It was no secret that Union Pacific was planning to dismantle Norfolk Southern's significant cab signal territory that was inherited from Conrail after it was absorbed in 1999. While 91% of NS locomotives are cab signal equipped, few if any UP locomotives are after they dropped their own cab signal system around 2022 and a cab signal requirement would hinder creating a nation-wide pool of yellow locomotives. Well it seems that NS has decided to go ahead and file for discontinuance of the legacy Conrail cab signal system notwithstanding the results of the merger decision and what is perhaps even more interesting/alarming is the proposed replacement.
Unlike CSX or Union Pacific, NS had made significant investments in cab signal territory that lacks fixed wayside signals (what NORAC refers to as Rule 562). While both CSX and UP disposed of their former cab signal territory by just turning it off in favor of existing waysides, UP-NS would have to replacement the wayside capability on hundreds of miles of high density main lines. On CSX's sole Rule 562 route, the former Conrail Boston Line, the solution has been to run trains under Rule 280a "Clear to Next Interlocking" and petition the state for money to restore the wayside block signals. Something similar was my expectation since the UP-NS was announced with UP installing its flavor of wayside block signals from Perryville, MD to Cleveland, OH.
Well, it seems that NS's plan is to implement a PTC based Rule 562 with the PTC system transmitting track authority based on track conditions. While this is pretty much a statement on how ETMS PTC works, the sea change is that everywhere else PTC is still subordinate to good old fashioned wayside signal indications. This removes a sizable chunk of safety and security burden from the system under the concept of "PTC can make you stop, but it can't make you go." NS's request to the FRA would take ETMS as a safety overlay change it into a bonafide communications based train control system, possibly without any additional modifications.
Like with CSX, the NS plan would remove the cab signal codes as a source of movement authority which requires the installation of ETMS wayside interfaces at every track circuit block point and hand operated switch. Unlike CSX, wayside signals would only be present at control points with Rule 280a "Clear to Next Interlocking" being the available for various PTC failures.
The roots of this plan might lay with a trial "Rule 562" system Union Pacific installed on the Hiawatha Sub in Kansas. Since UP discontinued its Automatic Cab Signal system in 2022, the Hiawatha Sub did not gain wayside signals, just PTC antennas at the old Signal Indication Points. Since nothing bad seemed to happen on this low density main line on the prairie, UP might be looking to bring the concept to populated areas regardless of how secure ETMS really is. This might even be the camel's nose for what PTC proponents had envisioned, nationwide moving block signaling.
It's not entirely clear if the FRA will bite, but public comments would certainly help make them aware of the stakes. Coded track circuits are a secure and reliable way of transmitting movement authority that cannot be easily hacked by AI agents or whatever. Wide area ETMS outages are not uncommon because the system is effectively running on servers in some back office. Of course when these occur its mostly the passenger operations that get canceled because that's where the liability is. The real shame is that even if the locomotives are no longer responsible for picking up the codes, they will likely exist in the rails transmitting block state for decades to come.
Looking past the safety and security concerns for a second, I read the implementation and it would arguably be a more efficient system that could enable slightly better flow.
ReplyDeleteThe Signal Interruption Points will all get Wayside Interface Units.
Rather than using traditional signal aspects, NS has instead said they intend to use three enforcement groups:
1. Stop: Like with current interlockings, ETMS enforces a stop.
2. Restricted: ETMS enforces restricted speed with the zone indicated by a striped yellow box on the ETMS display.
3. Clear/Proceed: The third and most broad group, where every other aspect is governed under this.
For example, instead of giving an Approach Medium in the cab, ETMS will instead set a speed target of 30 mph at that interlocking and enforce the braking curve on it. This allows a train to operate at full speed right up to its braking curve. This would have the biggest effect on Amtrak.
It could provide slightly better flow while being compatible with every locomotive that can lead a train.
The safety issues need to be addressed but it is operationally efficient and steamnlined.
Never forget that this is first and foremost a cost cutting project. None of the performance and capacity improvements that the PTC proponents hyped ever came to pass and instead we have a system that heaps delay on all trains, but on passenger operations in particular.
ReplyDeleteFirst, see the MBTA study on the marginal capacity benefits of CBTC.
https://position-light.blogspot.com/2019/11/cbtc-is-scam-and-mbta-backs-me-up.html
Second, wirelessly delivered PTC still has reliability problems such that every Amtrak LD train I have been on recently has suffered from at least one block at restricted speed due to a PTC connectivity hiccup. The exception of course is the NS cab signaled route. This combined with wide area PTC outages which can outright cancel passenger service on host railroads leads to the situation where one is trying to pick up nickels of speed improvement in front of a steamroller of PTC failures.
Third, a relaxed speed curve to a stop signal or occupied block doesn't save any time because the obstruction is still there. It's basically hurry up and wait. In the case of diverging movements by passenger trains the fix would be to cut out/modify the ATC in favor of cab signal informed PTC like the freight trains currently use.
Thanks for posting the text from the FRA application BTW.