I misheard the dispatcher and thought that they were working east from Hazen (about ten miles east of Fernley), but it turns out they were working west. It was sheer luck that I went outside just as the test car was going by.
I had heard Amtrak #5, running several hours late, call "advance diverging approach, east Fernley" on the scanner. This means the California Zephyr was being put through the siding rather than holding the main at Fernley. When I went out to see what was going on, I saw the test train. Thinking quickly, I ran out a little closer to the track and got this shot. Had Amtrak been a few seconds earlier, I would have had the shot I actually wanted, which was the Zephyr passing the test car (which had been on the main) right near the house. As it was, you might be able to see the test car in the distance as the "people train" (as the dispatcher calls it) runs around on the siding.
Looking back in to the east, I could see a fleet of maintenance of way vehicles coming slowly up the main following the test car to follow up on any defects the detector found.
This afternoon, as Lisa and I came back home from a short errand, the UP maintainer was parked in front of our house talking to the local cable serviceman. Lisa went and talked to the maintainer, who said that they've been changing out rails where the detector car found faults, and that's a good thing, but it ties up traffic on the railroad. It probably doesn't tie things up as much as a 17-car grain-train derailment that happened up at Flanigan NV a few days back. Lisa surprised the maintainer by telling him that she'd been there. It's a pretty desolate place, but we did visit it once.