Idle signal aspects

NW Mailing List nw-mailing-list at
Fri Nov 18 22:54:23 EST 2016


Plus, the inconsistency I pointed out. Yes, you will see Clear on the 
right-hand main and Stop and Proceed on the left (reverse main) along 
some sections of the main line, however you will see Clear on both mains 
along other sections of the main line. For example, and this may be 
extreme, reverse-main automatics did not display Stop (either Clear or 
Approach) between Bluefield and Maybeury, but did display Stop from 
Maybeury to Powhatan. From Powhatan to Eckman they did not display Stop, 
but did from Eckman to Big Four. If memory serves, reverse-main 
automatics on the Christiansburg District displayed Stop with fewer 
exceptions. To be sure took access to signal charts, the early CTC 
panels, or knowing the territory as a maintainer or experienced bystander.

Grant Carpenter

On 11/17/2016 2:35 PM, NW Mailing List wrote:
> Grant,
> Thanks for your note.  Let me see if I understand the "reverse main" 
> thing.  N&W used right-hand running so traffic headed toward 
> Portsmouth/Columbus on the right-hand main would be running in the 
> "normal" direction (let me know where I screw up here).  Movements 
> headed towards Norfolk on the other main (right-hand for them) would 
> also be the norm. Signals facing opposite the flows just described on 
> either main would then be considered as giving "reverse main" 
> indications?  So, if I understand you correctly, and I am out in 
> intermediate land several blocks from any control point on a day with 
> no traffic (no routes set), I would see clears for the right-hand main 
> and stop-and-proceeds on the left-hand main, no matter what direction 
> I am looking.  Is this anywhere close to what you were telling me?
> Thanks,
> JIm Cochran
> On Thu, Nov 17, 2016 at 10:13 AM, NW Mailing List 
> <nw-mailing-list at <mailto:nw-mailing-list at>> wrote:
>     Jim,
>     I think what you are asking about is a signal's idle aspect which
>     is displayed in the absence of traffic, lined routes and faults.
>     Controlled signals displayed Stop and Stay and automatic signals
>     displayed Clear, except for Approach aspects in advance of a Stop
>     and Stay. An exception to this in double-track territory was that
>     the reverse main automatics all displayed Stop and Proceed, but
>     only in some sections. Lacking an apparent operational reason,
>     this inconsistency may be just different versions of installed
>     logic. (Abram?) In addition to signal system blueprints, early CTC
>     panels featured a graphic symbol for each signal that, in part,
>     indicated the idle aspect.
>     Grant Carpenter
>     On 11/16/2016 6:26 AM, NW Mailing List wrote:
>>     What was the "default" aspect for N&W CPLs in the absence of
>>     traffic?  Since they ostensibly simply indicate block occupancy,
>>     it would seem that if there were no trains, all intermediates
>>     would be showing CLEAR, but somehow this doesn't "feel" right to
>>     me.  If I had had the foresight to go out along the line on a
>>     Christmas day in the 70's and examine the state of intermediate
>>     signals, would I have seen all green?
>>     adthanksvance
>>     Jim Cochran

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