I haul in and out of mines, state parks, that have roads that the drivers are breaking loose in 1st gear climbing them, you can,t stop or you will never get started again. The Hot Gyser's in Northern Cal, Devils slide in Death Valley, Parts of Groom Lake. Even the back side of Tehachapi (90th st west). With doubles and triples you can not back down, you have one shot.
Many a times I've had to have been pulled up a moutain in PA, WV, and NY. I deliver to rigs up that way and the "roads" are far from being considered roads, more like trails. Just this past week I had to deliver to a rig in PA and the trail to the rig was just being built. I started up the "road" in 3rd with the differentials locked. By the time I made it to the rig I was all the way down in 1st. I'm surprised I made it all the way to the top.