From: joekor@earthlink.net   
      
   On 1/9/2016 6:02 PM, Stephen Sprunk wrote:   
   > On 08-Jan-16 11:46, Joseph D. Korman wrote:   
   >>>> Stephen Sprunk  wrote:   
   >>>>> Sounds like this is coming west from Expo/Bundy Station; the yard   
   >>>>> is on the left after the line returns to grade, but according to   
   >>>>> the FEIR, the two mains are on the far right and the only siding (a   
   >>>>> yard lead, plus the yard itself) is on the left.  I don't see   
   >>>>> anything in the plans that would indicate a crossover or other   
   >>>>> interlocking involvement on the right track, but since the left   
   >>>>> track does and thus needs a two-headed signal, they may have given   
   >>>>> the right the same for consistency.   
   >>   
   >> On the NY subway BMT-IND and new IRT signals, there would be a bottom   
   >> head that only displays green or red.  This is an interlocking signal   
   >> protecting a training point switch, so the only valid aspects are G-G,   
   >> Y-G or R-R.   
   >   
   > In the case above, there is apparently _no_ switch on this track,   
   > trailing point or otherwise.   
   >   
   > S   
   >   
      
   I'm not sure why you think there no trailing point switch.  R-R is stop   
   and stay.  In the old days an automatic red by itself was a stop and   
   proceed expecting to stop again for a train or obstruction ahead.  Now   
   the command center has to be contacted, but nothing special about   
   passing it.   
      
   A R-R needs a call on (R-R-W) that's controlled by the tower and the   
   train operator needs to move a small lever near the signal to drive the   
   stop arm down.   
      
   An example would be entering Pacific (Atlantic) on the D, N, & R   
   southbound.  Coming from the local track to cross to the express it's   
   Y-Y.  At that time the express would see R-R to prevent a train from   
   fouling.  Once the crossing is done, the express train would see Y-G or   
   G-G, proceed  on main (and only) route.   
      
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