Signal Question and rule term

NW Mailing List nw-mailing-list at
Wed Oct 30 17:42:46 EDT 2013

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 more
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


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


> 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 was

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 needed.


> 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 new
CTC equipment in the 1940s !


> -- abram burnett,

> frustrated electron jockey

More information about the NW-Mailing-List mailing list