Clear to Next Interlocking Rule 280a Displayed at CP-SOLOMON (EAST PITT)

In NORAC-aligned cab signal territory where wayside intermediate signals are not provided, Rule 280a, "Clear to Next Interlocking", allows trains without cab signals to proceed under signal indication instead of needing a track warrant or moving at Restricted speed. Related to the old concept of manual block clear, Rule 280a consists of a flashing lunar white light under the letter 'C' adjacent to a wayside controlled signal. These are normally pretty hard to catch in the wild because they are intended to be used to remedy en-route cab signal failures which are both rare and impossible to predict. For a time it was policy for Norfolk Southern dispatchers to run some Amtrak trains under absolute block protection and I was informed that some would display the  Rule 280a "C Lamp" where available, but I never managed to observe this practice for myself. 

That being said I did stumble upon a scheduled use of Rule 280a that one can catch if they are ever in the Pittsburgh area. After arriving at its Pittsburgh terminus, Amtrak Pennsylvanian Train 43 must reverse about 5 miles to CP-HOME where the closest turning wye is located. Because the rear coach lacks cab signal capability, the "C lamp" is displayed in along side the interlocking signal at CP-PITT, CP-EAST PITT (aka CP-SOLOMON), CP-BLOOM (if necessary) and depending on the order of the wye move, CP-HOME. 

Somewhat ironically the first three interlockings, CP-PITT, CP-EAST PITT and CP-BLOOM, are all back-to-back with no code change points between them. NS could have designated that track segment as normal Rule 261 without the "C" lamps, but their policy followed that of Conrail to provide the "C" even where it is not necessary. (Amtrak had chosen to do the opposite up until about 2010).

Anyway, here we see the 2E mast signal governing track #1 eastbound at CP-SOLOMON (EAST PITT) on the former Conrail Pittsburgh Line displaying Rule 280a in conjunction with a Medium Clear indication reverse move of Amtrak's westbound Pennsylvanian Train 43. CP-EAST PITT is only about half a mile from CP-BLOOM and directly adjacent to office parking making it and ideal spot to Rule 280a in the wild. 

I got this video from the east end of CP-PITT, which a shorter walk from downtown. About 30 minutes after its outbound passage, Train 43 will get more more "C" lamps displayed for a second long reverse move back into Pittsburgh Penn Station however the 2W signal at CP-PITT will display a Restricting into the station track without the "C" indication.

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.

RF&P Cab Signals Out of Serice Mid-June

When CSX first announced in plan to discontinue cab signal rules on the RF&P in 2021 I went into some detail about the possible motivations. A year later when the FRA petition was approved (despite a national spotlight on rail safety issues) I again explored some possible timelines for the process. Well it seems that we have our answer and the cab signal system will be taken out of service on June 15th, 2024. 

As a result of the process, I had to assume the worst and I embarked on a program to document the remaining RF&P intermediate signals that somehow survived the great 2010's re-signaling effort. Between 2023 and 2024 I didn't notice any changes on the physical plant so it appears that so far the discontinuation of the CSS has consisted of adding the PTC integration to all of the intermediate signal locations and hand throw switches. Because CSX does not use large visible antennas at every signal location, the process was largely invisible to outside observers. 

 

What this means on a technical level is that for the near term the cab signal codes will still be present in the rails to transmit block state. CSX in its filings indicated that moving to ETMS PTC for ABS speed enforcement will allow it to remove the mid-block code change points where Approach drops to Restricting. Since these are all less than 10 years old and theoretically reliable, it will be interesting to see if this is given any sort of priority. It will also be interesting to see if VRE has to retain the cab signals on its locomotives for the Washington Terminal area, which I heard is planning to actually install cab signaling in the 1st Street tunnels between CP-VIRGINIA and A interlocking. With VRE looking to purchase the Manassas Line, who knows, CSS might make a return. 

PS: Also keep an eye on the patches of former Conrail/PRR cab signaling around Philly. CSX does not have to run equipped locomotives on this territory so they might keep it active for the benefit of NS.

