So you can make objects in sketchup and export them as object files... Then use the BLB editor to make it a brick in Blockland? And that's all? Epic... Will try.
If you're willing to do/help with this, Furling, cool... But if not I'll do it myself. It should be just like the Railroad, with the different pieces in it's own tab.
Last question: can a vehicle (mine cart, whatever) be smoothly fixed onto the track so that it cannot come off, but runs without jerky motion and like any other vehicle?
Uxie and I has successful tested mine cart hit brick wedge track wall, which make it turn while I using map editor showed me how it does work as the collison box bounce off by brick wedge walls give me ideas. First create track bricks along with brick track collison allowed support vehicle have under friction wheels or Up-Stop wheels which hug the bottom of the rail, like their name implies they help the train from coming off the track. The next set of wheels touch the sides of the rails are named side friction wheels. These wheels help the train stay in the center of the two rails to help the train from derailing. The last wheel set are called tractor wheels, or running wheels. Tractor wheels have a simple but important purpose. These wheels keep the train "running" on the track. Tractor wheels lift off the track in zero G situations, but the Up-Stop wheels keep the train from coming completely off the Rails.

it will be place mine cart under body. not outside sides, only inside (middle) between wheel look like this:

has to be set 4 (front and back) wheel under it. Gravity is the force against curve track brick collison allowed mine cart turn.