To extract the subarea junction file from the entire network junction file, you can use a few Voyager steps, as demonstrated in the attached example.

communities.bentley.com/.../ex_5F00_subarea_5F00_junctions_5F00_extr.zip

The first step is dumping the subarea nodes into a DBF table. Note that the old node numbers need to be used (those consistent with the full network).

The second step is listing the junction nodes with all approaches within the subarea (only those are selected).

The third step is extracting the junction coding for those selected junctions.