Complex sentence: The northern platforms are used for Amtrak services to Milwaukee, Portland and Seattle; and the Metra Milwaukee District West, Milwaukee District North and North Central Service lines; the southern platforms are used for the rest of the Amtrak and Metra services.
Split into simpler sentences: The northern platforms are used for Amtrak services to Milwaukee, Portland and Seattle, as well as the Metra Milwaukee District West, Milwaukee District North, and North Central Service lines. The southern platforms are used for the remainder of the Amtrak and Metra services.