Hiked the North Ridge National Recreation Trail in Oak Ridge, TN yesterday. It was just like the AT. Up down up down up down, 7.7 miles with 1900 feet of elevation gain and a similar amount of elevation loss. Woods, white blazes. If one wanted to train for the AT, I’d recommend doing this as an out-and-back for 15.4 total miles and 3800 feet elevation gain/loss.