Last night, the BNSF crew left the locomotives for the local job tied up on the siding in front of the house. I'm speculating that the crew went "dead on the law" — that is, they worked so long that they would have exceeded the federally-mandated 12-hour service limit before getting back to Sparks. If that had happened out on the main, they would have been obliged to stop wherever they were, tying up traffic and creating a mess. As it was, tying up here on the siding (and having BNSF probably send a truck to pick them up and drive them back to Sparks) was no big deal.
It has been getting cold here in Fernley now, and in cold weather you can't just turn locomotives off and leave them. As I understand it, they don't use antifreeze coolant, so you can't risk them freezing overnight. These BNSF locomotives appear to be equipped with devices that automatically start them up and idle them for a while whenever they determine that they're getting too cold. This saves fuel over simply leaving them to idle all night long. But it does mean that we've had the sounds of two locomotives starting, idling, then shutting down since last night.
Fortunately, we aren't at all troubled by the sounds of idling locomotives. Also, they aren't actually in our front yard: just about 30 or 40 meters away. I'd take a picture, but I broke my camera at Worldcon and house-buying expenses take priority over replacing the camera.