I was at the U.P. industry yard today to work on a Tropicana reefer. The car I had to work on was in the center track of a small yard ladder. I had to wait for the switch crew to finish switching before I could "blue flag" the track and work on the car. The ladder had a small hump in the yard lead. The crews would line the switches and "kick" off a couple of cars at a time. The cars, most loaded, slowly rolled down the slight grade to their waiting tracks. I doubt they ever got going more than two or three miles per hour. It would seem to me, that doing something similar on a model yard using cars with free rolling trucks like Kato, or Atlas would work pretty slick. I was thinking that if it was a double ended ladder with a small grade at each end, the cars would end up in the middle.