Reading and Northern's Flexible CTC

From loose car switching to running coal fired steam excursions at main line track speeds, the Reading and Northern has a thing those traditional operating methods that other railroads have shunned out of cost and liability concerns. Based on recent observations this also applies to signaling under degraded conditions, which is a real breath of fresh air compared to public transport agencies that are more comfortable canceling service than working around failure. 

RBMN Pittston train having passed Lehigh Line Signal 148S under normal operation

RBMN Pittston train passing Lehigh Line Signal 148N under normal operation

If you recall my post on Lehigh Line signaling locations, the milepost 148 intermediate signals are located on the former Central RR of NJ part of the line and date from that road's ownership in the 1960's. The signals use a route based approach lighting system where the signals are normally dark unless a route is set in the direction they govern. (Opposing signals remain dark unless the track circuit in front of them is occupied.) The CTC is based on pulse code transmission through the rails and the signal logic also dates from the CNJ era. According to locals the section of CNJ era signaling is not the most reliable.

Signal 148N remaining lit after the passage of the #2102 excursion.

Signal 148N at Approach for UP #4014 following the passage of #2102

The situation I am about to describe was a downstream outcome of a minor derailment of the train used for the Reading and Northern's regular weekend excursion service between Pittston and Mach Chunk through the Lehigh Gorge.  This damaged 3 of the 4 cars regularly used in the consist and because the RBMN was hosting both a Reading #2102 and a Union Pacific #4014 steam excursion the next day, it seemed likely that the "regular" Pittston to Mach Chunk train would be annulled. Sure enough, upon arrival at the Milepost 148 location a route had already been established in the northbound direction for #2102 instead of southbound for the Lehigh Gorge train. Upon passage of said #2102 excursion the 148N signal remained lit and then progressed to Clear for what would be the following UP #4014 movement.  

Single car Pittston to Mach Chunk excursion train passing 148N at Clear for UP #4014

However after about 15 minutes the 148N dropped first to Approach and then to Stop and Proceed. It turned out that even with just a single car available, the Reading and Northern was still going to run the "regular" Lehigh Gorge train. However RBMN management was not too keen on a signaling failure for the "celebrity" #4014 train and instead chose to run against an established CTC route. What I observed was the  gorge train roll past the 148N signal and towards the dark 148S signal at around 20mph. Upon entering the overlap circuit between 148N and 148S, the 148S illuminated to display Stop and Proceed. The Gorge train maintained its speed past the 148S and disappeared out of view around a curve.

#2023 and the single Pittston car approaching 148S at Stop and Proceed against the current of traffic.

Because I didn't have a scanner on me I didn't hear the exact details of what was going on, but there are several valid options. The first would be a permission past the stop signal at CP-CRESTWOOD followed by Restricted speed operation to CP-WHITE HAVEN, likely with additional Form D Line 2 authority. However the even speed of the train around curves and no attempt to stop at the Stop and Proceed intermediate signal implied that the Gorge train was moving under Line 6, "non-signaled DCS rules in effect", with an additional Line 2 movement authority. This method removes the need to stop within half vision and obey intermediate signal indications. 

While this method of degraded mode operation is available to all passenger railroads there is a reluctance to use it during signal failures because the crews have very little experience with moving against the current of traffic and track warrants in general. A few extra minutes delay or bustitution is considered preferable to some sort of accident, which of course makes the "lack of practice" issue even worse. 

Automatic Signals To Be Axed From NY Penn Station Lines 1 and 2

Amtrak is currently halfway through a project to rehabilitate its East River Tunnels that were damaged during Hurricane Sandy way back in 2012. Lines 1 and 2, the southern pair of tunnels between Manhattan and Queens, were subjected to significant salt water intrusion and although this water was removed in short order, the salt created long term reliability problems. The solution has been a three year project to completely gut the tunnels to the 1910 iron rings and then rebuild them with a new concrete liner and a no ballast trackway. As of now the project is half way complete with Line 2 rebuilt and ready for service.  

Unfortunately Amtrak has also taken the opportunity to remove the automatic block wayside signaling within the tunnel. A total of 13 automatic block signals, some dating all the way back to 1910, were removed from the 2.75 mile long Line 2 tunnel. The 5 eastbound and 6 westbound and 2 westbound repeater signals were replaced by Rule 562 cab signaling without fixed wayside signals.  Rule 280a "C" lamps were added to the 708WA and 704W signals in F interlocking along with a new 580E signal at JO interlocking at the western Line 2 tunnel portal replacing the 1E02 automatic. Similar to CP-MID in the North River tunnels between Penn Station and New Jersey, a new controlled point, CP-LOW, was installed 1000 feet east of the 1st Ave shaft for westbound movements. This creates two Rule 280a "super blocks" within the tunnel in case of cab signal failure. 

Existing ABS configuration for Lines 1 and 2 west 

Existing ABS configuration for Lines 1, 2, 3 and 4 east

In a similar fashion to Grand Central and the defunct Cleveland Union Terminal, Penn Station used a unique style of color light signal as the technology of high intensity, long life electric bubs was still relativity new with semaphores being the then state of the art. ABS signals in the East River tubes were of the "frog eye" variety to create an "offset head" appearance that was customary for automatic signals. The upper "head" had the typical R/Y/G lamps with G/Y on the lower. This allowed for a 4 or 5 block progression for trains approaching the slow speed Penn Station complex, Clear -> Approach Medium -> Approach Slow -> Restricting. As signals at Penn Station can only display slow speed indications at best, the two western ABS locations would best display Approach Medium -> Approach Slow. It is unclear how many cab signal blocks have replaced the 5-6 wayside blocks, but CP-LOW's ability to display Cab Speed (60mph) implies that it matches the high density cab signaling installed on the Jersey approaches. 

