Dwarf PL's

Dwarf PL signals, aka PL-4's, use 4" lenses, and are frosted white to reduce their effective range so they won't be confused with high signals.  Lunar white was used some time later. 

These signals come in both "right-hand" and "left-hand" versions, where the rounded side can be on either the left or right side.  Although I guess the Pennsy could have placed these signals in a square housing, they placed them in "rounded corner" housings.  The vertical aspect was originally on the left, and later, as the railroad wanted to use them on tracks with smaller spacing's, they changed the housing around 1930.

Older versions of the signals have shorter mounting legs, and have access covers on the sides.  Newer versions, like the ones on the short masts at Perryville, and on the Baltimore Light Rail system, have longer legs, and access to the bulbs is via a single cover on the back covering the entire rear of the signal - this requires only one lock vs two for the older version.

Interestingly, the Pennsy PL dwarf has seen widespread use all over the world.  For example, the Baltimore Light Rail System uses them for route indicators.  The Canadian Pacific uses them in at least one yard as shove signals. 

Dwarf PL signals can be found in many other countries besides the United States, as evidenced on many of the sites covering railroads of other countries.

Typical dwarf PL, this one is at the Strasburg RR.

Dwarf signals can be mounted on the ground (above), on poles, and on signal bridges (below).  Some transit systems, like the Baltimore Light Rail system, use them as route indicators.  This dwarf is mounted on a pole about 6ft high, and is used at the wye in Perryville MD.  The Pennsy commonly used dwarf signals in this application, where trains were coming on or off a main line and operated at slow speeds.

In a different application, CP Rail uses dwarf PL's at Pigs Eye yard St Paul MN as a shove signal, indicating to the engineer when the rear of a train is at a certain point at the tail (south) end of the yard.

Here is a set of newer style PL-4's in use on the Baltimore Light Rail system.  These two are on the tail track at the end of the line at Hunt Valley MD.  You'll notice that the legs of the signal are considerably longer than that of older units.





 

 






 

Pedestal PL's

The other "small form" a Position Light signal can take is known as a Pedestal, or a PL-5.  This type of signal places two dwarf signals in one housing, one atop the other.  Through a discussion on the Yahoo Railway Signaling group, it is a medium speed signal, limiting speed to 40MPH, even though it can display clear block" (which on the main line with a high signal, would allow the train to go at the posted speed).  On the north side of the Wilmington (DE) station, the Pennsy used pedestals on the overhead signal bridge, maybe because of clearance issues with a larger full size head.

The left photo is a pedestal signal in Newark DE, on the approach to the NEC.
The second photo of a pedestal and dwarf is at the Baltimore Amtrak station from approx 1972.
Third photo is an unused pedestal in Huntingdon PA, more info below.
Photo on the right is the only place I know of pedestals being used as a high signal, north of the Wilmington DE Amtrak station, LED's are used in the left one.

  A drawing giving the dimensions for the pedestal and dwarf PL signals.

Pedestal signals can also be found with "red-eyes" as shown in the next section below.  If you are used to the all white signals, they are most unique to see in person.

Red-Eye Signals
aka Red Snake-Eyes

The Pennsy started changing some of their PL signals in the mid 50's.  They replaced the two horizontal  lenses with red lenses, keeping the center one yellow to use with the other aspects.  The first application of these signals was apparently at Overbrook, "OB", in suburban Philadelphia, about three miles west of ZOO Interlocking in September of 1954.  After a couple of years of testing, they were put into service west of Harrisburg.  The speculation for their origination is because of the fog that was prevalent on the Buffalo line.  This changed manifested itself in the high-signals as well as the pedestal signals.  No dwarf signals were affected, as far as anyone knows.

We have had 2 or 3 discussions on both the Yahoo railway Signaling and Pennsy Signaling groups, of which one sourpuss complained that we've discussed them too often.  Well, I was the latest instigator, but every time we do a discussion about them, we have new list members, and some new tidbit of info always comes to light in the discussion... so maybe in a few months I'll start another round of discussion :-)  The info below is from these discussions and I would like to thank everyone for their contributions! (don't forget that some of what is presented are personal opinions as opposed to fact).....

