When I saw reports of the project restart, I spent half a day looking for the new tunnels dimensions. My Google-fu failed me, because I wasn't able to turn up anything except a 2017 Gateway "Fourth Plan" that said at least one tunnel should be tall enough to handle double-stacked containers (21' clearance).
The Gateway Program's own description mentioned only that some avenue overpass would be raised to create 19' clearance on an approach to the tunnels. I inferred (apparently incorrectly), that spending money to raise the overpass clearance meant that a tunnel would be at least as tall (but I've never been able to think like a government project). It also includes an expansion to Penn Station.
Looking again, I find an
Amtrak Hudson River Tunnel "Preferred Alternative" planning doc from 2021 specifying inner diameter of 25'. That would be plenty of room for a double-height (16' 2") passenger car.
Was an inferior alternative approved instead? Where is Amtrak saying that it will spend billions of dollars to build new tunnels as substandard as the old ones? I'd just like to see the bad news in writing before telling others how incompetent our government is.