It is always fun to design fanciful ideas but when it comes to building these ideas a whole different logic takes over. It's called the real world. Anytime the public can walk under or over something we build it has to be fabricated to an extremely high standard. The last thing we want to do is hurt someone because of a structural failure.
The train and log car need to be securely fastened to the log trestle that supports it. I thought of many ways to accomplish this task but in the end simple won the day. Three inch angle iron will be securely fastened inside the rails and the train will be structurally supported from them. Behind the wheel sets sturdy two inch square supports go up to the frame of the train. No one is going to move this train once it is fastened into place - ever! The wheels and trucks are merely there for show.