It took a bit of figuring out to see what upgrades/purchases are the most important, but it was fun to get that balance right. I eventually got to a point where the orders were coming in so fast I couldn't keep up with the clicking anymore (though the number of trains was also an issue).
My only complaint is that the rails weren't all that impactful; at the start, you can place practically all the rails you'll ever need, since a small improvement in time with additional rails for one location probably won't outdo the equivalent upgrades for transfer or move speed.
Anyway, I really enjoyed this. It's simple and compact, with a tight set of mechanics that work really well together. Nicely done!