New Pittsburgh Line Interlockings

Norfolk Southern's ability to extort the state of Pennsylvania to add additional passenger frequencies on the old Pennsylvania Railroad Main Line is resulting in a slew capacity expansion projects in the form of "new" interlockings and additional tracks. I use the quotes as some of the interlockings are actually restorations of those that existed within living memory, but were removed for the sake of efficiency. 

Restoration of the old SG and NY interlockings.

The first phase of this work is underway at the set of the old SG interlocking west of Johnstown. The new crossovers will allow Amtrak trains to use both sides of the single island platform that serves tracks 2 and 3. Currently if track #2 is unavailable, trains must use main track #3 which follows the slower route of the old Sang Hollow Extension for 15 miles between CP-CONPIT and CP-C since SG interlocking was removed by Conrail around 1980. 

Returning 3 tracks to the Rockville Bridge

Additional changes include the restoration of CP-WEST PITT, removed by NS around 2007, a new crossover on the West Slope near the old NY interlocking between CP-SO and CP-MO, a new third main track between CP-ALTOON and CP-ANTIS, a new interlocking on the Altoona raceway between CP-ANTIS and CP-GRAY and another third main track between CP-BANKS and CP-HARRIS, which would restore a third track to the Rockville Bridge which was lost around 2000. Summary details of the project can be found here with a 2021 report providing more details of the track and interlocking changes. Note the report is not gospel as photos of the new CP-SG show parallel crossovers instead of a universal crossover.

Although no longer equipped with Conrail/PRR era signals, the NS Pittsburgh Line is still Rule 562 cab signaled with "C" lamps, so more interlockings means adding signals where automatics were previously removed.

New Signals Up At THORN

 Although not much has changed regarding the ultimate fate of THORN tower, recent photos do show what the new signaling situation is going to look like. In the eastbound direction the triple signal bridge covering tracks 1, 2 and 5 Running, have gotten the Safetrain upgrade with Rule 562 'C' boards turned. Although not yet in photos, it is expected that track 4 will also be getting a PL mast signal to replace the existing reverse direction dwarf. SEPTA is tentatively resuming service to Coatesville upon the completion of new station facilities in 2025 which includes a semi-restoration of #2 track to a point just past the new station for the daily NS regional freight. 

In the westbound direction new PL masts are up on tracks 1 and 2 to replace the reverse direction dwarfs and its assumed that a new gantry mounted signal will be in store for #4 track.  The real surprise is what looked to be a new westbound full PL mast signal on what used to be the Low Grade Freight Line track. The old THORN had maintained a vestigial signal in that same location, but despite the rationalization of the former 6-track full crossover, it seems the low grade stub track has not only been retained, but is being prepared for use. What that use might be remains to be seen, but a mast capable of displaying Medium and Limited speed signals could imply SEPTA trains making some sort of switchback maneuver after discharging on Thorndale's track #4 platform or coming out of some yet to be built storage tracks on the footprint of the old PRR Thorndale facility. 

The THORN interlocking cutover is still planned for later in June with DOWNS to lose its switches before complete removal. GLEN and FRAZER will be turned over to the dispatcher by the end of 2025 closing THORN as an active interlocking station.

Harrisburg Power Office Is Now Mostly Up and Running

When we last checked in on the Harrisburg Power Director's office about a year ago in 2024, the Big Board had been fully illuminated and most of the Westinghouse "Visicode" SCADA equipment had been reactivated with the help of modern technology simulating the presence of the field equipment like substations and such. However, because the 1930's PRR electrification projects had been funded with depression era WPA loans, the PRR had to spread the wealth and about half the office used GE "Code Selector" hardware that was more complex in operation and not as well documented. 

Well between March and September 2024, members of the Harrisburg Chapter NRHS managed to locate the documentation for the GE gear (it was sitting on a storage shelf) and were then able to restore most of the GE panels to operation, which is especially useful that represents the bulk of what was still operational on the old PRR Main Line up through 2013. The GE gear brings the added fun of step switches being used to store digits instead of all-relay registers for the Westinghouse part of the office.

As if step-switches weren't enough, between September 2024 and March 2025, the team also reconnected the alarm lamps and bell which further adds to the effect.

Still to be addressed are the metering circuits along with programmed simulation elements that would allow visitors to participate in directing flows of 25hz power to virtual train movements. Still, the Harrisburg power office  is mostly complete in terms of being "a thing that functions as it once did" so watch out for planned opening dates as the chapter is still trying to figure out how to manage regular hours.

