This is just the tail end of the train heading west toward Sparks, where I assume they planned to tie up so the crew can have the holiday.
This train was sounding its horn freely as it rolled by because there was a track maintainer in a high-rail truck on the siding. After the MOW train passed, the maintainer headed west on his business. Maintainers don't actually get holidays, it seems. They're always on call because railroading is a round-the-clock job, and broken rails or malfunctioning signals don't care if it's Thanksgiving or not.