Amtrak's Superliners cannot be used on the Northeast Corridor for several reasons:
- They are too tall for the tunnels under the Hudson and East Rivers to Penn Station New York.
- Amtrak uses mostly high level platforms on the NEC; Superliners are designed for low level platforms and can't use high ones. Many stations have ONLY high platforms including Boston, Back Bay, New Haven, Stamford, New Rochelle, New York, Newark (NJ), Metropark, Trenton, Philadelphia, Wilmington, Baltimore, BWI Airport, and New Carrollton.
- They won't fit through the tunnels at Baltimore (at both ends of the station).
- There are several places where the catenary is too low to clear Superliners. Though some of them could be remedied, there would be no point to doing so since the cars still would not be useful.
At Washington Union Station, one or two tracks have high catenary wire so Superliners can reach the station and maintenance facilities.