Pawtuckaway-Blair Woods Trail Closed?

I went to Pawtuckaway yesterday to boulder around Blair some and there is a big sign that says that the trail across the pond/stream is closed? What gives? Anyone know for how long?

Because the sign stated no reason for the closure, and no punishment for its disobience I assumed that perhaps they are working on the trail farther down the way, perhaps logging, pehaps military training? So I crossed the stream upstream a little and bushwhacked in from there, not using the closed trail. There was no sign of any reason for the closure in Blair Woods.

Went there last week and saw a sign, but it was night so i didn't look to hard. I thought it was referencing the up coming snowmobile season. I crossed the bridge had no problems, though I must say the next time I head to Blair I'm gonna bring some clippers the loop trail is getting a bit bushy.