Well, isn't it because Acela II is supposed to hit 180mph, and I assume it will be narrower so it will be allowed to tilt in more territory so thus sustain higher speeds?
I don't think a separate right of way will start in this decade, and likely not the next either. Which means you and me will be dead by the time a new one carries the first revenue train. Therefore, we get serious about improving what we got. None of this 110mph limit b.s. through Union/Rahway interlocking, that's a fairly straight railroad that with new catenary can easily allow for 135mph or some such. I know this because I saw the X2000 fly past close to that speed back in 1993 during revenue testing.
In the area of Trenton station it is bracketed by turnouts on old wooden ties which if renewed with concrete high speed ones, would or should boost the speed from the current 110mph limit to 125. There are two curves, one fore one aft, of the station that are gentle low radius that a tilting HST ought to have no problem with this.
Of course these are just a couple of examples of treasures close to the surface that never came to full fruition. There are oodles of others, namely the five miles east of 30 st Philadelphia station, with jointed rail and busted up turnouts, even the runs that run up to the Sckuykill River bridge as well as the North Phil. station. What Amtrak is waiting for, the cows to come home, I guess. The impact of speeds in this area I shall argue is worse than the conditions of Baltimore B & P tunnels. At least those are fairly smooth and direct in alignment. With CSX and NS demonstrating in real life that existing tunnels can be enlarged and redone with new lining, a short distance of tight curves is not as bad as the conditions in Phiily Pennsylvania; BUT, i'm not a civil engineer, so I say that with considerable room for deference to someone out there who knows both areas well enough to render a report that compares the conditions of both thorough enough to make a type of judgement an entity like Amtrak shall need to rely on in making a decision of where to allocate limited resources.
There are so many worn out turnouts/switches, prematurely broken concrete ties, and bad catenary that all cuts into high speeds of both Acela and Amfleet alike. Also there are commuter trains, NJT for example, whose recent capital purchases are that of a horse's behind. They bought multi decker cars that are heavy and not eough MU's, and spent millions/billions/willions on things like Seacauses Transfer, built right at the mouth of the most heavily used tunnel in the U.S. if not the world, clogging up the works for all trains, NJT and Amtrak, rolling towards Penn Station. What this has to do with slow Acelas? This: a Metroliner in the 1980's was scheduled NY Penn to Newark, NJ in twelve minutes, usually arriving ahead of time in ten. Today an Acela needs fifeteen. NJT's own express trains require ten or more minutes to make the time from Trenton to NY Penn than in the recent 90's. No one understand that to benefit the most by running trains at greater speeds, on time, ya gotta get it over and off the railroad QUICKLY, not dilly dallying with silly Seacaucus station that Hoboken route can easily handle, and just had a multi million dollar tunnel rehab of it's own over ten years ago, and to take that traffic and funnel it onto an already congested line requiring new tunnels and Portal bridge of its own.
And finally, GG, I know and feel your frustration, (hand on my broken heart), and we are tired of hearing the if's, should's, would's, maybe's, to the point of nausea. Where we (you and me, that is,) part separate ways is the need for a new right of way. It's a lot of money and alot of time before such of what amounts to several long concrete bridges of 100 miles in length has never been done here, and yes it ought to get started at some point, but in my opinion California is better for something like that because they have squat right now as far as high speed tracks. Here in the Northeaset we have a line that exists but is in awful bad shape, and i'm willing to bet hypothetically that if all the decades of neglect were reversed by a disciplined renewal, a CLOSE to two hour running time NY to DC is withing reach.