THORN Tower's Last Act

Amtrak's THORN tower has been staffed 24/7 and routing trains on the former Pennsylvania Railroad Main Line since 1938, however after having gone on a rather extensive diet in recent years, THORN tower appears to be entering its last act. However its not going without a few strange twists.

As a CTC era tower with both local and remote relay based interlockings, THORN presents a fairly easy case for remote control, as was the case with THORN's sister tower COLA back in 1987. Already Amtrak has chipped away at THORN's territory, re-signaling CALN interlocking and transfering control to the Section C dispatcher in 2020.  Now it appears that the plan is to re-signal and transfer control of the local THORN interlocking in the middle of 2025.  

While this would typically mean the closing of THORN tower itself, the news is that the tower will continue in service controlling GLEN interlocking via the 1938 CTC machine and FRAZER interlocking on the 1994 vintage unit lever panel. Much of THORN's work involves FRAZER interlocking as that is where SEPTA trains for the busy R5 Paoli/Thorndale service lay over.

Plans also include the removal of DOWNS interlocking with deadhead movements continuing on to THORN. For years track #2 between THORN and GLEN had been in terrible shape with Amtrak operators and dispatchers looking for ways to avoid using it.  However it has been recently rehabilitated and train managers are looking to make better use of the asset. 

With these changes I would expect to see "C" boards for Rule 562 operation on both sides of THORN and if DOWNS is removed it is possible that cab signal only operation will extend all the way to FRAZER (track #1) and GLEN (track #4). Whatever happens, I'll keep everyone informed.

PHOTOS: Amtrak CORK Tower

 A while ago I posted the first part of my coverage of the Pennsylvania Railroad's 1929 CORK interlocking tower in Lancaster, PA which covered the tower's history and the layout of the interlocking on the PRR's Main Line. Today we cover the tower itself, heading inside to see how it functioned in both its pre and post re-signaling phases. The exterior photos date from 2005 when the interlocking complex was in the process of being resignaled. 

To recap, CORK interlocking and tower were constructed as part of the 1929 Lancaster station project which moved Lancaster's busy passenger depot away from a downtown alignment with slow speeds, lots of grade crossings and partial street running. The resulting interlocking plant spanned approximately 3.3 miles of main line track, which was an outlier for early 20th century direct wire controlled interlockings in North America. Like the contemporary Lancaster station. CORK was built of a dark brick and featured a prominent bay window sheathed in copper cladding. 

 

 

The tower had one auxiliary building that housed the primary compressed air plant and was situated on the south side of the tracks in line with the extreme west ends of the high level station platforms. The tower had an internal staircase with the shelf type relay room on the first floor. With its brick construction and slate roof, the tower was in excellent physical shape as it entered the 21st century. 

 

Heading inside the tower we find a typical layout with the operator's desk sitting in front of the US&S Model 14 interlocking machine. A defect detector readout and overhead catenary section breaker control panel are to the operator's right with the lockers, clock and old telecom plugboard sitting to the left. One interesting feature is that the room has retained its original 1929 vintage overhead lamp fixtures. 

The operator's space is feels like a more cramped version of HARRIS tower with less space around the interlocking machine on all four sides. The gap between the scoreboard style model board and the rear aligned internal staircase is particularly small. As with other PRR Main Line towers, lever blocking devices are stored on top of the interlocking machine and the bathroom is in the left rear corner. Also note the location of the refrigerator, notice board and train order hoops. 

The sprawling CORK interlocking plant was controlled by a relatively modest 67 lever interlocking machine with 49 active levers in its 1960's configuration consisting of 23 levers for switches, 23 levers for signals, 2 levers for electric switch locks and 1 crossing lever for the Reading's Lancaster Branch diamond crossing. The plant was divided into three timer zones, A, B and C with the A timer handling the Conestoga section, the B timer the central Cork plant and the C timer the Reading crossing. The short run was 1 minute with the long run being about 5 minutes and 30 seconds. The tower also had 4 horns for Conestoga, the tower itself, Lancaster West, Dillersville yard and the Reading crossing (Longs Park).

One interesting feature was the presence of Rusty Rail tabs instead of the more usual placard. Besides that the levers were of the standard US&S crank type.

