I was just at the I-70 I-75 interchange and noticed that the eastbound to northbound ramp is closed.

Thats Exit 33..they are telling you to get off on Exit 36 now which is Huber Heights and Route 202.
So If your coming from the west (Indiana) you'll experience this issue.
If so just continue on for 3 more miles and take Exit 36. Make a left and head north on 202.
As you leave town you'll come to one last light at the crossing of SR40.
Continue Straight North on 202 (Troy Pike) until you come to another light (Just a few miles) and Turn Left (Ross Rd.)
The Campground will be approximately 2-3 miles on the right. If you cross the river, you just passed it.
