Early signaling on the N&W

NW Mailing List nw-mailing-list at nwhs.org
Tue Oct 28 13:53:21 EDT 2014

To advance a train into an occupied block under Permissive Block Rules, the
signalman ("operator") held the semaphore at Red and gave a highball to the
train with a Yellow flag or lantern, and hooped up a "Permissive Card."
 The Permissive Card was a type of clearance that authorized a train to
pass a signal in Stop position and enter an occupied block.

Attached is a scan of an N&W Permissive Card.  I found a pad of them in old
"AN" Telegraph Office at Shenandoah about fifty years ago.

The N&W had some interesting permutation on the Manual Block System of
operation.  For instance, on the North Caroline Branch, freight trains were
operated by Time Table and Train Order only, and were not "blocked."  But
passenger trains were operated under Manual Block Rules.  However, it was
not a hard-and-fast Manual Block operation, as freight trains could be
allowed to follow a passenger train into an occupied block "after ten
minutes."  Someone with access to a fairly complete set of N&W Time Table
could probably work up an interesting article on this subject.

The subject of Clearance Cards is in itself an interesting study.  Some
larger railroads used four different types of Clearance Cards, called A, B,
C and D.  Each was printed on a different color paper.  One was used to
advance a train by a signal which was set at Stop to indicate that Train
Orders were to be received.  Another was to advance a train past a Stop
Signal into an occupied block under Permissive Block rules.  Another was to
advance a train past a signal which could not be cleared due to a
mechanical malfunction (e.g. the wire or chain pulling the signal arm had
broken.)  The final type was to advance a train "when the means of
communication have failed," allowing the train to run on its Time Table
schedule and any Train Order rights it may be holding. Over the years, the
system was simplified on most road to just two forms of clearance cards:
 Clearance Form A and Clearance Form C.  I've long intended to make a write
up on this subject, but have not done it yet.  I have seen no indication
that the N&W ever used a clearance card system of this complexity.

And while we're at it, Jim...  How about calling us signal afficianados
"Signal Arms" instead of "Signal Heads" ???  :-)   :-)  "Arm" was always
the proper official, proper nomenclature for that part of the signal which
changed and conveyed information.  Being known as "Signal Arms" would set
us apart in a class all our own!  The use of the term "head" in referring
to signals only came around within the last fifty years and always struck
me as railfan weenie talk.


-- adb
Self-Professed Curmudgeon and "Signal Arm"  :-)

Sent to You from my Telegraph Key
    ... better than AT&T 4G LTE


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