[N&W] N&W Signals - More

[nw-mailing-list at nwhs.org]

Further in connection with the recent question and answer on N&W Position
Light ("PL") signals...

The 1945 N&W Operating Rules show one arm, two arm and three arm PL signals.
The one arm signals would obviously be automatic signals; the two arm signals
would obviously be the distant signals to interlockings; and the three arm
signals would obviously be home signals at interlockings.  (I won't even
address the issue of dwarf signals here.)

It is obvious that the scheme of the N&W signal engineers with these early
PL's was simply to replicate, using rows of lamps, the appearance of  >>UPPER<
<  QUADRANT semaphores. (The N&W, like most other roads, had switched from
lower quadrant to upper quadrant semaphores around 1913.)  This is the key to
the whole matter !

On all pages of the signal section of the Rule Book, semaphores are shown
alongside the newer PL signals.

What makes the  >discussion< of N&W signal aspects difficult is that, in
1945, proper   >>names<<   had not been applied to the indication.  The
signal pages only give picture representations of how the signals looked,
abut there are no >>names<< associated with the aspects.  For instance, the
name "Medium Approach" is not applied to an aspect consisting of Red over
Yellow over Red.  From our perspective in the year 2000, it is really
difficult to discuss signal indications without using names !

It is obvious that the PL signal aspects and indications given in the 1945
Rule Book were tied in to the earliest N&W attempts at Centralized Traffic
Control, which date to about 1942.

What I am not able to fathom is why the N&W would have chosen to install >>
three<<  arm PL signals replicating the indications of the old semaphores,
when the Pennsylvania Railroad had, twenty years before, developed a very
good and flexible system of PL signal indications using only >> two <<  arms.
  So, what we have is the N&W adopting the wonderful PL signal, but making an
application of it which was at once more expensive and less flexible than
what the PRR had put in some years beforehand.  Strange, indeed.  (At any
rate, the three arm PL's did not last long, and were  >probably<  all changed
to two arm PL's by the early 1950s.)

===============================
Here's what the "Automatic Block Signal System Rules" say.  (And I quote
verbatim, without attempting to correct the grammar, punctuation, or style,
which are indeed cumbersome!)

801.  There are three types of signals in use, as follows:

(a)  Two-arm, two-position, lower quadrant, semaphore signals, working in the
horizontal and vertical positions.  When both arms are horizontal or
displaying lights, red over yellow, it indicates Stop.  When top arm is
vertical and bottom arm horizontal or displaying lights, green over yellow,
it indicates prepare to stop at next signal; trains exceeding medium speed
must at once reduce to that speed.  When both arms are vertical or displaying
lights, green over green, it indicates Proceed.

(b)  One arm, three-position, upper quadrant, semaphore signals, working in
the horizontal, diagonal, and vertical position.  Whena rm is horizontal, or
displaying red light, it indidcates Stop.  When arm is diagonal, or
displaying yellow light, it indicates prepare to stop at next signal; trains
exceeding medium speed must at once reduce to that speed.  When arm is
vertical, or displaying green light, it indicates Proceed.

(c)  Three-position, position-light signals.  When lights are horizontal, it
indicates Stop.  When lights are diagonal, it indicates prepare to stop at
next signal; trains exceeding medium speed must at once reduce to that speed.
  When lights are vertical, it indicates Proceed.

806.  Semaphore signals with other than square end arms or staggered lights,
are STOP and PROCEED; those with square end arms and staggered lights are
STOP and STAY signals.  A staggered light is a red light on the mast below
all other signals and on the opposite side of the mast from the other signal
lights.

Position-light signals are STOP and STAY signals when equipped with marker
lights below all signal lights.  When not equipped with marker lights, they
are STOP and PROCEED signals.

--- End of Quote---

As for TWO ARM PL signals,  the Rule Book shows four aspects (four of which
have the "marker light.")  These signals are roughly equivalent to today's
Clear, Approach, Stop, Restricting, Medium Clear and Medium Approach.

As for THREE ARM PL signals, the Rule Book shows seven aspects (five of which
have the "marker light.")  These signals are roughly equivalent to today's
Clear, Approach, Stop, Medium Approach, Medium Clear and Restricting.

==================
The final question I would like to raise is this:  What names were applied to
these numerous signal aspects?  I'm sure the crews developed their own
informal ways of calling these signals, but the only information given by the
1945 Rule Book is this:

<< Rule 34a:  In registering the indication of automatic and interlocking
signals, the following words should be used, irrespective of the type of the
signal:  "Red Block," "Yellow Block," "Approach Medium," "Clear Block." >>

=========================
SUMMARY, based in the 1945 Rule Book only:

1.  The early N&W attempts at PL signaling utilized one, two and three arm
signals, plus "marker lights" below.

2.  The orientation of the row of lights (horizontal, vertical, or diagonal)
was in all cases was a visual representation of the position of upper
quadrant semaphore arms.

3.  A full system of "names" had been developed at this time, and the terms
"aspect" and  "indication" were used somewhat ambiguously, without the
precision we now assign to these technical terms.

4.  In some cases, signal aspects conveyed speeds, and in some cases they
only indicated a "diverging route" ahead.  The signal system was neither a
pure system of "route signaling" nor a pure system of "speed signaling," but
contained elements of both.

==============
REMAINING QUESTIONS:

1.  When and where was the first application of PL signals on the N&W?  (It
was probably in connection with the first applications of CTC.)

2.  When was the use of  >>three<<  arm PL signals discontinued?

3.  When were the last of the semaphores phased out for automatic block and
interlocking use?  (We are NOT asking about semaphores used as train order
signals at stations.)

4.  Someone needs to research back issues of "Railway Signal Engineer"
1930s-1950s for specific developmental information.
=============

We've only touched the beginning of the issues, but thank you for your
patience !

----- Abram Burnett
      E-mail:  Pius10th at aol.com