I saw the layout in the summer of 1964. It was a marvel of engineering. The builders used topo maps of the area to construct it and it was very accurate. The only compromise was the length from Silver Plume to Waldorf. The model had the full 7 switch backs up Mt McClellan . The model had a return loop under floor at the Georgetown end of track which you walked over when you entered the building. When the model was taken apart , pieces of it were offered for sale . Several thousand pine trees were offered in bunches I remember. Some lucky person purchased the Loop Bridge intact from the model. The area was dismantled with the aid of a chain saw to get it out. I have some slides of the model when we visited and one large photo made from a slide showing the Loop bridge. A very impressive model.
I never thought that it would be possible to ride over the Loop again in my life time. History has a way of repeating itself , which is great for train buffs.
Charles M
I