4 ms·

I assume they just never bothered to name it. And I'm not too sure how useful of a feature is it. Transit tunnels are useally built in places that are so built

by phire 4y ago

I assume they just never bothered to name it. And I'm not too sure how useful of a feature is it. Transit tunnels are useally built in places that are so built up that land is at a premium. They actually want the tunnel to start underground, because they want to install the station underground too. So you have to build a shaft anyway. And also, they are trying to minimize elevation changes for efficiency.

Robotbeat 4y ago
Stations are one of the common reasons given for why tunnel projects are so ridiculously expensive. Porpoising would avoid that while still allowing you to go from one place to another underground.
- piva00 4y ago
  How would it avoid that? It'd still be mega expensive to purchase plots of land in densely developed land (aka: cities) so your boring machine can tunnel up and down from these station points. One would also need to be careful to not dig the upwards and downwards slope on existing infrastructure: pipes, underground electric and communications lines, etc. Porpoising doesn't help with any of that, if you need a slope of less than 2-3% inclination the machine will pass through a lot of potential infrastructure to surface and then dig down again. It doesn't make sense it'd save that much money considering that the expensive part of a project in developed land is that the land has a massive premium on it by being so productive.
  - Robotbeat 4y ago
    Because surface land is still cheaper than digging an underground station.
- pintxo 4y ago
  Stations are also the ultimate reason for most tunnel projects in urban areas, as you want to make the train accessible to the population locally.
  - Robotbeat 4y ago
    The idea with porpoising is you can just install basically a bus stop on the surface, which is orders of magnitude cheaper than a massive excavated station, grand as it may be. We actually don’t need TBC to do this stuff. We COULD just have extreme restraint on scope and limit the stakeholder input as much as possible, like is more often the case in every country other than the US. But the incentives are all totally misaligned, bordering on corruption here in the US.

by phire 4y ago

Robotbeat 4y ago

Stations are one of the common reasons given for why tunnel projects are so ridiculously expensive. Porpoising would avoid that while still allowing you to go from one place to another underground.

piva00 4y ago
How would it avoid that? It'd still be mega expensive to purchase plots of land in densely developed land (aka: cities) so your boring machine can tunnel up and down from these station points. One would also need to be careful to not dig the upwards and downwards slope on existing infrastructure: pipes, underground electric and communications lines, etc. Porpoising doesn't help with any of that, if you need a slope of less than 2-3% inclination the machine will pass through a lot of potential infrastructure to surface and then dig down again. It doesn't make sense it'd save that much money considering that the expensive part of a project in developed land is that the land has a massive premium on it by being so productive.
- Robotbeat 4y ago
  Because surface land is still cheaper than digging an underground station.
pintxo 4y ago
Stations are also the ultimate reason for most tunnel projects in urban areas, as you want to make the train accessible to the population locally.
- Robotbeat 4y ago
  The idea with porpoising is you can just install basically a bus stop on the surface, which is orders of magnitude cheaper than a massive excavated station, grand as it may be. We actually don’t need TBC to do this stuff. We COULD just have extreme restraint on scope and limit the stakeholder input as much as possible, like is more often the case in every country other than the US. But the incentives are all totally misaligned, bordering on corruption here in the US.