NJT's Speed Enforcement System: A Thing That Existed

You might have heard me reference the Northeast's preferred transponder based PTC system ACSES, or the Advanced Civil Speed Enforcement System. In most cases when something called itself "Advanced" its usually a bit of marketing speak, but in this case the basic Speed Enforcement System was a thing that actually existed for a brief period of time on New Jersey Transit's Pascack Valley Line. However because of the rapid pivot to more "Advanced" systems and the 2008 PTC mandate, information on the SES pilot is remarkably hard to come by, however I have been able to piece together a few bits of information that can hopefully shed some light on the technology.

In 1996 NJT suffered its worst accident as of the time of this writing when two trains collated at WEST END interlocking where the diesel Bergen County and Main Lines diverge from the electrified Morris and Essex lines. The cause was a veteran engineer who had been hiding a medical condition that had severely impacted his visual acuity mistaking a Stop signal for a R/R/Y Restricting. In the aftermath NJT began an effort to implement what they called "Positive Train Stop" functionality across its system, which came on the heels of a near system-wide adoption of cab signals and automatic train control (ATC). At the same time Amtrak was completing implementation of its ACSES speed control and PTC system on parts of the NEC in conjunction with the new 150mph Acela rollout. This is where things get a bit murky, but going into the 2000's, both Amtrak and NJT had two different yet compatible transponder systems for "civil" (aka track) speed control, however Amtrak "Advanced" system was integrated with cab signals where as NJT left SES as an intermittent system.

The location for NJT's SES pilot was the Pascack Valley Line, a stepchild service that ran some 30 miles north from the old Erie Main Line to dip its toe into New York State. The single track line offered only weekday single direction peak service and, like the similar old Boonton Line, the PVL was essentially unre-signaled since the Erie days. This signaling came in the form of an Automatic Permissive Block-like bi-directional ABS with occasional non-number plated (ie absolute) automatic signals that would have once appeared at the ends of hand operated passing sidings. Without any actual interlockings and only a single block of cab signaling on approach to Pascack Jct, the limited service PVL was an ideal test bed. 

 

Reading through the SES special instructions in a 2004 NJT Employee Timetable (posted below) we can gain some insight into how the system worked. The evidence points towards SES was an intermittent transponder based system that would convey track speed information in a manner compatible with Amtrak's ACSES, but also fixed signal indications. A positive stop was enforced for Stop, Stop and Proceed and Restricting indications, with the positive stop zone extending 500 feet in advance of the signal. Stop and Proceed, and Restricting could then be passed after an acknowledgement, while Stop needed the dispatcher to provide a numerical override code in addition to the verbal Rule 241 instructions. This would have come into play at the non-plated automatics and the home signal at Pascack Jct. Special instructions about cab signal upgrades and other rules not applying in SES territory further strengthen the intermittent use case. 

 

This of course begs the question about how the system would account for signal upgrades after passing an Approach signal if the associated transponder flags a positive stop point like it does in ACSES. As easy solution would be to place additional active transponder at the start of the stop zone 500 feet from each signal, but I have nothing to confirm this theory. An additional feature of the PVL that made it attractive for the SES pilot and that was the presence of signal overlaps. From what I can tell from 2007 era photos, each set of ABS signals had several car lengths between them which would provide sufficient distance for a train running at reduced speed to get stopped before it might encounter an obstruction. This would explain why the SES stop zone is 500 feet vs 1500 for the ACES zone.

PVL automatic signal location with overlap in 2007 with what might be SES transponders (or grade crossing impedance bonds).

SES was always intended to be a temporary pilot and by 2002 NJT had let a contract for its own Advanced SES that integrated cab signals similar to Amtrak, but without the finicky data radio capability for temporary speed restrictions and stop release. Interestingly the $2 million contract with Union Switch and Signal would have outfitted the entire NJT system with PTS and track speed control by 2008! The wireless data free ASES vs off the shelf ACSES debate would extend into the post-2008 PTC era with the ASES plans eventually morphing into ACSES, but perhaps the original SES hints at what NJT's solution would have looked like. Version 1 ACSES also lacked data radios and needed temporary physical transponders for TSR's and use of the stop release procedure to pass certain signals with a proceed indication. Active SES-style transponder could have solved some of those issues without wireless data.

