I'm going to take the idea of 10x daily trains that was cited from the FRA in a now-hidden post, give or take, and run with it for a moment. This works on a number of medium-distance city pairs (say, WAS-NYP on the NEC, MIA-ORL on FEC, or LAX-SAN in California). In a lot of cases you can stitch corridors like that together pretty nicely (so in the case of the NEC, you get BOS-NYP, NYP-WAS, and WAS-RVR strung together).
Here's the thing: When you get over six hours, some of those frequencies start having to do very odd things. Let's take Hampton Roads as a handy example: Norfolk is presently about five hours from Washington, DC (it's a bit less, but for the moment that's close enough to illustrate). In order to get a train into Washington by 0900, you basically have to leave Norfolk at 0400 (which, backing things up, means waking up at or before 0300). Norfolk is one market where this sort of thing may sell, but that's because you have a military-heavy travel constituency in the mix. The market is still good for a host of reasons, but the travel options here start bordering on the obscene to make those arrivals work. On the other end of things, the 1900 departure from WAS arrives a bit shy of midnight. IMHO midnight is passable whereas 0400 gets to be a problem.
Swinging around to the western part of Virginia, you start getting similarly bad times if you try to consolidate your crew/equipment base out to Roanoke (which is a reasonable candidate for substantial daily service in the long run...the market just isn't big enough for any of the airlines to really bother with and it is part of a string of workable markets in Lynchburg, Charlottesville, and so on)...a commuter-timed train into Washington would have to have a pretty bad time, and it is worth noting that train scheduling issues mean that you would probably end up with someone's train getting pushed aside by at least half an hour...leading to some truly nasty possibilities like departures from Roanoke in the middle of the night. And all of this sets aside service aimed further up the NEC...where a string of markets (NYP, PHL, BAL, etc.) are quite significant (if not on the scale of WAS) for Virginia.
Now it is true that in some of these cases the train is making what I will call a "revenue equipment move" (i.e. the move is being made more for operational reasons than revenue reasons and the extreme ends of the trip are being run fairly empty to allow consolidated crew bases), but at some point sleeper ops become feasible on routes like this for the "oddball" departures (i.e. allowing occupancy of a sleeper at 2300 for a train leaving at 0200). I feel compelled to point out that you don't need a mass of riders to sell out a sleeping car...a pair of Viewliner II cars operating in tandem with no turnover would sell out at 20,440 riders/year assuming all spaces take double occupancy and 16,425/year assuming double occupancy of the bedrooms and 1.5x occupancy of roomettes. This is, frankly, not a huge number and that may be one problem (a pair of similarly-constrained LD Amfleets adds 43,070 riders/year while a pair of NEC Coach Amfleets adds 52,560; if I'm fretting about my topline figures, 52.5k sounds a lot better than 16.4k).
There are other examples scattered through the system (KCY-STL-CHI is a good case in point...the first train out of STL extends back to KCY with a decent evening departure while the last one out of CHI would hit KCY in the morning), almost all involving through operations between 2+ corridors. Honestly, a major shuffle in Chicago akin to what I've mentioned for New York might make sense (DET-CHI hovers at 5:30, STL-CHI at about the same, CLE-CHI at about 7:00, and so on). Additionally, a morning "wave" of these trains coming in around 0600-0700 (i.e. before the commuter trains swamp the station) would allow transfers to other reasonably local markets without killing a FULL day in transit.
I'm going to run a reboot while I have good Wifi, and then I'm going to try and stick together a hypothetical system for the NEC to illustrate what sort of thing should be able to work.
Here's the thing: When you get over six hours, some of those frequencies start having to do very odd things. Let's take Hampton Roads as a handy example: Norfolk is presently about five hours from Washington, DC (it's a bit less, but for the moment that's close enough to illustrate). In order to get a train into Washington by 0900, you basically have to leave Norfolk at 0400 (which, backing things up, means waking up at or before 0300). Norfolk is one market where this sort of thing may sell, but that's because you have a military-heavy travel constituency in the mix. The market is still good for a host of reasons, but the travel options here start bordering on the obscene to make those arrivals work. On the other end of things, the 1900 departure from WAS arrives a bit shy of midnight. IMHO midnight is passable whereas 0400 gets to be a problem.
Swinging around to the western part of Virginia, you start getting similarly bad times if you try to consolidate your crew/equipment base out to Roanoke (which is a reasonable candidate for substantial daily service in the long run...the market just isn't big enough for any of the airlines to really bother with and it is part of a string of workable markets in Lynchburg, Charlottesville, and so on)...a commuter-timed train into Washington would have to have a pretty bad time, and it is worth noting that train scheduling issues mean that you would probably end up with someone's train getting pushed aside by at least half an hour...leading to some truly nasty possibilities like departures from Roanoke in the middle of the night. And all of this sets aside service aimed further up the NEC...where a string of markets (NYP, PHL, BAL, etc.) are quite significant (if not on the scale of WAS) for Virginia.
Now it is true that in some of these cases the train is making what I will call a "revenue equipment move" (i.e. the move is being made more for operational reasons than revenue reasons and the extreme ends of the trip are being run fairly empty to allow consolidated crew bases), but at some point sleeper ops become feasible on routes like this for the "oddball" departures (i.e. allowing occupancy of a sleeper at 2300 for a train leaving at 0200). I feel compelled to point out that you don't need a mass of riders to sell out a sleeping car...a pair of Viewliner II cars operating in tandem with no turnover would sell out at 20,440 riders/year assuming all spaces take double occupancy and 16,425/year assuming double occupancy of the bedrooms and 1.5x occupancy of roomettes. This is, frankly, not a huge number and that may be one problem (a pair of similarly-constrained LD Amfleets adds 43,070 riders/year while a pair of NEC Coach Amfleets adds 52,560; if I'm fretting about my topline figures, 52.5k sounds a lot better than 16.4k).
There are other examples scattered through the system (KCY-STL-CHI is a good case in point...the first train out of STL extends back to KCY with a decent evening departure while the last one out of CHI would hit KCY in the morning), almost all involving through operations between 2+ corridors. Honestly, a major shuffle in Chicago akin to what I've mentioned for New York might make sense (DET-CHI hovers at 5:30, STL-CHI at about the same, CLE-CHI at about 7:00, and so on). Additionally, a morning "wave" of these trains coming in around 0600-0700 (i.e. before the commuter trains swamp the station) would allow transfers to other reasonably local markets without killing a FULL day in transit.
I'm going to run a reboot while I have good Wifi, and then I'm going to try and stick together a hypothetical system for the NEC to illustrate what sort of thing should be able to work.