Stephen Sprunk wrote:   
   > jimmygeldburg@gmail.com wrote:   
   > > 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.   
      
   No, I was referring to a flip-down platform edge.  They have to be flipped   
   manually, which is why they only make sense where the vast majority of traffic   
   is passenger trains and narrow freights.   
      
   http://upload.wikimedia.org/wikipedia/commons/7/78/Reading_MBTA_   
   tation_mini-high_platform.JPG   
      
   > Now that the old South Ferry is closed, I'm not sure there are any   
   > remaining examples of such gap fillers in the US.   
      
   Union Square on the Lexington Avenue IRT.   
      
   http://www.citytransport.info/NotMine/NYCS_IRT_LexAve_14Sta.jpg   
      
   Jimmy   
      
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