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. 

PTC Capacity Impact Visualized

 I've frequently pointed out the impacts of Positive Train Control on train performance in general. While not technically inherent to the requirement, they are an inevitable consequence of policy and implementation choices. These include things such as stacked safety margins, overly conservative performance assumptions and locations tracking uncertainty. While the ACSES system used by cab signal equipped railroads in the northeast is generally superior to the wireless data based ETMS used by the class 1 freight railroads, certain ACSES implementations have continued to demonstrate the performance problems I identified almost a decade ago. Recently I was able to capture a concrete example of one on video.

Here we see an NJT Morris and Essex train led by ALD-45 #4510 entering Newark Broad St station on Track #2. The 4E signal for BROAD interlocking is immediately east of the platform end and the eastbound train gets hit by a positive stop about 700 feet (6-8) carlengths short of the signal location. Instead of being able to complete its station work as the signal system was designed to allow, the train sits off the platform for over 2 minutes, adding to the delay.

ACSES implements its positive stop feature using a two step process.  First a fixed track mounted beacon that transmits other permanent speed and positioning data will inform the onboard system that the train is approaching a positive stop. Next, if no cab signal code is detected , the onboard system will enforce a positive stop by calculating a 0mph stop point based on its super conservative assumptions of ice covered rails and a train with cheese in place of brake pads. The train stops up to 1500 feet from the signal and, well, the current policy is to wait there. The initial concept was for crews to use a stop release procedure to creep up on the signal, a feature implemented by specific freight railroads using ETMS, however most most if not all northeast commuter railroads have taken the CYA approach and just let the trains sit several hundred feet in advance of the signal, even if that means being unable to platform.

Supplementary ACSES transponders at Valley Stream

Apart from stop release, one alternative mitigation is to add additional ACSES transponders that can reduce the location uncertainty. The LIRR has installed two additional sets at Valley Stream that sees the same problem with platform-end signals, although I have heard this can still stop trains 1 or 2 carengths short of the stop point. A quick look at the overhead shows that NJT has not implemented this mitigation at Newark Broad Street. Another mitigation is to set the stop point to the legal requirement of the fouling point of the first trailing point switch or diamond. At NJT's BROAD interlocking this point is about 1 carlength beyond the 4E signal. Finally, they can be more realistic about the performance of the equipment. 

Just like the New York City Subway a decade ago, its always safer to cover ones ass than to fight for performance in a post-pandemic transit landscape were trains are running half empty anyway. If NJT feels like it is looking at service cuts, investing in capacity makes no sense.

ATCS Caught in Frequency Realignment

I know I'm a couple years late on this news, but ATCS (Advanced Train Control System) radio relay that replaced pole based code lines for Centralized Traffic Control schemes is in the process of changing frequencies (or just being completely phased out) due to an FCC directive that will reallocate its 900Mhz spectrum for wireless broadband in 2025. For the last 20+ years ATCS has been super useful for enthusiasts to monitor railroad dispatching in real time as data packets are relayed from station to station, just like with an old CTC code line, only now they can be sniffed and displayed.

Although some railroads like CSX shifted away from ATCS in favor of satellite links years ago and hard links like fiber optics were popular for a window in the 80's and 90's, ATCS has been a massively useful took for those looking to take photos of trains or just gather data that can be used for all manner of public policy. Word is that for those railroads wanting to keep the ATCS system, the data will piggyback on the frequencies allocated for PTC communications. However because the PTC communications specifications have to be purchased for a sizable amount of money (who'd have thunk it), the ATCS monitoring community is facing a reverse engineering challenge. 

The silver lining could be that after some amount of outage, the community will be able to monitor not only lineups, but also PTC signaling and authority information.

State DoT's Got My Memos

Seems like my blog has been having an impact on some state highway departments based on some of the innovating new road traffic signal indications I have been seeing lately. For example I that Diverging Clear has been one of the more common "non-standard" highway signals for a while now, but in New Jersey I found an example of Approach Diverging!

And if that doesn't get your cab signals flipping, while in Maryland I caught an example of another popular new highway signal indication, the flashing diverging arrow, which I assume is either an alternative to R/Y→ Diverging Approach or perhaps some kind of Slow Approach 🤔

This is a somewhat new development after the appearance of flashing Red arrows which is some kind of Diverging Restricted Proceed 🤷.  Anyway, who knows what they'll think of next? Perhaps something with flashing green. 😏