Signal Question and rule term

NW Mailing List nw-mailing-list at
Tue Oct 29 22:32:27 EDT 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 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) 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 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

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