Through Train

I guess the definition of a Through Train would be transferring a group of cars from one yard to another yard, and then sending them on a Freight to be delivered to their destinations.  My use of this train will be to put any oddball loads into it, and not switching them. If we put a track cleaner on this train, it would clean all the main lines as it goes, bonus!
The gondola with the road roller, the gondola with the gravel load, hoppers we have put aside because of their length, and a few others come to mind. Not that you couldn't send them to a certain industry, but there is now way to pick them up, with the train orders we will be using.
We could make this train as long as possible, as it does no switching. It is sent by it's  train order from the Ortona yard to the Elsewhere yard, then from Elsewhere yard to the Wellington yard, and then back to Elsewhere and then Ortona.