RE: (erielack) Erie Signals

[pat.moore_@_att.net]

Gordon,

Thank you very much for that very informative post.  I had a feeling that I was confused and incorrect with some of the terminology used, especially the signal arm and signal aspect definitions.  Thanks for clearing that up in my mind.

- -pat moore 


- -------------- Original message ----------------------
From: Gordon Davids <g.davids_@_verizon.net>
>
> For a short story, the reason for two arms (the correct term for each 
> element, regardless of whether it is a semaphore or some form of a light 
> signal) is that at least one of the aspects displayed by the signal 
> requires two arms, as in "Approach Medium," (Yellow over Green).
> 
> For the long story, a signal that displays only three aspects using 
> Green, Yellow or Red, one color at a time, requires only one arm.  The 
> indication conveyed by a single Red aspect is further distinguished as 
> either "Stop" (Rule 292) or "Stop and Proceed" (Rule 291) by the absence 
> (Stop) or presence (Stop and Proceed) of a number plate on the mast.  As 
> Steve Timko notes, the indication can be further modified by the 
> presence of a "G" plate on the mast, which permits designated tonnage 
> trains to proceed at a "Stop and Proceed" signal without having to stop, 
> and the Erie further complicated things with Telephone Train Order 
> signals, which is a whole 'nother topic.
> 
> In the case of a signal that displays four or more aspects, two arms (or 
> three) are necessary.  If the most restricting indication conveyed by 
> the signal is "Stop and Proceed," the arms will be staggered from the 
> vertical position, and the mast will still hold a number plate.  If the 
> most restricting indication is "Stop," the arms will be vertical and the 
> mast will not hold a number plate.  That practice holds true on both 
> single and multiple track.
> 
> In Erie practice, much of the automatic block and TCS territory used 
> four-indication signaling, where the progression of indications on these 
> intermediate signals was "Clear," (Green over Red); "Approach Medium," 
> (Yellow over Green); "Approach," (Yellow over Red); and "Stop and 
> Proceed," (Red over Red).  "Approach Medium" had a dual purpose.  It 
> could govern the approach to any signal indicating "Approach" or to an 
> interlocking home signal indicating "Clear Medium" or "Medium Approach."
> 
> Just as another technical note, besides the fine point of the term 
> "arm," a signal "aspect" is the appearance of the signal as viewed from 
> the rear (the direction from which a train is approaching.  A signal 
> "indication" is the information conveyed by the aspect, such as "Stop, 
> then proceed at restricted speed."  Each indication has a rule number 
> (Rule 291) and a name, which is "Stop and Proceed" in this instance.  
> One indication may have several different aspects associated with it, 
> depending on the configuration of an individual signal.  For instance, 
> "Approach" is a top Yellow with all lower arms Red regardless of how 
> many arms are installed on the signal.  But every individual aspect may 
> be associated with only one indication on any railroad, so there can be 
> no ambiguity over the information conveyed by any signal.
> 
> Gordon Davids
> > > Rich,
> > > 
> > > Many of the signal masts on the Erie NY Division were two 
> > > searchlight heads, the upper being on the right side of mast 
> > > and the lower on the left. As far as I can tell, these were 
> > > located on double or quadruple track at locations not having 
> > > Xovers, sidings or interlockings. What was the purpose of the 
> > > lower head?
> > > 
> > > Paul B 
> >   
> 
> 
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