The good received from trains are random. I think it would be a good idea to offer each train a number of different destinations that allow a choice of materials, say three for each train? I have found that I need a lot of, eg, glass but keep getting bricks our something I have enough of. The idea is to have a bit more control over which buildings you want to develop or complete first.

I'm sorry if this, or something similar had already been suggested. I did search for “trains”, “train” & “railway” keywords and couldn't find anything.