CSX to discontinue cab signals on RF&P and use I-ETMS instead

Mod feel free to move to freight group if more appropriate - but given it’s PTC related I figured it most affected passenger operations.

CSX seeks to permanently discontinue the cab signal system on the RF&P. The RF&P is the only I-ETMS PTC equipped CSX subdivision that has cab signals with wayside intermediate signals.

The subdivision is equipped with visual wayside intermediate signals and a cab signal system. A wire from the cab signal aspect display to the I-ETMS on board computer provides the current cab signal aspect while wayside interface units on the home signals provide interlock switch position speed information and home signal status. Additionally, the legacy automatic train control system on the locomotives require cab signal downgrades to be acknowledged by the engineer and, on the passenger equipment, provides traditional enforcement of cab signal speeds.

Because of the configuration of the system on this subdivision - a wayside or on board failure that requires the cab signal unit to be cut out also requires PTC to be cutout as absent an indication from the cab signal display in this system configuration, PTC will not allow movement above restricted speed - and the RF&P lacks the “clear to next interlocking” indication at the control points that serves as a workaround on other cab signaled subdivisions without waysides.

Previously CSX planned to only discontinue the use of the legacy ATC speed control on its locomotives - unsure whether they were granted this. Now they plan to install wayside interface units on all the intermediate blocks and discontinue the cab signal system altogether. Amtrak, VRE, and the Commonwealth of Virginia all concur with the request - in addition to the issues cited regarding cutouts I'm guessing another reason is avoiding the extra costs related to cab signals for some of Virginia’s planned upgrades.

https://www.regulations.gov/document/FRA-2021-0111-0001

Sounds like an eminently reasonable thing to do.

It should improve reliability and OTP without any loss of safety.

At Bell Labs we were taught that any component that you are able to remove without losing functionality is one less component that will not ever fail.

While they are at it they should add a universal crossover about half way between Crossroads and Milford, and also perhaps between Doswell and Lakeside to increase fluidity in the face of a train failure in those long segments. Maybe they will do it as part of the VDOT build out.

Presumably, Virginia would not have agreed to this unless they were sure that the FRA would authorize the use of PTC for the 90 mph operation on the RF&P that they plan. I am still hoping that after FRA approves PTC for 110 with grade crossings on Brightline this can be applied to Chicago-St Louis.

NES28 said:

Presumably, Virginia would not have agreed to this unless they were sure that the FRA would authorize the use of PTC for the 90 mph operation on the RF&P that they plan. I am still hoping that after FRA approves PTC for 110 with grade crossings on Brightline this can be applied to Chicago-St Louis.

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By PTC you probably mean I-ETMS? Afterall PTC in the form of ACSES II is already approved on the NEC for 150mph, and getting raised to 160mph.

I-ETMS implementation on Brightline/FECR/FDC will be approved for 110mph on the coast line and 125mph on the Cocoa - Orlando segment. But one needs to be aware that the I-ETMS implementation for higher speed does require a few additional things for trains to actually operate at those higher speeds. As it turns out even TriRail has to add some additional stuff to their I-ETMS equipped locos and cab cars to operate on the Brifghtline/FECR/FDC I-ETMS, even for the short relatively slow segment from Hialeah Diamond Crossing (CP Iris) to Miami Central Station.

Strictly speaking the grade crossing intrusion detection interlock and timing is not part of I-ETMS, but is an additional FRA requirement, and very reasonably so.

RF&P had a form of cab control long before it became CSX. So this is or might just be a standardized of a PTC system. It a bit technical for someone not very invested in this area.

I do recall RF&P had to provide a lead Locomotive for passenger trains traveling thur there short system, due to there form of Cab Control.

Just-Thinking-51 said:

RF&P had a form of cab control long before it became CSX. So this is or might just be a standardized of a PTC system. It a bit technical for someone not very invested in this area.

I do recall RF&P had to provide a lead Locomotive for passenger trains traveling thur there short system, due to there form of Cab Control.

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RF&P had pretty much the same Coded Track Circuit based Cab Signaling System like the PRR. Neither met the full set of requirements laid down in the PTC regulations. CSX installed I-ETMS as a parallel system interlinked with but not dependent on the CSS to get PTC. Amtrak built upon the CTC/CSS using parts of the Alstom TVM430 technology overlaid on the PRR system after enhancing the PRR system with a second carrier frequency so that they could encode speed blocks above 80mph. In both cases the biggest thing that was missing was the enforced stop at home signals at danger.

