Thanks for the update. I guess it cleared up "pretty" quickly compared to other NEC electrical outages. Of course, the stranded passengers are sure to disagree.
The good news is that it never actually became an outage. It was a loss of supply that required trains to be stopped to prevent the voltage from dropping which would cause an actual outage. If the system is controlled, as it was today, then once supply is restored, the trains can restart. But, if the system trips off completely like it did in 2006 (breakers open, supply stations shut down), then restart is a complicated process that takes several hours.
Whatever happened, it sounds like the Amtrak power dispatchers did a great job holding the system on-line.