Suck It In! - PRR Compact Position Lights

 When the Pennsylvania Railroad needed a reduced clearance version of their brand new position light signal, they made a position light version of the semaphore dwarf signal. About a decade later when the PRR needed a compact signal that could also display the full range of signal indications they invented the pedestal. 

But what if you are worried that pedestals with their pairs of plain white lamps just weren't visible enough in fog or smoke at main line speeds? Well you might need a compact position light. 

If one looks at the back of a Union Switch and Signal position light setup, one will see the lamp modules are mounted on the ends of metal tubes extending out from a central tub. The backing plate, if present, is then affixed to the ends if the tubes. However you might realize that there is nothing in this setup that physically requires the lamp modules be mounted where they are mounted. They can be placed at any point along the tube. As long as there is a hole for the wire they could even be placed directly against eachother! Which is exactly what the PRR did when it needed a reduced clearance PL format.

Don't let the square targets fool you. These signals on the LIRR Main Line are completely ordinary US&S position lights, just shoved together. The compact format for the Milepost 7.6 automatics was chosen to be visible underneath an overbuild just south of the Kew Gardens station.

You can see the size difference in comparison with the full size signals on the opposite side of the signal gantry.

While these LIRR square backed compact PL's are now likely unique due to the HAROLD interlocking re-signaling project, compact PLs in general still exist in several others locations with the most accessible being DOCK interlocking in Newark, New Jersey, on Amtrak's NEC.

At the east end of the station on tracks 1 and A, the 90LA and 90LB signals were both in compact formats of varying degrees of compactness. The 90LA on track #1 even had different geometries for the upper and lower head given the unique clearance requirements.

As the Safetran style position lights currently on the market cannot tighten their belts as effectivly, the 1930's vintage US&S signals were retained where absolutely necessary when DOCK was re-signaled in 2017. You can see the different between the 90LA and 90LB post re-signaling.

At the other end of the station one might not immediately notice that the 122R and 124R signals were in the compact format, but they were to be visible under the Newark trainshed overhang.

When DOCK was re-signaled the 124R went off its diet and the 122R was relocated to a mast placement.

The 126R, shown here, also survived the cut along with the bridge mounted 128R.

Although the 128L was converted from a compact format to the world's goofiest looking full sized Safetran unit.

So are there more compact position lights apart from DOCK and the LIRR Milepost 7.6 automatic? I believe so, but I just don't have the time to sift through all my photos looking for them. Definitely let me know in the comments if you spot any more!