Unfortunately I have been unable to determine the exact timeline of the ABS SES system on the PVL. I know it was in service in 2004 with the CNJ vintage GP40PH locomotives operating in a dedicated pool. I know that SES was still in service as of Jan 1, 2006, however by the fall of 2007, the line had been re-signaled with Rule 562 cab signaling and upgraded with passing sidings to allow for all-day bi-directional service. Unfortunately, starting in August 2006, all PVL physical characteristics and rule changes were put into a separate supplementary bulletin order that I do not have any examples of. Interestingly, the 300 section of NJT special instructions covering SES were left in place with slight modifications likely to cover the upcoming ASES or ACSES installations due to the 2008 PTC mandate probably resulting in some savings in crew re-training. 

If anyone has any additional information on NJT's SES please let me know so I can update this post or make a new one. I've heard a bunch of other stories regarding issues with hair trigger penalty brake applications, but not much more than anecdotes and speculation.

CTA Skokie Swift Smackup

In November 2023 an inbound "Skokie Swift" Chicago El train rear-ended an MoW vehicle stopped on the track waiting for signal clearance into the Horward terminal interlocking complex. The impact took place at a speed of 26mph and the NSBT was quick to blame "outdated" signal stopping distances that were last set whenever cab signaling was installed on the line, likely in the 1970's or 80's. The result was a multi-month service suspension and a reduction in maximum authorized speed from 55mph to 35mph, which was achieved by disabling the 55mph cab signal code at ever block location. To the lay person this might seem open and shut, the CTA did something wrong and they fixed the problem. In reality this is a classic example of go slow safety scolds and risk averse CYA officials pushing people away from public transport. This case is especially ironic since when the Skokie Swift opened in 1964, it was a demonstration project on how rapid transit could be high tech, modern and fast compared with the "square cut gear" era equipment.

For background, the CTA uses a pretty standard audio frequency cab signaling system with automatic speed enforcement and speed codes for 15, 25, 35, 55 and 70mph. Lack of code is fail safe and registers 0 mph and it is standard practice on this type of system to have sufficient 0 code behind any train for fail safe stopping. While most of the Skokie Swift is straight and uncongested, allowing for 55mph operation, the the busy Howard terminal will frequently see Skokie trains encountering stop signals and thus need to reliably slow from 55mph to 0 starting at a point about 2500 feet from Howard Interlocking's home signal. This would be carried out by progressively slower cab signal codes, although it is not clear if the operator gets a 0mph code ahead of the wayside absolute signal or at it, where a physical trip stop is also provided. The following CTA produced head end video of an inbound Skokie Swift run shows how this progression from 55mph to stop is well within the vehicle's performance envelope. The 55 to 35mph code change point is encountered at 7:55. Code change points are identified by small black boxes, called impedance bonds, located between or adjacent to the rails.



Feel free to judge for yourselves, but it appears that the first code drop is just before the hand throw crossovers about 2500 feet before the Howard absolute signal as stated in news reports and the last code drop is located under the overpasses at the final curve. It is not entirely clear if the final drop is to 0mph and the train takes the time shown to react and stop (likely) or if the operator chooses their stop point on a more favorable 15mph code (possible) or even if a timer that drops out the code mid-block is involved (unlikely). (Note: It's pretty trivial to determine how CTA trains get stopped before absolute signals by observing the cab signal display in the cab from the first car, I just haven't done so in a while so let me know if the comments.) The difference between normal operations and the day of the collision was the presence of an MoW snow melting vehicle on the inbound main track about 370 feet short of the Howard interlocking home signal. Had everything been working as intended, the train following the MoW vehicle should have gotten stopped before the final code change point under the overpasses.

The NTSB's knee jerk assessment implied that the following train somehow couldn't get stopped in time. As in it got the proper speed codes, but the speeds and distances were calculated incorrectly and it ran into the snow melter. Given that the line has been operating without incident for 60 years this seems unlikely, however the train was a newer 5000 series car that has only been operating for 15 years so it is possible something like crushed leaves resulted in decreased braking that combined with a heavier vehicle could have resulted in the observed accident. Still, is there an alternative explanation?