All that CSX is doing now is removing the redundant features provided by the historical CSS, since their I-ETMS provides the same functionality but more efficiently and does not depend in any way on the cab segment of it. So they can get rid of the coding in the track circuit and additional paraphernalia on board the rolling stock for the CSS.

They do have to install additional wayside PTC equipment on all the blocks before they can shut off the CSS as in the original install CSX only installed wayside units and the corresponding wireless equipment at the Control points and relied on the I-ETMS - cab signal display connection for status on the intermediates - presumably to save money. Now with Virginia’s planned expansions it’s likely cheaper to build out a full overlay of WIUs across the current subdivision than it is to modify and expand the cab signal system for the projects. CSX estimates it will take a year after FRA approval to complete the full overlay of WIUs and put them in service -‘after which the cab signals will be retired.

Yeah. They had a choice to carry on with maintaining the CSS and add that to all new trackage or add the I-ETMS infrastructure to intermediate signals and other point of interest (e.g. manually locked switches), and remove the coded track circuit paraphernalia. Most likely a cost benefit analysis showed the latter course to be more cost effective over a long period.

The NEC and other Amtrak areas are similar to the RF&P in how the WIUs are only installed on home signals - but the main problem on the RF&P is that I-ETMS lacks any work around for a cab signal failure without the ability to get a C signal indication from a WIU - all of CSX’s other cab signal plus I-ETMS subdivisions have no waysides and thus have the C signal - without a C signal there’s no way to just clear out the block enforcement and keep the other features of the system online. In an identical area on Amtrak territory you’ll lose your signal speed enforcement if ATC it cutout and relying on you obeying the visual waysides but ACSES will keep on working to enforce your civil speeds and positive stops.

lordsigma said:

The NEC and other Amtrak areas are similar to the RF&P in how the WIUs are only installed on home signals - but the main problem on the RF&P is that I-ETMS lacks any work around for a cab signal failure without the ability to get a C signal indication from a WIU - all of CSX’s other cab signal plus I-ETMS subdivisions have no waysides and thus have the C signal - without a C signal there’s no way to just clear out the block enforcement and keep the other features of the system online. In an identical area on Amtrak territory you’ll lose your signal speed enforcement if ATC it cutout and relying on you obeying the visual waysides but ACSES will keep on working to enforce your civil speeds and positive stops.

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Are the I-ETMS dependent locomotives on the NEC also dependent on the CTC/CSS or do they get the civil speed and signal speed notifications through I-ETMS via back office link between I-ETMS and ACSES? It has never been clear to me what exactly is exchanged over the back office link. Maybe you can educate me about it.

jis said:

Are the I-ETMS dependent locomotives on the NEC also dependent on the CTC/CSS or do they get the civil speed and signal speed notifications through I-ETMS via back office link between I-ETMS and ACSES? It has never been clear to me what exactly is exchanged over the back office link. Maybe you can educate me about it.

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On the section where I-ETMS is overlayed the WIUs at the home signals are capable of sending both I-ETMS and ACSES messages - CSS is relied upon for intermediates. Wabtec had to put out a special software module for the NEC due to the 9 aspect CSS. I believe most of the area is rule 562 so if cabs are cut out the dispatcher will set up the C lights and both systems will enforce a restricted speed until they say a C signal indication from the next interlocking WIU.

lordsigma said:

On the section where I-ETMS is overlayed the WIUs at the home signals are capable of sending both I-ETMS and ACSES messages - CSS is relied upon for intermediates. Wabtec had to put out a special software module for the NEC due to the 9 aspect CSS. I believe most of the area is rule 562 so if cabs are cut out the dispatcher will set up the C lights and both systems will enforce a restricted speed until they say a C signal indication from the next interlocking WIU.

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Ah OK. That makes it much simpler. Just enforce restricted speed. Got it.

I think it’s possible to send wayside status over the spectrum with I-ETMS from the back office as you mentioned and you can also setup a wayside relay service in the back office in which the WIUs subscribe and send their status but I don’t know if any of the roads are actually using that or to what degree - I think even if you use back office communication about the wayside its supposed to be a secondary source of information and you still have to have communications with WIUs (or WIUs on homes and checking cab signal aspects between them) as your primary mode of checking the wayside.

