I'm afraid that trains are taking over!
That sounds like a
good thing!
Thanks for the photos, Gordon - they make a great step-by-step guide. I had purchased several bags of Playmo "coal" but quickly realized that I still didn't have enough to do the job, but your idea solves the problem beautifully.

Your use of styrofoam also suggests the possibility of cutting some larger random pieces of foam and painting them to look like boulders, either for hauling or for landscapes - I bet some folks have already tried this - anyone???