Although CORK's model board was a standard PRR illuminated type, it had several interesting features features. Grade crossing status lights were located at either end of the board to indicate the activation status of the Irishtown Road (east) or Eby Chiques (west) crossings. There were three low air alarms for East and West Conestoga in addition to the Cork main plant. In the post-1960 era two block indication lamps were added for tracks 1 and 4 eastbound. These had some interaction with PARK tower to the east as well as the intervening temporary block station at LEAMAN with track #1 being lit by the regular 2 lever and track #4 by a button on the operator's desk console. Best I can tell this was some technical method to prevent conflicting movements beyond what would be afforded by train orders and the dispatcher. Finally the most endearing model board feature was a framed photo of CORK tower itself that is also present in photos from c. 1992.

 

Pittsburgh Line Points of Interest

While NS's move to embrace cab signaling without fixed wayside signals (which I will refer to as Rule 562) on the former Conrail Pittsburgh Line was a big loss for the casual observation of railroad signaling in action, there remain a few points of interest between Harrisburg and Pittsburgh that I was able to identify during a journey on Amtrak's Pennsylvanian in 2023. If you find yourself railfanning in that corridor, you might want to check them out.

The first thing worth pointing out are the few remaining number plated intermediate signals that still exist along the line. There is one on the Main Line adjacent to CP-HOMER due to the retention of Rule 261 operation between CP-ANTIS and CP-ALTOONA. There are also a pair of autos on the Altoona Yard leads west of CP-ANTIS.

Another distant type automatic exists on the South Fork Secondary adjacent to the Main Line near CP-SO for trains approaching CP-W.

We've all seen the signed "signal indication points", but did you see the two different SIP's located right next to each other between CP-MO and CP-AR/UN near Gallitzin due to slight differences in the mileage chaining between the two alignments.

Also present are half size SIP huts like this one near CP-MARY in Marysville, PA that serves only a single track.

Of course when a SIP shares a relay hut with an interlocking why not sign them both like at CP-JW in Johnstown.

Finally we have the mystery of those places where full speed three headed interlocking signals are still present. When the Rule 562 operation went in, many back-to-back interlockings that supported signals like Medium Approach Medium (R/Y/G), saw their replacements only support Medium Clear (R/G) with the cab signal being held at Approach Medium. 

 

However a few locations on the Pittsburgh Line retain full speed three headed masts. The first are obviously where trains might immediately exit Rule 562 territory such as at CP-ATOONA, CP-ANTIS, CP-ROCKVILLE and CP-BLOOM, or are not in Rule 562 territory at all (CP-WORKS).

However around Pittsburgh we also see three headed signals at CP-PITT and the former CP-EAST PITT. These might exist for the benefit of certain area short lines that might be able to run unequipped locomotives, or to provide better advance routing information for shortline and Passenger movements that need to use specific tracks and/or get off the Pittsburgh Line.

Anyway, keep all these locations in mind if you are looking for something a little bit extra signaling wise to capture in your photos.

Harrisburg Power Office Gets Up and Running

Since my last update on the status of the former Pennsylvania Railroad Harrisburg Power Director's Office a surprising amount of progress has been made to get the equipment functioning in its 1943 configuration. For those of you who might not be aware, the Harrisburg Power Office used a relay based SCADA system to remote control all of the 1937-39 westward extension of the 12kv 25hz electrification network that first began operation in 1915.  The second phase of the PRR's electrification from New York to Boston had largely relied on tower operators to directly control the substation equipment via local control boards in the towers (although some substations may have been staffed 24/7 themselves). Although remote control SCADA equipment was installed in some towers and the Baltimore power office, the expansion of electrification west of Paoli, Morrisville and Perryville to Harrisburg and Enola would be under the purview of a single office in Harrisburg with a code based remote control system. 

The office was in service using most of the same equipment from 1939 through to 2013. When the Harrisburg Chapter NRHS took over the space in 2022, it was still in roughly the same condition it had been in when the doors were locked 9 years before. Known for their preservation work at HARRIS tower, including a fully functional and completely interactive Model 14 interlocking machine, the Harrisburg Chapter had its work cut out to achieve a similar level of interactivity for the Power Director's office. Based on the amount of time it took to restore HARRIS, my own personal estimate was on the better part of a decade. Therefore you can imagine my surprise when I learned that a good chunk of the active equipment had already been restored to functionality in only 18 months. In fact the video below records the moment I learned that the office relay logic had been hooked up to an Arduino mimicking the field stations.

