Bridge decks clear the water by at least this much, metres.
Register flatten modifiers on the world (roads and building pads).
Also flatten a pad under every building.
Walls reach this far below the lowest ground under a building, metres.
Blend distance beyond a building pad, metres.
Steepest road grade after smoothing (rise / run).
Blend distance beyond a road's edge, metres.
Road surfaces sit this far above the flattened ground (hides terrain mesh facets), metres.
Spacing of road profile points, metres.
How the settlement shapes the ground under it.