As to the cost of the Acela IIs ($2.45bn, presuming that the whole package associated with them is considered part of the purchase), that would fund about a thousand new single-level railcars. Using a trainset model for this (even if they would be individual cars), let's say you want your "standard" LD train to be 12 cars (bag, 4 sleepers, diner, cafe, 5 coaches) and two locomotives. Per Amtrak's estimates from a few years ago that's going to be $2.5m/car and $5-7m/locomotive (so $40-44m/set). That's 54-61 sets.
Right now the LD system uses something like 52-53 sets of equipment plus spares (I forget how many the Sunset Limited uses), so in theory you'd be able to increase LD service by somewhere around 100%, maybe a hair more if you were then able to use those frequencies to improve equipment turn rates (e.g. reducing the amount of equipment that sits idle for close or more than to 24 hours somewhere). My guess is that you'd be able to roughly get a 110-115% increase in service.
To be fair, there's not a strict apples-to-apples comparison here given the nature of some of the Western LD consists but you'd suddenly have a ton of additional LD capacity. Still, you'd probably be looking at ridership on the LD system coming close to doubling...maybe more, maybe less depending on the schedules that you opted for as a result (and any knock-on effects to other schedules and through-traffic). Still, that's probably somewhere in the ballpark of another 4m riders give or take.
Edit: If a mass order like that knocked the unit price of the cars down by 10% that's $37-41m/set that's another five sets. At $2m even (20% down) that's $34-38m/set and 64-72 sets (10-11 additional).
 Obviously there would be variations: The Silver Star presently runs with 7-8 cars and a single locomotive while replacing the Builder with single-level equipment while preserving present capacity would probably involve something like a 15-20 car train (I'm thinking 6-7 sleepers, 7-9 coaches, and 2-3 food service cars). You could also stipulate that on some routes with multiple long-haul trains there would be one or two "A trains" with a diner, second cafe/lounge, and more sleepers and one or two "B trains" with just an enhanced cafe and fewer sleepers. Playing with the Builder as an example, a Western Star/Mainstreeter running with more limited amenities on an alternate schedule would arguably cover many of the same riders...but should induce additional riders as well through the added convenience of a second daily train. In this respect, two 12-14 car trains might well perform better than a single 20-car train in terms of attracting ridership, even if one of them is obviously the "lesser" of the two.
I like the way you think. Here's an elaboration. And I'm not trying to compete with the Avelia Liberty order here; I'm trying to make a straight-up pitch for more cars.
How much would it cost, and how many cars would we need, to simply do this on the eastern services? So:
-- LSL, and my "TWO A DAY" proposal running on the opposite schedule (6 trainsets?)
-- Broadway Limited -- TWO A DAY (6 trainsets?)
-- One a day Cardinal (worst case, 4 trainsets?)
-- One a day CL (3 trainsets?)
-- Two a day Silvers (as now -- 8 trainsets?)
-- Two a day Crescent -- one to New Orleans, one to Fort Worth (9 trainsets?)
That's about 36 sets of equipment. Amtrak is trying to make its platforms in the East suitable for 12-car trains consistently, so 12-car is a good standard to work with. So call it 1.44 to 1.58 billion dollars... except that a large order should be able to cut that down a bit. We do already have 50 perfectly good Viewliners and 50 more on order, not counting the baggage cars, so you can reduce that by $250 million. The order should still be large enough.
I think the exceedingly important thing to do is, however, to start buying the tracks. The freights have caused trouble with almost all attempts to get more service. Build South of the Lake and you relieve NS's biggest national headache, and this sort of proposal becomes a lot easier (note that I just proposed running 4 new passenger trains per day through that section from Porter to Chicago).
Edited by neroden, 21 April 2017 - 06:18 PM.