Complex sentence: The station has a large central island platform serving the Red Line, there are also platforms on the outside tracks that once served Evanston express trains, but these are no longer used as Purple Line express trains pass through the station without stopping.
Split into simpler sentences: The station has a large central island platform serving the Red Line. There are also platforms on the outside tracks that once served Evanston Express trains, but these are no longer used as Purple Line Express trains pass through the station without stopping.