doesn't it also run on leased track like, as far as I know, all of Amtrak's other trains? Along that corridor, which I tend to travel, Amtrak is 2nd fiddle to freight carriers that own the track, so it's an additional situation that increases travel times--a train that leaves it's destination even 20 minutes late, can face cascading delays throught the trip because it misses all of its optimum windows for travel time when running parallel with freight. I mean...I've had 6 hour trips (non-Acela, but still deplorably slow for the distance) go to 13 hours because of a 1 hour initial delay (yes, that trip almost turned into a bit of a Thunderdome situation in our train car, lol).
Building dedicated to track to commuter-only trains is of course incredibly expensive, but it's a major game changer when it comes to effectively moving people in responsible ways. I'm 100% certain that the high-speed rail critics have never traveled in Europe. They simply don't understand the system and how well it works when properly targeted.