It's kind of a yes and no answer. A few years back, persons living near the old railroad grade that was used as an access trail tried to prove in court that they owned the land. The DNR fought that and won. However, because that 7 mile stretch of trail has several dozen driveway crossings that would need to have banks pushed back by the groomer and stop signs put up, it was decided that it was just not realistic to have a groomed trail on that stretch of grade.
If someone were to travel down it, I do not believe that they would be breaking the law, but don't quote me on that 100%. Keep in mind that the trail is not groomed or signed and that you will be traveling through persons front and back yards, in very close proximity to their homes in many cases, so travel should be done with courtesy and at a safe speed.
We are currently working on trying to restore the Painesdale to Chassell trail and hope to have it up and running in the next year or two, but will not be going for this season.
-John