This abandoned part of the Lehigh Valley main line along the Lehigh River extends from West Catasaqua to Slatington (where there was a connecting track to the Reading), to Lehigh Gap, Bowmanstown, to Lehighton. This section was reportedly torn out in the late 1980s, but was officially abandoned in the mid 1970s before the formation of Conrail. There was a LV branch from Bowmanstown to the southwest to Lizard Creek, Andreaus and Snyders (it paralleled a Lehigh & New England branch along this section), then to Rauschs, McKeansburg, Orwigsburg and to a connection with the Pennsylvania at Schuylkill Haven. This branch was apparently abandoned in the 1950s.
Matt Gibbons provides additional information about the picture: The signal you can see in the picture still faces east on the old LV main and is still displaying a stop indication for tracks that are no longer there. From what I have been told, the way the interlocking is wired, that signal has to remain standing and lit, otherwise the interlocking will not function. The track you a see curving to the right is the ramp the CNJ built in 1965 to get from its main to the LV main. This was part of the CNJ and LV efforts to reduce their redundant trackage. You can see the old CNJ main behind the signal. The bridge that was there was there was torn out a few years ago. Click on the picture for a larger view.
Thanks to Matt Gibbons for contributing information about this route.