Wolv: I of course have set up a somewhat complex spreadsheet to figure out my "target roster". I started by trying to figure out the requirements for each railroad, based on the following. Road engines: I figured out how many consists a particular railroad could run at the maximum (given spacing, average length of train, sort of a gut feel more than anything), and multiplied that by 2.8 (again, a rough figure based on locomotives in a consist and allowing for some variety and replacements in case of maintenance). Switchers: there are going to be five yards on my layout, rather small in nature, the biggest of which will be MOPAC in Wichita. I rated these either as 1.0, 0.8, or 0.6. I then multiplied this by 4 (i.e., the Wichita yard would have four switchers), and then added large-scale industrial clients (i.e., those clients that would have dedicated switchers, like a refinery, my potash facility, etc.). The sum of this I multiplied by 1.20 (to again allow for variety and maintenance replacements). Both methods seemed to come out with results I'm happy with, a total of 115 locomotives (80 road, 35 switchers). Oh yeh, I also multiplied the "maximum consists" by 1.3 to arrive at the number of cabooses I'll need. The only place I see a fallacy in this system is for MOPAC switchers - where it says I need *SIXTEEN*. But, again, these are all targets, and I don't expect to get to these figures for quite a few years. So then I'm left with a "target" for switchers, road engines, and cabooses. I take each railroad's actual motive roster in 1980 (or as near as I can get), and do some quick multiplication, and arrive at which locomotives I need. I also compensate for a few locos I already have which don't figure into this system (i.e., I have a Cotton Belt SD35 and they never owned one, but I kinda like it so too bad). To cap it all off, I've plunked these down into my final "purchase" spreadsheet, which indicates locomotive models, who makes models for 'em, road numbers available, etc., etc. If anyone would like to see it I'm more than happy to share it, but I think it's probably a "Michael" sort of thing, and most other people would just laugh at the complexity of the thing. Course, I'm the same guy who had an incredibly intricate and complicated economic system for my Dungeons & Dragons world, complete with a banking system, bonds and stock market.