It starts on the lower section with the green dot and goes up a hill. But check out the slope on the upper leg coming down, it’s linear! That means the road must have been engineered to have a constant slope. I’ve never seen that before - pretty cool. I haven’t seen the descending portion yet, but maybe it was cut recently. I didn’t know this was done, but makes sense.
Yes the Old River Rd looks like the grade of the road was the controlling factor when built. It snakes around the hills to maintain the consistent grade. I measured that long uniform grade as about 9.7%.
The Bragg Hollow Rd follows property lines and the edges of tillable fields and such with less regard to maintaining a consistent grade. The steepest part of that road seems to be about 11.4% for a short section near the top with much of it being a much lower grade.