[N&W] Punkin' Vine Signalling (Re: J Class Marker Lights)

[nw-mailing-list at nwhs.org]

[Ed King wrote:]
<< N&W dispensed with the use of classification signals in single-track CTC and
  double-track ABS territory operated under rule 251 of the rule book.  All
  classification lights would have been dark.  All freight trains were run as
  extras by superintendent's bulletin superseding the timetable schedules -
  that let scheduled time freights leave ahead of time if the yard got them
  ready.  No green flags or lights were used to denote sections of schedules,
  either.
  The lead J of the Eisenhower doubleheader would have carried white flags as
  an extra on the Punkinvine, though; that was train order single track
  territory - no CTC.  >>
____________________________________________
I agree with what Mr. King has written.  It is interesting to read the
timetable special instructions in the various timetables from the 1950s,
concerning this topic.  It would be an interesting research to catalogue all
the various permutations of the concept in chronological order, to get the
development.

 From my time of working in train service on the Shenandoan, Radford and
Norfolk Divisions, I have two observations:

1.)  I believe the J's were restricted on the Punkin' Vine account the length
of the cab, which would not fit comfortably through a bridge south of Pine
Hall.  When I worked there in the early 1960s, almost all the men were steam
men, and they told me that only one J had ever operated on the Punk, and that
the rear of the cab scraped the bridge, which resulted in the J's were
restricted.

2.)  The automatic block signal system on the Punkin' Vine was interesting.
After I went to work on PRR territory, I learned that they were what the
industry calls a system of "Absolute Permissive Block" ("APB.")  That is,
they permitted signal indications for following movements, but prevented
signal indications for opposing movements.  (The Pennsy men said APB was "a
poor man's CTC.")   This type of signalling did not >>authorize<< train
movements.  Authority was granted by timetable and train order.  As I recall,
the CTC was installed in stages in the early 1970s, starting in connecting
with the new business generated by the Belews Creek Power Plant.

-- Abram Burnett, Harrisburg, Pa.
    Retired Manager-Operating Rules,
        Conrail Harrisburg Division