Because the third phase of PRR electrification was financed with depression-era WPA loans, the PRR had to spread the wealth and contract half the system to Westinghouse and half the General Electric. Westinghouse and its Visicode scada system is the simpler of the two to reverse engineer and debug (one can send digits with a literal rotary phone) so currently it is the Westinghouse half of the equipment that has been wired up to modern digital logic simulating the field stations. The General Electric equipment uses a more complex protocol that requires another round of development, but that is not insurmountable. Interestingly the Westinghouse equipment was largely used on the low grade freight lines that last saw service in 1981 when Conrail discontinued its electrified operations. Therefore that equipment came back to life not after sitting idle for 10 years, but for 40 years!

The large display wall has also been restored to mostly full functionality, however compared to the SCADA consoles this functionality was somewhat limited. The indications on the display show switches being open (green) and closed (red), as well as the use of white lights to show de-energized track segments. These are wired to reflect the position of switches on the SCADA consoles or on the operator's consoles where remote operation is not in effect. Therefore the board is more of a visualization device than a real time status indicator. 

The longer term plans for the office are still under consideration. The equipment is a bit less interactive than a railroad interlocking machine with active train movements, however there are quite a few scenarios that can be played out including routine operations, breaker trips, transmission line problems and current load issues. Whatever the case may be, I'll be sure to report on it here.

ALTO Tower Preservation Plans At Risk

It has been a decade since ALTO tower in Altoona, PA closed and after a conversation with persons directly involved in the process I have come to learn that the likelihood of its preservation seems increasingly remote. The good news is that there are currently no plans to demolish the tower by Norfolk Southern, however the previously touted move the tower in its entirety to the Railroaders Museum about a half mile to the east are unlikely to ever come to fruition due to the structural condition of ALTO tower itself. 

 

Immediately after the tower's closure there were two competing plans about how to preserve it. The first was to move the tower in its entirety in a similar process to the recent move of WB tower in Brunswick, MD. The second plan was to gut the tower of all internal components, strip off all of the architectural ornamentation and then reconstruct the tower from scratch. One of the advocates for the second plan expressed that his motivation to sacrifice the 1915 structure was due to it being fatally compromised by termites and requiring asbestos remediation. All up, full preservation and relocation of the 1915 structure would cost multiple times construction of a duplicate fitted out with the internal components and external ornamentation. It would also avoid the fate of MO tower about 10 miles down the Main Line in Cresson, PA that literally fell apart during a late 1990's effort to relocate the structure to a nearby railfan park due to compromise of the 100 year old wooden structure.

Nevertheless, higher-ups at the Altoona Railroadsers Museum decided on the full preservation plan and drew up a phone book sized document about the tower and the process (with more than a few of my photos included I might add). At this point the sizable cost of the preservation plan became a barrier to implementation along with whatever roadblocks NS would be inclined to throw up. In the following decade the tower has started to lose interior items to theft with the bank of glass timers being an early casualty. Although it is more secure than some of its peers, the wooden structure remains vulnerable to vandalism and fire. BTW I attempted to gain a PDF digital copy of the preservation document from the the individual I was speaking to, but he never followed up after I gave him my contact information. Hopefully he will become aware of my interest and reach out.

Let me be clear. I am not saying that ALTO tower is doomed to demolition or fire. It is immediately adjacent to a major roadway and could still be saved according to the 2012 plan. The point of this report is to provide the community with an update/explanation after the well known preservation plans seemed to go nowhere. I don't have independent verification of the claims expressed to me or independent analysis regarding the best course of action. The better option is absolutely relocation of the 1915 structure, but we should all be clear eyed about that not being possible. It's also unfortunate that the ideal option of preserving ALTO in situ appears to have never been on the table due to NS and liability paranoia.

MG Tower Still Lives!

I had the opportunity to get some rear window time on Amtrak's Eastbound Pennsylvanian and although the last of the position light signals vanished nearly 4 years ago, a few scraps of history linger on. First amoung these is MG Tower located between Horseshoe Curve and the PRR summit at Gallitzin. Targeted for demolition in the summer of 2020 (along with the nearby AR tower), it has nevertheless held on due to its remote location and linger asbestos issues. 

Another surprise was that artifacts from the 1970's era re-signaling west of Johnstown also survived the 2018 re-signaling blitz. Specifically the relay and air compressor houses. The air plants in particular date from the PRR interlocking tower era. I was able to capture many of these air plants when they were still in service and some also contained 100hz power supplies for the signals.

The line segment between CP-C in Johnstown and CP-SO in South Fork was the last bit resignaled under Conrail in the 1997-1999 time frame and it appears that NS retained the late model Conrail era relay huts, outfitting them with new Conrail blue Signal Indication Point signs. 
 

