IMO the ability to buy cars taller than Superliners comes down to one big modification. That would be to somehow modify CHI union station to allow taller cars. How ?? have no idea. Of course there probably are stations that may need overhead clearances raised especially sheds or overhanging canopys but one route at a time. But getting clearances for taller cars thru CHI may be impossible.
Do any of our posters know of stations that might need raising overhead clearances?
EDIT: Just remembered that if HSR is ever to go thru CHI US clearances will need to be raised as Superliners cannot clear the CAT.
Regarding HSR through Chicago Union Station, there is a long-term plan to build four tracks, served by two island platforms, in a deep tunnel under Canal Street for HSR. The HSR trains would diverge from the CUS lead tracks around Taylor St., under Canal, through CUS, turning west near Kinzie St. and emerging from the tunnel somewhere near Racine St.
There had been an idea to locate HSR tracks under Clinton, as part of the proposed West Loop Transportation Center. The WLTC was supposed to be four subterranean levels; one for pedestrians to walk between Ogilvie Station and CUS, one for CTA and intercity bus, one for a 2-track CTA L station, and one for a 2-track HSR station. Thankfully the idea was dumped; it was too expensive and Amtrak was unhappy with only two tracks as well as the grading required for trains to get down to that level.
It was then decided that Amtrak would take Canal if they chose (it's wider than Clinton and would allow four tracks) for HSR, and the CTA would get Clinton if they wanted to run a subway into the West Loop.
I personally haven't seen any proposals on how to accommodate catenary in the train sheds at CUS. Lowering the rails could be a problem, especially if Amtrak uses the basement-level steam tunnels to access the converted mail platforms in the future. Also, considering that the tracks are right along the river, I'm not sure having lowered tracks below water level is a great idea.
Superliners are 16 feet 2 inches. Gallery cars are 15 feet 10 & 13/32 inches.
The application by Amtrak, Metra, CDOT, IDOT, and MDOT for a MEGA grant includes money to perform NEPA and engineering/design work for a new ventilation system in both train sheds. Performing this work would finally address the issue of concrete falling from the train shed ceilings. Whether a redesign would allow for even slightly higher ceiling heights (which might allow catenary
and Superliners/Gallery cars), I don't know.
Edit - to shift a line of text elsewhere