The High Speed Train Amtrak Corridors really aren't European/Japan fast. 110 mph is significantly slower than 200+mph.
To go faster than 110 mph, you're going to need dedicated, entirely grade separated, electrified tracks.
What Amtrak suggests as High Speed Corrdors are diesel powered locomotives over upgrade existing freight tracks. The fastest diesel power locomotives in the world run around 120 mph, up to 150 mph during a recent test.
Like what Amtrak uses in the Pacific Northwest "Cascade" services. The "Cascades" uses Talgo equipment, which are FRA compliant.
To reach 120 mph max speeds, the existing freight tracks will have to be upgraded to Class 6 specifications.
Sec. 213.9 Classes of track: operating speed limits.
(a) Except as provided in paragraph (b) of this section and
Secs. 213.57(b), 213.59(a), 213.113(a), and 213.137(b) and (c), the following maximum allowable operating speeds apply--
[In miles per hour]
Freight trains / Passenger trains
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Excepted track..................10 N/A
Class 1 track.....................10 15
Class 2 track.....................25 30
Class 3 track.....................40 60
Class 4 track.....................60 80
Class 5 track.....................80 90
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Sec. 213.307 Class of track: Maximum operating speed limits.
(a) Except as provided in paragraph (b) of this section and
Secs. 213.329, 213.337(a) and 213.345(c), the following maximum allowable operating speeds apply:
Passenger trains only
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Class 6 track............................ 110 m.p.h.
Class 7 track............................ 125 m.p.h.
Class 8 track............................ 160 m.p.h.
Class 9 track............................ 200 m.p.h.
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Most freight tracks in the USA are Class 4 or less. Very few miles of track allow faster than 79 mph speeds. Most built for Class 4 decades ago are maintained at Class 3 or less today.
Which is why Amtrak cross country trains average 45 mph and less vs the much higher 60-70 mph average speeds.
A significant investment will be needed to upgrade a relatively few miles of tracks to Class 6, it'll be much more expensive to upgrade all the tracks Amtrak uses to Class 6, and really unaffordable to upgrade HSC designated tracks to Class 9.
To add, Amtrak doesn't own most of the tracks it runs on. The Freight RR Corporations aren't going to want to perform these upgrades for nothing. Since Class 5 (90 mph max) is the highest they can run freight cars on, that's probably what they will upgrade their tracks to with Federal/State supplemental funds (public/private funding). To upgrade to Class 6 or higher causes freight operational problems they will want to avoid.
Still, 90 mph speeds is much faster than what Amtrak trains can do today. It will be an upgrade with faster service. But, don't think for one moment the Feds are thinking of 200 mph speeds over freight tracks. That's not going to happen!