When I asked about the red-eye installation timeframes, this is what I got:

1. Test installation at "Overbrook" - circa 1954-5.
2. Evidently adopted widely west of Harrisburg - circa 1956-7 and after.  Exact dates not certain. Installations were phased in over time.
3. Installed widely east of Hbg. - starting after PC merger - ditto Pedestal-type signals. Possibly only new construction.
4. Amtrak NEC PCLs adopted circa 1980s (a Claytor-ism).
The only Dwarf Signals known to be PCL type were tested at "OB".
Hope this clarifies the timeframes.

They are in the 1956 rulebook.  The test installation would have been in Philadelphia Terminal Div./District ETT and GOs.

The "red snake eyes" were seen all the way to East St. Louis and Chicago.  I have many General Orders converting the original PL-type signals to the Position-Color Light (proper terminology) format west of Indianapolis in the late-1950s.

I would not say that there were never any ABS Signals that had them but I do not recall ever seeing any that did. They were generally, if not exclusively, used in signals that could display Stop. Thus, an APB Head-Block Signal could have been an appropriate use for them but I am not aware that they were so used.
Three post from Lin B, Thanks!

The September 25, 1954 date must be the first date that field tests were started, as I dug out an interlocking chart that states the red-eye high signals at Overbrook were cut in with General Order No. 712 dated October 7, 1954.  Signals 4R, 8R, 10R, 12R, 12L, 14R, 14L, 16L, 18L, 018R, 018L, and 20R were so equipped. Unfortunately, I don't believe I have this GO for further details.

The information on the backgrounds may come from an A.H. Rudd article in the July 1921 issue of Railway Signal Engineer. There he indicates that a background was only applied to the vertical row of lights in the lower arm since those aspects are approached at speed (Approach Medium and Medium Clear, using their current names). The diagonal and single marker slow speed aspects (Slow Approach, Restricting, and Stop and Proceed, using their current names) did not need a background since long range sighting was unnecessary. The reduced size of the background and wind pressure area allowed the use of standard sized signal masts (weight and wind were issues with the early four-light position signals on masts).

With the introduction of Approach Slow in the late 1940's and Medium Approach in 1955 and 1956, there were lower arm aspects that would be approached at higher speeds. I suspect this was the driving force behind full backgrounds for the lower arm. I have no specific references, but it does seem that those full backgrounds seemed to become much more common starting in the later 1950's.
Thanks Dave M.

This link: http://mysite.du.edu/~jcalvert/railway/prr/prrsig.htm#pos includes this quote:

Curiously, some position-light home interlocking signals were equipped after 1955 with two red lenses to show the Stop aspect, the pivot light being extinguished. The first trial was at Overbrook on 25 September 1954.

While the author doesn't use footnotes, this entry in the bibliography may be the source:  6 E. Waytel, The First Position Light Signals and Subsequent Developments, The Keystone, Vol. XIV, No. 4, December 1981.

This site answers many questions about PRR signal history, and the author attempts to uncover and correct mistakes in earlier accounts by going to primary sources. However, due to the lack of footnotes tying all of the remarks to sources, I am worried that some conclusions may be just his personal opinion.  For instance: Approach-medium and Medium-clear are used at main line crossovers and junctions, where the turnouts can be used at higher speeds than the usual 15mph, in order to avoid slowing trains unnecessarily. There is a background around the lower arm in this case, since it is viewed at speed. The lights used to display the Slow-approach and Restricting aspects are not provided with a background, since they are approached only at low speed.  Is this based on logic and reverse engineering, or does he have a PRR source for the statement? 
Thanks Jim B.

3. Installed widely east of Harrisburg. - starting after PC merger - ditto Pedestal-type signals.  Possibly only new construction. (a note on Lin's post above)

The only red eyes that I can remember in Lancaster County were over at Cola.  I sort of remember that the westbound home signal on the A&S had them, just before Conrail replaced them, when they closed Cola in the mid 80s.  The Lancaster Branch never had them, even after Conrail single tracked it.  I do not know of any installed on the passenger main from Lancaster to Middletown.  All have been replaced/removed within the last two years by Amtrak.  I do not recall them at Roy either.  I will have to check my pictures of Shocks, but I do not think they had any either.  Wago may have received them when Cly was removed, but that was in the 80s too.  So maybe further east then Lancaster County... 
Thanks C.O.S.

