Doormouse, in response:
What are these roads like? Both are steady downgrade, Roberts Mill much more than the W. Roberts Mill...braking to avoid picking up speed is a must. W road has curves and a few straighter stretches but is a "pleasant" drive up and down. Roberts Mill is another story, pay attention the entire drive and frequent short corners.
Is it heavily wooded, or more sparsely?
W road is wooded with a few sparse areas, but the "outside" edge does have some very steep vertical areas. A couple of "driveway" wide areas which are not guardrailed but not for the faint of heart to drive down. More people living closer together or closer to the road.
Roberts Mill - the woods along it are not populated in several areas at all. Definitely could get back into a couple of areas with a 4WD. Has many steep verticles and rolling rocky areas with jutting rock formations back off of the road. Not dense enough to stop walking as long as you were paying attention but, almost all of it sloping and quite a bit of rock face.
Density? As far as a visual inspection, two or three weeks ago you could see about 20-30 feet in. Now, with the leaves and other cover growing it cuts the range to at least 1/2 in most places or less. I just keep hoping to catch a glint of windshield or glass reflecting...
Is it a high drop off the side, or barely? In some areas YES. Some sections (mostly guardrailed) ar high enough and steep enough to give you a moment of vertigo. Very few "flat" spots.
Whats at the bottom? Do people hike/fish/adventure in the area that a jeep would land in off the road?
Remember that these roads both are cut across the face of the mountain, and across and along the edge of the mountain where it is physically possible. On the W there are more houses built around it. But yes, there are areas where it would be possible. Not all of the areas of the base immediately below the roads would be highly traveled by hikers or hunters without purpose. And yes some do, but it is not a terrain to just go out and walk without preparation. Have been some tricky rescues in the area requiring repellers assitance. Hope this helps.