All about PTC, I-ETMS and ACSES

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Thought it might be good to have a thread to place all good information about PTC systems and technology in. As a starter I would like to share this neat document that I found, published by Alstom on PTC using ACSES and a neat description of some of the technical components used:

https://www.yumpu.com/en/document/read/49420783/ptc-alstom
 
I am not familiar at all with signal systems. It's my understanding that many Amtrak routes in the Northeast/mid-Atlantic area use cab signals. Is it true that the wayside signals are just duplicates, or are they necessary for freight operation?

Will we see the removal of signals from the Hartford/Springfield Line and Shore Line Mill River-Boston? For that matter, does MNRR need wayside signals anymore?

If wayside signals go by the wayside 😅 what happens during a cab signal failure? Severe speed restriction?
 
I am not familiar at all with signal systems. It's my understanding that many Amtrak routes in the Northeast/mid-Atlantic area use cab signals. Is it true that the wayside signals are just duplicates, or are they necessary for freight operation?

Will we see the removal of signals from the Hartford/Springfield Line and Shore Line Mill River-Boston? For that matter, does MNRR need wayside signals anymore?

If wayside signals go by the wayside 😅 what happens during a cab signal failure? Severe speed restriction?
Read the posted article. It is not all wayside signals that are getting removed. Home signals stay as is. It is just the automatic block signals, including the signal just preceding a home signal which gives advance warning of the state of the home signal. They are really more or less redundant given the availability of Cab Signals and ACSES or I-ETMS.
 
I would think that some redundancy would be desirable as with those wayside signals preceding and including home signals. The decision to leave those in place is virtuous.

It could be beneficial for the PTC implementation to include cab-signal visual indication of the imminent approach toward both those mentioned above, as a way of incorporating primary and secondary alerts for physical confirmation (by sight) of the threshold proximity to those approached (upcoming) wayside geographical control points. It's sort of like an automobile driver's use of a built-in 360º Surround "Bird's-Eye" camera-assist system to gauge her/his proximity to stationary objects. The stitched-view quad-camera system may also have ancillary indicators as real-time alerts, but the driver still must visually confirm her/his frame of reference and instantaneously update the mental orientation accordingly, in order to remain aware of what's out there.

That analogy might sound over-simplified, since a locomotive engineer is dealing with a fixed-guideway vehicle of massive proportions, as opposed to "measly" automobile.
 
In princiiple IMO think keeping the intermediate signals are a good idea. However, if for some reason the RR wants to change the distance for separation by any following train then implementation is much easier using the PTC and ATC.
 
In princiiple IMO think keeping the intermediate signals are a good idea. However, if for some reason the RR wants to change the distance for separation by any following train then implementation is much easier using the PTC and ATC.
That is indeed very true. When they rearranged the block sizes to better reflect actual deceleration profiles on the NEC between New Brunswick and Trenton, it was done after removal of wayside automatics and hence did not involve any repositioning of signals, since they were absent to start with. The dynamic speed profile safety envelope is enforced by ACSES anyway, and if ACSES fails then the train operates using just Home signals "clear to next" (The "C" indicator) on, at restricted speed.

What CSX and Amtrak have done on the old RF&P segment is to not only remove wayside automatic block signals, but also remove cab signals, since the whole thing is enforced through speed profile and absolute stop at adverse home signal by I-ETMS anyway. This actually speeds up the railroad significantly for reasons that have been discussed extensively on AU about 10 years back. It has to do with the way the old PRR cab signals work which inherently slows down the railroad considerably compared to operation using a distance to target speed profile system, which is what I-ETMS is based on.

Note that trackside Home Signals are still in place so that the railroad can operate a train with either non-existent or failed I-ETMS should it become necessary using the "cleared to next" operation with severely restricted speed, so as to be able to get such equipment off the system.

Incidentally TGV on high speed lines, never had lineside block signals under both TVM 300 and TVM 430 systems, and now under ERTMS Level 2. They just have the "Yellow triangle on Blue background" line side block markers. The signal and associated speed enforcement is displayed on the display unit in the cab. Of course, an additional argument there was that when running at full speed you would not see the wayside signal from far enugh away to be able to act on it in a timely fashion anyway. So why have it?
 
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ironically a slide deck from the UK but has some very high level comparisons and info on I-ETMS, E-ATC, ITCS and ACSES.
 

Attachments

  • 2-3 Positive Train Control in the United States (Robert Burkhardt).PDF
    2.9 MB · Views: 4
Interestingly, even though the slide authors include folks from Alstom, they do not mention that ACSES originally had no radio link and was purely based on coded track circuit messages and static transponder transmitted messages. Radio came with ACSES II. The ACSES transponders are still static and while they are located near the WIUs they have no electronic connection with them. The only way to change Transponder messages is to change the encoded message plugin piece. Of course ACSES I did not have the radio communicated TSR functionality, but it did have the core safety features of enforcing stops at Home signal and enforcing all PSRs. TSRs were doable using temporary transponder placement, but it was cumbersome.
 
I'm a former CFII/MEI (Instrument flying instructor) and the above descriptions give me a headache. And I thought shooting an RNAV approach to minimums without an autopilot was hard.

Would have been easier to stick with block signals and hire someone to whack the engineer if they miss one. :)

Actually, really appreciate all the info above. Puts PTC into perspective.
 
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I'm a former CFII/MEI (Instrument flying instructor) and the above descriptions give me a headache. And I thought shooting an RNAV approach to minimums without an autopilot was hard.

Would have been easier to stick with block signals and hire someone to whack the engineer if they miss one. :)
Well , this one is sort of with the autpilot looking over your shoulders :)

The block signal aspect is displayed within two feet of the nose of the Engineer inside the cab. ;) In addition whatever it says is enforced should the Engineer forget to do so. The cab signal system with some automatic enforcement has been in place since the 1930s, so it is nothing new. What is new is the stricter automatic enforcement, which makes the trackside signals even more redundant.

Note that the Home Signals still remain so as to enable safe operation during cab signal failure in the equipment. The procedures are laid out in the relevant rule.
 
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Got 2 old presentations on ACSES and ITCS along with info on brightline Flordia's PTC system
 

Attachments

  • Incremental_Train_Control_System_2007.pdf
    472.5 KB · Views: 0
  • brightline PTC.pdf
    10.9 MB · Views: 0
  • 2000_A PRESENTATION OF 9 ASPECT CAB SIGNAL SYSTEM AND A-compressed.pdf
    2.3 MB · Views: 0
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