"Frog Eye' type NY Penn automatic signal pressed into absolute service.

At this point the adjacent Line 1 will be shut down and reconstructed in a similar fashion over the next 18 months. Fortunately Lines 3 and 4, primarily used by the LIRR, were not damaged in the storm and will be left in their original condition for the foreseeable future. As I mentioned before the North River tunnels were already re-signaled in the late 1990's and will be fully rebuilt after the opening of the new Gateway tunnels in the 2030's.

Decoding Transit Signal Labels

 As I have been covering for some time, North American railroad interlocking stations are generally well labeled. However rail transit is quite a different beast and although some systems have adopted railroad practices, the majority have settles on a pair of labeling schemes that at first may look impenetrable, but are actually pretty straightforward. To avoid burying the lead these schemes are:

• Sequential - Interlockings are numbered, often by line.
• Prefix - The interlockings have names, but a prefix is used for observable signage.
• Milepost - The interlockings may have names, but all signals show a generic milepost.

Of the three systems, sequential and prefix are easiest to decode as it is clear what is the interlocking name and what is a signal designation. Milepost is often unhelpful at identifying the real signal number and the real interlocking designation. Even within these broad bins there is aa bit of variation so here are some examples to help with the lesson.

The WMATA DC Metro is one of the more involved sequential systems. Each line segment is given a letter and interlockings are then numbered sequentially from one end of the line to another with any infill interlockings going on top of that.  Above we see the 08 signal of interlocking 03 on the "G" line at Morgan Blvd. 

The MBTA also uses a sequential system for signal markings and formal documents, although human relatable names also seem to exist. Here we see the 1N signal at interlocking #7, aka Park. Both the DC Metro and MBTA have to ensure that a signal number is not mistaken for an interlocking number so in the case of DC the interlocking has a letter prefix while the MBTA uses a directional letter suffix after the signal number.

MATRA also uses a system with somewhat sequential numbers in addition to a line prefix. These are combined with a 3 digit plus alpha signal ID that consists of a track number followed by some sort of two digit configuration or frog type (seems to be 20, 30 or 40) followed by a signal specific letter.  The signal above would be Line "S" (South), interlocking #225, track #2, type 40, signal G.

The second popular system is to use a letter prefix in front of a signal number. The prefix is usually short for a more human relatable name and can usually be decoded by lay observers.  For example the Pittsburgh Light Rail interlocking on the old PRR Panhandle Bridge station is prefixed by FS.

St. Louis Metrolink uses literally signal number prefixes on the same typographic line. This can cause some confusion for visiting observers when prefix like "S" matches a common direction prefix.

Milepost labeling is the least helpful at providing observers with hints as to the proper way to identify interlockings or other railway locations. In this example from the Denver RTD light rail we can see that interlocking signals have the exact same number plate as automatics. This consists of an S prefix for "Signal" a milepost and a line suffix like PR, CC or SW. The lack of information is somewhat mitigated by the provision of switch identification boards which provide both "lever" number and the switch specific letter suffix for paired turnouts.

The San Jose VTA light rail uses a line prefix letter followed by a milepost-y number and then a modifier like A/B or R (for reverse direction).

There are of course many light rail and transit systems all with their own variations or exceptions, like San Diego still using the L/R system found on US&S CTC consoles, but these examples should get the novice most of the way to decoding transit signal labeling. 

Caught on Camera: Clear to Next Interlocking for UP #4014

For much of the Union Pacific Big Boy 2026 Coast to Coast excursion tour, #4014 was able to operate like any other Class 1 main line locomotive with an ETMS PTC box in the cab allowing the engine to operate in the leading position. However the former Pennsylvania Railroad Main Line between Harrisburg and Rochester, Pennsylvania not only remains cab signal equipped, but was converted to operation without wayside intermediate signals in 2018. Until recently Union Pacific was also a major user of continuous cab signals, however in 2022 they chose to scrap their system due to legacy design considerations that created a lack of synergy with ETMS. While it would have certainly been possible to reactivate the cab signals on #4014 and integrate them with ETMS, the increasingly popular solution to run the movement under Rule 280a, Clear to Next Interlocking, was chosen. I was able to catch this procedure at CP-ROCKVILLE on July 7th, 2026.

Here we can see the westbound track 2 signal at CP-ROCKVILLE displaying Slow Approach, R/R/*Y*, with the "C" lamp illuminated for a stop signal at CP-MARY about 5000 feet to the west on track #1. When the dispatcher lines a route between CP-MARY and CP-BANKS, the signal at CP-ROCKVILLE upgrades to R/Y/R Medium Approach with the "C" lamp lit. The plan for #4014 was to proceed past the far end of CP-MARY and then reverse into Enola Yard to spend the night. Note that the Slow Approach and "C" lamps are flashing with the  same cadence. This indicates that the interlocking has a single source for pulsed lamp current that is then directed to the lamps that require it.