Pittsburgh's light rail system is descended from PCC-based streetcar lines running south of the city that had the good fortune to have both their own rights of way and the use of a dedicated tunnel through Mount Washington. These advantages earned the system a light rail style conversion in the 1980's complete with a downtown subway and dedicated bridge across the Monongahela River. While the rebranded Mount Washington Transit Tunnel continued to underpin the network, the Allegheny Port Authority and its predecessors had recognized the Mount Washington Tunnel as a single point of failure and therefore maintained an alternate surface route up and over the hill. Christened the 52 Allentown in 1984, this alternate route, terminating at South Hill Jct, would see declining levels of service until it was discontinued entirely in 2010. However tunnel diversions kept the old 52 Allentown in service as a ghost line, light rail trains running doors closed through the eponymous neighborhood on an as-needed basis. For out of town railfans catching a ride over the 52 was particularly difficult as the diversions were not often scheduled in advance, however in 2025 the tunnel was to undergo a long term renovation with Route 47 and 42 trains diverted over the 52 for the better part of a year. This allowed me to schedule a trip to Pittsburgh to get photos and videos of this rare occurrence.
My arrival in Pittsburgh was too late in the day to properly ride the 52 Allentown, but I was able to catch the arrival of westbound Amtrak Pennsylvanian Train 43 with P42DC leading the usual consist.
It was at this point I had my first ever encounter with a Rule 280a "Clear to Next Interlocking" signal indication displayed eastbound on Track #1 at the former CP-EAST PITT. Displayed as a flashing white marker light next to a standard Medium Clear, the signal us used in cab signal territory without wayside intermediate signals for train movements that are not cab signal equipped. In this case said movement would be Train 43 shoving back to CP-HOME where the turning wye is located.
By displaying Rule 280a instead of a Restricting, the shove move would be able to operate at speeds up to 45mph, saving considerable time across the 8 mile round trip.
The following morning I caught a light rail train at Steel Plaza and was in place to get photos as it crossed over at Panhandle Interlocking and onto the short single track that would lead to the street running up and over Mt. Washington via Allentown.
The whole trip takes about 8-10 minutes, about 5 minutes longer than the trip through the tunnel. The ride was downright exciting as my LRV's operator was really flooring it up the twisty grade. A temporary infill station was also added along the route in the Allentown neighborhood.
My outbound SD400 LRV, running on a 47S service, at South Hills Jct
South Hills Jct is built around a large double track scissors crossover. Although from the point of view of the platforms the crossing routes over the diamonds are in a geometrically straight path, from a railroad interlocking point of view those would be the diverging routes. Normally the light rail trains get a solid yellow lamp for a Restricting indication into street running track. However for the "diverging" route, they get a flashing yellow.
In its original configuration trains from the Overbrook and Beechview lines would merge into the transit tunnel with the option to use the 52 Allentown Route.. With Overbrook Line trains making use of a new flying junction since 2004 and the 52 being discontinued in 2010, the scissors crossover sees rather limited use in its role as a crossover. Here SD400 LRV #4221 crosses northbound over from the Beechview Line to the 52 Allentown line.
Pride month pay have been over, but SD400 pride unit #4239 was still roaming across the light rail system in early July, along with 4202.
Here we see SD400s #4227 and #4201 along with CAF LRV #4317 running out of the junction and up the incline towards Allentown.
CAF LRV #4315 descending southward from the Allentown route. The CAF LRVs were a supplemental order of vehicles to support the re-opening of the Overbrook line, which was closed between 1993 and 2004.
Like the northbound trains, southbounds would roll towards the junction and get a Restricted Diverge flashing yellow signal on the dwarf.
View along the axis of the scissors crossover route from the Beechview/Overbrook lines to the Allentown Line with CAF LRV #4317 and SD400 #4253.. While this routing is physically straight, as far as the interlocking is concerned this a diverging route.
In this video we see an inbound 42S South Hills Village (via Beechview) train with SD400 LRV's #4231 and #4235 passing an outbound 42S with CAF LRV's #4310 and #4313 with #4310 sporting the new "Pittsburgh Regional Transit" paint scheme.
In my previous visit to South Hills Junction in 2023, both PCC loops were still present for short turns both from the north and south. Since that time the southward loop for PCC's coming off the 52 Allentown has been removed along with its boarding platform. PCC's were used through 1993 as the old Overbrook line had wooden trestles that could not support the weight of LRVs.
On the other hand, the old Route 47/52 platform had been re-paved. Before the Overbrook Line rebuild this platform had served the PCC's using the 47 route as well as all 52 Allentown cars which terminated at South Hills Jct.
Another view of LRV's crossing over to the Route 52 with SD400 #4250 and CAF LRV #4308.
The tunnel closing also affected local bus traffic which also had to detour up and over Mt Washington. Here bus #6236 passes inbound SD400 #4227.
All of the construction miscellany made getting a view into the tunnel a bit difficult, but I was able to manage a photo.
Back to the South Hills Jct platforms where I caught SD400 #4224 passing #4201 and #4206 arriving southbound.
The return trip was not quite as exciting, I'm guessing the operators know they have a bit more leeway for speed on the steep ascent since the grade will quickly bring the car to a stop without use of brakes.
Heading north across the Panhandle Bridge I encountered CAF LRV #4314 painted in the new "Pittsburgh Rapid Transit" branding.
Final photo of this set if SD400 #4224 after dropping me off at the Honorable United States Steel Plaza.
All in all Pittsburgh Light Rail is a great little system that still presents a lot of heritage due to the early date of its light rail conversion. If the MWTT ever shuts down again I urge you all to schedule a visit.
