More on signal "roolz"

NW Mailing List nw-mailing-list at
Sun Aug 18 18:25:36 EDT 2013

For those wanting to understand Ben's signal explanations attached find
photos taken at the new signals at Ashby, Success and Berryville.
Mason Cooper


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Subject: More on signal "roolz"

the other day the subject came up about why do some signals give a Diverging
Clear, while others will only display a Diverging Approach.

This gets LONG and complicated and is hard to explain. If you get confused,
ask before you throw tomatoes at me, because I may not word it the best way.
I'm a signalman, not a book writer! And, I'm lousy and proofreading my own
stuff, so...

This is more or less how it's been explained to me by the signalmen who
trained me through the years.

It depends on how the track is designated in the operating rules. If a
track is designated as a Double Track situation, with Main One, and Main
Two, (or in the old rules as Eastbound, Westbound, Northbound, Southbound),
the signals will be able to give a Diverging Clear coming out of a siding,
but will not be able to give a Clear coming out of the siding. Why?
Because the siding is the inferior route. Yes, there were and are
exceptions to this, but for the most part, that's how the N&W's doubletrack
was everywhere I've been.

A good example of this is the Christiansburg District. It used to be double
tracked as we all know, and now is designated as a Double Track to Single
Track situation because some of the double track was removed after the
Virginian merger. For the mostpart, the westbound track was left intact,
and the eastbound track that remained became the sidings and also became the
inferior route (because you'd be traveling westward on what was the
eastbound track). Confused yet? It gets worse.

A single track with sidings had no directional designation, so there was no
inferior and superior route. (Or well, actually there was, but because the
track itself was bi-directional, the inferior route received a shorter
signal mast to designate it as the inferior route).
Still not confused? I'll keep trying!!

Here's a good example of confusion: At the new Ashby and Marsh Run double
track north of Front Royal, those signals were set up for Diverging Clear
out of the siding as a double track would be. That was because they
originally were setting it up as a Main One/Main Two operation. Then, they
changed their mind at the last minute and designated it as a Main One/Siding
setup. We left the signals as they had been designed when we put all that
in service. The new siding extensions between Berryville and Audley can
give clear out of the siding, and this only adds to the confusion!

Here's another exception: Before the pole line elimination/signal
changeover on the Bristol Line, the east end of Abingdon and the east end of
Glade Spring could only give Diverging Clear coming out of their sidings,
but they were not in double track territory. So, why were they set up this
way? They were in Yard Limits when they were originally installed, and I
assume that was why, but I'm not certain.
Now, they give Clear coming out of the sidings because they are designated
as Main One track and Siding and the yard limits are long gone.

If I've got anything wrong, maybe Mr. H.W. Bundy can straighten me out.
But, learning how signal systems work takes years of dealing with them.
When I hired, I was told it would take me ten years to get a good grasp on
them, but they told me I had that in five years.

With signals, there are situations and rules and so many other factors to
consider, that each situation requires its own specific engineering. That
is why they are so hard to understand. Every location is a little
different, and specific to what is around it.
Switches nearby, crossings, slide fences, foreign railroads, etc.all factor
in to the design and engineering. It is not an exact science.
They design it for what they need at the time.

So, for the modeler, if you had a signal that seemed to be "out of place",
you can explain it with your specific rules. If I had all position lights
on my layout except for one searchlight signal, I would justify it by saying
its "bulletined in the special instructions"!

That's enough rambling for now.

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