PTC In Practice - A Passengers Perspective

 It was once again time for my annual round trip to Georgia via Amtrak Trains 79, 19 and 20 and I was actually able to experience some PTC related issues, one on CSX and one on NS, which can perhaps shed a bit of light on how PTC has been impacting passenger trains on the national network.  

SOUTH MILFORD, exact site of the positive stop event.

The first incident took place at SOUTH MILFORD interlocking on the CSX RF&P sub, which is equipped with both cab signals and ETMS PTC (for now). As my southbound Train 79 rounded the curve on Clear signals, the southbound track 3 signal dropped to Stop which tripped the PTC system and put the train into emergency. The train actually got stopped before passing the Stop signal, but the emergency brake application resulted in the crew having to stop and inspect the train. Total delay was about five minutes, but the interesting PTC takeaways were that it was able to trigger an emergency brake application instead of a full service penalty type application typically used with these types of safety system. Penalty applications don't require an inspection and, in the case of freight trains, are unlikely to cause a derailment.  Not sure if this is a passenger or Amtrak specific configuration. 

The other point of note was that the PTC was able to get a notification as to the change of block state after the train already had effective movement authority through the interlocking. This isn't surprising, but it is worth noting.  Not sure how long it took to get the update or if the concurrent cab signal system was involved. Under ACSES and potentially NS's implementation, approaching an absolute signal under restricting cab signals is what triggers the positive stop functionality. Without cabs the update would require wireless data reception. 

Approach Diverging on the Southern Main Line

The second event happened on the Norfolk Southern, Southern Main Line at the Milepost 564.8 automatic signal as it displayed an Approach Diverging (Y/G) signal indication for a diverging movement at BALDWIN interlocking.  For whatever reason the PTC system detected the block as occupied and enforced Restricting speed throughout its entire length. Because this took place at night, this meant a 10mph crawl for nearly 3 miles. The restriction lifted upon taking the Diverging Clear signal at BALDWIN. Engineer notified both the PTC trouble desk and the dispatcher. Total delay for this one issue was a whopping 19 minutes. My takeaway was perhaps a rules modification that allows for a train passing a proceed wayside indication to be relieved of the 1/2 vision stop requirement of Restricted speed being imposed by an erroneous PTC indication upon the permission of the dispatcher and/or PTC trouble desk.