What stands out to me is the impact speed of 26mph. That's pretty much full speed approaching the final code change point. Typically when stopping distances have gotten out of sync with the equipment you see the rail equivalent of foot faults where the train can't quite get stopped in time. Remember in this case, if the block before Howard interlocking is occupied the second to last code change point should be giving a 0mph. It's almost like the train was approaching the MoW vehicle like it wasn't there. Moreover the operator indicated that the signal system commanded a speed reduction from 55 to 25 or 35 ~2100 feet from the equipment (or ~2500 feet from the Howard signal). If you refer to the video you can see the train begin to slow from 55mph at that same point, but again, that is for an unobstructed block before the Howard signal. If that block was occupied the inbound train should have gotten a signal drop one block before.

By this point I've already given away the twist. Maintenance of Way vehicles and other things the FRA likes to classify as "track cars" are known to not reliably shunt the track circuit and therefore need to be run with absolute block protection, especially to the rear and double especially when cab signals are involved. In cab signal territory if a track car fails to properly shunt the track circuit, not only will it not be detected by the signaling system, but favorable cab signal codes can also be transmitted to trains approaching from behind. Rail contamination like leaf debris only makes this problem worse.

 

To be clear, I have heard stories of trains having braking issues and sliding past calculated stop points as a result. For example an Acela locking up its wheels approaching Trenton and sliding for over 2 miles allegedly resulted in an extra block of speed control being added. Still, every detail about the indecent matched up with a loss of track circuit shut involving a track car and an approaching Yellow Line train that received cab signals in the sequence expected for a stop at the Howard interlocking home signal. It's certainly possible that the signal design created some grossly unsafe condition as the NTSB is implying, but the decades of safe operation imply otherwise. Unfortunately signal distances are easy to calculate and in addition to using the worst possible braking performance and the worst possible rail condition, the NTSB might actually believe rail vehicles need to emergency brake short of any obstruction they encounter within the range of vision.

Mazda Cab Signals are the PTC Solution We Needed

While driving in a brand new rental Mazda sport wagon in Colorado I noticed something interesting on the instrument cluster.

There was a dynamic speed limit indication accompanied by a red tick on the speedometer indicating the currently detected speed limit. Now this sort of information has been available in Waze for some time, accurately using smart phone grade GPS to pull a road segments speed limit from a crowd sourced database and displaying it on the interface. Using something like Android Auto this could be displayed to he driver in any number of ways.

The cybersecurity implications of this aside, I noticed an interesting Mazda party trick that Waze could not perform and that was the seeming ability to detect temporary speed restrictions, aka work zone speed limits. Waze explicitly rejects trying to track TSR's, even for long term work zones. Although achievable through traditional data collection methods, I was aware that the vehicle was equipped with forward facing cameras for its lane-assist feature (or MCAS) and if on-board systems could keep track of lanes, they could also recognize wayside speed limit signs and display them on cab signal, possibly augmented by a Waze style database.

The current national Class 1 PTC standard, ETMS, relies on wireless data and GPS to track a trains position and compare is, Waze style, to a database of authorized speed limits. The problem this creates are clunky data networks that result in slow setup time and en-route loss of connectivity as well as occasional mass outages that can halt traffic across a railroad's entire network. The preferable solution has been evident in the field of vehicle automation for over a decade now. Computer vision systems just look at wayside signs (and/or signals) the same way the human engineer does. To the extent that wayside signs are vulnerable to impairment computer vision doesn't have to replace the current "Waze" type system, but in case ETMS suffers a failure, the backup solution isn't halt all traffic (or god forbid just let the crews do their job), but fall back to wayside sinage detected by computer vision and enforced by the on board apparatus 

Go No Go: Cab Signaled Transit Wayside Dialects

In the late 1960's a new crop of "Space Aged" rapid transit systems began to take shape in North America making use of the new materials and electronics developed since the end of World War 2. In particular was a push to replace wayside signals and trip-stops with cab signals which would enable both automated operation and a reduction in wayside hardware. Of course this forced the question about contingency operations in case of cab signal or related failure. Railroad explorations of wayside elimination in the 1930's and 40's had retained wayside signals at interlockings and other controlled points and rapid transit followed suit with the further innovation of reduced aspect signals displaying Stop and Proceed aspects with the occasional Diverge and Absolute Block. Also like railroads, the rapid transit systems adopted a mix of "dialects" for their reduced aspect signals that I hope to categorize below.

