On my recently dismantled 6x9 layout I had a simple operating scheme. I would run a passenger train and a freight or 2 freight trains. If I was running a passenger and a freight I'd stop the passenger train (MTH PS3) at the station and let it go through the passenger announcements. When it left the station I'd let it run unattended while I switched a siding with the freight train. Then continue switching between the two, stopping at the station and switching cars. If I ran 2 freights I'd alternate between the 2 switching cars. I found this operating scheme more fun than just watching the wheels go round. This is the trackplan. The section to the top right with 3 spurs was a 30"x30" addition for more switching opportunities. My next, bigger layout will feature a similar operating scheme.
