Chain gang cleaning up the W&OD

For the second time this week, this morning there was a group of prisoners clearing brush on the W&OD Trail in Sterling.  They were wearing what looked like pajamas with green-and-white horizontal stripes, like in old movies.  (Okay, they're usually black-and-white in old movies, but then so is everything else.)  The work crew appeared to be well-behaved and well-supervised, at least while I was there.

I wonder if this is an attempt to teach prisoners a useful skill, or an attempt to save money on park maintenance?