The hidden Danville staging yard contains six tracks. It's located east of Radford, behind and lower than, the Roanoke staging tracks. The mainline in the foreground runs directly into Radford, just beyond the bottom of the photo.

Danville staging

The red lines show the path taken by the laser beam used in my occupancy detector (see the June 1999 Model Railroader magazine). The laser is in the center foreground, there are two mirrors along the wall and one in the left of the photo. The photocell is at the end of the red lines, in the background.

Any train in the throat will interrupt the laser beam and an electronic circuit informs the staging yard controller (Model Railroader, May 1999) that the throat is occupied. The bright laser light gives virtually unlimited range - I tested it at more than 15 feet. This means that one laser can cover a very large throat, and you can reflect the beam as many times as needed to cover the entire throat.

Access for maintenance in Danville staging is through holes in the benchwork, outlined with yellow paint so I can find them. It's also possible to pop up in the far corner of the room; you can barely see where the benchwork is cut off at an angle there.