Fremont, NE is where the C&NW mainline from Chicago joined the UP mainline from Omaha. C&NW freights came in and UP power was added to the front to continue west. Vise versa for Eastbound trains. Here a GP30 is coupled to C&NW GP50 and SD40-2. The GP30 was probably used as the area switcher as that's what I saw when I visited there in the eighties.