[PRCo] Re: WP signals

[Dwight Long]

Phil

I don't know what the frame of reference was for this post, but I can add this:

Yes, there were two "paddle" switches in the West Penn system--one turned off the lights in the section just vacated and the other turned them on in the section ahead. West Penn often operated their spring switch-equipped crossing sidings left-handed so that the motormen could lean out the door and throw these switches when located in the space  between the tracks.  This, however, was not universally true.

The system over the years presented very few problems from "signal failure."  But it was not a fail safe system.  Such a system would have had the lights on constantly except when the block was occupied.  In that manner, signal lights out would have meant that a car could not enter the block.

The biggest problem was that the lights were connected in series, just like old fashioned Christmas tree lamps, and if one went out, all did.  However, the most likely time for one to fail was when first switched on from cold, and motormen were not permitted to pass into a non-lit section without dispatcher authority. The problem was mitigated somewhat by running the voltage at less than for what the lamps were rated.

Second sections were rare on WP, but one could follow into the block on its leader, maintaining visual contact but with sufficient distance to stop if the leader did.  The alternative, for a not-too-close following section, or an excursion car, was to wait for the leader to vacate the block ahead (lights out!) and then proceed as normal, lighting up the block before entry.

There were intermediate lights at places such as curves with limited visibility, etc, but this of course did not help the spacing problem with following moves, just alerted the motorman if an opposing car had ignored the crossing point and entered the block.

Human error as well as electrical error was always a potential in a system as primitive as this.  However, on the up side, WP motormen were very professional, conscientious, and alert to their surroundings, the schedules and normal crossing points, and the like.  Such a system would probably be asking for a collision with today's far less well trained and disciplined work force.

What prompted this enquiry?

Dwight
  ----- Original Message ----- 
  From: Phillip Clark Campbell 
  To: pittsburgh-railways at dementia.org 
  Sent: Tuesday, 23 November, 2010 19:59
  Subject: [PRCo] WP signals


  I assume that releasing the signals behind at a siding and
  activating the signals ahead were separate functions.  The
  drawing suggests they 'may' work simultaneously.  This is
  in regards to the manual signals.
  With 30-60 min headways there isn't much problem with
  following cars, just opposing.  Did this system of signals
  present many problems?  Did WP have cornfield meets
  from signal failure?

  How were signals handled when a second section was added
  to a schedule?  Did both cars occupy the single track at the
  same time?  Spacing could be a problem with all the curves.
  I could see the first car forgetting about the second section
  then shutting down the signals at the next siding.  This could
  allow an opposing car to meet the second section on single
  track.


   Phil
  Without  a   'coast'   but  not  a   'cause.'