i'm not sure if there is a rail-side access road - but jump on train tracks here
https://goo.gl/maps/rtZkcZApmCT2 -
ride west to the high bridge train station,
east on columbia trail - then drop into nassau trails - (columbia trail is the top left of this ride)
https://www.strava.com/activities/525510705
i always wanted to do this ride....no time today.
oh - ringoes -go out to sargentsville, 523 north, left on stanton-lebanon road, jump into the rv property at the south damn(past the youth center - you'll see the double fence) - head north-east.
https://goo.gl/maps/itjdR8jSHGz