I have a confession to make, I'm not a steam enthusiast in the way most railfans are steam enthusiasts. For steam people if something goes "chug chug", its an excuse to drive at unsafe speeds and elbow others out of the way to get that perfectly composed photo that looks like everyone else's perfectly composed photo. When I have been in the company of steam excursions it has been to ride the excursion to get both covered in cinders and get an open window view of the line and by extension its pieces of historic infrastructure. However when riding a RBMN #2102 excursion to Pittston in 2024 I was able to make note of the surviving CNJ searchlight signal locations on the former Conrail Lehigh Line. So since I was obviously going to have to come out again to photo these signals, why not do it in conjunction with a #2102 trip and generate some content that everybody can enjoy? So anyway here are photos from my first time being trackside for a man line steam excursion.
Like I said, my primary mission that day was to get photos of former Central RR of NJ searchlight signals between White Haven and Mountain Top. After the CNJ abandoned operations west (north) of Lehighton in the 1960's, the Lehigh Valley RR incorporated this section of the CNJ route due to its superior alignment and industrial connections. The CNJ vintage searchlights were distinctive for having a square "basket" like structure around each maintenance platform. Here we see the Milepost 146 southbound intermediate signal displaying an Approach indication for the holdout signal at CP-WHITE HAVEN. The former CNJ signals are normally dark, but will illuminate when a route has been established by the dispatcher.
At first I was confused why the Reading and Northern was running a southbound train within an hour of the northbound 2102 excursion. It turns out the signal was for the "regularly scheduled" Pittston to Mach Chunk diesel hauled excursion train featuring Reading and Northern 40th anniversary GP38-2 #2023, which I caught at the northbound Milepost 148 signal.
As expected the previously dark northbound signal popped up with a Clear signal indication for #2102. I could hear the engine approaching in the distance when what I will call the "traveling circus" of train chasers began to show up with their tripods. When #2105 did arrive it was applying all 5000 of its horsepower to muscle the 21 cars of the excursion train up the stiff grade. This spectacle was quite a bit more thrilling trackside and made it easy to understand what was motivating the traveling circus to chase these trains again and again.
The R&N's latest innovation in making money is open observation car #22 which offers a premium view to those lucky enough to grab one of the 30 tickets available for each departure. Not going to lie, but #22 is definitely on my radar for a future trip, even if it covers territory I have already traveled.
Closed railroad interlocking towers have a lot in common with the Three Little Pigs nursery rhyme. If the ones made of wood aren't burned down by vagrants, it doesn't take much for the railroads to huff and puff and knock them down. The ones made of brick fare a bit better, but unless asbestos gets in the way, a couple of swipes with a back hoe is enough to turn them into rubble. However a tower made of reinforced concrete borderline indestructible and nobody liked reinforced concrete more than the Delaware, Lackawanna and Western. In June 2025 I set out for the Poconos to check out a string of surviving DL&W interlocking towers between the Delaware Water Gap and Scranton. Because that on its own isn't super exciting I also mixed in some photos from the Washington, DC area, so enjoy.
First up is the tower at Slateford Jct. Built around 1910 as part of the famed Lackawanna Cutoff project, it governed the western junction between the new cutoff and the old main line the cutoff was cutting off. The like most other cutoff structures the tower was poured from the then new wonder material of reinforced concrete. As processes around reinforced concrete had not been fully optimized for cost and the project was located near Pennsylvania's "Cement Belt" and the DL&W was flush with cash from the anthracite coal trade, the concrete used in this and nearby towers has proven exceptionally durable.
SLATEFORD JCT itself was closed in the 1950's in favor of CTC. Now increasingly hidden by trees and underbrush the tower is used as a hangout by local kids with both the relay room and operator's floor accessible for inspection. Note the steel supports for the mechanical lever frame.
The next tower is the exception that proves the rule. EAST STROUDSBURG is perhaps the only surviving wooden DL&W tower and is located in East Stroudsburg, PA. It was obtained by a local preservation group after Conrail retreated from the region in the early 1980's and retains a fully functional lever type interlocking machine and model board.
EAST STROUDSBURG sits adjacent to the old DL&W station site that, sometime between now and 2002, has been subjected to substantial alteration.
Just a few miles up the road is another DL&W standard concrete tower, GRAVEL PLACE. Once the location of a yard and NYS&W interchange point, GRAVEL PLACE declined in importance until the interlocking was re-signaled and placed under remote control by the operator at EAST STROUDSBURG in the 1950's. Similar to SLATEFORD, GRAVEL PLACE is hidden amongst the trees.
In 2025 a friend in southern New Hampshire I had stayed with during the HART tower trip back in October 2024 informed me that they would be soon be moving back to Ohio. Although I had largely completed by Connecticut Valley signal documentation project there were still a few odds and ends I wanted to check on so I found a free weekend with cheap Acela runs. Unfortunately, my friend was presented with a surprise gift of tickets to see Ringo Star's All Star Band at Carnegie Hall on the night where I would arrive via Amtrak's Valley Flyer to Greenfield, MA. Well, no problem, instead of transferring to the Flyer, I could just backtrack from New Haven to where my friend would be parked at Stamford, killing the remaining time at a brewery in South Norwalk. Here is a set of photos from what turned out to be a surprisingly successful Plan B.
Somehow I managed to get a reasonably priced seat on the 330pm Acela out of BWI which arrived with a classic set and power cars #2027 and #2033.
Using an upgrade to first class I was able to two meals on my trip to New Haven, crab meat enchiladas and a cheese plate.
I managed to make a very short connection to the next westbound Metro-North local with M8 MU #9729 leading. The previous eastbound MNRR NHL train was on the adjacent track with M8 #9365 on the rear.
I arrived at South Norwalk well after dark. I had been to the station a couple times before to visit the nearby preserved SS44 interlocking tower, but never inside the actual station building.
