More on signal "roolz"
NW Mailing List
nw-mailing-list at nwhs.org
Fri Aug 16 10:22:45 EDT 2013
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
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
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
That's enough rambling for now.
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