When I first ran into the RF&P setup while working on WMATA in the early 1970's construction phase, it struck me that their signal and train control system overkill, given that this was a 70 mph maximum railroad, two main tracks throughout and both tracks signaled for movements in both directions. I believe that at that time the State of Virginia was a part owner. Incidentally, unlike most state lines defined by a river, the state line between Virginia and Maryland, or the District of Columbia is defined by the low waterline on the Virginia side instead of the centerline. Why is this significant here? Because this also defined the line between Pennsylvania Railroad and Richmond Fredericksburg and Potomac ownership. When the freight line was still electrified into Potomac yard,, which it was at that time, the electrification was owned and maintained by the PRR. Incidentally, the passenger route south out of Union Station to the connection with the freight route was not and so far as I know has never been electrified.

You are not ever going to get a significant improvement in run time over the RF&P as it is due to curves. A significant increase in maximum speed would primarily be for the purpose of saying, hey, look what we did.

Interesting post criticizing the plan. While Amtrak and the other VA partners undoubtedly support the application (most likely because maintaining cab signals would increase the costs of Virginia's plans) this offers some arguments against - instead arguing CSX should pursue the approach NS took in its former PRR territories. The Position Light

Amtrak diesels will continue having cab signals although not activated by RF&P signal system. Maybe remove RF&P hardware? Cab Signals needed on NEC

west point said:

Amtrak diesels will continue having cab signals although not activated by RF&P signal system. Maybe remove RF&P hardware? Cab Signals needed on NEC

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I thought Amtrak had replaced the old PRR cab signal displays with the new fangled ACSES ADUs on the NEC capable locomotives. These can display both ACSES stuff and old ATC stuff.



I wonder if there is anything really to remove in the locomotives since RF&P used the same 100Hz coded track circuit with the same original PRR codes (except the LIRR 270ppm code used around Penn Station) for their four aspects, which continue to be used on the NEC under ACSES II in addition to the new 250Hz channel to support the 9 aspect system on the NEC. All of that hardware is still necessary to operate on the NEC.

BTW, has NS decided to remove all their cab signaling on their cab signaled routes?

How about UP's 60 Hz carrier system on the transcon? And the CB&Q (BNSF) on the Chicago Speedway?

NS went to rule 562 on their former Conrail/PRR cab signaled lines when they did their signal upgrade to support PTC and I believe the upgrades resulted in a capacity improvement on some of their lines - with the additional capacity benefits of rule 562 one would think they'd stick with it. CSX also has some former Conrail rule 562 territory - Hudson line (Which Amtrak runs) and the B&A line (Berkshire and Boston subdivisions) in Mass. They haven't announced any plans to make any changes there. RF&P is unique in that I believe is the only line on both railroads that has waysides with cab signals (or at least the only one where they had to install PTC) - which is probably the motivation to get rid of it and shift operations to being more in line with the other nearby territories - along with the added costs of maintaining it with Virginia's expansion plans. With the waysides present much simpler to decommission the cab signals there than to try to unravel a rule 562 territory. The "Clear to Next Interlocking" indication on rule 562 areas also likely mitigates some of the operational challenges they have with PTC+cab signals on the RF&P as I have to imagine that indication can be communicated through the WIU to the locomotive once it reaches the next control point (similar to how ACSES WIUs do the same on the NEC) and release the speed restriction caused by a cab signal cut out which would avoid having to cut out PTC every time you cut out cab signals.

For comparison Amtrak actually has cab signals, plus still has waysides on their part of the Northeast Corridor as far as I know. Also the MBTA in massachusetts is almost finished with a brand new installation of cab signals/ATC on their lines that didn't have it before since they found out that ACSES did not work very well without it.

amtrakpass said:

For comparison Amtrak actually has cab signals, plus still has waysides on their part of the Northeast Corridor as far as I know. Also the MBTA in massachusetts is almost finished with a brand new installation of cab signals/ATC on their lines that didn't have it before since they found out that ACSES did not work very well without it.

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Amtrak is actually in the process of removing all block signals. They will retain only the home signals. Already there are no block signals between Newark and New York. Those were removed when they converted to high density signaling, since the blocks are extremely short and there would have been a forest of signals if they had waysides for those.

ACSES is an overlay on cab signaling system. So it would be impossible to install ACSES in the absence of a cab signaling system.

The NEC cab signaling system is the one originally installed by PRR many decades back before there was Amtrak. It has been enhanced with additional codes and an additional carrier frequency and then ACSES overlaid on it. This unfortunately means that it carries forward the deficiencies of the PRR CSS and is a little less efficient than a pure green field installation of a distance to target based system like e.g the TVM430 in France. The transponder aspects of ACSES are vaguely derived from the French system. Alstom basically adapted some aspects of it to come up with the ACSES overlay.

