Today for fun I watched an AutoTrain[1] being loaded. This was at UP's Richmond, California auto-loading lot, near their big Richmond yards (don't know the name of them, but it's the biggest railyard in the Bay Area).
Interesting procedure: there's a ramp at one end the cars drive up and onto the current level (out of 3) being loaded, then drive the length of the train; you can see autos passing the gaps between railcars.
The whole thing takes a *lot* longer than I would have figured: it is apparently limited by the size of the crew. Today, they had 10 people working; you'd see a batch of 10 cars drive onto the train. Then a van (the "crummy", I'm guessing) would drive the length of the train, picking up the drivers, and drive to the part of the lot where the cars were, drop off the drivers, and another batch of 10 cars would depart. I would have thought that they'd want this operation to go fast, and have cars continuously coming up the ramp, but it seemed to proceed at a pretty leisurely pace, at least from the distance I was watching at.
I was wondering how the drivers get out of the autos and out of the cars; I'm guessing that there's a walkway the length of each level, presumably on the left (driver's) side of the train, whereby they exit at the ends of the cars via ladders. I couldn't see that side of the train.
Also don't know how this fits in with the current economic situation; I'm guessing that these cars may have come from our local NUMMI auto plant in Fremont, which has recently cut back its hours of operation.
It would be a pretty kewl thing to model, if one had lots of identical car models.
[1] Dunno if AutoTrain is the actual name for these vehicles or not; these were the triple-decker auto carriers, completely covered.