I didn't see any references to red-eye pedestals in the last round of Pennsy timetables before the merger, nor did I see any in the first round of Penn Central timetables issued in 1968.  The first place I found them was in PC Central Region Timetable No. 2 dated December 1, 1968, which shows Medium Clear, Slow Approach, Restricting, Stop and Proceed, and Stop aspects and indicates they were in use at East Fair, West Fair, East Muncy, West Muncy, Linden, West Bud, and Pine on the Main Line-Harrisburg to Buffalo and North Neff, South Neff, North Pan, South Pan, North Try, and South Try on the Chautauqua Branch. Later General Orders added more locations, e.g. GO 205 that added East Keating, East Farwell, East Baker, and West Baker to that list. 

These aspects carried through various PC and Conrail timetables covering these lines until they were added into the 1982 CR rule book. At some point West Brown on the Pittsburgh Division (West Brownsville, PA) got one or more of these, but all other references I've found are to the Buffalo line and Chautauqua Branch. 

All of this confirms my impression that these were rare away from the Buffalo line.  Since the red lenses prevent "high speed" aspects such as Clear and Approach from being displayed, there really are only limited applications for them -- like the ends of CTC sidings. Also, pedestal signals are not really meant for high-speed tracks, so sighting a stop aspect at a distance shouldn't be much of an issue. 

That last thought, however, leads to my theory that there was an operating reason behind adding the red lenses. The Buffalo line and the Chautauqua Branch had 30 MPH signaled sidings that had Medium Approach as the best entering aspect. Many of these sidings were long - over two miles - so a train could run down the siding at a good pace until approaching the pedestal signal at the end, where you'd have to be ready to stop per the Medium Approach aspect.  If you were lined out of the siding, perhaps it would be easier to recognize a cleared exit signal from a distance if it were red-over-something white rather than all white, allowing you to maintain 30 MPH instead of having the brakes set.  Just a thought... 

As mentioned, the Marion Branch in Indiana has pedestal signals at the ends of signaled sidings too - installed in the mid-1970's - but they don't have red lenses even though they could without trouble.  The high signals have red lenses. I don't know what the original speed limit was on the sidings on that line, but it's 10 MPH by timetable today (last I heard), and I just recently saw a train enter the siding at Leesburg, IN on a Slow Approach high signal and exit on a Medium Clear pedestal.  If these sidings have always used Slow Approach as an entering aspect, that may support my theory above because trains would be approaching the signal at slow speed.  On the other hand, it may have been decided that the red lenses didn't provide enough of a benefit and they weren't used in later installations.
Thanks Dave M., and thanks for all of the research you did and for taking the time to type it all up for the post.

Someone also commented that red-eye signals can be seen as far west as Chicago, but another person said that there are none on the Marion Branch.....

The pictures below show two high signals and a pedestal signal.  The right photo is looking north, or WB on the eastern side of the Susquehanna River, across from Duncannon PA.  This is the Buffalo line.  The other three are the SB signals.

Phase Break Signals

There are two "oddball" PL aspects that are made from the standard full size PL signal head: one is the TAKE SIDING signal , the other is the PHASE BREAK signal  .   The phase break signal today, if my sources are correct, only exist in Philadelphia and Thorndale PA.  One source also states that the phase break signal originated with SEPTA, but one picture I have of a phase break signal (the last one below) is on the NEC in rural Maryland around the Aberdeen or Havre de Grace area (supposedly gone now).  The signal below is north east of the 30th Street station on the ex Reading line, 1.8 miles away as the crow flies.  The picture by Bob Vogel must have been shot out of a rear facing window from a commuter train, for there are no platforms along this stretch of tracks. The picture comes from here.









  Photo by George Pitz