels. I'm not sure what you mean. Train stations are definitely sized according to train lengths. In my hometown, a significant roadblock to expanding our public train system is that we started off with short trains (and short stations to match), and it is very expensive to extend the length of the stations now that we use longer trains.
  - semi-extrinsic 8y ago
    So they may not have metal tracks, but they will be limited to similar turning radii as a subway line just to maintain passenger comfort going at 120 mph. No trains travelling faster than 60 mph are limited in turning radius by mechanical properties. Wrt. fire suppression: Tesla can state whatever they want, but they will either have to fulfill the demands set forth in NFPA 502 for fire suppression in tunnels, or they will never be allowed to open to the public. Civil engineering is very strict on these things, for a very good reason. For an underground train, you can have the train platform extend well beyond the actual station building. If you've ever taken the subway/tube in NY or London or similar you know what I mean. If not, look e.g. at this Google Maps of the Gloucester Road tube stop: https://goo.gl/maps/KQwuSz6RCUE2 https://goo.gl/maps/KQwuSz6RCUE2 The station building is the small square labeled Gloucester Road tube stop. But the platform extends all the way under the shopping mall (Waitrose's etc) out to the intersection between Cromwell Road and Ashburn Place.
usrusr 8y ago
> fire suppression systems Why wouldn't it need a fire suppression system? Because once a battery pack has started catastrophic failure, they are all dead anyways? The proposed system has more need for fire suppression than conventional subway, not less.
- txcwpalpha 8y ago
  Because the tunnel is pretty much just concrete and nothing else. There's no flammable asphalt or high-voltage electrical cables running through it that could cause or contribute to fires.
trainmew 8y ago
> 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.
- txcwpalpha 8y ago
  >The article clearly states the tunnels with have a tunnel ventilation system, which is standard fire suppression strategy for underground tunnels for subways. 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. >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. A power cable for low-voltage lighting is much, much, much different than the electrical systems required for powering a subway train. It's like the difference of running an extension cord to your lamp versus laying mains wiring for an entire house. There's also no reason to believe that the vehicles would be dependent on the lighting system. Many cars on the market today already come with sonic- or LIDAR-based cameras that do not need lamps to detect obstructions. Tesla's own autopilot on its cars works just fine on unlit roads. 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. >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. You wouldn't want them, but not being bound to the grade and angle restrictions of a tracked metro train means that you have more flexibility of where your system can go if you need to. It makes it easier to route around existing tunnels, piping, sewers, etc without having to make huge detours or being forced to use elevators. An example of this is given in the linked website where they talk about the eastern terminus of the tunnel - it uses a ramp (from the looks of it, a ramp with a steepness that a subway train would never be able to use). If space allows for such a ramp, it's probably cheaper than using an elevator.
pantalaimon 8y ago
You can run a metro though small, simple tunnels. https://en.wikipedia.org/wiki/Glasgow_Subway https://en.wikipedia.org/wiki/Glasgow_Subway

semi-extrinsic 8y ago

It will definitely have some sort of tracks. They've shown demos of a Model X on tracks in their demo tunnel. The project will also have to deliver on the same demands wrt. fire suppression as any other tunnel. The station building iself must be sized according to the number of people per hour, not the train length; the physical platforms that you use to step on/off trains on subways typically extend into the tunnels.

txcwpalpha 8y ago
>It will definitely have some sort of tracks. They've shown demos of a Model X on tracks in their demo tunnel. The website linked specifically says that it will not have tracks. The concrete itself acts as the 'guide' for the skates without needing any type of other tracks (such as traditional metal train tracks). >The project will also have to deliver on the same demands wrt. fire suppression as any other tunnel. This is also address by the website. Fire suppression isn't needed because the tunnel is made only of concrete. There is no concern about other materials (asphalt, high-voltage electrical, etc) catching on fire. >The station building iself must be sized according to the number of people per hour, not the train length; the physical platforms that you use to step on/off trains on subways typically extend into the tunnels. I'm not sure what you mean. Train stations are definitely sized according to train lengths. In my hometown, a significant roadblock to expanding our public train system is that we started off with short trains (and short stations to match), and it is very expensive to extend the length of the stations now that we use longer trains.
- semi-extrinsic 8y ago
  So they may not have metal tracks, but they will be limited to similar turning radii as a subway line just to maintain passenger comfort going at 120 mph. No trains travelling faster than 60 mph are limited in turning radius by mechanical properties. Wrt. fire suppression: Tesla can state whatever they want, but they will either have to fulfill the demands set forth in NFPA 502 for fire suppression in tunnels, or they will never be allowed to open to the public. Civil engineering is very strict on these things, for a very good reason. For an underground train, you can have the train platform extend well beyond the actual station building. If you've ever taken the subway/tube in NY or London or similar you know what I mean. If not, look e.g. at this Google Maps of the Gloucester Road tube stop: https://goo.gl/maps/KQwuSz6RCUE2 https://goo.gl/maps/KQwuSz6RCUE2 The station building is the small square labeled Gloucester Road tube stop. But the platform extends all the way under the shopping mall (Waitrose's etc) out to the intersection between Cromwell Road and Ashburn Place.

usrusr 8y ago

> fire suppression systems Why wouldn't it need a fire suppression system? Because once a battery pack has started catastrophic failure, they are all dead anyways? The proposed system has more need for fire suppression than conventional subway, not less.

txcwpalpha 8y ago
Because the tunnel is pretty much just concrete and nothing else. There's no flammable asphalt or high-voltage electrical cables running through it that could cause or contribute to fires.

trainmew 8y ago

> 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.

txcwpalpha 8y ago
>The article clearly states the tunnels with have a tunnel ventilation system, which is standard fire suppression strategy for underground tunnels for subways. 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. >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. A power cable for low-voltage lighting is much, much, much different than the electrical systems required for powering a subway train. It's like the difference of running an extension cord to your lamp versus laying mains wiring for an entire house. There's also no reason to believe that the vehicles would be dependent on the lighting system. Many cars on the market today already come with sonic- or LIDAR-based cameras that do not need lamps to detect obstructions. Tesla's own autopilot on its cars works just fine on unlit roads. 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. >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. You wouldn't want them, but not being bound to the grade and angle restrictions of a tracked metro train means that you have more flexibility of where your system can go if you need to. It makes it easier to route around existing tunnels, piping, sewers, etc without having to make huge detours or being forced to use elevators. An example of this is given in the linked website where they talk about the eastern terminus of the tunnel - it uses a ramp (from the looks of it, a ramp with a steepness that a subway train would never be able to use). If space allows for such a ramp, it's probably cheaper than using an elevator.

pantalaimon 8y ago

You can run a metro though small, simple tunnels. https://en.wikipedia.org/wiki/Glasgow_Subway https://en.wikipedia.org/wiki/Glasgow_Subway