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Sunday, June 21, 2020


The PRR's GWYNN tower, originally named GWYNNS RUN, was built in 1931-32 and replaced the small, wood frame VN (CalVertoN Yard) tower on the same location adjacent to the viaduct over Gwynn's Falls.  GWYNN served the function of a main line crossover, but being located only 1.5 miles from the end of 4-track territory at FULTON interlocking, its primary reason for existence was to support various industrial tracks south of the City of Baltimore in a similar fashion to MILLHAM interlocking north of Trenton.  With the collapse of urban industry in the Northeast along with a specific reduction of freight services along the Northeast Corridor in the Amtrak era, GWYNN and its entire interlocking plant were ultimately found to be redundant and subsequently removed and abandoned.

GWYNNs layout consisted of a 4-track complete crossover with connections to industrial leads at three of the four corners.  The original main track layout was 2+2 single direction Rule 251 in both directions, although by the Penn Central era track 3 had been converted to Rule 261.  By the 1940's both logical pairs of crossovers were equipped with Limited Speed #20 turnouts with signals having the appropriate yellow triangles. The intent was to allow both passenger and through freight to bypass local industrial movements tying up the outer tracks directly south of the city The tower also had remote control of two nearby interlockings to the south, LOUDON PARK and WINANS.

The demise of GWYNN came with the Northeast Corridor Improvement Program (NECIP) of the early 1980's.  With the aim to increase speeds to 125mph and remove costs associated with legacy freight infrastructure, Amtrak rationalized GWYNN by replacing the old interlocking with the MP 99.3/4 automatic signal location and, in 1985, transferring some of the functionality to a new interlocking named BRIDGE, 1.1 miles to the north (although it can be argued that BRIDGE is more a devolved FULTON than a relocated GWYNN).  Note in the 1992 Amtrak diagram below that the #5 track, #0 track and Gwynn industrial track have all been removed as of 2020.

The former northbound signal bridge now serves as automatic signal location 993 for southbound trains and 994 for northbound trains.  The NECIP completely eliminated Rule 251 operation south of Philadelphia and at this point all 4 tracks were bidirectional.  Note that the track to the far right is track #3 and the track to the far left is track #A, which is different from the PRR which numbered them 1 to 4.

Here we see GWYNN tower and the straight railed interlocking plant looking first northbound then southbound, which compares rather poorly to this 1977 view.

The southbound signal gantry today sits empty north of the Gwynn's Falls viaduct, but is past function is still obvious.

Similar in design to towers like CORK, GWYNN was a throwback to the more ornate towers of the teens and twenties, just before the general adoption of  the cleaner designs of the 1930's.  Compare the wooden bay window to that of WINSLOW tower, built just a few years later.  In the photo below, taken around 2005,  we can see that whole the structure is clearly decaying, it is relatively graffiti free and appears to have had a spot of paint applied to its concrete foundation. 

15 years later the tower has seen some significant deterioration with the wooden bay window structure having completely rotted off and the walls not covered in spray paint.  Unlike the DL&W style towers which had poured concrete roofs, the PRR tended to use wooden roofs and once the roof is compromised it tends to undermine the rest of the structure.  Fortunately the cantilevered bay window floor did not appear to be going anywhere. 

Both sides of the tower were similarly decorated with little effort being taken to board up the second story windows.

Remains of the old air line was still present in front of the tower despite having been out of service for almost 35 years.

The rear of the tower showed no sign of any compressed air equipment, although there were window bars from the age of crime. 

On the upper level, some of the outer plywood panels had fallen off revealing the original wooden double hung windows and muntins.

The ground floor relay room did not show any signs of permanent habitation or "top shelf" relay equipment, however two relay racks were in place as well as the rusty remains of some "bottom shelf" equipment such as rectifiers and transformers.

The metal internal staircase was sturdy and not caked with debris.

The 47-lever US&S Model 14 interlocking machine was still present in the operator's room.  The diagram at the top of this article shows only levers 6 through 25 being in use, which makes me wonder if the extra levers at the right of the machine were intended to take over FULTON interlocking via some sort of direct wire control.

Years of exposure to the elements had resulted in a surprising amount of corrosion, with the levers and interlocking frame having effectivly become a single unit of rust.  Although only the first 25 levers were in use, the full frame was outfitted with crank handles and indicator lamps.

The Penn Central diagram below actually shows the lever layout, which levers are active and other key details of both GWYNN machine and the WINANS CTC console.  By the Penn Central era, the GWYNN machine had 7 levers for signal, 9 levers for switches, one traffic lever for the the bi-directional track #3 and a combination electric switch lock and traffic lever for the Catonsville track hand throw switch on track #1, for a total of 18 working levers.  Meanwhile were 24 spare levers and 5 spare spaces which seems to indicate plans that were never realized like power switches on the west side yard tracks, but one can only speculate.

The CTC machine was faring no better as after the removal of LOUDON PARK, the 30 lever console only had two active levers for WINANS' single switch and three signals where track 1 split from track 2.  Some of the other levers were used for catenary sections and defect alarms, but nothing of the panel survived for further comment.

The interlocking machine was generally open for inspection, but I was unable to take a look at the locking bed as a good deal of the roof had collapsed on top.

Some of the electric locking spindles were still present, however almost everything with even a hint of copper had been stripped out over the years.

Of course the elephant in the room was the hole in the roof that make it look as if an elephant had been in the room.  Water ingress from the compromised roof had eaten away the wet wall plaster ceiling and now much of the operator's room was effectively open air.  This did expose some of the wire pipes used for the overhead lighting and what would have been a suspended model board.

This had the effect of turning the interlocking machine into an ad hoc planter.

According to the diagram the CTC machine was located to the left of the Model 14, but no sign of it remains.  The Model 14's builders plate was also missing.

 When the bay window was removed, Amtrak crews had tried to seal up the opening with large pieces of plywood, but this quick fix had generally failed.

Cable conduit running to the operator's desk would have served the telephone concentrator and panel blocking device.  

The loss of the  wooden bay structure did appear to affect the structural integrity of the larger tower.

 Plaster on the walls was still hanging in there, but time and the elements were definitely having an effect. 

 As was common the tower was fitted with a panel to handle local catenary sectionalization.  These likely would have operated local section switches in and around the interlocking as opposed to anything at the nearby Loudon Park substation which would have been under the purview of the Power Dispatcher in Baltimore.

Other equipment still present in the operator's room was a telecommunications terminal board.

The bathroom was still present, but it had been stripped of all fixtures. 

The floor tiles were made of some sort of red colored material and the cage door to the relay room was not sitting on the operating room floor.  It was standard practice for the PRR to prevent operator access to the relay room to prevent unsafe hacks to the interlocking logic.

 Failed plywood provides views along the tracks in both directions including the 1915 concrete viaduct that is immediately adjacent to the tower.

Well that's all I have to show of GWYNN tower, additional photos can be found in this gallery here.  As the old tower approaches its 90th birthday on August 17th, 2022, the poor condition of the roof has certainly placed GWYNN on the slow road to demolition. Still, the sturdy brick and concrete construction will make it less of collapse risk than partly wooden towers such as BELL, SHORE and LANDOVER.  It's isolated location in a generally poor neighborhood will also reduce the risk of "beautification" attempts by the forces of redevelopment.  Still, it is worth a visit or the odd photograph from a passing MARC or Amtrak train.

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