My name is Harrison, I'm new to this forum, but my 2 cents:
I think I have found the state 17/ Interstate 86 crossing point everyone (including my father) were mentioning. While I may not have seen the line running, google maps confirms this location is what is left of the crossing. The RoW is pretty hard to see, but I would doubt it is there somewhere.
Here is an aerial view from Bing Maps: http://www.bing.com/maps/default.aspx?v ... New%20York
Here is the google maps street view: http://maps.google.com/maps?hl=en&tab=wl
If neither works, it is visible on aerial photograph, north of State 302 Pine Brush Rd. interchange, but south of the Sands Rd overpass, with a guardrail + route sign on the northbound side, and a billboard on the southbound side.
Is this former crossing of teh Erie Pine Bush Branch, or is it O&W?