In the survey DGN file, you can create multiple field books. If you can make one field book per intersection, then each field book can make its own terrain model.
Alternatively, you can add some shapes (just draw microstation shapes) and add these shapes to the terrain model as void or drape void features.
Alternatively, you can add some shapes (just draw microstation shapes) and add these shapes to the terrain model as void or drape void features.