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What are the costs involved in "retrofitting via cut-and-cover" as opposed to "building more capacity by mining" that makes the second option more palatable for

What are the costs involved in "retrofitting via cut-and-cover" as opposed to "building more capacity by mining" that makes the second option more palatable for the 100-year timeline?

Schiendelman 6y ago
I don't understand. That's not the tradeoff MTA is making. They're building more capacity now rather than having to try to do it later. Later would be nigh-impossible because of the skyscrapers going up on every side, and the railyard above. Hudson Yards is a massively complex project.
- quacked 6y ago
  The parent comment that you responded to: "... Oversized stations are even more problematic when you consider that the MTA wants to build all of these by mining rather than using cut-and-cover, because cut-and-cover has too much disruption to surface tenants. And mining is far more expensive than cut-and-cover..." Your response: "... It is ALWAYS cheaper to build capacity now than to retrofit later, even inflation adjusted. ..." The implication of your response is that on a 100-year timeline, the way that the modern stations are apparently being built (by mining) is cheaper than building them by the way the parent commenter says (cut-and-cover). I was just curious why it's "always" cheaper. Is "mine and build big" the cheaper method only when there's a ton of density on top like Hudson Yards, or is it also the case in places with less surface density?
  - Aeolun 6y ago
    I think that you’re probably always better off building bigger if you expect growth in the next 100 years. How big you should build is just a matter of how much current and future traffic you expect to have.
  - soneil 6y ago
    I think what they're looking at is over-sizing rather than right-sizing. Think of it as cost=size*method. Future-proofing increases the size, not the method.
  - Schiendelman 6y ago
    Apologies - I may have skipped over something when reading. I was responding to the implication that a smaller station now is an appropriate cost savings.
- kevin_thibedeau 6y ago
  Capacity for what? The line could theoretically be extended by a tunnel to Secaucus but even then only a fraction of the ridership will take that branch and get off at the first stop. The West side is already serviced by two lines so where else can the 7 go?

What are the costs involved in "retrofitting via cut-and-cover" as opposed to "building more capacity by mining" that makes the second option more palatable for the 100-year timeline?

Schiendelman 6y ago

I don't understand. That's not the tradeoff MTA is making. They're building more capacity now rather than having to try to do it later. Later would be nigh-impossible because of the skyscrapers going up on every side, and the railyard above. Hudson Yards is a massively complex project.

quacked 6y ago
The parent comment that you responded to: "... Oversized stations are even more problematic when you consider that the MTA wants to build all of these by mining rather than using cut-and-cover, because cut-and-cover has too much disruption to surface tenants. And mining is far more expensive than cut-and-cover..." Your response: "... It is ALWAYS cheaper to build capacity now than to retrofit later, even inflation adjusted. ..." The implication of your response is that on a 100-year timeline, the way that the modern stations are apparently being built (by mining) is cheaper than building them by the way the parent commenter says (cut-and-cover). I was just curious why it's "always" cheaper. Is "mine and build big" the cheaper method only when there's a ton of density on top like Hudson Yards, or is it also the case in places with less surface density?
- Aeolun 6y ago
  I think that you’re probably always better off building bigger if you expect growth in the next 100 years. How big you should build is just a matter of how much current and future traffic you expect to have.
- soneil 6y ago
  I think what they're looking at is over-sizing rather than right-sizing. Think of it as cost=size*method. Future-proofing increases the size, not the method.
- Schiendelman 6y ago
  Apologies - I may have skipped over something when reading. I was responding to the implication that a smaller station now is an appropriate cost savings.
kevin_thibedeau 6y ago
Capacity for what? The line could theoretically be extended by a tunnel to Secaucus but even then only a fraction of the ridership will take that branch and get off at the first stop. The West side is already serviced by two lines so where else can the 7 go?