From what I know, the westbound lanes of 17 are in on the R-O-W thru Roscoe.
Follow 52 west from Liberty's center. Crosses line up the hill near Yuan Supply.
Old Ferndale trestle footings visible. Take Sullivan Ave from 52 on east side of 17 past the fast food joints and under 17 (this is also where exit 101 is, I think). Old piers are between the Exxon and the antique shop. The shop is open Thur-Mon, and I believe they have a couple pics of the trestle there.
Heading east on 17, after cresting summit you can see where the line crossed at a 90 degree, easier to see on east side.