There are some klengthy threads deep in the past of AU discussing the details of the shortcomings of the PRR CSS, so no need to rehash them again.

I did not hear Amtrak has been removing waysides. I think they are still there between Boston and New Haven but I haven't actually paid a lot of attention lately. The MBTA actually did have ACSES on several lines without cab signals to comply with the PTC mandate. But as you said it is more of an overlay system so that is probably why it didn't work well and now they are installing Cab signals/ATC too

amtrakpass said:

I did not hear Amtrak has been removing waysides. I think they are still there between Boston and New Haven but I haven't actually paid a lot of attention lately. The MBTA actually did have ACSES on several lines without cab signals to comply with the PTC mandate. But as you said it is more of an overlay system so that is probably why it didn't work well and now they are installing Cab signals/ATC too

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How would they install full PTC compliant ACSES without the train knowing what the signal aspects are? Either it has to be communicated via coded track circuit or radio or something. Afterall it is all about getting a train to stop short of home signal at danger. Did they just install the civil speed aspects of ASPECT and use I-ETMS for authority?

My guess is that most likely we are miscommunicating. Could you perhaps specifically say what was installed and commissioned to meet the PTC requirements by the PTC deadline? Afterall, it is entirely possible that they were running on pure I-ETMS too.

Here is what I found is MBTA's own take on the matter:

https://www.mbta.com/projects/commuter-rail-positive-train-control-ptc
Now I am even more curious about what technology MBTA used to deploy PTC on the North side. The South side clearly had to use ACSES on CSS based on coded track circuit.

OK my curiosity led to this excellent document about the MBTA PTC deployment. Section 3 has a detailed description of the technology base. So for everyone's reference....

MBTA PTC-IP Rev 7

Anyway, the short answer to my question, probably not stated as clearly as I could, is that the North side is equipped with LIRR ABS compliant implementation in conjunction with Rule 261 existing signal system, on which ACSES is overlayed (See section 3.2.4). These ABS segments will be missing full ATC functionality until they are added. They are being added, to be completed by the end of 2022 according to the original plan.

Here is how the ABS based ACSES II works as invented by LIRR and adopted by MBTA:

In the ABS territories without ATC, WIUs will be installed at every Automatic signal
location intermediately between the interlockings. These WIUs will be programmed in
the same manner as if being installed at the normal interlocking. The BCPs associated
with these WIUs will transmit the radio release for a more permissive signal than Stop
and Proceed. Stop and Proceed indication will be enforced as a positive stop
enforcement similar to that which is being implemented for interlocking home signals

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jis said:

Now I am even more curious about what technology MBTA used to deploy PTC on the North side. The South side clearly had to use ACSES on CSS based on coded track circuit.

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To meet the PTC Deadline on the non cab signaled/ATC lines MBTA implemented a version of ACSES without an underlying cab signals deployment that LIRR had gotten approved for a few outlying sections of their line that don't have ATC. MBTA had the eventual goal of implementing ATC system wide. They essentially used the positive stop functionality of ACSES to accomplish it - they installed a WIU on intermediate signals similar to what they do at home signals. Basically if the intermediate signal was either a Restricting or Stop and Proceed then the WIU would return a no go and ACSES would do a positive stop and then enforce a restricted speed until it received a favorable packet from a WIU. If the signal was more favorable than restricting then the WIU would return a go and the train could continue. Not an ideal setup but it was good enough for them to meet the deadline.

lordsigma said:

To meet the PTC Deadline on the non cab signaled/ATC lines MBTA implemented a version of ACSES without an underlying cab signals deployment that LIRR had gotten approved for a few outlying sections of their line that don't have ATC. MBTA had the eventual goal of implementing ATC system wide. They essentially used the positive stop functionality of ACSES to accomplish it - they installed a WIU on intermediate signals similar to what they do at home signals. Basically if the intermediate signal was either a Restricting or Stop and Proceed then the WIU would return a no go and ACSES would do a positive stop and possibly then enforce a restricted speed until it received a favorable packet from a WIU. If the signal was more favorable than restricting then the WIU would return a go and the train could continue. Not an ideal setup but it was good enough for them to meet the deadline.

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Thanks. Yup. I found the mother load of information on the details in the document that I linked above. So now I am a very happy camper.

Actually I think LIRR is not even converting the very extreme east end to track circuits terribly quickly, though they plan to eventually.

Anyhow, this was educational for me.

Now then back to RF&P.....