Frmr IO Dispatcher and Cheviot Hill hit it right on the head - it's remote. Van Wedding road crosses line where the Jackson Block Station sign used to be in Conrail days. Weisburg road cross line at Weisburg. There another road that goes underneath track down from Weisburg, but I can't recall it's name - this is the road that Bonnell "Road" connects to at it's west end. Other than that, there is another county road (can't remeber name) from Kennedy to Guilford that is usually passable that you can catch glimpses of the line. But between Kenedy and Weisburg, it's is rugged and remote.
As info, I think Bonnell ends at the little wye just after you go under that tracks in the box culvert tunnel (immediatly after fording creek). From there west I think is just some sort of trail. Last time I was down there, road zig-zaged up RR embanment, crossed tracks, zig-zagged down other side, got on the old original right of way until you got to where a bridge used to be, down the embankment, throught the creek, back up the emanakment, under the active track through the creek again, up onto a county "road" right of way until you got to the wash out, down into the creek around the washout, then back out to civilization.
4 wheel drive ONLY - plus you probalby shouldn't be alone and have some way of getting yourself out of a jam (shovels, winch, etc). Also, if you go, make sure it hasn't rained for a while and no rain is forcast - those creeks you will be in will come up FAST and get might nasty. About only people out there are 4 wheelers playing, a few "hard core" locals, and some unsavory types tending to various, how whall we say, agricultural enterprises. And if you get stuck, don't count on your cell phone - heck, they have to pipe sunshine into some of those areas!
Last I was down there (few years ago now), creek bed was still littered with the remains of freight cars from multiple PC and NYC derailments. In fact, there's one area where several cars where shoved agains the creek bank to form a retaining wall for the right of way.