From the German monster HO layout, here is a video on how they made the ARFF group. It is in German but it says there are subtitles available.
If you look at the videos of the Layout it is just beyond belief.
Location: NW Pennsylvania
Saw this on the ARFF Info group board and its unbelievable. The models themselves are super but when you add in the computer programming that allows the vehicles to move around the model airfiled it makes the whole thing almost real.
Location: Dalton, GA