Dose anyone know if they are fright trains on the Union Pacific Kenosha sub?

Dose anyone know if freight trains use the Union Pacific Kenosha sub (ie the tracks Metra uses for the Union Pacific North Line?) I know that afew use the tracks north of Lake Bluff however I have seen some on the tracks South of Lake Bluff why do you sometimes see freight trains on the Kenosha Sub south Of Lake Bluff?