Also in this segment is the stump of AO tower that also served air compressing duties up through the early 2000's, long after control had been passed to C tower in Johnstown during the PRR period. We also see that CP-AO, in service on track #1 has also been supplied with a SIP sign covering the ABS cab signal location in service on tracks #2 and #3. 

Finally I can confirm that the entire Altoona terminal between CP-ALTOONA and CP-ANTIS remains under Rule 261/CSS operation instead of cab signal only operation. The sole main track automatic signal is located at CP-HOMER for the non-interlocked track #2. 

Limited Triangles!

 A little while ago I mentioned NORAC Rule 280b Approach Normal, a signal indication that has been effectively extinct in the wild for over two decades. However we will look at another marker type signal indication that used to be fairly widespread, but as far as I can tell, has now been reduced in the United States to just a pair of locations on the former PRR Main Line. Of course I am referring to the limited speed triangle.

Introduced sometime around the 1940's, the bright yellow Limited Speed Triangle was deployed on speed signaled railroads in conjunction with the introduction of the #20, Limited Speed turnout. For the uninitiated this translates to speeds of about 40-45mph. Prior to this speed signaled railroads tended to have a main line Normal (Maximum Authorized) speed of  50-70mph, a Medium (aka Reduced) speed of 30mph and a Slow speed of 15mph. The system worked from both a track engineering standpoint given the speeds involved and logical standpoint in terms of full speed, half speed and quarter speed. As equipment improved throughout the 1920's and 30's, the gap between the maximum speed trains could regularly achieve and the 30mph Medium Speed began to grow. Because its easier to decrease running time by not going slow as opposed to just going fast, a number of Eastern railroads invented both faster turnouts and the concept of Limited speed. 

#20 Limited Speed turnout at BRYN MAWR interlocking.

Just like in the 1980's when High Speed 60 and 80mph turnouts were invented, railroads suddenly had to fit the round peg of a new speed into the square hole of their existing signaling system. In a time when flashing signal relays were generally shunned as unreliable the solution was the Limited Speed Triangle. The black bordered yellow triangle would upgrade Approach Medium and Medium Clear indications to Approach Limited and Limited Clear. In cases where a #15 turnout was being replaced by a #20, the signaling change would involve change to interlocking wiring or logic. 

Although some railroads including the Reading, did invent new non-flashing limited speed color light signal like Y/G/G or R/G/G, limited speed triangles were embraced by the PRR, B&O, L&N, ACL/SAL and Southern. They also appeared in Canada with the addition of the letter L inside the triangle. Of course one of the biggest users of the triangles was the PRR, which would employ them at select junctions and along its 4 track main lines that features frequent non-reverse running crossover movements.  More specifically the PRR deployed limited speed upgrades (and triangles) to places where its 4-track lines would shift orientation from ⏬⏬⏫⏫ to ⏬⏫⏬⏫ and also as part of its general World War 2 era NEC re-signaling effort.

DV Interlocking with a mix of Limited and Slow speed diverging routes.

Starting in the 1950s flashing signals became more accepted and the Limited Speed Triangle began its slow decline. The main downsides was the inability to mix Limited and Medium speed routes, the issue of Approach Limited indications proceeding Medium Approach and the reduced visibility of the triangle vs a color light, especially at night. By the dawn of 21st century I was only aware of two remaining installations of limited speed triangles. The first was at COUNTY interlocking on Amtrak's NEC in New Brunswick, NJ with a full set of four triangles at the interlocking itself and the milepost 31 and 34 automatic locations adjacent to it. These were unfortunately replaced in the early 2010's as part of the larger 562 re-signaling effort between COUNTY and FAIR near Trenton.

 

The other use of limited speed triangles, and the only one still in service today, were the milepost 8 and 11 automatic signal locations adjacent to BRWN MAWR interlocking on the name brand "Main Line" portion of the Amtrak Harrisburg Line. These two signal locations are adjacent to the Ardmore and Villanova stations respectively and easily photographed. The reason BRWN MAWR itself lacks the triangles is because the tower caught fire in 1994 and the interlocking redone with modern hardware including flashing relays. The two distant locations will certainly keep their triangles until the Main Line between ZOO and PAOLI is slowly re-signaled over the next 10-20 years.

 

Note I have been invoking the United States instead of North America in terms of the endangered nature of these signals.  That is because Canada still retains quite a few of its Limited triangles generally on its western transcontinental routes at the ends of single track passing sidings. Highly ironic that the land that hasn't seen a flashing signal indication it doesn't love, has become the final refuge for a hack intended to avoid flashing signals.