Lunar White - The Granddaddy of them all, the Lunar White proceed indication can be considered the "default" rapid transit proceed signal aspect. First appearing on the PATCO Speedline in South Jersey (at least as far as I can tell), lunar proceed was later adopted by systems including DC Metro, SEPTA MFL and Route 100, HBLR, Cleveland Rapid Transit and Baltimore Metro (as built). The rationale was to be distinct from the existing ABS signal aspects using Green and Yellow and present as a railroad Restricting style aspect for non-cab signal equipped movements.

PATCO Lunar White Cab Speed

Steady Green - Considered the "obvious" solution since Green means Go, use of Green in place of Lunar White has been gaining in popularity with newer systems as any perceived need to be distinct from older ABS systems has faded. Notably appearing on DC Metro peer system BART in 1972 it was also adopted by Maimi MetroRail, St Louis Metrolink, Baltimore Light Rail and the Baltimore Subway as modified. Some systems will use flashing green to indicate a diverging route, others yellow. 

Baltimore Metro Steady Green Cab Speed

Flashing Green - Taking another page from the railroad playbook, flashing has made a few appearances to indicate a proceed indication on rapid transit systems. On the New York city subway flashing green straight up means Cab Speed for both straight and diverging movements under the control of the CBTC system. On Atlanta's MARTA, flashing green is the default proceed signal with steady green indicating a diverging route. 

Yellow - Similar to lunar white, this substitutes lunar for yellow similar to that dialect of railroad Restricting indications. This is most prominently used in Boston with Y/R for straight routes and R/Y for diverging.  

MBTA Y/R Cab Speed

Green Arrows - This most prominently appears on the cab signaled  portions of the Dallas DART system to differentiate from the ABS signals and avoid the use of flashing. 

DART arrow signals, not illuminated.

 

DART arrow signals, illuminated.

White Arrows - Like the green arrows above, but using either lunar or plain white. This is popular with airport people movers including the JFK AirTrain but also in use on the Sound Transit light rail with stylized direction indicators.

Sound Transit stylized arrow.

ABS - Currently used on Chicago, this method of go-no-go signaling takes a cue from the cab signal state to display a Green if the cab speed is "clear" (55/70mph) and a yellow if it is "restricted" (35/25/15mph). The cab signals can be from either block state or due to civil speed restrictions.

CTA Proceed Clear

 

CTA Proceed Restricted

This is my best shot at a taxonomy. I'm sure I've forgotten about a few systems or corner cases so if you, the reader, can think of any, please let me know in the comments. Please make sure that the line is actually cab signaled as there are quite a few ABS signaled light and heavy rail transit systems in North America.

LIRR East Side Access Signaling Surprises

When the LIRR's new East Side Access opened to Grand Central Terminal earlier this summer and I was expecting the signaling to follow the pattern of the LIRR's other recent projects with the new reduced aspect signals like G/L that have become the new standard. However, now that cab view videos have become available the new signaling setup came with a few surprises.

Once trains enter the ESA tunnels at HAROLD interlocking they are exclusively presented with transit style 3-lamp signals displaying single light Green, Yellow and Red aspects. Although these two videos can't necessarily reveal all possible operating conditions, the lack of anything aside from Green, Yellow and Red over both straight and diverging routes implies that those are what one gets in the ESA tunnels even with track speeds up to 45mph. It also appears that intermediate signals are provided in the few parts of the route that have significant distance between interlockings.

I suspect that the decision was made to lean on both the track speeds and speed code based cab signals to simplify the ESA wayside signaling based on the LIRR's existing practices before the implementation of the Reduced Aspect Signals. Remember, ESA has been under construction for almost 20 years and the design work was likely completed a decade before the Main Line capacity expansion projects motivated the new signals. A review of the videos shows a combination of diverging routes at the prevailing line speed (15, 30 or 45mph) or sufficient distance between the signal and the turnout for a cab signal code drop to take effect. On the outbound video there appears to be an unprotected slow speed crossover so I am not sure if that would rate Green signals over cab drops or a Yellow approaching a flashing red or what. I made some inquiries and I will post an update if those pan out.

