Complex sentence: The Bay Freeway, also referred to as the Mercer Street Connection, was a proposed elevated freeway in the South Lake Union neighborhood of Seattle, Washington, replacing of Mercer Street between Interstate 5 (I-5) and Aurora Avenue North at the Seattle Center.
Split into simpler sentences: The Bay Freeway, also referred to as the Mercer Street Connection, was a proposed elevated freeway in the South Lake Union neighborhood of Seattle, Washington. The freeway would have run parallel to a section of Mercer Street between Interstate 5 (I-5) and Aurora Avenue North at the Seattle Center.