With AG4, it is possible to designate tracks any way you choose. I have designated a few tracks as coal car only, both empty and loaded, duly marked in the TDB file. When I tell the program to take as many as 35 cars from one or more of these coal tracks as the source track and no work inbetween them and the destination tracks, I get a mixture of cars as if the track was designated as "A" rather than coal car only. More importantly, the rest of the source tracks have various cars sitting on them as though they were all marked as "A" tracks. They are all marked as coal cars in the TDB file. What is happening that I am missing?

It sounds like you may be designating the coal car tracks as "Source" tracks. If you do this they are considered to be "Yard" tracks and any type of car will be placed there, as needed by any "Work" or "Industry" tracks to be serviced. If you choose none but instead only select "Destination tracks", then, since Destination Tracks be definition will accept any kind of car that has been picked up at "Work" or "Industry" tracks along the way. To solve this designate the starting tracks as "Industry" tracks, then, select one or more "Destination Tracks" for these cars to be hauled to/set out on. As long as you set a high number for "Maximum number of cars to be picked up from any one track", say, 35, you should get a train of all coal cars.

The reason the program works this way is, if source tracks DIDN'T automatically allow any type of car, many people would be disappointed when generating activities unless the kind of car that was on the source track happened to be the same kind of car that was "wanted" by all the industry tracks down the line.

I hope this answer helped.

Thanks,

Steve