First attempt at scratch building.

[MasonJar]

You can load three 40' box cars if you make the 80' loading dock 10 - 12' longer. Only the doors have to line up with the platform - the ends of the #1 and #3 car can extend past the dock. So if space is a concern, you can load 2 40' cars at a ~50' dock. This of course assumes that the box cars can extend past each end of the loading dock...!

Andrew