Signal Question and rule term

NW Mailing List nw-mailing-list at
Wed Oct 30 23:14:33 EDT 2013

it seems there were so many variables for each circumstance, trying to match
a signal aspect for it was an impossibility.
Just as a general observation most signals reflect track circumstances such
as turnout routing but gives you a clue about speed to operate,
doing a double duty, how the railroad directly says those signal indicate is
put in the rulebooks and what to do.

Advance medium might say a turnout is ahead, but it could be a track
condition indication a speed to run and no turnout, such as its the end of
the track ahead, or a sharp curve, or just a 2nd railroad crossing.

These are just a general observations.

----- Original Message -----
From: "NW Mailing List" <nw-mailing-list at>
To: <nw-mailing-list at>
Sent: Wednesday, October 30, 2013 4:42 PM
Subject: RE: Signal Question and rule term

> I have never understood why "medium" came about for aspect names on the

> N&W. It sounded big-time? The term has little relevance to how the

> diverging aspects were applied in the field. "Diverging" always seemed


> intuitive and a better fit for the relatively basic signal system the N&W

> used. Thank you for the background! I even caught the tease about the new

> CTC equipment--what stuff?


> And please, write that article.


> Grant Carpenter


> > Date: Wed, 30 Oct 2013

> >

> > The matter can be summed up this way: The N&W Operating Rules for 13

> years used the word "Medium" in the names of three of its signal aspects,

> but that word didn't authorize "Medium Speed" (30 MPH) over the turnout.

> The speed over the turnout was "as prescribed" in the Time Table Special

> Instructions.

> >

> > The >>ONLY<< N&W Rule Book which uses the term "Medium" in naming signal

> aspects is the 1951 Rule Book. (Those aspects are Approach Medium, Medium

> Clear and Medium Approach.)

> >

> > There is one other key ingredient of a Speed Signaling system which is

> missing: the N&W never used "Slow Speed" (15 MPH) signals over switches

> having No. 10 frogs. Slow Speed signal aspects (Approach Slow, Slow Clear,

> Slow Approach) are entirely missing from all N&W Rule Books. Given that


> N&W had two arms on its home and distant Position Light signals, and


> lamp spaces on its Position Light dwarf signals, it would have been quite

> easy (and beneficial) to have given Slow Speed signals where required, but

> they didn't do it. Nor did the N&W ever use Limited Speed (40/45 MPH)

> signals.

> >

> > For these reasons, it would probably be best to say that the N&W never

> had a real Speed Signaling system, the use of the word "Medium" for a few

> years notwithstanding.

> >

> > As someone on this List remarked a few days ago, the N&W clung to the

> "semaphore mentality."

> >

> > In one way, not using the equipment they had to its fullest potential


> a waste. But in another way, they didn't need a Speed Signaling system.

> Their interlockings were not complex and they did not operate trains on

> close headways. They got by with a simple system that did what they


> >

> > Remember the old K.I.S.S. principle? "Keep it simple, Stupid!"

> >

> > Nonetheless, I would really love to get inside the head of W.P. Wiltsee,

> the Chief Signal Engineer in the 1930s and 1940s, to find out what he was

> really thinking... especially with some of that stuff he ordered on his


> CTC equipment in the 1940s !

> >

> > -- abram burnett,

> > frustrated electron jockey





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