[Alon]

Re HSR versus incremental improvements, Spain should be in the same category as France, not Germany and the UK. In all of those countries, there was a medium-speed express intercity service - the original Kodama in Japan, the Mistral in France, etc. Germany and the UK spent money on raising the speed of those medium-speed lines. France and Spain built HSR early. (Spain only opened its first line in '92, but it was also starting from a lower level of development than the parts of Europe that hadn't been fascist since the end of WW2.) Of course it's not as simple as that - France also heavily upgraded the legacy line to Bordeaux and Toulouse and is only now building a full LGV that far southwest, Germany built some strategic bypasses and also upgraded the Berlin-Hamburg line so heavily that with tilting 230 km/h trains it achieves higher average speed than the 300 km/h lines.

Either way, in the NEC, this medium-speed express intercity service already exists. There's demand for it, and there'd be much more demand for faster service.

Of course, it depends on the price of boosting speeds. That's why it's so important to keep costs down. This means that a lot of the wishlist items, even bridge replacements, need to be treated as secondary priorities. The Canton Viaduct is older than the Maryland bridges that Amtrak wants to replace. The priority should be fixing the slowest segments - e.g. Elizabeth, Metuchen, Frankford Junction, New Rochelle - and getting cutting edge rolling stock and systems that can run on mixed-quality track.