Shard Mountain — Joseph Mitchell

They were asleep for 572 years... Shard Mountain is an epic science-fiction fantasy novel set in a distant post-apocalypse future America. Three young men involved in a highway accident are surprised to wake up not in a hospital, but in a dark underground tomb, five-hundred years in the future. They emerge to discover a world completely unlike anything they knew, where bizarre mutations are common among people, and scraps of futuristic technology are dug from the ground like ancient buried treasure. They will have to learn to survive in this dangerous new world, and to unravel the mystery of what happened while they slept, to discover why they would be categorized as something other than human beings.