I was watching a Russian adventurer on youtube traveling through Siberia on foot and this is a real thing in Russia - the Road of Bones:. He kept finding skulls and human bones near the highway he was traveling, and stumbled across more than a few work and camps used to construct it:

"The road is treated as a memorial by some, as the bones of the estimated 250,000–1,000,000 imprisoned laborers who died while constructing it were allegedly laid beneath or around the road"

https://en.m.wikipedia.org/wiki/R504_Kolyma_Highway