All in all, the signaling is more interesting than an endless string of Green over Lunar and the use of US&S transit style signals is nice, but its unfortunate we didn't get a full set of LIRR "tunnel" signals similar to the Atlantic Ave branch.

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. 

SEPTA's PTC Implementation Is Still Terrible

Unlike previous generations of automatic train control, the on board PTC software has as much if not more to do with the operational impact of the safety system than fixed infrastructure like code rates and block length. In the case of ACSES, Amtrak's PTC implementation, track mounted transponders conveys data about upcoming civil speed limits, grades and positive stop points and it is up to the on board system to develop a braking curve. In theory this curve should represent the maximum braking effort the rail vehicle is capable of if tripped by the PTC system to prevent an unsafe level of overspeed. The concept of a penalty brake application exists for thus purpose as a full on emergency application requires some additional inspections. (Although I have been present when the "freight" ETMS PTC system threw my Amtrak train into emergency.) 

Four years ago I benefited from a SEPTA training run to capture two videos of how their PTC implementation functions and the braking curve was ridiculously bad. Granted I lack similar curve information for other operators, but the SEPTA engineer could stay under the curve with a very mild brake application. I got some comments on the order of "PTC is new and SEPTA will inevitably made modifications to improve the performance."  Well on my most recent winter SEPTA fan trip I lucked into another training run on the Airport Line and I can report that the system has not been changed and it still causing significant delays.

Unfortunately I was only able to capture video of the cab display unit returning from the Airport to Eastwick which had no PTC speed downgrades and therefore no demonstration of the braking curve (although I did capture a missed transponder reading). In fact my inability to get a video angle was doubly unfortunate because the braking curve is so conservative that it caused the engineer to trigger a penalty brake application just north of PHIL interlocking's southbound home signal. This is where the line speed of 45mph transitions to 30mph for the Airport Line curve just south of PHIL interlocking. (Even before ACSES this curve was protected by a 45mph Approach Medium cab signal) This meant that the on board system calculated a braking distance of about 4500 feet to slow from 45mph to 30mph.

Time for some math. The starting velocity is 66 fps and final velocity is 44fps.  From my observations the braking "curve" is linear which gives us an average speed of 55fps and thus a deceleration time of 81 seconds. This lets us solve for acceleration with a solution of 1.38fps^2 or 0.9 mphps, which is an absolutely pathetic braking rate. Even if I assume I was wrong about where the speed curve kicked in and the penalty took place just after the limits of PHIL interlocking, 2800 feet from the restriction, the resulting deceleration rate is still 1.4 mphps, less than half of the design acceleration rate of 3 mphps.

In this example we have the two bugaboos of PTC working together to sap performance on what should be a speedy trip to the airport. The first is a stacked safety margin. The older ATC system enforced a 45mph limit on approach to and around the 30mph curve. That would have been a rough ride and close to the overturn speed, but would likely be enough to prevent a derailment without getting in the way of the engineer. Today the ACSES takes the 30mph as gospel even though that figure already accounts for human error. Next, the conservative braking curve compels a speed reduction about three times farther away than would be necessary with the full braking force available. The end result is net gain of 10 seconds to traverse the same 4500 foot distance and you can see why this is a problem. 10 seconds isn't much.  It's certainly not enough for anyone to fight for or risk being blamed for if something goes wrong. unfortunately this 10 second loss happens again and again and again over the course of a run with the end result of SEPTA having to lengthen scheduled running times by an average of 4 minutes across all of its lines. Add in more small delays like low maximum speeds, long dwell times, slow terminal operations and voila, rail transport is uncompetitive with private road transport.

