From: stephen@sprunk.org   
      
   On 12-Apr-15 22:05, jimmygeldburg@gmail.com wrote:   
   > Stephen Sprunk wrote:   
   >> A mini high block requires bridge plates if it's not going to   
   >> conflict with freight trains, and that slows boarding--and   
   >> unpredictably so, which is worse.   
   >   
   > If the vast majority of trains are passenger trains (or freight   
   > trains that clear high platforms), and a wide freight is a rarity,   
   > they can leave the flip-down high platform edges deployed most of the   
   > time, and only retract them before a freight comes through.   
      
   A bridge plate needs support at both ends; it doesn't just hang out in   
   space by itself.  What you're describing is more like a retractable gap   
   filler, which would extend on arrival and retract before departure; you   
   wouldn't want to leave it extended between passenger trains and count on   
   it being retracting remotely before the next freight passed through.   
      
   Now that the old South Ferry is closed, I'm not sure there are any   
   remaining examples of such gap fillers in the US.   
      
   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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