Great Lakes,
I hear you. My initial thought was for a yard 3 times the size I built. There really is no actual "STORAGE" that happens during a Driver session. You probably won't have any locos or cars that will stay static throughout your session.
I've decided to spread my industries to many far away places. I increased the output and consumption amount of each industry by a lot. The route I am working on have industries grouped together (3 to 6) for each branch line. My double track main line will eventually span several "cities", each with a sizable yard and each "city" having several branch lines.
So far I've finished my FIRST main yard for "San Angeles" which will have 3 or 4 branch lines. I've finished laying the main line track to the next two cities. I'm 75% done with with my first branch line that has a huge coal mine, a huge cement factory and several small general goods industry. Each branch line will have a "local" yard. Very long, but with maybe 4 to 8 tracks, a small shed to house the "local switcher" and maybe a small turntable. To make this type of layout interesting, for me, the run time to the branch yard is at least 20 minutes length. This will be true for all future branch lines from my main yard. Run time to another city is at least 30 minutes. All with lots of curves, grades and scenery.
Building is fun but operation is just as much fun. My first branch line serves 2 huge industries. In one session, its to serve the coal mine from the main yard (2 hours). Another session is to serve the cement plant 2 to 2-1/2 hours). Another session is to take the "empties" for the coal mine and the cement factory to the branch yard, pick up the "full" ones there and drive back to the main yard (1hr. 15min.). Another session is to be the "local" switcher, separate the "empties", load them up with cement and coal and prepare a consist to go to the main yard (2 to 3 hours). And many more pssibilities. Just imagine 2 or 3 more similar branch lines from my main yard all 20 minutes away. A similar set up in 4 or more cities alon the main line . . . and you've got a small railroad with plenty of activities.
My consist for the Cement factory is 32 empty 2 bay hoppers (bulk cement), 10 86ft. hi cubes (cement bag pallets), 8 tankers full of deisel fuel (fuel for equipment in the limestone quarry) and 9 bethgons full of sand (an ingredient for cement production).
My consist for the Coal Mine is 26 Bethgons and 8 tankers full of diesel. In the session to take the "empties" up to the branch yard, thats a 93 car train, up a 0.75% grade most of the way. A triple headed 4-axle locos (gp-38) can barely keep 48mph up the hill on the 25 minute run. The yard is long enough for 70 cars so the consist has to be split in two at delivery. Its a 5 track yard with two other tracks taken up with the "full" consists which you need to take back to the main yard. The locos takes forever to get up to speed at notch 8 . . . after you crest the summit, you have to really drive and watch your speed. Just for fun, I once uncoupled the train at the top . . . it was a TVG by the time it went through the yard and finally changed direction half way up the 1% main line grade to the next city.
The other thing in the plan is that the "consumers" of the coal and cement is located in two other cities. Which means they have to be shunted at the main yard and trains made up for opposite directions, not to mention other cars from other industries . . . if the computer can handle it, thats 3 to 4 hundred cars in the yard ! But since the comuter can't handle that, smaller bits of it has to be done as sessions.
I chose this type of operations because it offers literally hundreds of session opportunities. Later, if the entire route is too much to handle for the computer, just make copies of it and split it up into several routes with portals.
Instead of ONE MEGA YARD, think SEVERAL LARGE YARDS far apart from each other. Make each yard the "main yard" for each "city". So on and so forth . . . get the picture?
I'm not saying this is what you should do . . . rather, this is just what I'm doing.
