There's one in Bethlehem, near Moravian College. It's at the bottom of that hill/bluff where W. Elizabeth Ave turns into Mach Chunk Rd., and then turned west into Schoenersville Rd. Although I'm not sure if it was installed by the Lehigh & New England or the Jersey Central when they took over line in the '1960's. The bridge was replaced and relocated several years ago, and while the booth is still in the same location as 20 years ago, it's now at the end of a dead-end street (Mauch Chunk Rd.). However, you can clearly see it when driving east on Schoenersville Rd down the hill from the Eaton Ave. junction as you cross the bridge.
I always wondered if that was the original location. Not only is it about 100 yards or so east of the old L&NE line, to Bath and Martins Creek, but it's located on the opposite side of the creek from the tracks.
This Google Street view doesn't do it justice, but you can see the booth in the middle against the hill. The brush makes a good background.
http://maps.google.com/maps?q=Mauch+Chu ... 8,,0,-2.65
http://data.cei.psu.edu/pennpilot/era19 ... v_6_77.jpg