Passenger Trains > PTC vs. ATC

GenePoon's earlier post re. MSNBC drives my question --

Is the "PTC" in place on segments of the NEC,  PTC or ATC, or
a third variant ?
 

NKP715 Wrote:
-------------------------------------------------------
> GenePoon's earlier post re. MSNBC drives my
> question --
>
> Is the "PTC" in place on segments of the NEC,
>  PTC or ATC, or
> a third variant ?
>  

ATC is the CSS Cab Signal System on the NEC that is a speed signal system connecting speeds with signal indications that only governs speeds other than a CLEAR indication but doesn't govern Maximim autborized track speeds while PTC IS a Max authirized speed control system that will govern All speeds associated with all main line tracks equipped with PTC ...

in other words ATC doesn't control a train with a CLEAR indication and a maximum authorized speed and it also doesn't govern permanent speed restrictions under a CLEAR indication whereas PTC would be able to automatically restrict ANY overspeed train and would apply a penalty brake application to that train ... there's more to it with train in block situations and other safety conditions/situations but that's not the topic of this conversation

Posted from Android



Edited 1 time(s). Last edit at 05/18/15 14:11 by Out_Of_Service.

NKP715 Wrote:
-------------------------------------------------------
> GenePoon's earlier post re. MSNBC drives my
> question --
>
> Is the "PTC" in place on segments of the NEC,
>  PTC or ATC, or
> a third variant ?
>  

On the NEC The CSS together with ACSES constitutes the PTC system that is being deployed. Currently such is deployed between New Haven and Boston, and also between New Brunswick  and Hamilton in NJ (tracks 2 and 3) and I think Ragan to Principio in Delaware/Maryland. There may be additional segments where it is already deployed since it is a fluid situation as they bring it on line in all of NEC by the end of the year.

In contrast to this the freight railroads are using a system called I-ETMS which is GPS based and is apparently is not supposed to work above 110mph and also in extremely heavy traffic conditions. Also Amtrak has a system called ITCS on the Michigan line that also provides PTC functionality.

It is important to understand that PTC is a set of functional requirements specified by the FRA that has to be met to claim PTC compliance. They can be met using many different systems and even different implementation of the same system. Amtrak has had a system that meets such requirements in place and operational in the northern portion of the NEC since the elctrification was completed to Boston and Acelas were introduced to run at 150mph up there. All that is being done on the NEC is that the same system is being installed in the rest of the NEC.



Edited 1 time(s). Last edit at 05/19/15 05:09 by Jishnu.

Saying ETMS is GPS based isn't entirely accurate.  Trains keep track of their exact position primarily through wheel rotation counting so if the GPS signal drops out the train doesn't have to stop.  This is benchmarked at fixed points using differential GPS to reset the wheel rotation distance measure.  In ACSES this functionality is handled by transponders.