As far as what this means for capacity increases I would imagine much of the line will see signaling that it doesn't currently have. There's CTC right now from West River to Windsor, a total of about 50 miles. You also have roughly 15 miles of ABS right now. But you still have at least 120 miles on the NECR that's exclusively Track Warrant. Now I will admit ignorance here, I have no idea what the situation is on Pan Am as far as signaling goes, but I want to say they're on CTC, which helps your case tremendously. But they will have to overcome two big obstacles on the NECR. First you're still using stick rail for pretty much the entire line, it's going to be hard to increase speeds without switching to CWR. Plus on both Pan Am and the NECR you're going to need PTC before too long, which won't be a cheap date.
I'm almost 100% sure that Pan Am is CTC. A few years ago I was on a cycling trip from Burlington to CT and I came across a stretch of the Pan Am line on the MA/VT border. It was CTC and CWR, as I recall.
The NECR has been slowly working on moving to CWR for some time now - I think they have about 25 miles or so at this point (not contiguous, though). But I'd expect they'd move the rest over to CWR. And while they do run track warrants north of Windsor, I wonder how much more infrastructure they'd need to build to move to a signaled line. I know there are signals in Essex Jct where the Burlington subdivision breaks off from the mainline to connect to the VRS downtown.
Now that we're on the topic, I'm wondering how much work it would be to upgrade the Burlington sub and have the train end in downtown Burlington and park in the VRS yard for the night. That might be cheaper than upgrading the tracks north of Essex, though its in pretty bad shape. I believe it's excepted class track right now, but it could be class 1.
I'm also not sure what kind of resources they need to service the train overnight and if that would be possible. But that would restore service to downtown Burlington and also slightly shorten the running time, which would save on operating costs. The problem is that this would bypass the Essex Jct station, and Essex would have an absolute fit over that. St Albans wouldn't be happy either, but they don't have the ridership to justify going up there. And the Burlington station is 100x nicer than what's over in Essex.
Man, that would nice if it could be done. I'd be able to watch the trains come and go right from my window, which looks out over Winooski and a brief stretch of that track. And it would bring service to downtown Burlington after all.
Heck, I'm pretty sure the Texans would be OK with links to Mexico (a surprisingly rail oriented country) but I wouldn't want to get into that hornet's nest....
Didn't Mexico eliminate practically all passenger trains a few years back? How are they a 'surprisingly rail oriented country?'