Since the superliners used for the Capitol Limited can fit under the catenary for DC, and there is evidence that the Cardinal used to run superliners for some time from DC (https://railpictures.net/photo/722335/), then wouldn't they fit under the northeast corridor between DC and NY, or are some of the tunnels too low? (I know most of the high level platforms would not fit for the superliners, but I am focusing on if they fit under northeast corridor catenary).
"Look down, step over, and watch the gap!" - Dr. John Clarke, The Gap Rap (2010)