Is there any word yet on whether ROA will be built to overnight just 1 train, or would they go ahead and make it 2? My first guess is that ROA can't "afford" 2, mostly because of the economics of finding trainsets. Recall that a lot of what makes Amtrak Virginia "work" is the low cost of extending NEC trains on the shoulders of their day (when the train would be idle or poorly used), plus the revenue benefit of having Virginians fill empty "midday" seats on the NEC>
The NEC didn't need any more trains in the 5am to 8am time window or 6pm to Midnight, but Virginia has been a great place to put these "free" trainsets to work when they'd otherwise be (mostly) idle...starting northbound in the wee hours of the morning and returning back after NEC primetime.
So Virginia is also a great place to have trains layover overnight, and has shown that trains can start earning money as early as 5am (e.g. NFK). From this, it seems like Amtrak Virginia would want to berth a train everyplace that could support a 5am Start (LYH, RIC, NFK and NPN...with ROA in the future, and probably someplace to serve CVS with a 6am start, either CVS itself or Clifton Forge (or work with West Virginia to start at White Sulphur Springs) .
Based on the success of 5am trains from NFK to WAS, it seems pretty clear to me that when Roanoke comes online its first train will simply be an extension of today's 176 (which will start in ROA at about 6:20am instead of LYH, where it starts at a leisurely 7:38
.
That will free up the Layover at LYH for a new Rapahannock "supercommuter" train to DC that could depart an hour before the Crescent and work similarly to the NFK train, in that it gets riders to DC in time for a true full day. A 5am LYH start to train 184 (which, today is a 9:00 am northbound start from WAS) would look like:
NB -ROA- - -LYH- - -CVS- AR -WAS
DP ------- - 05:00 - 06:12 AR 08:40 NER #184...to PHL by 11:12a and NYP by 12:40p, where it would terminate)
DP ------- - 05:56 - 07:09 AR 09:53 Crescent #20
DP 06:20 - 07:38 - 08:52 AR 11:20 NER #176 started farther South
DP ------- - ------ - 14:53 AR 17:30 Cardinal (SuWeFr only)
DP 15:30 - 16:50 - 18:00 AR 20:30 * Hypothetical far-future ROA Daytime Turn
Meanwhile, we don't know where the Southbound trains would "come from" but an extension of train 185 has been discussed:
SB -NYP- - -WAS- - -CVS- - -LYH- - -ROA
DP -------- 09:30- - 12:00 - 13:10 - 14:30 *Hypothetical far-future ROA Daytime Turn
DP 06:45 - 11:05 - 13:55 ------------------ Cardinal #51 (SuWeFr only)
DP 08:10 - 11:30 - 14:00 - 15:10 --------- NER #185 Extended (paired with 184 for rotation)
DP 12:55 - 16:50 - 19:23 - 20:36 - 22:00 NER #171 Extended (paired with 176 for rotation)
DP 14:15 - 18:30 - 20:52 - 22:00 --------- Crescent #19
About that Daytime ROA turn. The advantage is that it would operate at the opposite ends of the day from existing trains. But in doing so, loses the trainset utilization benefits and has one, big, economic problem: it would have to steal a trainset from elsewhere in the Amtrak system. It probably can't "outbid" any existing midday use on the NEC (there's just too much money between the big cities). So a ROA daytime train would have to "outbid" some other current non-NEC use of NEC-capable equipment. PRIIA is going to have to trim a trainset from someplace else before that happens.