MTA spokesman Terry Owens says the reason three trains have been canceled and others subjected to delays of up to 80 minutes on the Penn Line is that an Amtrak Acela train stalled out about 4 minutes south of Baltimore.

Something like that isn't the fault of MTA or MARC. It's  just a fact of life on the Amtrak-owned Penn Line. What is a lapse on the  MTA's  part is  that the Acela  stalled out  at 12:25  p.m., according to Owens, and as of 3:10 p.m.  the main MTA web site was reporting service on schedule. (See below.)

Meanwhile MARC Tracker was giving more  accurate information. Too bad there's such an inconvenient, well-hidden, multi-step link between the two web sites.