those are what we locals called the upper tracks that is not the Paulinskill, which was the lower tracks. Paulinskill dumps you off by the Columbia/Portland bridge which can be crossed by the adjacent walk bridge. ....
By the way it would be worth every mile, extremely scenic for 90% and a reason I need to build a gravel grinder...
^This. This ride was my very first mountain bike ride back in 91 or so. I did it on a rigid bike, wearing swim trunks, a t-shirt and wasn't carrying any tools or tubes. Started at the Lacakawanna Cutoff in Lake Hopatcong (gravel all the way, too much pounding for a chamois-less newbie on a rigid bike
😀), so picked up up the Paulinskill in Blairstown, then hopped on the upper tracks (the tail end of the Cutoff) where you stated, and rode mid-way across the bridge to PA. Then turned around and headed back.
I've been actually planning out a "4 by 40" ride for this fall. I was going to post up when I'm ready. It would string together 4 rail-trails in a big loop (probably about 40 miles or more). Starting somewhere west of Andover with the Cutoff (head west through the Roseville Tunnel, then catch the Paulinksill in Blairstown, and head northeast towards Swartswood, then hop on the Lehigh/New England towards Branchville, and then catch the Sussex Branch and head south through Newton, KVSP and Andover to end back on the Cutoff. Cutoff to my knowledge still has some ballast on it, but the others are all cinder/dirt. However, NJ transit is slowly bringing the Cutoff back into active service, so it's only a matter of time before the Cutoff is no longer rideable.
if anyone's interested in this ride through history (old stations, bridges, tunnels), let me know and I'll post it up. May be best in the fall when the leaves turn.