As you can see in the above video SEPTA cares very little about speed in general. As seen in the video about, the R1's 4-station airport terminal complex has blanked Restricted speed limit, even when approaching CP-AIRPORT JCT after passing a wayside automatic distant displaying Approach Limited. Why even bother with the wayside at that point! Prior to ACSES, SEPTA had plans to use the 4-speed cab signaling system to implement rapid transit style signaling when Rule 562 operation was installed on its Reading territory. Maybe we'll see a realization similar to NYCTA's that speed improvements, even small ones do matter. Or maybe we'll see the response to poor post-COVID ridership to be service cuts.

FRA Approves RFP Sub Cab Signal Removal

The FRA has granted CSX's December 2021 request to discontinue use of cab signals on the former Richmond, Fredericksburg and Potomac route between Washington, DC and Richmond, VA. Several months into a full blown rail safety panic it seems a bit tone deaf for the FRA to approve the removal of a well proven, reliable and completely failsafe signaling mechanism for good old fashioned waysides with a PTC safety overlay, but what do I know. Although we have seen similar cab signal removals by Union Pacific and BNSF, the RF&P cab signals had actually been integrated with the ETMS PTC system in a similar fashion to Norfolk Southern's Conrail territory. This makes CSX's post facto decision to ditch them an unfortunate surprise especially since the railroad choose to extend the northern limits of its RF&P CSS territory to CP-ANACOSTIA within the last decade. 

The motivation for the move is two fold. First, CSX doesn't have to worry about maintaining a large pool of CSS equipped locomotives to run over a single subdivision as well as performing a required CSS test before locomotives run over said subdivision. Likewise Virginia Railway Express no longer has to worry about CSS equipment or tests for its fleet and Amtrak can likely get away with neglecting the CSS on its Washington based diesel fleets. 

Cab Signal pickup on a VRE MP36

The second motivation is that despite the RF&P being "like" the successful PRR/Conrail system, it did have a major shortcoming wherein Medium Clear and Medium Approach signals would draw a Restricting (20mph) cab signal within interlocking limits instead of Approach Medium (45mph) or Approach (30mph) respectively.  This relay era cost saving measure that was never rectified and is likely the basis for some of the claims that the RF&P CSS does not play well with the ETMS PTC system that attempts to rely on the presence of cab signal codes for movement authority..

Like many FRA applications it may be a number of years for CSX to follow through on its plans. Unlike Union Pacific and BNSF that could literally wave away their ATS ATC and ACS systems at the stroke of midnight, CSX actually integrated the RF&P Sub CSS into its PTC solution with ETMS wayside interface units located only at interlockings to enforce the positive stop. Between interlockings the presence or absence of CSS codes would inform ETMS as to the enforcement of restricted speed situations such as an occupied block or open switch. CSX will need to install additional ETMS wayside interfaces at every automatic block signal location and every hand operated switch. Unless this work had already started it is likely to take a year or more before the CSS can be completely decommissioned.

As I have stated numerous times before, use of coded track circuits are both more reliable and provide a greater level of safety than wireless systems. Since the start of 2023 there have been at least two serious ETMS PTC outages to affect both Amtrak and MARC resulting in the cancellation of one or more days of scheduled service. CSS with ATC provides redundant speed control functionality that is completely independent of ETMS that can allow for (in a CYA sense) continued operation during a PTC outage. from an operations point of view CSS allows for mid-block signal upgrades and also provides for an easy path to 110mph service on the RF&P via the eventual extension of Rule 562+ACSES south from the NEC. Removal of the intermediate CSS code change points will significantly raise the costs of restoring CSS or just expanding the number of signal blocks to increase capacity.

For all we know CSX might still change its mind as the current rail safety panic continues to unfold and increases the political liability of removing safety systems to save a buck. Amtrak's plans to extend Rule 562 into the First Street tunnels further questions the cost savings if VRE and Amtrak diesels retain the need to be cab signal equipped for operation into Washington Union Station. In a further bit of irony CSX's purchase of Guilford Rail Service saddled it with additional Rule 562/ACSES territory that it will be unable to shake due to the MBTA. 

It will be interesting to see what happens to the remaining stub of CSS territory on the Philly Sub between CP-BELMONT and CP-PENROSE that was part of the old PRR West Philadelphia Elevated line to the South Philly freight yards. Leading locomotives do not need to be CSS equipped, but the system is still in service with all of the associated "costs".