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Eastern Railroad Discussion > Question concerning PTC and Cab Signals


Date: 02/09/19 09:06
Question concerning PTC and Cab Signals
Author: Englewood

I have a specific reason for asking this question and would appreciate answers ONLY
from employees who actually work in PTC / Cab Signal territory.

When operating on a Restricting cab signal indication, if the cab signal upgrades to a more favorable indication, 
does PTC keep you at restricted speed until reaching the next signal (or until the entire train passes the next signal
on those roads where restricted speed requires it) ?



Date: 02/09/19 09:29
Re: Question concerning PTC and Cab Signals
Author: DevalDragon

Once you take a restricting signal your train is at restricted speed until the next signal per the rule book. PTC cannot change the meaning if a signal once you take it.

PTC is a safety overlay and not a method of train control.



Date: 02/09/19 10:03
Re: Question concerning PTC and Cab Signals
Author: Englewood

DevalDragon Wrote:
-------------------------------------------------------
> Once you take a restricting signal your train is
> at restricted speed until the next signal per the
> rule book.


Is GCOR Rule  13.2.1 no longer in effect ? 

13.2.1 Restrictive to More Favorable 
Cab signal indications do not supersede the indication displayed on block and interlocking 
signals. 
However, when a cab signal changes to a more favorable indication after having passed 
the block or interlocking signal, the train may immediately comply with the indication.



PTC cannot change the meaning if a signal once you take it.

I am not arguing with you, just asking questions trying to wrap my head around PTC. 

So in PTC you ignore the cab signals?

Does PTC not read the cab signal code?

What if the cab signal goes from Clear to Restricting?



> PTC is a safety overlay and not a method of train
> control.

Yet it appears they are taking away a tried and true system of train control by not interfacing with 
the cab signal system.

Thanks for your reply



 



Edited 1 time(s). Last edit at 02/09/19 10:09 by Englewood.



Date: 02/09/19 14:13
Re: Question concerning PTC and Cab Signals
Author: engineerinvirginia

If the cab signal either upgrades or downgrades PTC will recognize the change and if slower speed is needed it will enforce. If the signal upgrades PTC will indicate the higher speed is doable but it is up to you to comply with cab signal rules....PTC is programmed to be lenient when the rules of the road it is on are complied with. It will not enforce unless it senses danger of not slowing down, or of passing a stop signal or entering an occupied block at more than restricted speed or entering work limits without permission. If the track ahead is clear at least two blocks PTC will be a happy camper, yet it is always looking six miles ahead so you will know what to expect...nevertheless its up to you to observe actual field conditions and comply as needed. 



Date: 02/09/19 15:37
Re: Question concerning PTC and Cab Signals
Author: bioyans

As someone who uses PTC routinely, the easiest explanation is this ... PTC is always right. Whatever speed PTC says you are authorized to do, you do and don't exceed it. If it says you are authorized for restricted speed, do it. If it says you are still in a speed restriction, comply. It doesn't matter if you think it is in conflict with a more favorable condition. It will enforce you, and any of those who have been dismissed for not complying will tell you it isn't a fun process.

Once PTC goes to restricting, it doesn't matter what your cab signal does. Until the restricted fence drops out of PTC and it says authorized for a higher speed, nothing else matters.

Posted from Android



Edited 1 time(s). Last edit at 02/09/19 15:40 by bioyans.



Date: 02/10/19 00:02
Re: Question concerning PTC and Cab Signals
Author: DevalDragon

In this case GCOR Rule 9.11 applies:
9.11 Movement from Signal Requiring Restricted Speed
When a train passes a signal requiring movement at restricted speed, the train must move at restricted speed until its leading wheels have passed the next goveming signal or the end of the block system
> Is GCOR Rule  13.2.1 no longer in effect ? 


Both should agree, though you have to follow the most restrictive. Otherwise the train goes into penalty.
> So in PTC you ignore the cab signals?

Nope. It's not that smart. PTC runs on GPS where cab signals run on track circuits.
>Does PTC not read the cab signal code?


It puts the train into penalty.
> What if the cab signal goes from Clear to Restricting?

Yup. This is what happens when you get politicians involved in an industry they know nothing about. 
> Yet it appears they are taking away a tried and true system of train control by not interfacing with  the cab signal system.



Edited 1 time(s). Last edit at 02/10/19 00:03 by DevalDragon.



Date: 02/10/19 05:55
Re: Question concerning PTC and Cab Signals
Author: Englewood

> Yup. This is what happens when you get politicians
> involved in an industry they know nothing
> about. 
> > Yet it appears they are taking away a tried
> and true system of train control by not
> interfacing with  the cab signal system.

OK, thank you, that clears it up.  I knew PTC was bad but didn't realize it was so stupid.
I retired just before PTC testing began.  Part of me wanted to stay working so that I could learn about PTC, the 
other part knew it would just be frustrating seeing further degradation of the industry.

I had worked in cab signal territory both with and without wayside ABS signals.  When operating on a restricting signal you could
go back to warp speed once the cab signal went Clear.  The code the cab signal receives gives a true condition of the track
between you and the next signal.  I didn't realize the system had been so bastardized.



Date: 02/10/19 06:12
Re: Question concerning PTC and Cab Signals
Author: JUTower

I-ETMS PTC can and does interface with cab signals provided the PTC equipment was purchased intentionally for a locomotive with cab signals. On such units, it should be the case that PTC will see when the cab signal upgrades. Whether or not it stays in restricting, I don’t know yet, but can offer a reply on that in a few months.  This type of setup will be required wherever PTC is overlaid on cab signal territory with no wayside intermediates. 

On the other hand it is possible to install IETMS in such a way that it would be ignorant of the cab signal system. But in that case, the PTC system would have no way to know what upcoming signal indications are in a CSS-no wayside environment. This type of configuration would probably work in locations that have Intermediate signals that are equipped with PTC antennas and lend itself to the type of behavior described by the OP. 


 



Date: 02/11/19 07:29
Re: Question concerning PTC and Cab Signals
Author: Englewood

Thanks to everyone for the answers



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