it allows the size of the grid in surveyor to change from 10 m to 5 m in size. The smaller which is the 5m allows very good control on building landscape,open trs, go to manual,new surveyor tools and you will find it there on how to change the grid,I think you right click on something in the topology tool, I don't remember exactly what .
In that shot of the train crossing the trestle;
in the background there's two dirt wheel-tracks running through the forest.
Do you find that with the 5m grid it 'sits' better/.
In that shot it certainly looks like it does.
The hills are a bit jaggy in real life as you can see by the pics below. The "smoother tool" is not a smoother tool, it resizes the grid in surveyor to give better control when building landscape