An Odd Walk

Me, my brother, my dad, and my uncle are going to Alaska in my uncle's RV. We stopped at an RV park today that has some trails nearby. They're really just dirt ATV tracks, and I'm not sure how far the RV park people meant for them to go, but I followed them quite a ways (a mile? two miles?) to a recently paved path four or five feet wide. It looked like something fairly major, so I followed it a couple miles. It had benches along it and must have taken a lot of effort to make, so I was surprised that I never saw anyone else on it. Eventually I saw something off behind a hill that looked like well (if that's what you call it) for a uranium mine. As I got closer I saw two sheds, a picnic table, some things that looked like small sandbags hanging from metal frames, something big and wood on the side of hill that vaguely made me think of a catapult without it's throwing arm, and some other stuff I didn't get close enough to describe because a hawk started to look very annoyed with me. I walked back to camp, wondering the whole time what in the world all that stuff was. I never actually saw either end of the paved trail, although I saw that it did continue past all the stuff. I also never saw anyone else on it. ??? What the heck is all that?