arcgis desktop - Select "interior" lines of a polygon-to-line layer

I have a polygon featureclass that has adjacent features. Using Arc10, I am turning those polygons into lines using the "Featureclass to Lines" tool.

Now I would like to select ONLY THE INTERIOR line(s) (color=grey) so that I can run some ADDITIONAL processes on them. The key is that some (but not all) feature may touch the boundary line (color=blue). I am trying to use "Select By Location", but I cannot come up with a way to accomplish this task.

I might just be overthinking this one, but I am stuck. Any suggestions?

Answer

In doing some brainstorming with a colleague, we finally came up with a solution to this problem.

1. We exported all polygons to lines


2. Dissolved the original polygons and preserved no attributes and not allowing multi-part features (giving the fewest # of single-part polygons possible).


3. Select by Location, using the lines as the input layer, the dissolved polygons as the selection layer, and "SHARE_A_LINE_SEGMENT_WITH" as the selection method. This selected all features that were on the boundary.



4. Switch the Selection. This gave us all interior lines that did not match the outer dissolved boundary.

While I have not tested it for 100% accuracy, it seems to have accomplished the task that we were after very well. Of course, to automate this task, I just dropped all of these functions into a ModelBuilder routine, which makes the task much less tedious for future operations.