Rte. 102 will be closed to regular vehicular traffic through Oirase Gorge (国道１０２号惣辺交差点～子の口交差点 (約10km)) from Sat. Oct. 30-Sun. Oct. 31 9:00-16:00 in order to promote "eco(logically friendly) tourism."
For more details, see the Oirase Gorge Eco Tourism website (Japanese only).
Since the road is closed from 9am onwards, I guess it's still OK for me go to on Saturday morning from about 6-8am to see the fall foliage... (I was planning on going last weekend but ended up sleeping in... ^^;;).