These are no Caltrain tracks: Instead, they are tracks for Union Pacific Railroad's commercial freight trains, who seem to transport quite a number of goods over these tracks everyday with their charming yellow engines. I didn't know very many commercially used railroad tracks still used wood as their base (as opposed to concrete), though.
I took this at 200mm focal length, which resulted in a rather short DOF. I liked the result more than the same photo taken at 50mm. It nicely frames the tracks as the subject of this picture.