Idle signal aspects

NW Mailing List nw-mailing-list at
Thu Nov 17 15:35:33 EST 2016

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?
JIm Cochran

On Thu, Nov 17, 2016 at 10:13 AM, NW Mailing List <nw-mailing-list at>

> 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
> ________________________________________
> NW-Mailing-List at
> To change your subscription go to
> Browse the NW-Mailing-List archives at
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the NW-Mailing-List mailing list