From: stephen@sprunk.org   
      
   On 09-Oct-14 12:25, hancock4@bbs.cpcn.com wrote:   
   > On Thursday, October 9, 2014 12:49:15 PM UTC-4, John Levine wrote:   
   >> I wonder if they considered the possibility of replacing the   
   >> ballast, ties, and rails in whatever increment they could do   
   >> overnight or on a weekend.   
   >   
   > I'm no engineer, but I can't help but suspect that, if they really   
   > wanted to, they could design and build a new tunnel reasonably   
   > quickly.  Tunnel technology has improved since 1910, though   
   > construction times (e.g. Second Avenue Subway) seem worse.   
      
   They could, as evidenced by projects in other countries, but we pay   
   about about ten times as much per mile.  For what we spend to "study"   
   projects, other countries actually _build_ them.   
      
   For instance, Madrid's latest subway expansion cost only $59M/mi and   
   took only 3 years, whereas NYC's SAS is costing $2B/mi--and taking a lot   
   longer.   
      
   (Even London, which is probably a fairer comparison to NYC, built their   
   latest line for only $250M/mi.)   
      
   > I don't know if digging a tunnel or digging a trench and laying a big   
   > pipe is faster.   
      
   Boring is faster but more expensive.  Cut-and-cover cheap but slow--and   
   highly disruptive to surface activity.   
      
   S   
      
   --   
   Stephen Sprunk         "God does not play dice."  --Albert Einstein   
   CCIE #3723         "God is an inveterate gambler, and He throws the   
   K5SSS        dice at every possible opportunity." --Stephen Hawking   
      
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